ar Towards harmonization of voriconazole CLSI and EUCAST breakpoints for Candida albicans using a validated in vitro pharmacokinetic/pharmacodynamic model [Susceptibility] By aac.asm.org Published On :: 2020-03-30T10:04:32-07:00 Background. CLSI and EUCAST susceptibility breakpoints for voriconazole and C. albicans differ by one dilution (≤0.125 and ≤0.06 mg/l, respectively) whereas the epidemiological cutoff values (ECOFF/ECV) with both methodologies are the same (0.03 mg/L). We therefore determined the pharmacokinetic-pharmacodynamic (PK/PD) breakpoints of voriconazole against C. albicans for both methodologies with an in vitro PK/PD model, which was validated using existing animal PK/PD data.Methods. Four clinical wild-type and non-wild-type C. albicans isolates (voriconazole MICs 0.008-0.125 mg/l) were tested in an in vitro PK/PD model. For validation purposes, mouse PK were simulated and in vitro PD were compared with in vivo outcome. Human PK were simulated and the exposure-effect relationship fAUC0-24/MIC was described for EUCAST and CLSI24/48h methods. PK/PD breakpoints were determined using the fAUC0-24/MIC associated with half-maximal activity (EI50) and Monte Carlo simulation analysis.Results. The in vitro 24h-PD EI50 of voriconazole against C. albicans were 2.5-5 (1.5-17) fAUC/MIC. However, the 72h-PD were higher, 133 (51-347) fAUC/MIC for EUCAST and 94 (35-252) fAUC/MIC for CLSI. The mean (95% confidence interval) probability of target attainment (PTA) was 100(95-100)%, 97(72-100)%, 83(35-99)%, and 49(8-91)% and 100(97-100)%, 99(85-100)%, 91(52-100)% and 68(17-96)% for EUCAST and CLSI MICs 0.03, 0.06, 0.125, and 0.25 mg/L, respectively. Significantly, >95% PTAs were found for EUCAST/CLSI MICs ≤0.03 mg/ll. For MICs 0.06-0.125 mg/l trough levels 1-4 mg/ll would be required.Conclusion. A PK/PD breakpoint of C. albicans voriconazole at the ECOFF/ECV of 0.03 mg/L was determined for both EUCAST/CLSI methods, indicating the need for breakpoint harmonization for the reference methodologies. Full Article
ar Complex response of the CpxAR two-component system to {beta}-lactams on antibiotic resistance and envelop homeostasis in Enterobacteriaceae [Mechanisms of Resistance] By aac.asm.org Published On :: 2020-03-30T10:04:32-07:00 The Cpx stress response is widespread among Enterobacteriaceae. We have previously reported a mutation in cpxA in a multidrug resistant strain of Klebsiella aerogenes isolated from a patient treated with imipenem. This mutation yields to a single amino acid substitution (Y144N) located in the periplasmic sensor domain of CpxA. In this work, we sought to characterize this mutation in Escherichia coli by using genetic and biochemical approaches. Here, we show that cpxAY144N is an activated allele that confers resistance to β-lactams and aminoglycosides in a CpxR-dependent manner, by regulating the expression of the OmpF porin and the AcrD efflux pump, respectively. We also demonstrate the intimate interconnection between Cpx system and peptidoglycan integrity on the expression of an exogenous AmpC β-lactamase by using imipenem as a cell wall active antibiotic or inactivation of penicillin-binding proteins. Moreover, our data indicate that the Y144N substitution abrogates the interaction between CpxA and CpxP and increase phosphotransfer activity on CpxR. Because the addition of a strong AmpC inducer such as imipenem is known to causes abnormal accumulation of muropeptides (disaccharide-pentapeptide, N-acetylglucosamyl-1,6-anhydro-N-acetylmuramyl-l-alanyl-d-glutamy-meso-diaminopimelic-acid-d-alanyl-d-alanine) in the periplasmic space, we propose these molecules activate the Cpx system by displacing CpxP from the sensor domain of CpxA. Altogether, these data could explain why large perturbations to peptidoglycan caused by imipenem lead to mutational activation of the Cpx system and bacterial adaptation through multidrug resistance. These results also validate the Cpx system, in particular the interaction between CpxA and CpxP, as a promising therapeutic target. Full Article
ar Nonclinical Pharmacokinetics, Protein Binding, and Elimination of KBP-7072, An Aminomethylcycline Antibiotic in Animal Models [Pharmacology] By aac.asm.org Published On :: 2020-03-30T10:04:32-07:00 KBP-7072 is a semi-synthetic aminomethylcycline with broad-spectrum activity against Gram-positive and Gram-negative pathogens including multidrug resistant bacterial strains. The pharmacokinetics (PK) of KBP-7072 after oral and intravenous (IV) administration of single and multiple doses were investigated in animal models including during fed and fasted states and also evaluated the protein binding and excretion characteristics. In Sprague-Dawley (SD) rats, Beagle dogs, and CD-1 mice, KBP-7072 demonstrated a linear PK profile after administration of single oral and IV and multiple oral doses. Oral bioavailability ranged from 12% to 32%. Mean Tmax ranged from 0.5 to 4 hours, and mean half-life ranged from approximately 6 to 11 hours. Administration of oral doses in the fed state resulted in a marked reduction in Cmax and AUC compared with dosing in fasted animals. The mean bound fractions of KBP-7072 were 77.5%, 69.8%, 64.5%, 69.3%, and 69.2% in mouse, rat, dog, monkey, and human plasma, respectively. Following a single 22.5 mg/kg oral dose of KBP-7072 in SD rats, cumulative excretion in feces was 64% and in urine was 2.5% of the administered dose. The PK results in animal models are consistent with single and multiple ascending dose studies in healthy volunteers and confirm the suitability of KBP-7072 for once daily oral and IV administration in clinical studies. Full Article
ar OPC-167832, a novel carbostyril derivative with potent anti-tuberculosis activity as a DprE1 inhibitor [Pharmacology] By aac.asm.org Published On :: 2020-03-30T10:04:32-07:00 There is an urgent need for new, potent anti-tuberculosis (TB) drugs with novel mechanisms of action that can be included in new regimens to shorten the treatment period for TB. After screening a library of carbostyrils, we optimized 3, 4-dihydrocarbostyril derivatives and identified OPC-167832 as having potent anti-tuberculosis activity. The minimum inhibitory concentrations of the compound for Mycobacterium tuberculosis ranged from 0.00024 to 0.002 μg/mL. It had bactericidal activity against both growing and intracellular bacilli, and the frequency of spontaneous resistance for Mycobacterium tuberculosis H37Rv was less than 1.91 x 10-7. It did not show antagonistic effects with other anti-TB agents in an in vitro checkerboard assay. Whole genome and targeted sequencing of resistant isolates to OPC-167832 identified the decaprenylphosphoryl-β-D-ribose 2'-oxidase (DprE1), an essential enzyme for cell wall biosynthesis, as the target of this compound, and further studies demonstrated inhibition of the DprE1 enzymatic activity by OPC-167832. In a mouse model of chronic TB, OPC-167832 showed potent bactericidal activities starting at a dose of 0.625 mg/kg. Further, it exhibited significant combination effects in 2-drug combinations with delamanid, bedaquiline, or levofloxacin. Finally, 3-4 drug regimens comprised of delamanid and OPC-167832 as the core along with bedaquiline, moxifloxacin, or linezolid showed superior efficacy in reducing bacterial burden and preventing relapse compared to the standard treatment regimen. In summary, these results suggest that OPC-167832 is a novel and potent anti-TB agent and regimens containing OPC-167832 and new or repurposed anti-TB drugs may have the potential to shorten the duration of treatment for TB. Full Article
ar Pharmacokinetics-pharmacodynamics of enmetazobactam combined with cefepime in a neutropenic murine thigh infection model [Pharmacology] By aac.asm.org Published On :: 2020-04-06T08:49:25-07:00 Third-generation cephalosporin (3GC)-resistant Enterobacteriaceae are classified as critical priority pathogens, with extended-spectrum β-lactamases (ESBLs) as principal resistance determinants. Enmetazobactam (formerly AAI101) is a novel ESBL inhibitor developed in combination with cefepime for empiric treatment of serious Gram-negative infections in settings where ESBLs are prevalent. Cefepime-enmetazobactam has been investigated in a phase 3 trial in patients with complicated urinary tract infections or acute pyelonephritis. This study examined pharmacokinetic-pharmacodynamic (PK-PD) relationships of enmetazobactam, in combination with cefepime, for ESBL-producing isolates of Klebsiella pneumoniae in 26-hour murine neutropenic thigh infection models. Enmetazobactam dose fractionation identified time above a free threshold concentration (fT > CT) as the PK-PD index predictive of efficacy. Nine ESBL-producing isolates of K. pneumoniae, resistant to cefepime and piperacillin-tazobactam, were included in enmetazobactam dose-ranging studies. The isolates encoded CTX-M-type, SHV-12, DHA-1 and OXA-48 β-lactamases and covered a cefepime-enmetazobactam MIC range from 0.06 to 2 μg/ml. Enmetazobactam restored the efficacy of cefepime against all isolates tested. Sigmoid curve fitting across the combined set of isolates identified enmetazobactam PK-PD targets for stasis and for a 1-log10 bioburden reduction of 8% and 44% fT > 2 μg/ml, respectively, with a concomitant cefepime PK-PD target of 40 – 60% fT > cefepime-enmetazobactam MIC. These findings support clinical dose selection and breakpoint setting for cefepime-enmetazobactam. Full Article
ar Population Pharmacokinetics and Dosage Optimization of Linezolid in Patients with Liver Dysfunction [Pharmacology] By aac.asm.org Published On :: 2020-04-06T08:49:25-07:00 Linezolid is the first synthetic oxazolidone agent to treat infections caused by Gram-positive pathogens. Infected patients with liver dysfunction (LD) are more likely to suffer from adverse reactions such as thrombocytopenia when standard-dose linezolid is used than patients with LD who didn't use linezolid. Currently, pharmacokinetics data of linezolid in patients with LD are limited. The study aimed to characterize pharmacokinetics parameters of linezolid in patients with LD, identify the factors influencing the pharmacokinetics, and propose an optimal dosage regimen. We conducted a prospective study and established population pharmacokinetics model with the Phoenix NLME. The final model was evaluated by goodness-of-fit plots, bootstrap analysis, and prediction corrected-visual predictive check. A total of 163 concentration samples from 45 patients with LD were adequately described by a one-compartment model with first-order elimination along with prothrombin activity (PTA) and creatinine clearance as significant covariates. Linezolid clearance (CL) was 2.68 L/h (95% confidence interval [CI]: 2.34-3.03 L/h); the volume of distribution (Vd) was 58.34 L (95% CI: 48.00-68.68 L). Model-based simulation indicated that the conventional dose was at risk for overexposure in patients with LD or severe renal dysfunction; reduced dosage (300 mg/12 h) would be appropriate to achieve safe (Cmin, ss at 2-8 ug/mL) and effective targets (the ratio of AUC0-24 at steady state to MIC, 80-100). In addition, for patients with severe LD (PTA <= 20%), the dosage (400 mg/24 h) was sufficient at an MIC <= 2 ug/mL. This study recommended therapeutic drug monitoring for patients with LD. Full Article
ar Pharmacodynamics of Cefepime Combined with the Novel Extended-Spectrum Beta Lactamase (ESBL) Inhibitor Enmetazobactam for Murine Pneumonia caused by ESBL-Producing Klebsiella pneumoniae [Pharmacology] By aac.asm.org Published On :: 2020-04-06T08:49:25-07:00 Klebsiella pneumoniae that produce extended spectrum beta lactamases (ESBLs) are a persistent public health threat. There are relatively few therapeutic options and there is undue reliance on carbapenems. Alternative therapeutic options are urgently required. A combination of cefepime and the novel beta lactamase inhibitor enmetazobactam is being developed for treatment of serious infections caused by ESBL-producing organisms. The pharmacokinetics-pharmacodynamics (PK-PD) of cefepime-enmetazobactam against ESBL-producing K. pneumoniae was studied in a neutropenic murine pneumonia model. Dose ranging studies were performed. Dose fractionation studies were performed to define the relevant PD index for the inhibitor. The partitioning of cefepime and enmetazobactam into the lung was determined by comparing area under the concentration time curve (AUC) in plasma and epithelial lining fluid. The magnitude of drug exposure for cefepime-enmetazobactam required for logarithmic killing in the lung was defined using 3 ESBL-producing strains. Cefepime 100 mg/kg q8h i.v. had minimal antimicrobial effect. When this background regimen of cefepime was combined with enmetazobactam half-maximal effect was induced with enmetazobactam 4.71 mg/kg q8h i.v. The dose fractionation study suggest both fT>threshold and fAUC:MIC are potentially relevant PD indices. The AUCELF:AUCplasma for cefepime and enmetazobactam was 73.4% and 61.5%, respectively. A ≥2-log kill in the lung was achieved with a plasma and ELF cefepime fT>MIC of ≥20% and enmetazobactam fT>2 mg/L of ≥20% of the dosing interval. These data and analyses provide the underpinning evidence for the combined use of cefepime and enmetazobactam for nosocomial pneumonia. Full Article
ar Oral Fosfomycin Treatment for Enterococcal Urinary Tract Infections in a Dynamic In Vitro Model [Pharmacology] By aac.asm.org Published On :: 2020-04-06T08:49:25-07:00 There are limited treatment options for enterococcal urinary tract infections, especially vancomycin-resistant Enterococcus (VRE). Oral fosfomycin is a potential option, although limited data are available guiding dosing and susceptibility. We undertook pharmacodynamic profiling of fosfomycin against E. faecalis and E. faecium isolates using a dynamic in vitro bladder infection model. Eighty-four isolates underwent fosfomycin agar dilution susceptibility testing (E. faecalis MIC50/90 32/64 μg/mL; E. faecium MIC50/90 64/128 μg/mL). Sixteen isolates (including E. faecalis ATCC 29212 and E. faecium ATCC 35667) were chosen to reflect the MIC range and tested in the bladder infection model with synthetic human urine (SHU). Under drug-free conditions, E. faecium demonstrated greater growth restriction in SHU compared to E. faecalis (E. faecium maximal growth 5.8 ± 0.6 log10 CFU/mL; E. faecalis 8.0 ± 1.0 log10 CFU/mL). Isolates were exposed to high and low fosfomycin urinary concentrations after a single dose, and two-doses given daily with low urinary exposure. Simulated concentrations closely matched the target (bias 2.3%). E. faecalis isolates required greater fosfomycin exposure for 3 log10 kill from the starting inoculum compared with E. faecium. The fAUC0-72/MIC and f%T > MIC0-72 for E. faecalis was 672 and 70%, compared to 216 and 51% for E. faecium, respectively. There was no rise in fosfomycin MIC post-exposure. Two doses of fosfomycin with low urinary concentrations resulted in equivalent growth inhibition to a single dose with high urinary concentrations. With this urinary exposure, fosfomycin was effective in promoting suppression of regrowth (>3 log10 kill) in the majority of isolates. Full Article
ar Imipenem population pharmacokinetics: therapeutic drug monitoring data collected in critically ill patients with or without extracorporeal membrane oxygenation [Pharmacology] By aac.asm.org Published On :: 2020-04-06T08:49:26-07:00 Carbapenem pharmacokinetic profiles are significantly changed in critically ill patients because of the drastic variability of the patients' physiological parameters. Published population PK studies have mainly focused on specific diseases and the majority of these studies had small sample sizes. The aim of this study was to develop a population PK model of imipenem in critically ill patients that estimated the influence of various clinical and biological covariates and the use of Extracorporeal Membrane Oxygenation (ECMO) and Continuous Renal Replacement Therapy (CRRT). A two-compartment population PK model with Creatinine clearance (CrCL), body weight (WT), and ECMO as fixed effects was developed using the non-linear mixed effect model (NONMEM). A Monte Carlo simulation was performed to evaluate various dosing schemes and different levels of covariates based on the pharmacokinetic/pharmacodynamic index (f%T>MIC) for the range of clinically relevant minimum inhibitory concentrations(MICs). The results showed that there may be insufficient drug use in the clinical routine drug dose regimen, and 750mg Q6h could achieve a higher treatment success rate. The blood concentrations of imipenem in ECMO patients were lower than that of non-ECMO patients, therefore dosage may need to be increased. The dosage may need adjustment for patients with CrCL ≤ 70ml/min, but dose should be lowered carefully to avoid the insufficient drug exposure. Dose adjustment is not necessary for patients within the WT ranging from 50-80 kg. Due to the large variation in PK profile of imipenem in critically ill patients, TDM should be carried out to optimize drug regimens. Full Article
ar Ceftazidime-avibactam resistance mediated by the N346Y substitution in various AmpC {beta}-lactamases [Mechanisms of Resistance] By aac.asm.org Published On :: 2020-04-06T08:49:26-07:00 Chromosomal and plasmid-borne AmpC cephalosporinases are a major resistance mechanism to β-lactams in Enterobacteriaceae and Pseudomonas aeruginosa. The new β-lactamase inhibitor avibactam effectively inhibits class C enzymes and can fully restore ceftazidime susceptibility. The conserved amino acid residue Asn346 of AmpC cephalosporinases directly interacts with the avibactam sulfonate. Disruption of this interaction caused by the N346Y amino acid substitution in Citrobacter freundii AmpC was previously shown to confer resistance to the ceftazidime-avibactam combination (CAZ-AVI). The aim of this study was to phenotypically and biochemically characterize the consequences of the N346Y substitution in various AmpC backgrounds. Introduction of N346Y into Enterobacter cloacae AmpC (AmpCcloacae), plasmid-mediated DHA-1, and P. aeruginosa PDC-5, led to 270-, 12,000-, and 79-fold decreases in the inhibitory efficacy (k2/Ki) of avibactam, respectively. The kinetic parameters of AmpCcloacaeand DHA-1 for ceftazidime hydrolysis were moderately affected by the substitution. Accordingly, AmpCcloacaeand DHA-1 harboring N346Y conferred CAZ-AVI resistance (MIC of ceftazidime of 16 µg/ml in the presence of 4 µg/ml of avibactam). In contrast, production of PDC-5 N346Y was associated with a lower MIC (4 µg/ml) since this β-lactamase retained a higher inactivation efficacy by avibactam in comparison to AmpCcloacaeN346Y. For FOX-3, the I346Y substitution did not reduce the inactivation efficacy of avibactam and the substitution was highly deleterious for β-lactam hydrolysis, including ceftazidime, preventing CAZ-AVI resistance. Since AmpCcloacaeand DHA-1 display substantial sequence diversity, our results suggest that loss of hydrogen interaction between Asn346 and avibactam could be a common mechanism of acquisition of CAZ-AVI resistance. Full Article
ar Development of probiotic formulations for oral candidiasis prevention: Gellan gum as a carrier to deliver Lactobacillus paracasei 28.4 [Experimental Therapeutics] By aac.asm.org Published On :: 2020-04-06T08:49:25-07:00 Probiotics might provide an alternative approach for the control of oral candidiasis. However, studies on the antifungal activity of probiotics in the oral cavity are based on the consumption of yogurt or other dietary products, and there is a necessary to use appropriate biomaterials and specific strains to obtain probiotic formulations targeting local oral administration. In this study, we impregnated gellan gum, a natural biopolymer used as a food-additive, with a probiotic and investigated its antifungal activity against Candida albicans. Lactobacillus paracasei 28.4, a strain recently isolated from the oral cavity of a caries-free individual, was incorporated in several concentrations of gellan gum (0.6% to 1%). All tested concentrations could incorporate L. paracasei cells while maintaining bacterial viability. Probiotic/gellan formulations were stable for 7 days when stored at room temperature or 4°C. Long-term storage of bacteria-impregnated gellan gum was achieved when L. paracasei 28.4 was lyophilized. The probiotic/gellan formulations provided a release of L. paracasei cells over 24 hours that was sufficient to inhibit the growth of C. albicans with effects dependent on the cell concentrations incorporated into gellan gum. The probiotic/gellan formulations also had inhibitory activity against Candida spp. biofilms by reducing the number of Candida spp. cells (p < 0.0001), decreasing the total biomass (p = 0.0003), and impairing hyphae formation (p = 0.0002), compared to the control group which received no treatment. Interestingly, probiotic formulation of 1% w/v gellan gum provided an oral colonization of L. paracasei in mice with approximately 6 log of CFU/mL after 10 days. This formulation inhibited the C. albicans growth (p < 0.0001), prevented the development of candidiasis lesions (p = 0.0013), and suppressed inflammation (p = 0.0006) when compared to the mice not treated in the microscopic analysis of the tongue dorsum. These results indicate that gellan gum is a promising biomaterial and can be used as a carrier system to promote oral colonization for probiotics that prevent oral candidiasis. Full Article
ar Safety, Pharmacokinetics, and Drug:Drug Interaction Potential of Intravenous Durlobactam, a {beta}-lactamase Inhibitor, in Healthy Subjects [Pharmacology] By aac.asm.org Published On :: 2020-04-13T08:15:30-07:00 Durlobactam (DUR, also known as ETX2514) is a novel β-lactamase inhibitor with broad activity against Ambler class A, C, and D β-lactamases. Addition of DUR to sulbactam (SUL) in vitro restores SUL activity against clinical isolates of Acinetobacter baumannii. The safety and pharmacokinetics (PK) of DUR alone and with SUL and/or imipenem/cilastatin (IMI/CIL) were evaluated in healthy subjects. This was a randomized, placebo-controlled study. In Part A, subjects including an elderly cohort (DUR 1 g) received single ascending doses of DUR 0.25-8 g. In Part B, multiple ascending dose of DUR 0.25-2 g were administered every 6 hours (q6h) for 29 doses. In Parts C and D, the drug-drug interaction (DDI) potential, including safety, of DUR (1 g) with SUL (1 g) and/or IMI/CIL (0.5/0.5 g) was investigated after single and multiple doses. Plasma and urine concentrations of DUR, SUL, and IMI/CIL were determined. Among 124 subjects, DUR was generally safe and well tolerated either alone or in combination with SUL and/or IMI/CIL. After single and multiple doses, DUR demonstrated linear dose proportional exposure across the studied dose ranges. Renal excretion was a predominant clearance mechanism. No drug:drug interaction potential was identified between DUR and SUL and/or IMI/CIL. SUL-DUR, 1 g (of each component) administered q6h with a 3 hour IV infusion, is under development for the treatment of serious infections due to A. baumannii. Full Article
ar Phase 2a Pharmacokinetic, Safety, and Exploratory Efficacy Evaluation of Oral Gepotidacin (GSK2140944) in Female Participants With Uncomplicated Urinary Tract Infection (Acute Uncomplicated Cystitis) [Clinical Therapeutics] By aac.asm.org Published On :: 2020-04-13T08:15:31-07:00 Gepotidacin, a triazaacenaphthylene bacterial type II topoisomerase inhibitor, is in development for treatment of uncomplicated urinary tract infection (uUTI). This Phase 2a study in female participants with uUTI evaluated the pharmacokinetics (primary objective), safety, and exploratory efficacy of gepotidacin. Eligible participants (N = 22) were confined to the clinic at baseline, received oral gepotidacin 1,500 mg twice daily for 5 days (on-therapy; Days 1 to 5), and returned to the clinic for test-of-cure (Days 10 to 13) and follow-up (Day 28±3). Pharmacokinetic, safety, clinical, and microbiological assessments were performed. Maximum plasma concentrations were observed approximately 1.5 to 2 hours postdose. Steady state was attained by Day 3. Urinary exposure over the dosing interval increased from 3,742 μg.h/ml (Day 1) to 5,973 μg.h/ml (Day 4), with trough concentrations of 322 to 352 μg/ml from Day 3 onward. Gepotidacin had an acceptable safety-risk profile with no treatment-limiting adverse events and no clinically relevant safety trends. Clinical success was achieved in 19 (86%) and 18 (82%) of 22 participants at test-of-cure and follow-up, respectively. Eight participants had a qualifying baseline uropathogen (growth; ≥105 CFU/ml). A therapeutic (combined clinical and microbiological [no growth; <103 CFU/ml]) successful response was achieved in 6 (75%) and 5 (63%) of 8 participants at test-of-cure and follow-up, respectively. Plasma area under the free-drug concentration-time curve over 24 hours at steady state divided by the MIC (fAUC0-24/MIC) and urine AUC0-24/MIC ranged from 6.99 to 90.5 and 1,292 to 121,698, respectively. Further evaluation of gepotidacin in uUTI is warranted. (NCT03568942) Full Article
ar A novel deletion mutation in pmrB contributes to concurrent colistin resistance in carbapenem resistant E. coli ST 405 of clinical origin [Mechanisms of Resistance] By aac.asm.org Published On :: 2020-04-13T08:15:30-07:00 We report the first clinical Escherichia. coli strain EC3000 with concomitant chromosomal colistin and carbapenem resistance. A novel in-frame deletion, 6-11(RPISLR), in pmrB contributing to colistin resistance was verified using recombinant DNA techniques. Although decreased fitness compared to the wild-type (WT) strain or EC3000 revertant (chromosomal replacement of WT pmrB in EC3000), a portion of serially passaged EC3000 strains preserving colistin resistance without selective pressure raises the concern for further spread. Full Article
ar Detection of Protein Aggregation in Live Plasmodium Parasites [Pharmacology] By aac.asm.org Published On :: 2020-04-13T08:15:30-07:00 The rapid evolution of resistance in the malaria parasite to every single drug developed against it calls for the urgent identification of new molecular targets. Using a stain specific for the detection of intracellular amyloid deposits in live cells we have detected the presence of abundant protein aggregates in Plasmodium falciparum blood stages and female gametes cultured in vitro, in the blood stages of mice infected by Plasmodium yoelii, and in the mosquito stages of the murine malaria species Plasmodium berghei. Aggregated proteins could not be detected in early rings, the parasite form that starts the intraerythrocytic cycle. A proteomics approach was followed to pinpoint actual aggregating polypeptides in functional P. falciparum blood stages, which resulted in the identification of 369 proteins, with roles particularly enriched in nuclear import-related processes. Five aggregation-prone short peptides selected from this protein pool exhibited different aggregation propensity according to Thioflavin-T fluorescence measurements, and were observed to form amorphous aggregates and amyloid fibrils in transmission electron microscope images. The results presented suggest that generalized protein aggregation might have a functional role in malaria parasites. Future antimalarial strategies based on the upsetting of the pathogen's proteostasis and therefore affecting multiple gene products could represent the entry to new therapeutic approaches. Full Article
ar Pharmacokinetic-Pharmacodynamic Characterization of Omadacycline Against Haemophilus influenzae Using a One-Compartment In Vitro Infection Model [Pharmacology] By aac.asm.org Published On :: 2020-04-13T08:15:30-07:00 Omadacycline is a novel aminomethylcycline with activity against Gram-positive and -negative organisms, including Haemophilus influenzae, which is one of the leading causes of community-acquired bacterial pneumonia (CABP). The evaluation of antimicrobial agents against H. influenzae using standard murine infection models is challenging due to the low pathogenicity of this species in mice. Therefore, 24-hour dose-ranging studies using a one-compartment in vitro infection model were undertaken with the goal of characterizing the magnitude of the ratio of the area under the concentration-time curve (AUC) to the MIC (AUC/MIC ratio) associated with efficacy for a panel of five clinical H. influenzae isolates. These five isolates, which had MIC values of 1 or 2 mg/L, were exposed to omadacycline total-drug epithelial lining fluid (ELF) concentration-time profiles based on those observed in healthy volunteers following intravenous omadacycline administration. Relationships between change in log10 colony forming units (CFU) from baseline at 24 hours and total-drug ELF AUC/MIC ratio for each isolate and the isolates pooled together were evaluated using Hill-type models and non-linear least squares regression. As evidenced by the high coefficient of determination (r2) of 0.88 to 0.98, total-drug ELF AUC/MIC ratio described the data well for each isolate and the isolates pooled together. The median total-drug ELF AUC/MIC ratio associated with net bacterial stasis and 1- and 2-log10 CFU/mL reductions from baseline at 24 hours was 6.91, 8.91, and 11.1, respectively. These data were useful to support the omadacycline dosing regimens selected for the treatment of patients with CABP, as well as susceptibility breakpoints for H. influenzae. Full Article
ar Population pharmacokinetics of piperacillin following continuous infusion in critically ill patients: Impact of renal function on target attainment [Clinical Therapeutics] By aac.asm.org Published On :: 2020-04-13T08:15:30-07:00 Pharmacokinetic changes are often seen in patients with severe infections. Administration by continuous infusion has been suggested to optimize antibiotic exposure and pharmacokinetic/pharmacodynamic (PK/PD) target attainment for β-lactams. In an observational study, unbound piperacillin concentrations (n=196) were assessed in 78 critically ill patients following continuous infusion of piperacillin/tazobactam (ratio 8:1). The initial dose of 8, 12 or 16 g (piperacillin component) was determined by individual creatinine clearance (CRCL). Piperacillin concentrations were compared to the EUCAST clinical breakpoint MIC for Pseudomonas aeruginosa (16 mg/L), and the following PK/PD targets were evaluated: 100% fT>1xMIC and 100% fT>4xMIC. A population pharmacokinetic model was developed using NONMEM 7.4.3 consisting of a one-compartment disposition model with linear elimination separated into non-renal and renal (linearly increasing with patient CRCL) clearances. Target attainment was predicted and visualized for all individuals based on the utilized CRCL dosing algorithm. The target of 100% fT>1xMIC was achieved for all patients based on the administered dose, but few patients achieved the target of 100% fT>4xMIC. Probability of target attainment for a simulated cohort of patients showed, that increasing the daily dose by 4 g increments (piperacillin component) did not result in substantially improved target attainment for the 100% fT>4xMIC target. To conclude, in patients with high CRCL combined with high-MIC bacterial infections, even a CI regimen with a daily dose of 24 g may be insufficient to achieve therapeutic concentrations. Full Article
ar Epidemiological study on prevalence, serovar diversity, multi-drug resistance and CTX-M-type extended-spectrum {beta}-lactamases of Salmonella spp. from patients with diarrhea, food of animal origin, and pets in several provinces of China [Epidemiology an By aac.asm.org Published On :: 2020-04-20T08:36:46-07:00 A total of 2,283 Salmonella spp. isolates were recovered from 18,334 samples including patients with diarrhea, food of animal origin and pets across 5 provinces of China. The highest prevalence of Salmonella spp. was detected in chicken meats (39.3%, 486/1,237). Fifteen serogroups and 66 serovars were identified, with Typhimurium and Enteritidis being the most dominant. Most (85.5%, 1,952/2,283) isolates exhibited resistant to ≥ 1 antimicrobial and 56.4% were multi-drug resistant (MDR). A total of 222 isolates harbored extended-spectrum β-lactamases (ESBLs), 200 of which were CTX-M-type that were mostly detected from chicken meat and turtle fecal. Overall, eight blaCTX-M genes were identified, with blaCTX-M-65, blaCTX-M-123, blaCTX-M-14, blaCTX-M-79, and blaCTX-M-130 being the most prevalent. Totally, 166 of the 222 ESBL-producing isolates had amino acid substitutions in GyrA (S83Y, S83F, D87G, D87N, and D87Y) and ParC (and S80I), whilst the PMQR-encoding genes oqxA/B, qepA, and qnrB/S were detected in almost all isolates. Of the fifteen sequence types (STs) identified in the 222 ESBLs, ST17, ST11, ST34, and ST26 ranked among the top 5 in the number of isolates. Our study revealed considerable serovars diversity, high prevalence of co-occurrence of MDR determinants, including CTX-M-type ESBLs, QRDRs mutations and PMQR genes. This is the first report of CTX-M-130 Salmonella spp. from patients with diarrhea and QRDRs mutations from turtle fecal samples. Our study emphasizes the importance of actions, both in the health care settings and in the veterinary medicine sector, to control the dissemination of MDR, especially the CTX-M Salmonella spp. isolates. Full Article
ar Population Pharmacokinetics and Exposure-Response Relationships of Baloxavir Marboxil in Patients Infected with Influenza at High Risk of Influenza Complications [Clinical Therapeutics] By aac.asm.org Published On :: 2020-04-20T08:36:47-07:00 Baloxavir marboxil, a prodrug of cap-dependent endonuclease inhibitor, baloxavir acid, reduces the time to improvement of influenza symptoms in patients infected with type A or B influenza virus. To characterize its pharmacokinetics, a population pharmacokinetic model for baloxavir acid was developed using 11846 plasma concentration data items from 1827 subjects including 2341 plasma concentration data items from 664 patients at high risk of influenza complications. A three-compartment model with first-order elimination and first-order absorption with lag time well described the plasma concentration data. Body weight and race were found to be the most important factors influencing clearance and volume of distribution. The exposures in high-risk patients were similar to those in otherwise healthy patients, and no pharmacokinetic difference was identified regarding any risk factors for influenza complications.Exposure-response analyses were performed regarding the time to improvement of symptoms and the reduction in the influenza virus titer in high-risk patients. The analyses suggested that body weight-based dosage, 40 mg for patients weighing < 80 kg and 80 mg for patients weighing ≥ 80 kg, can shorten the time to improvement of influenza symptoms and reduce virus titer for both type A and B influenza virus regardless of the exposure levels of the high-risk patients as well as for the otherwise healthy influenza patients.The results of our population pharmacokinetic and exposure-response analyses in patients with risk factors of influenza complications should provide useful information on the pharmacokinetic and pharmacodynamic characteristics of baloxavir marboxil and also for the optimization of dose regimens. Full Article
ar Nafamostat mesylate blocks activation of SARS-CoV-2: New treatment option for COVID-19 [Letters] By aac.asm.org Published On :: 2020-04-20T08:36:47-07:00 The currently unfolding coronavirus pandemic threatens health systems and economies worldwide.... Full Article
ar Cardiovascular safety and population pharmacokinetic properties of piperaquine in African patients with uncomplicated falciparum malaria - a pooled multicentre analysis [Clinical Therapeutics] By aac.asm.org Published On :: 2020-04-20T08:36:47-07:00 Dihydroartemisinin-piperaquine has shown excellent efficacy and tolerability in malaria treatment. However, concerns have been raised of potentially harmful cardiotoxic effects associated with piperaquine. The population pharmacokinetics and cardiac effects of piperaquine were evaluated in 1,000 patients, mostly children enrolled in a multicentre trial from 10 sites in Africa. A linear relationship described the QTc-prolonging effect of piperaquine, estimating a 5.90ms mean QTc-prolongation per 100ng/mL increase in piperaquine concentration. The effect of piperaquine on absolute QTc-interval estimated a mean maximum QTc-interval of 456ms (EC50=209ng/mL). Simulations from the pharmacokinetic-pharmacodynamic models predicted 1.98-2.46% risk of having QTc-prolongation > 60ms in all treatment settings. Although piperaquine administration resulted in QTc-prolongation, no cardiovascular adverse events were found in these patients. Thus, the use of dihydroartemisinin-piperaquine should not be limited by this concern. Full Article
ar Prediction of antibiotic susceptibility for urinary tract infection in a hospital setting [Epidemiology and Surveillance] By aac.asm.org Published On :: 2020-04-20T08:36:46-07:00 Objectives: Empiric antibiotic prescribing can be supported by guidelines and/or local antibiograms, but these have limitations. We sought to use data from a comprehensive electronic health record to use statistical learning to develop predictive models for individual antibiotics that incorporate patient-, and hospital-specific factors. This paper reports on the development and validation of these models on a large retrospective cohort.Methods: This is a retrospective cohort study including hospitalized patients with positive urine cultures in the first 48 hours of hospitalization at a 1500 bed, tertiary care hospital over a 4.5 year period. All first urine cultures with susceptibilities were included. Statistical learning techniques, including penalized logistic regression, were used to create predictive models for cefazolin, ceftriaxone, ciprofloxacin, cefepime, and piperacillin-tazobactam. These were validated on a held-out cohort.Results: The final dataset used for analysis included 6,366 patients. Final model covariates included demographics, comorbidity score, recent antibiotic use, recent antimicrobial resistance, and antibiotic allergies. Models had acceptable to good discrimination in the training dataset and acceptable performance in the validation dataset, with a point estimate for area under the receiver operating characteristic curve (AUC) that ranged from 0.65 for ceftriaxone to 0.69 for cefazolin. All models had excellent calibration.Conclusion: In this study we used electronic health record data to create predictive models to estimate antibiotic susceptibilities for UTIs in hospitalized patients. Our models had acceptable performance in a held-out validation cohort. Full Article
ar Species Distribution and Comparison between EUCAST and Gradient Concentration Strips Methods for Antifungal Susceptibility Testing of 112 Aspergillus Section Nigri Isolates [Susceptibility] By aac.asm.org Published On :: 2020-04-20T08:36:46-07:00 Aspergillus niger, the third species responsible for invasive aspergillosis has been considered as a homogeneous species until DNA-based identification uncovered many cryptic species. These species have been recently reclassified into the Aspergillus section Nigri. However little is yet known among the section Nigri about the species distribution and the antifungal susceptibility pattern of each cryptic species. A total of 112 clinical isolates collected from 5 teaching hospitals in France and phenotypically identified as A. niger were analyzed. Identification to the species level was carried out by nucleotide sequence analysis. The Minimum Inhibitory Concentrations (MICs) of itraconazole, voriconazole, posaconazole, isavuconazole and amphotericin B were determined by both the EUCAST and gradient concentration strips methods. Aspergillus tubingensis (n=51, 45.5%) and A. welwitschiae (n=50, 44.6%) were the most common species while A. niger accounted for only 6.3% (n=7). The MICs of azoles drugs were higher for A. tubingensis than for A. welwitschiae. The MIC of amphotericin B was 2 mg/L or less for all isolates. Importantly, MICs determined by EUCAST showed no correlation with those determined by gradient concentration strips methods, these latter being lower than the former (Spearman's rank correlation tests ranging - depending on the antifungal agent - from 0.01 to 0.25; p>0.4). In conclusion, A. niger should be considered as a minority species in the section Nigri. The differences in MICs between species for different azoles underline the importance of accurate identification. Significant divergences in the determination of MIC between EUCAST and gradient concentration strips methods require further investigation. Full Article
ar Anidulafungin and Micafungin concentrations in Cerebrospinal Fluid and in Cerebral Cortex [Pharmacology] By aac.asm.org Published On :: 2020-04-27T08:14:56-07:00 Anidulafungin and micafungin were quantified in cerebrospinal fluid (CSF) of critically ill adults and in cerebral cortex of deceased patients. In CSF, anidulafungin levels (<0.01-0.66 μg/ml) and micafungin levels (<0.01-0.16 μg/ml) were lower than the simultaneous plasma concentrations (0.77-5.07 μg/ml and 1.21-8.70 μg/ml, respectively). In cerebral cortex, anidulafungin and micafungin levels were 0.21-2.34 μg/g and 0.18-2.88 μg/g, respectively. Thus, MIC values of several pathogenic Candida strains exceed concentrations in CSF and in brain. Full Article
ar Emergence of Mycobacterium leprae rifampicin resistance evaluated by whole-genome sequencing after 48 years of irregular treatment [Epidemiology and Surveillance] By aac.asm.org Published On :: 2020-04-27T08:14:57-07:00 A case of M. leprae rifampicin resistance after irregular anti-leprosy treatments since 1971 is reported. Whole-genome sequencing from four longitudinal samples indicated relapse due to acquired rifampicin resistance and not to reinfection with another strain. A putative compensatory mutation in rpoC was also detected. Clinical improvement was achieved using an alternative therapy. Full Article
ar Effect of the Lysin, Exebacase, on Cardiac Vegetation Progression in a Rabbit Model of Methicillin-Resistant Staphylococcus aureus (MRSA) Endocarditis as Determined by Echocardiography [Pharmacology] By aac.asm.org Published On :: 2020-04-27T08:14:56-07:00 Background: MRSA pose significant therapeutic challenges, related to their: frequency in clinical infections; innate virulence properties; and propensity for multi-antibiotic resistance. MRSA are among the most common causes of endovascular infections, including infective endocarditis (IE).Objective: To employ transthoracic echocardiography (TTE) to evaluate the effect of exebacase, a novel direct lytic agent, in experimental aortic valve MRSA IE.Study Design: TTE was utilized to evaluate the in vivo effect of exebacase on MRSA-infected vegetation progression when combined with daptomycin (vs daptomycin alone). Primary intravegetation outcomes were: maximum size; weights at sacrifice; and MRSA counts at infection baseline vs after 4 days of daptomycin treatment (alone or in addition to exebacase administered once on treatment Day 1).Results: A single dose of exebacase in addition to daptomycin cleared significantly more intravegetation MRSA than daptomycin alone. This was associated with a statistical trend toward reduced maximum vegetation size in the exebacase + daptomycin vs the daptomycin-alone therapy groups (p = 0.07). Also, mean vegetation weights in the exebacase-treated group were significantly lower vs daptomycin-alone (p < 0.0001). Maximum vegetation size by TTE correlated with vegetation weight (p = 0.005). In addition, intravegetation MRSA counts in the combination group were significantly lower vs untreated controls (p<0.0001) and the daptomycin-alone group (p<0.0001).Conclusion: This study suggests that exebacase has a salutary impact on MRSA-infected vegetation progression when combined with daptomycin, especially in terms of vegetation MRSA burden, size and weight. Moreover, TTE appears to be an efficient non-invasive tool to assess therapeutic efficacies in experimental MRSA IE. Full Article
ar A novel class of chikungunya virus small molecule inhibitors that targets the viral capping machinery [Antiviral Agents] By aac.asm.org Published On :: 2020-04-27T08:14:57-07:00 Despite the worldwide re-emergence of the chikungunya virus (CHIKV) and the high morbidity associated with CHIKV infections, there is no approved vaccine or antiviral treatment available. We here aim to identify the target of a novel class of CHIKV inhibitors i.e. CHVB series. CHVB compounds inhibit the in vitro replication of CHIKV isolates with 50% effective concentrations in the low micromolar range. A CHVB-resistant variant (CHVBres) was selected that carried two mutations in the gene encoding nsP1 (responsible for viral RNA capping), one mutation in nsP2 and one mutation in nsP3. Reverse genetics studies demonstrated that both nsP1 mutations were necessary and sufficient to achieve ~18-fold resistance, suggesting that CHVB targets viral mRNA capping. Interestingly, CHVBres was cross-resistant to the previously described CHIKV capping inhibitors from the MADTP series, suggesting they share a similar mechanism of action. In enzymatic assays, CHVB inhibited the methyltransferase and guanylyltransferase activities of alphavirus nsP1 proteins. To conclude, we identified a class of CHIKV inhibitors that targets the viral capping machinery. The potent anti-CHIKV activity makes this chemical scaffold a potential candidate for CHIKV drug development. Full Article
ar Population Pharmacokinetic Analyses for Omadacycline Using Phase 1 and 3 Data [Pharmacology] By aac.asm.org Published On :: 2020-04-27T08:14:56-07:00 Omadacycline, a novel aminomethylcycline antibiotic with activity against Gram-positive and -negative organisms, including tetracycline-resistant pathogens, received FDA approval in October, 2018 for the treatment of patients with acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP). A previously-developed population pharmacokinetic (PK) model based on Phase 1 intravenous and oral PK data was refined using data from infected patients. Data from 10 Phase 1 studies used to develop the previous model were pooled with data from three additional Phase 1 studies, a Phase 1b uncomplicated urinary tract infection study, one Phase 3 CABP study, and two Phase 3 ABSSSI studies. The final population PK model was a three-compartment model with first-order absorption using transit compartments to account for absorption delay following oral dosing and first-order elimination. Epithelial lining fluid (ELF) concentrations were modeled as a sub-compartment of the first peripheral compartment. A food effect on oral bioavailability was included in the model. Sex was the only significant covariate identified, with 15.6% lower clearance for females relative to males. Goodness-of-fit diagnostics indicated a precise and unbiased fit to the data. The final model, which was robust in its ability to predict plasma and ELF exposures following omadacycline administration, was also able to predict the central tendency and variability in concentration-time profiles using an external Phase 3 ABSSSI dataset. A population PK model, which described omadacycline PK in healthy subjects and infected patients, was developed and subsequently used to support pharmacokinetic-pharmacodynamic (PK-PD) and PK-PD target attainment assessments. Full Article
ar Experimentally engineered mutations in a ubiquitin hydrolase, UBP-1, modulate in vivo susceptibility to artemisinin and chloroquine in Plasmodium berghei. [Mechanisms of Resistance] By aac.asm.org Published On :: 2020-04-27T08:14:56-07:00 As resistance to artemisinins (current frontline drugs in malaria treatment) emerges in south East Asia, there is an urgent need to identify the genetic determinants and understand the molecular mechanisms underpinning such resistance. Such insights could lead to prospective interventions to contain resistance and prevent the eventual spread to other malaria endemic regions. Artemisinin reduced susceptibility in South East Asia (SEA) has been primarily linked to mutations in P. falciparum Kelch-13, which is currently widely recognised as a molecular marker of artemisinin resistance. However, 2 mutations in a ubiquitin hydrolase, UBP-1, have been previously associated with artemisinin reduced susceptibility in a rodent model of malaria and some cases of UBP-1 mutation variants associating with artemisinin treatment failure have been reported in Africa and SEA. In this study, we have employed CRISPR-Cas9 genome editing and pre-emptive drug pressures to test these artemisinin susceptibility associated mutations in UBP-1 in P. berghei sensitive lines in vivo. Using these approaches, we have shown that the V2721F UBP-1 mutation results in reduced artemisinin susceptibility, while the V2752F mutation results in resistance to chloroquine and moderately impacts tolerance to artemisinins. Genetic reversal of the V2752F mutation restored chloroquine sensitivity in these mutant lines while simultaneous introduction of both mutations could not be achieved and appears to be lethal. Interestingly, these mutations carry a detrimental growth defect, which would possibly explain their lack of expansion in natural infection settings. Our work has provided independent experimental evidence on the role of UBP-1 in modulating parasite responses to artemisinin and chloroquine under in vivo conditions. Full Article
ar Combination Therapy Using Benznidazole and Aspirin During the Acute Phase of Experimental Chagas Disease Prevents Cardiovascular Dysfunction and Decreases Typical Cardiac Lesions in the Chronic Phase [Clinical Therapeutics] By aac.asm.org Published On :: 2020-05-04T08:49:24-07:00 Chagas disease, caused by the protozoan Trypanosoma cruzi, is one of the main causes of death due to cardiomyopathy and heart failure in Latin American countries. The treatment of Chagas disease is directed at eliminating the parasite, decreasing the probability of cardiomyopathy, and disrupting the disease transmission cycle. Benznidazole (BZ) and nifurtimox (NFX) are recognized as effective drugs for the treatment of Chagas disease by the World Health Organization, but both have high toxicity and limited efficacy, especially in the chronic disease phase. At low doses, aspirin (ASA) has been reported to protect against T. cruzi infection. We evaluated the effectiveness of BZ in combination with ASA at low doses during the acute disease phase and evaluated cardiovascular aspects and cardiac lesions in the chronic phase. ASA treatment prevented the cardiovascular dysfunction (hypertension and tachycardia) and typical cardiac lesions. Moreover, BZ+ASA-treated mice had a smaller cardiac fibrotic area than that in BZ-treated mice. These results were associated with an increase in the number of eosinophils and reticulocytes and level of nitric oxide in the plasma and cardiac tissue of ASA-treated mice relative to respective controls. These effects of ASA and BZ+ASA in chronically infected mice were inhibited by pretreatment with the LXA4 receptor antagonist, Boc-2, indicating that the protective effects of ASA are mediated by ASA-triggered lipoxin. These results emphasize the importance of exploring new drug combinations for treatments of acute phase of Chagas disease that are beneficial for chronic patients. Full Article
ar Focusing the lens on the CAMERA concepts: Early combination {beta}-lactam and vancomycin therapy in methicillin-resistant Staphylococcus aureus bacteremia [Minireviews] By aac.asm.org Published On :: 2020-05-04T08:49:24-07:00 Methicillin-resistant Staphylococcus aureus (MRSA) has grown to become a major burden on healthcare systems. The cumulation of limited therapeutic options and worsened patient outcomes with persistent MRSA bacteremia has driven research in optimizing its initial management. The guidelines published by the Infectious Disease of America currently recommend combination therapy for refractory MRSA bacteremia, but the utility of combining antibiotics from the start of therapy is under investigation. The alternative strategy of early use of a β-lactam antibiotics in combination with vancomycin upon initial MRSA bacteremia detection has shown promise. While this concept has gained international attention, providers should give this strategy serious consideration prior to implementation. The objective of this review is to examine retrospective and prospective evidence for early combination with vancomycin and β-lactam antibiotics, as well as explore potential consequences of combination therapy. Full Article
ar Distribution of linezolid in tuberculosis lesions in patients with spinal multidrug-resistant tuberculosis [Pharmacology] By aac.asm.org Published On :: 2020-05-04T08:49:24-07:00 Linezolid has strong antimicrobial activity against the multidrug-resistant (MDR) strains of Mycobacterium tuberculosis. Little is known about the distribution of linezolid in tuberculosis (TB) lesions in patients with MDR-TB. The aim of this study is to evaluate the distribution of linezolid in TB lesions in patients with spinal MDR-TB. Nine patients with spinal MDR-TB were enrolled prospectively from August 2019 to February 2020. The patients received a linezolid-containing anti-TB treatment regimen and needed surgery for the removal of TB lesions. During the operation, nine blood samples, eight diseased bone tissue samples, seven pus samples and four granulation tissue samples were collected simultaneously and 2 h after the oral administration of 600 mg of linezolid. Linezolid concentrations in plasma, diseased bone tissue, pus, and granulation tissue samples were subjected to high-performance liquid chromatography–tandem mass spectrometry. At sample collection, the mean concentrations of linezolid in plasma, diseased bone tissue, pus, and granulation tissue samples of the nine patients were 11.14 ± 5.82, 5.94 ± 4.27, 11.09 ± 4.58, 14.08 ± 10.61 mg/L, respectively. The mean ratios of linezolid concentration in diseased bone/plasma, pus/plasma, and granulation/plasma were 53.84%, 91.69%, and 103.57%, respectively. The mean ratios of linezolid concentration in pus/plasma and granulation/plasma were higher than those in diseased bone/plasma, and the difference was statistically significant (t =-2.810, p = 0.015; t =-4.901, p = 0.001). In conclusion, linezolid had different concentration distributions in different types of TB infected tissues in patients with spinal MDR-TB. Full Article
ar Clinically relevant epithelial lining fluid concentrations of meropenem with ciprofloxacin provide synergistic killing and resistance suppression of hypermutable Pseudomonas aeruginosa in a dynamic biofilm model [Pharmacology] By aac.asm.org Published On :: 2020-05-04T08:49:24-07:00 Treatment of exacerbations of chronic Pseudomonas aeruginosa infections in patients with cystic fibrosis (CF) is highly challenging due to hypermutability, biofilm formation and an increased risk of resistance emergence. We evaluated the impact of ciprofloxacin and meropenem as monotherapy and in combination in the dynamic in vitro CDC biofilm reactor (CBR). Two hypermutable P. aeruginosa strains, PAOmutS (MICciprofloxacin 0.25 mg/L, MICmeropenem 2 mg/L) and CW44 (MICciprofloxacin 0.5 mg/L, MICmeropenem 4 mg/L), were investigated for 120h. Concentration-time profiles achievable in epithelial lining fluid (ELF) following FDA-approved doses were simulated in the CBR. Treatments were ciprofloxacin 0.4g every 8h as 1h-infusions (80% ELF penetration), meropenem 6 g/day as continuous infusion (CI; 30% and 60% ELF penetration) and their combinations. Counts of total and less-susceptible planktonic and biofilm bacteria and MICs were determined. Antibiotic concentrations were quantified by UHPLC-PDA. For both strains, all monotherapies failed with substantial regrowth and resistance of planktonic (≥8log10 CFU/mL) and biofilm (>8log10 CFU/cm2) bacteria at 120h (MICciprofloxacin up to 8 mg/L, MICmeropenem up to 64 mg/L). Both combination treatments demonstrated synergistic bacterial killing of planktonic and biofilm bacteria of both strains from ~48h onwards and suppressed regrowth to ≤4log10 CFU/mL and ≤6log10 CFU/cm2 at 120h. Overall, both combination treatments suppressed amplification of resistance of planktonic bacteria for both strains, and biofilm bacteria for CW44. The combination with meropenem at 60% ELF penetration also suppressed amplification of resistance of biofilm bacteria for PAOmutS. Thus, combination treatment demonstrated synergistic bacterial killing and resistance suppression against difficult-to-treat hypermutable P. aeruginosa strains. Full Article
ar Identification of antiviral drug candidates against SARS-CoV-2 from FDA-approved drugs [Antiviral Agents] By aac.asm.org Published On :: 2020-05-04T08:49:24-07:00 Drug repositioning is the only feasible option to address the COVID-19 global challenge immediately. We screened a panel of 48 FDA-approved drugs against SARS-CoV-2 which were pre-selected by an assay of SARS-CoV and identified 24 potential antiviral drug candidates against SARS-CoV-2 infection. Some drug candidates showed very low micromolar IC50s and in particular, two FDA-approved drugs - niclosamide and ciclesonide – were notable in some respects. Full Article
ar Influence of CYP2C8, CYP3A4 and CYP3A5 host genotypes on early recurrence of Plasmodium vivax [Mechanisms of Resistance] By aac.asm.org Published On :: 2020-05-04T08:49:24-07:00 CYP450 enzymes are involved in biotransformation of chloroquine (CQ), but the role of the different metabolism profiles of this drug has not been properly investigated in relation to P. vivax recurrences. To investigate the influence of CYPs genotypes associated with CQ-metabolism on early recurrence rates of P. vivax, a case-control study was carried out. Cases included patients presenting an early recurrence (CQ-recurrent), defined as recurrence during the first 28 days after initial infection, plasma concentrations of CQ plus desethylchloroquine (DCQ, the major CQ metabolite) higher than 100 ng/mL. A control (CQ-responsive) with no parasite recurrence over the follow-up was also included. CQ and DCQ plasma levels were measured on Day 28. CQ CYPs (CYP2C8, CYP3A4 and CYP3A5) genotypes were determined by real-time PCR. An ex vivo study was conducted to verify CQ and DCQ efficacy in P. vivax isolates. The frequency of alleles associated with normal and slow metabolism was similar between the cases and controls for CYP2C8 (OR=1.45, 95% CI=0.51-4.14, p=0.570), CYP3A4 (OR=2.38, 95% CI=0.92-6.19, p=0.105) and CYP3A5 (OR=4.17, 95% CI=0.79-22.04, p=1.038) genes. DCQ levels were higher than CQ, regardless of the genotype. Regarding the DCQ/CQ rate, there was no difference between groups or between those patients who had a normal or mutant genotype. DCQ and CQ showed similar efficacy ex vivo. CYPs genotypes had no influence on early recurrence rates. Similar efficacy of CQ and DCQ ex vivo could explain the absence of therapeutic failure, despite presence of alleles associated with slow metabolism. Full Article
ar Comparative Genomic Analysis of Third Generation Cephalosporin-Resistant Escherichia coli Harboring blaCMY-2-Positive IncI1 group, IncB/O/K/Z, and IncC Plasmids Isolated from Healthy Broilers in Japan. [Epidemiology and Surveillance] By aac.asm.org Published On :: 2020-05-04T08:49:24-07:00 The off-label use of third generation cephalosporin (3GC) during in ovo vaccination or vaccination of newly hatched chicks, was a common practice worldwide. CMY-2-producing Escherichia coli have been disseminated among broiler production. The objectives of this study were to determine the epidemiological linkage of blaCMY-2-positive plasmids among broilers both within and outside Japan because grandparent stock and parent stock were imported in Japan. We examined the whole genome sequences of 132 3GC-resistant E. coli isolates collected from healthy broilers during 2002-2014. The predominant 3GC-resistance gene was blaCMY-2, which was detected in the plasmids of 87 (65.9%) isolates. The main plasmid replicon types were IncI1-I (n=21; 24.1%), IncI (n=12; 13.8%), IncB/O/K/Z (n=28; 32.2%), and IncC (n=22; 25.3%). Those plasmids were subjected to gene clustering and network analyses and plasmid multi-locus sequence typing (pMLST). The chromosomal DNA of isolates was subjected to MLST and single nucleotide variant (SNV)-based phylogenetic analysis.MLST and SNV-based phylogenetic analysis revealed high diversity of E. coli isolates. ST429 harboring blaCMY-2-positive IncB/O/K/Z was closely related to isolates from broiler in Germany harboring blaCMY-2-positive IncB/O/K/Z. pST55-IncI and pST12-IncI1-I and pST3-IncC were prevalent in western Japan. pST12-IncI1-I and pST3-IncC were closely related to those detected in E. coli isolates from chicken in American continent, whereas 26 IncB/O/K/Z were related to those in Europe. These data will be useful to reveal the whole picture of transmission of CMY-2-producing bacteria in and out of Japan. Full Article
ar Activity of epigenetic inhibitors against Plasmodium falciparum asexual and sexual blood stages. [Susceptibility] By aac.asm.org Published On :: 2020-05-04T08:49:24-07:00 Earlier genetic and inhibitor studies have shown that epigenetic regulation of gene expression is critical for malaria parasite survival in multiple life stages and a promising target for new anti-malarials. We therefore evaluated the activity of 350 diverse epigenetic inhibitors against multiple stages of Plasmodium falciparum. We observed ≥90% inhibition at 10 μM for 28% of compounds against asexual blood stages and early gametocytes, of which a third retained ≥90% inhibition at 1 μM. Full Article
ar Comparative plasma pharmacokinetics of ceftriaxone and ertapenem between normoalbuminemia, hypoalbuminemia and with albumin replacement in a sheep model. [Pharmacology] By aac.asm.org Published On :: 2020-05-04T08:49:24-07:00 BackgroundOptimal concentrations of unbound antimicrobials are essential for maximum microbiological effect. Although hypoalbuminemia and albumin fluid resuscitation are common in critical care, the effects of different albumin concentrations on the unbound concentrations of highly protein-bound antimicrobials are not known. The aim of this study was to compare effects of different albumin states on total and unbound concentrations of ertapenem and ceftriaxone using an ovine model.MethodsDesignProspective, three phase intervention observational study.SubjectsHealthy Merino sheep.InterventionsEight sheep were subject to three experimental phases; normoalbuminemia, hypoalbuminemia using plasmapheresis and albumin replacement using a 25% albumin solution. In each phase, ceftriaxone 40 mg/kg and ertapenem 15 mg/kg were given intravenously. Blood samples were collected at pre-defined intervals and analyzed using an ultra-high-performance liquid chromatography tandem mass spectrometry method. Pharmacokinetic parameters such as area under the curve (AUC0-24), plasma clearance (CL) and apparent volume of distribution in the terminal phase (Vd) were estimated and compared between the phases.ResultsThe protein and albumin concentrations were significantly different between phases. Hypoalbuminemia resulted in a significantly lower AUC0-24 and higher CL of total and unbound concentrations of ceftriaxone compared to the other phases. Whereas albumin replacement led to higher AUC0-24 and lower CL compared to other phases for both drugs. The Vd for total drug concentrations for both drugs were significantly lower with albumin replacement.ConclusionsFor highly protein-bound drugs such as ceftriaxone and ertapenem, both hypoalbuminemia and albumin replacement may affect unbound drug exposure. Full Article
ar Inhibition of SARS-CoV-2 infection by the cyclophilin inhibitor Alisporivir (Debio 025) [Antiviral Agents] By aac.asm.org Published On :: 2020-05-06T08:16:52-07:00 Cyclophilins play a key role in the lifecycle of coronaviruses. Alisporivir (Debio 025) is a non-immunosuppressive analogue of cyclosporin A with potent cyclophilin inhibition properties. Alisporivir reduced SARS-CoV-2 RNA production in a dose-dependent manner in VeroE6 cell line, with an EC50 of 0.46±0.04 μM. Alisporivir inhibited a post-entry step of the SARS-CoV-2 lifecycle. These results justify that a proof-of-concept Phase 2 trial be rapidly conducted with alisporivir in patients with SARS-CoV-2 infection. Full Article
ar Avast Defends Data Harvesting, Plans to Get Users to Agree to It By www.pcmag.com Published On :: On Tuesday, Avast responded to a PCMag-Motherboard investigation into the company's browser history collection practices, saying it was entirely legal. Avast users should expect to see a prompt from the antivirus products, asking them to consent to the data harvesting. Full Article
ar Avast to End Browser Data Harvesting, Terminates Jumpshot By www.pcmag.com Published On :: 'As CEO of Avast, I feel personally responsible and I would like to apologize to all concerned,' wrote Ondrej Vlcek following a PCMag-Motherboard investigation into the privacy risks around the data harvesting. Full Article
ar New Coronavirus Strain? Nope, Just Hackers Trying to Spread Malware By www.pcmag.com Published On :: The hackers have been using files and emails that warn about a new coronavirus strain to trick users into opening them. Doing so can secretly deliver malware to the victim's machine. Full Article
ar Google Photos Videos Were Shared With Strangers By www.pcmag.com Published On :: Google's Takeout service was designed to let people download their data, but accidentally sent videos from Google Photos accounts to strangers. Full Article
ar Malware Steals Data By Adjusting Screen Brightness By www.pcmag.com Published On :: Malware on an air-gapped computer can transmit data like Morse code by changing screen brightness in a way that's invisible to the naked eye but easily recorded with a camera. Full Article
ar The Best Parental Control Software for 2020 By www.pcmag.com Published On :: Parenting styles run the gamut and so do the features in parental control and monitoring utilities. We've tested the top hardware- and software-based services to help you choose the right one for your family. Full Article
ar Fin24.com | Brent crude oil drops to 21-year low as selling pressure intensifies By www.fin24.com Published On :: Wed, 22 Apr 2020 08:12:12 +0200 "The entire energy market is still on a knife edge," says an economist. Full Article
ar Fin24.com | Oil prices roar back on US-Iran tensions By www.fin24.com Published On :: Thu, 23 Apr 2020 20:43:56 +0200 Oil prices made a spectacular comeback Thursday as fresh US-Iran tensions erupted, also helping equities advance after US labour market figures provided a glimmer of hope for the world's top economy. Full Article
ar Fin24.com | Stock markets rally on virus hopes, but oil tanks By www.fin24.com Published On :: Mon, 27 Apr 2020 15:31:18 +0200 Equity markets have rallied Monday as countries eased coronavirus lockdown measures, but oil prices tumbled as a supply glut offset output cuts. Full Article
ar Fin24.com | Local bourse firms as global economies gear for partial reopening By www.fin24.com Published On :: Tue, 28 Apr 2020 17:54:10 +0200 Global markets rallied on the back of optimism that most governments were gearing up to at least partially reopen their economies following lockdowns to prevent the spread of the coronavirus. Full Article
ar Fin24.com | SA stocks are on track for a record month By www.fin24.com Published On :: Thu, 30 Apr 2020 15:08:20 +0200 Unprecedented demand for online services and entertainment during the Covid-19 pandemic lockdowns, along with a scramble for haven investments, have helped set South African stocks on course for a record month. Full Article