There are discrepancies regarding which treatment is best in clinical practice for children with parapneumonic empyema, with some authors favoring video-assisted thoracoscopy and others favoring intrapleural fibrinolytic agents.

This study is one of the few randomized clinical trials on this subject in children and the first multicenter trial. It exclusively included patients with septated empyema. Thoracoscopy and fibrinolysis with urokinase were equally effective for this condition. (Read the full article)

In 2000/2001, the American Academy of Pediatrics published recommendations for attention-deficit/hyperactivity disorder (ADHD) care. According to pediatricians’ self-report of adoption of these guidelines, community-based ADHD care appears to be marginally adequate.

Using reviews of >1500 patient charts, this study demonstrates that community-based ADHD care is not consistent with evidence-based practice. Furthermore, variability in much of community-based ADHD care is unrelated to the provider, suggesting that innovative, system-wide interventions are needed to improve ADHD care. (Read the full article)

Despite growing interest around clinical screening for health-related social and environmental risk factors, little evidence exists regarding screening formats that maximize disclosure of psychosocial information.

This study compares psychosocial and socioeconomic adversity disclosure rates in face-to-face interviews versus electronic formats in a large, urban pediatric emergency department. (Read the full article)

Fathers’ attitude and support affects breastfeeding outcomes. Fathers are currently not targeted in breastfeeding support and care provided by health care professionals. Breastfeeding interventions delivered to fathers have been shown to increase breastfeeding exclusivity and duration.

A coparenting breastfeeding support intervention delivered to mothers and fathers in the postpartum period showed beneficial effects on breastfeeding duration, paternal breastfeeding confidence, breastfeeding help provided by fathers, and mothers’ satisfaction with fathers’ involvement with breastfeeding. (Read the full article)

Influenza vaccine coverage is low, and young children in need of 2 doses in a given season are at particular risk, with less than half receiving both doses. Text message vaccine reminders increase receipt of first dose of influenza vaccine.

Little is known about what types of text message reminders are most effective, including embedding educational information. We demonstrate that text message reminders increase timely receipt of the second dose of influenza vaccine and embedding health literacy information improves effectiveness. (Read the full article)

Frequency of influenza vaccination is low, partially because of missed opportunities to vaccinate. Barriers to implementing successful influenza vaccination reminders in the electronic health record include alert fatigue and incomplete vaccination information due to scattered records.

A noninterruptive, immunization information system–linked influenza vaccination reminder can increase vaccination late in the winter when fewer vaccine doses are usually administered. Tailoring the reminder to clinicians’ needs can increase its use. (Read the full article)

Expert consensus recommends rest after concussion with stepwise return to activity. Animal and retrospective human data suggest that early mental and physical activity may worsen outcome. There are no pediatric studies testing the efficacy of recommending strict rest after concussion.

Recommending strict rest postinjury did not improve outcome and may have contributed to increased symptom reporting. Usual care (rest for 1–2 days with stepwise return to activity) is currently the best discharge strategy for pediatric mild traumatic brain injury/concussion. (Read the full article)

Pediatric traumatic brain injury (TBI) contributes to impairments in functioning across multiple settings. Online family problem-solving therapy may be effective in reducing adolescent behavioral morbidity after TBI. However, less is known regarding maintenance of effects over time.

This large randomized clinical trial in adolescents with TBI is the only study to examine maintenance of treatment effects. Findings reveal that brief, online treatment may result in long-term improvements in child functioning, particularly among families of lower socioeconomic status. (Read the full article)

Uptake of rotavirus vaccines has increased steadily since introduction. Despite their demonstrated impact, rotavirus vaccine coverage is lower than for other vaccines recommended in infancy and disease continues to occur.

We observed higher rotavirus detection rates among patients from provider locations with lower rotavirus vaccine coverage; providers who do not offer rotavirus vaccine to age-eligible children may create pockets of susceptible children that serve as reservoirs of ongoing disease transmission. (Read the full article)

Application of antenatal corticosteroids to mothers before delivery is highly beneficial to very low birth weight infants. Yet despite widespread quality improvement efforts, many eligible infants fail to receive this therapy.

We demonstrate improvement in antenatal corticosteroid use during the study period. However, significant regional variation persists, which network-level quality improvement efforts might help eliminate. (Read the full article)

Sleep apnea is a common condition in childhood, mainly managed by tonsillectomy. Codeine was recently contraindicated for pain management after surgery. Controversy exists regarding the safety and effectiveness of alternative medications, morphine, and ibuprofen.

Our findings suggest that ibuprofen does not increase tonsillar bleeding and in combination with acetaminophen is effective for pain management after tonsillectomy. Furthermore, standard morphine doses increased postoperative respiratory events and were not safe in all children. (Read the full article)

Sustained lung inflation and positive end-expiratory pressure would permit lung recruitment immediately after birth, improving lung mechanics and reducing the need for respiratory support. Previous clinical studies in preterm infants provided promising results but have some limitations.

This randomized controlled study found that prophylactic sustained lung inflation and positive end-expiratory pressure in the delivery room decreased the need for mechanical ventilation in the first 72 hours of life in preterm infants at high risk of respiratory distress syndrome. (Read the full article)

Previous trials reported no significant effect of triamcinolone acetonide aqueous nasal spray on growth velocity of children with perennial allergic rhinitis. However, they did not conform to Food and Drug Administration guidelines for evaluating effects of intranasal corticosteroids on growth.

This is the first published study consistent with the 2007 Food and Drug Administration–recommended study design evaluating growth velocity in children aged 3–9 years with perennial allergic rhinitis treated with triamcinolone acetonide or placebo for 12 months. (Read the full article)

Sleep deprivation is a worldwide problem in adolescents. The effectiveness of sleep education in enhancing sleep knowledge with consequent modification of sleep habits remains uncertain, in view of small sample sizes and lack of control groups in previous studies.

This large-scale, cluster randomized controlled study found that a school-based sleep education program was effective in enhancing sleep knowledge and improving behavioral and mental health, but it had no significant impact on sleep duration or pattern among adolescents. (Read the full article)

Early language delay is common in toddlers and is associated with poor academic outcomes, reading difficulties, and persistent communication problems. Despite these long-term sequelae, few interventions for toddlers with early language delays yield positive expressive and receptive language results.

A 28-session program delivered over 3 months can enhance parent language facilitation strategies. Unusually, the small short-term benefits were mainly in receptive, rather than expressive, language and vocabulary. Extended follow-up could determine the costs versus benefits of this promising approach. (Read the full article)

Topical corticosteroids are often used to treat atopic dermatitis (AD) in infants, although compliance is poor due to concerns over side effects. Pimecrolimus was shown to be a safe and effective noncorticosteroid treatment of AD in infants in short-term studies.

The Petite Study shows that long-term management of mild-to-moderate AD in infants with pimecrolimus or topical corticosteroids was safe without any effect on the developing immune system. Pimecrolimus had similar efficacy to topical corticosteroids and a marked steroid-sparing effect. (Read the full article)

Micronutrient deficiencies, including deficiencies of vitamin B-12 and folate, are common worldwide and may be a contributing factor to the estimated 165 million stunted children.

Routine supplementation of vitamin B-12 improved linear and ponderal growth in subgroups of young Indian children. We provide evidence that vitamin B-12 deficiency is a contributor to poor growth in low- and middle-income countries. (Read the full article)

Collaborative care is known to be an effective system to manage child behavioral health conditions in the primary care setting.

Among urban children with attention-deficit/hyperactivity disorder, using lay care managers to address barriers to engagement with care and challenging child behaviors has the potential to improve the effectiveness of conventional collaborative care. (Read the full article)

Neonatal arterial ischemic stroke is associated with later cerebral palsy and cognitive impairment. Many studies on neonatal ischemic stroke are limited by modest sample sizes, and prospective studies that include outcomes assessments are scarce.

Results from this prospective, nationwide, population-based study provide information on the epidemiology, associated clinical variables, clinical manifestation, vascular distribution, and treatment of neonatal arterial ischemic stroke. The study also provides outcomes regarding motor function and cognition. (Read the full article)

US parents trust the health care system and bring their infant children in for preventive care. Previous studies have demonstrated the ability of health care systems to identify, and sometimes address, the economic needs of low-income families.

Families of newborns at a safety-net primary care center have high levels of economic hardship. Compared with controls, Developmental Understanding and Legal Collaboration for Everyone families had accelerated access to concrete supports, improved rates of on-time immunization and preventive care, and decreased emergency department utilization. (Read the full article)

Parental hesitancy about childhood vaccines is prevalent and related to delay or refusal of immunizations. Physicians are highly influential in parental vaccine decision-making, but may lack confidence in addressing parents’ vaccine concerns.

A physician-targeted communications intervention designed to reduce maternal vaccine hesitancy through the parent-physician relationship did not affect maternal hesitancy or physician confidence communicating with parents. Further research should determine the most effective approaches to addressing vaccine hesitancy. (Read the full article)

More than 200 million children <5 years are not reaching their developmental potential. Lack of stimulating caregiving is a major cause, and effective scalable interventions are needed. Integrating parenting with health services has been recommended, but there are few evaluations.

An innovative parenting intervention can be delivered at routine visits for primary health care, with benefits to child cognitive development and parenting knowledge. This approach using films, discussion, and practice has the potential for delivery at scale. (Read the full article)

Although treatment programs for childhood obesity can demonstrate success, long-term outcomes have seldom been evaluated. The benefit of intervention when overweight is identified in a screening assessment and parental recognition of the problem is minimal is understudied.

A low-dose (sessions every 1–3 months), but long-term (2 years), family-based intervention was effective at reducing BMI compared with usual care in children recruited via a weight screening initiative in which many parents had been unaware their child was overweight. (Read the full article)

Prenatal diagnosis may lead to benefits in outcomes for certain forms of critical congenital heart disease. Despite recognized benefits, single-center studies and focused regional efforts suggest that prenatal detection rates for congenital heart disease remain low in the United States.

We describe prenatal detection rates for a large cohort of neonates and infants undergoing heart surgery across a range of congenital heart defects. Additionally, this study adds new information by demonstrating geographic variability of prenatal detection rates across the United States. (Read the full article)

The value of ultrasound imaging for the diagnosis, prognosis, and surgical planning of cryptorchidism is limited at best.

Ultrasound remains grossly overused by referring physicians throughout Ontario, Canada, which resulted in a 3-month delay to definitive surgery and unnecessary expenditures. (Read the full article)

Rudeness is routinely experienced by hospital-based medical teams. Individuals exposed to mildly rude behavior perform poorly on cognitive tasks, exhibit reduced creativity and flexibility, and are less helpful and prosocial.

Rudeness had adverse consequences on diagnostic and procedural performance of members of the NICU medical teams. Information-sharing mediated the adverse effect of rudeness on diagnostic performance, and help-seeking mediated the effect of rudeness on procedural performance. (Read the full article)

Intervention strategies are needed to reduce underage drinking. Meta-analyses of youth alcohol brief interventions (BIs) conclude that therapist-delivered BIs are efficacious; however, to maximize public health impact, recommendations include using technology to streamline intervention delivery, for which evidence is lacking.

A single-session BI, delivered by a computer or therapist in the emergency department, shows promise for underage drinkers. Findings for the stand-alone computer BI are particularly appealing given the ease of future implementation. (Read the full article)

The vitamin D concentration in breast milk of women taking 400 IU vitamin D per day is relatively low, leading to vitamin D deficiency in breastfeeding infants. As a result, the American Academy of Pediatrics recommends breastfeeding infant vitamin D supplementation within days after birth.

Maternal vitamin D supplementation alone with 6400 IU/day safely supplies breast milk with adequate vitamin D to satisfy the requirement of her nursing infant and offers an alternate strategy to direct infant supplementation. (Read the full article)

Urethral catheterization is a painful, yet common procedure to obtain a sterile urine sample in young children. There are conflicting results regarding the effectiveness of lidocaine to reduce pain, and it is unclear if it should be routinely used.

In young children, combined topical and intraurethral lidocaine does not reduce pain during urethral catheterization and is associated with more pain than nonanesthetic lubricant during instillation. Clinicians should use noninvasive methods of analgesia during this painful procedure. (Read the full article)

Deferral of consent avoids delaying emergency interventions while ensuring consent to ongoing participation and use of data. Deferred consent is particularly important for enabling trials in pediatric settings, where many medicines and devices are unlicensed and untested for use.

Approaches for seeking deferred consent should balance the potential burden of obtaining consent against risk of bias due to outcome-related attrition. Ethics committees could consider approving data use when best efforts to obtain deferred consent are met with no response. (Read the full article)

Children with medical complexity require a disproportionate amount of health services due to a multitude of chronic severe illness, and their impact on the health care system appears to be increasing.

This study provides one of the first comparisons of health care utilization patterns for children with medical complexity between medical centers in a population-based cohort. (Read the full article)

Endotracheal intubation is a mandatory skill for neonatal trainees. It is a difficult skill to acquire, and success rates of junior doctors are low and falling.

Videolaryngoscopy allows the supervisor to share the intubator’s view of the airway and provide more informed guidance. Teaching intubation using a videolaryngoscope with the screen visible to the instructor results in significantly higher success rates for inexperienced doctors. (Read the full article)

Previous studies have evaluated separately the effects of brief education and reminder/recall intervention strategies to increase human papillomavirus vaccine coverage. None have examined if intervention effects varied by race/ethnicity.

When compared with a general adolescent vaccine brochure, human papillomavirus vaccine-specific educational materials increased 1-dose coverage among Hispanic but not black individuals. Recalls for doses 2 and 3 were effective in increasing 3-dose coverage for both racial/ethnic groups. (Read the full article)

Continuous conventional EEG video is currently gold standard for identifying neonatal seizures and a substantial proportion of neonatal seizures are electrographic. Currently there is no direct evidence that EEG monitoring, seizure identification, or treatment impacts long-term outcomes.

In neonates with hypoxic ischemic encephalopathy, EEG monitoring and treatment of electrographic seizures results in significant reduction in seizure burden. Increasing seizure burden is associated with more severe brain injury and significantly lower performance scores on Bayley Scales of Infant Development III. (Read the full article)

The impact of neonatal abstinence syndrome is of concern because the number of newborns showing symptoms of withdrawal after intrauterine drug exposure is increasing worldwide. Newborns developing neonatal abstinence syndrome require prolonged medical treatment and longer hospital admission after birth.

This first randomized controlled trial presents data on newborns with neonatal abstinence syndrome treated with laser acupuncture. The findings suggest that adjuvant laser acupuncture has the potential to reduce duration of morphine therapy and length of hospital stay. (Read the full article)

Given the efforts to decrease the use of ionizing radiation in pediatric patients, there is significant variability in head computed tomography (CT) scan use in pediatric emergency departments for minor head trauma.

This study characterized variability in CT scan rates for all body regions in emergency department, observation, and inpatient encounters across 30 tertiary pediatric hospitals. Two-fold variation remained after case-mix adjustment, with higher volume hospitals having lower rates of CT scanning. (Read the full article)

The Financial Sector Conduct Authority warns the public not to conduct financial services business with Masibekele Funeral Parlour and MISI Burial Society.

A group of Bulgarian teenagers and leaders took part in this year’s TeenStreet Europe for the first time and experienced God in new ways.

This year at the sports and English camp in Bulgaria, the team noticed the fruit of building on relationships over time.

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Wide-scale use of insecticide-treated bed nets has led to substantial declines in global incidences of malaria in recent years. As a result, mosquitos have been shifting their biting times to earlier in the evening and later in the morning. In a new study, an international team of researchers has found that mosquitoes are most likely to transmit malaria in the early evening, when people are exposed, then at midnight, when people are protected by bed nets, or in the morning. The findings may have implications for malaria prevention initiatives.

Background: This study summarizes drug resistance analyses in 4 recent phase 2b trials of the respiratory syncytial virus (RSV) fusion inhibitor presatovir in naturally infected adults.

Methods: Adult hematopoietic cell transplant (HCT) recipients, lung transplant recipients, or hospitalized patients with naturally acquired, laboratory-confirmed RSV infection were enrolled in 4 randomized, double-blind, placebo-controlled studies with study-specific presatovir dosing. Full-length RSV F sequences amplified from nasal swabs obtained at baseline and postbaseline were analyzed by population sequencing. Substitutions at RSV fusion inhibitor resistance-associated positions are reported.

Results: Genotypic analyses were performed on 233 presatovir-treated and 149 placebo-treated subjects. RSV F variant V127A was present in 8 subjects at baseline. Population sequencing detected treatment-emergent substitutions in 10/89 (11.2%) HCT recipients with upper and 6/29 (20.7%) with lower respiratory tract infection, 1/35 (2.9%) lung transplant recipients, and 1/80 (1.3%) hospitalized patients treated with presatovir; placebo-treated subjects had no emergent resistance-associated substitutions. Subjects with substitutions at resistance-associated positions had smaller decreases in viral load during treatment relative to those without, but similar clinical outcomes.

Conclusions: Subject population type and dosing regimen may have influenced RSV resistance development during presatovir treatment. Subjects with vs without genotypic resistance development had decreased virologic responses but comparable clinical outcomes.

Malaria parasites invade and replicate within red blood cells (RBCs), extensively modifying their structure and gaining access to the extracellular environment by placing the plasmodial surface anion channel (PSAC) into the RBC membrane. Expression of members of the cytoadherence linked antigen gene 3 (clag3) family is required for PSAC activity, a process that is regulated epigenetically. PSAC is a well-established route of uptake for large, hydrophilic antimalarial compounds and parasites can acquire resistance by silencing clag3 gene expression, thereby reducing drug uptake. We found that exposure to sub-IC50 concentrations of the histone methyltransferase inhibitor chaetocin caused substantial changes in both clag3 gene expression and RBC permeability, reversing acquired resistance to the antimalarial compound blasticidin S that is transported through PSAC. Chaetocin treatment also altered progression of parasites through their replicative cycle, presumably by changing their ability to modify chromatin appropriately to enable DNA replication. These results indicate that targeting histone modifiers could represent a novel tool for reversing epigenetically acquired drug resistance in P. falciparum.

Continuous spread of antimalarial drug resistance is a threat to current chemotherapy efficacy. Therefore, characterizing the genetic diversity of drug resistance markers is needed to follow treatment effectiveness and further update control strategies. Here, we genotyped Plasmodium falciparum resistance gene markers associated with sulfadoxine-pyrimethamine (SP) and artemisinin-based combination therapy (ACT) in isolates from pregnant women in Ghana. The prevalence of the septuple IRNI-A/FGKGS/T pfdhfr/pfdhps haplotypes including the pfdhps A581G and A613S/T mutations was high at delivery among post-SP treatment isolates (18.2%) compared to those of first-antenatal care (before initiation of intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP); 6.1%; p = 0.03). Regarding the pfk13 marker gene, two non-synonymous mutations (N458D and A481C) were detected at positions previously related to artemisinin resistance in isolates from Southeast-Asia. These mutations were predicted in silico to alter the stability of the pfk13 propeller-encoding domain. Overall, these findings highlight the need for intensified monitoring and surveillance on additional mutations associated with increased SP resistance as well as emergence of resistance against artemesinin derivatives.

Since 2012, single low dose of primaquine (SLDPQ, 0.25mg/kg) has been recommended with artemisinin-based combination therapies, as first-line treatment of acute uncomplicated Plasmodium falciparum malaria, to interrupt its transmission, especially in low transmission settings of multidrug, including artemisinin, resistance. Policy makers in Cambodia have been reluctant to implement this recommendation due to primaquine safety concerns and lack of data on its efficacy.

In this randomized controlled trial, 109 Cambodians with acute uncomplicated P. falciparum malaria received dihydroartemisinin-piperaquine (DP) alone or combined with SLDPQ on the first treatment day. Transmission-blocking efficacy of SLDPQ was evaluated on Days 0, 1, 2, 3, 7, 14, 21, 28 and recrudescence by reverse transcriptase polymerase chain reaction (RT-PCR) (gametocyte prevalence) and membrane-feeding assays with Anopheles minimus mosquitoes (gametocyte infectivity). Without the influence of recrudescent infections, DP+SLDPQ reduced gametocyte carriage 3 fold compared to DP. Of 48 patients tested on Day 0, only three patients were infectious to mosquitoes (~6%). Post-treatment, three patients were infectious: on D14 (3.5%, 1/29), and on the first and seventh day of recrudescence (8.3%, 1/12 for each); this overall low infectivity precluded our ability to assess its transmission blocking efficacy.

Our study confirms effective gametocyte clearance of SLDPQ when combined with DP in multidrug resistant P. falciparum and the negative impact of recrudescent infections due to poor DP efficacy. Artesunate-mefloquine (ASMQ) has replaced DP and ASMQ-SLDPQ has been deployed to treat all P. falciparum symptomatic patients to further support the elimination of multidrug resistant P. falciparum in Cambodia.

Ceftobiprole medocaril is an advanced-generation cephalosporin prodrug that has qualified infectious disease product status granted by the US-FDA and is currently being evaluated in phase 3 clinical trials in patients with acute bacterial skin and skin structure infections (ABSSSIs) and in patients with Staphylococcus aureus bacteremia. In this study, the activity of ceftobiprole and comparators was evaluated against more than 7,300 clinical isolates collected in the United States from 2016 through 2018 from patients with skin and skin structure infections. The major species/pathogen groups were S. aureus (53%), Enterobacterales (23%), Pseudomonas aeruginosa (7%), β-hemolytic streptococci (6%), Enterococcus spp. (4%), and coagulase-negative staphylococci (2%). Ceftobiprole was highly active against S. aureus (MIC_50/90, 0.5/1 mg/L; 99.7% susceptible by EUCAST criteria; 42% methicillin-resistant S. aureus [lsqb]MRSA[rsqb]). Ceftobiprole also exhibited potent activity against other Gram-positive cocci. The overall susceptibility of Enterobacterales to ceftobiprole was 84.8% (>99.0% susceptible for isolate subsets that exhibited a non-extended-spectrum β-lactamase [lsqb]ESBL[rsqb]-phenotype). A total of 74.4% of P. aeruginosa, 100% of β-hemolytic streptococci and coagulase-negative staphylococci, and 99.6% of Enterococcus faecalis isolates were inhibited by ceftobiprole at ≤4 mg/L. As expected, ceftobiprole was largely inactive against Enterobacterales that contained ESBL genes and Enterococcus faecium. Overall, ceftobiprole was highly active against most clinical isolates from the major Gram-positive and Gram-negative skin and skin structure pathogen groups collected at U.S. medical centers participating in the SENTRY Antimicrobial Surveillance Program during 2016–2018. The broad-spectrum activity of ceftobiprole, including potent activity against MRSA, supports its further evaluation for the potential ABSSSI indication.

Background: Intensive care unit (ICU) patients may experience ceftriaxone underexposure but clinical outcomes data are lacking. The objective of this study was to determine the impact of ceftriaxone dosing on clinical outcomes amongst ICU patients without central nervous system (CNS) infection.

Methods: A retrospective study of ICU patients receiving intravenous, empiric ceftriaxone for non-CNS infections was conducted. Patients ≥18 years of age who received ≤2 grams of ceftriaxone daily for ≥72 hours were included and categorized as receiving ceftriaxone 1 gram or 2 grams daily. The primary, composite outcome was treatment failure: inpatient mortality and/or antibiotic escalation due to clinical worsening. Propensity score matching was performed based on the probability of receiving ceftriaxone 2 grams daily. Multivariable logistic regression determined the association between ceftriaxone dose and treatment failure in a propensity-matched cohort.

Results: A total of 212 patients were included in the propensity-matched cohort. The most common diagnoses (83.0%) were pneumonia and urinary tract infection. Treatment failure occurred in 17.0% and 5.7% of patients receiving 1 gram and 2 grams daily, respectively (p=0.0156). Overall inpatient mortality was 8.5%. Ceftriaxone 2 gram dosing was associated with a reduced likelihood of treatment failure (adjusted odds ratio=0.190; 95% confidence interval: 0.059 – 0.607). Other independent predictors of treatment failure included sequential organ failure assessment score (aOR 1.440, 95% CI 1.254 – 1.653) and creatinine clearance at 72 hours from ceftriaxone initiation (aOR 0.980, 95% CI (0.971 – 0.999).

Conclusions: Ceftriaxone 2 grams daily when used as appropriate antimicrobial coverage may be appropriate for ICU patients with lower mortality risk.

Highly conserved PenI-type class A β-lactamase in pathogenic members of Burkholderia can evolve to extended-spectrum β-lactamase (ESBL), which exhibits hydrolytic activity towards third-generation cephalosporins, while losing its activity towards the original penicillin substrates. We describe three single-amino-acid-substitution mutations in the ArgS arginine-tRNA synthetase that confer extra antibiotic tolerance protection to ESBL-producing Burkholderia thailandensis. This pathway can be exploited to evade antibiotic tolerance induction in developing therapeutic measures against Burkholderia species, targeting their essential aminoacyl-tRNA synthetases.

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 cpxA^Y144N 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.