Acquisition of extended-spectrum beta-lactamase producing Escherichia coli strains in male and female infants admitted to a neonatal intensive care unit: molecular epidemiology and analysis of risk factors

Sex differences in neonatal brain injury and inflammation

Neonatal brain injury and associated inflammation is more common in males. There is a well-recognised difference in incidence and outcome of neonatal encephalopathy according to sex with a pronounced male disadvantage. Neurodevelopmental differences manifest from an early age in infancy with females having a lower incidence of developmental delay and learning difficulties in comparison with males and male sex has consistently been identified as a risk factor for cerebral palsy in epidemiological studies. Important neurobiological differences exist between the sexes with respect to neuronal injury which are especially pronounced in preterm neonates. There are many potential reasons for these sex differences including genetic, immunological and hormonal differences but there are limited studies of neonatal immune response. Animal models with induced neonatal hypoxia have shown various sex differences including an upregulated immune response and increased microglial activation in males. Male sex is recognized to be a risk factor for neonatal hypoxic ischemic encephalopathy (HIE) during the perinatal period and this review discusses in detail the sex differences in brain injury in preterm and term neonates and some of the potential new therapies with possible sex affects.

In depth molecular interaction analyses of the complex of a proposed CTXM-inhibitor bound to the bacterial enzyme

A 'Thumb Rule for Antibiotic Design' against bacteria can be given as, 'The minimum pace of drug design ought to match the swiftness with which bacteria display cutting-edge resistance mechanisms; thereby outwitting the antibiotics and, in turn, the researchers'. Occurrence of drug resistance attributable to CXTM-variants in bacterial pathogens is widespread. In line with our above proposed thumb rule, the present article employed concatenation of virtual screening, docking and simulation to identify a potent in silico validated anti-CTXM-14 ligand. Specifically, this research used the 'MCULE' drug discovery platform to screen a total of 5 million candidate inhibitors to evaluate their binding efficacy with an antibiotic resistance enzyme, CTXM-14 found in bacterial pathogens. A new median approach between 'structure' and 'ligand'-based protocols was employed. Pharmacokinetic profiling was achieved by 'SWISS ADME'. Safety profile for humans was appraised by 'Toxicity Checker'. The complex consisting of the 'Top ligand' (obtained from the screen) harbored within the active pocket of the bacterial CTXM-14 was subjected to 60 ns molecular dynamics simulation with the aid of licensed YASARA STRUCTURE v.21.8.27. Complex tasks were performed by YANACONDA. Fine resolution figures (notably, plots generated from trajectory analyses) were constructed. Simulation snaps were acquired at every 250 picoseconds of the run. The ligand having the IUPAC name as 1-Amino-3-(4-hydroxyphenyl)pyrido[1,2-a]benzimidazole-2,4-dicarbonitrile demonstrated the overall best binding with CTXM-14. Fifteen amino acid residues were found to line the interacting pocket. Remarkably, all of these interacting residues were found to be present among the interacting residues displayed by the reference complex as well, i.e. CTXM-14:Vaborbactam complex (PDB ID 6V7H). A total of 240 simulation snaps were retrieved. The RMSD plot revealed that a plateau was achieved at 32 ns, after which the backbone RMSD fluctuations remained confined within 1.4-2 Å. Video recording of molecular actions was also achieved. In conclusion, this study provides a fresh lead molecule, 1-Amino-3-(4-hydroxyphenyl)pyrido[1,2-a]benzimidazole-2,4-dicarbonitrile against bacterial CTXM-14 protein. The study utilized a new median approach between 'structure' and 'ligand'-based drug design. The lead molecule passed ADMET conditions and an array of medicinal chemistry filters, and is further supported by a stable molecular dynamics. An acceptable skin permeation supports its probable use in antibiotic creams. Moreover, the study provides a clear 'Thumb Rule for Antibiotic Design' against bacteria, which although often assumed, can be clearly stated for the first time. Synthesis of the screening-proposed molecule followed by in-vitro and in-vivo validation is highly recommended.Communicated by Ramaswamy H. Sarma.

Molecular interaction of a putative inhibitor with bacterial SHV, an enzyme associated with antibiotic resistance

Tackling the ever-looming threat of antibiotic resistance remains a challenge for clinicians and microbiologists across the globe. Sulfhydryl variable (SHV) is a known bacterial enzyme associated with antibiotic resistance. The SHV enzyme has many variants. The present article describes identification and molecular interaction of a putative inhibitor with the bacterial SHV enzyme as a step towards novel antibacterial drug discovery. The MCULE-platform was used for screening a collection of 5 000 000 ligand molecules to evaluate their binding potential to the bacterial SHV-1 enzyme. Estimation of pharmacokinetic features was realized with the aid of the 'SWISS ADME' tool. Toxicity-checks were also performed. The docked complex of 'the top screened out ligand' and 'the bacterial SHV-1 protein' was subjected to molecular dynamics simulation of 101 ns. The obtained ligand molecule, 1,1'-(4H,8H-Bis[1,2,5]oxadiazolo[3,4-b:3',4'-e]pyrazine-4,8-diyl)diethanone, displayed the most favourable binding interactions with bacterial SHV-1. A total of 15 amino acid residues were found to hold the ligand in the binding site of SHV-1. Noticeably, 12 of the 15 residues were found as common to the binding residues of the reference (PDB ID: 4ZAM). The RMSD values plotted against the simulation time showed that nearby 11 ns, equilibrium was reached and, thenceforth, the 'SHV-1-Top ligand' complex remained typically stable. Starting from around 11 ns and straight to 101 ns, the backbone RMSD fluctuations were found to be confined inside a range of 1.0-1.6 Å. The ligand, 1,1'-(4H,8H-Bis[1,2,5]oxadiazolo[3,4-b:3',4'-e]pyrazine-4,8-diyl)diethanone, satisfied ADMET criteria. Furthermore, the practicability of the described 'SHV-1-Top ligand' complex was reinforced by a comprehensive molecular dynamics simulation of 101 ns. This ligand hence can be considered a promising lead for antibiotic design against SHV-1 producing resistant bacteria, and thus warrants wet laboratory evaluation.

Neonatal multidrug-resistant gram-negative infection: epidemiology, mechanisms of resistance, and management

Infants admitted to the neonatal intensive care unit, particularly those born preterm, are at high risk for infection due to the combination of an immature immune system, prolonged hospitalization, and frequent use of invasive devices. Emerging evidence suggests that multidrug-resistant gram-negative (MDR-GN) infections are increasing in neonatal settings, which directly threatens recent and ongoing advances in contemporary neonatal care. A rising prevalence of antibiotic resistance among common neonatal pathogens compounds the challenge of optimal management of suspected and confirmed neonatal infection. We review the epidemiology of MDR-GN infections in neonates in the United States and internationally, with a focus on extended-spectrum β-lactamase (ESBL)-producing Enterobacterales and carbapenem-resistant Enterobacterales (CRE). We include published single-center studies, neonatal collaborative reports, and national surveillance data. Risk factors for and mechanisms of resistance are discussed. In addition, we discuss current recommendations for empiric antibiotic therapy for suspected infections, as well as definitive treatment options for key MDR organisms. Finally, we review best practices for prevention and identify current knowledge gaps and areas for future research. IMPACT: Surveillance and prevention of MDR-GN infections is a pediatric research priority. A rising prevalence of MDR-GN neonatal infections, specifically ESBL-producing Enterobacterales and CRE, compounds the challenge of optimal management of suspected and confirmed neonatal infection. Future studies are needed to understand the impacts of MDR-GN infection on neonatal morbidity and mortality, and studies of current and novel antibiotic therapies should include a focus on the pharmacokinetics of such agents among neonates.

Prevalence and Risk Factor for Antibiotic-resistant Escherichia coli Colonization at Birth in Premature Infants: A Prospective Cohort Study

BACKGROUND

Escherichia coli causes neonatal early-onset sepsis (EOS) that is associated with high mortality and increasing antibiotic resistance. Thus, we estimated the prevalence, antibiotic susceptibility and risk factors for colonization of E. coli in premature infants at birth and characterized the pathogenicity of the isolates.

METHODS

A prospective surveillance study was conducted at three Japanese perinatal centers between August 2014 and February 2017. Infants weighing <2 kg and/or at gestational age <35 weeks at birth were enrolled. We screened the mothers and neonates for E. coli colonization. Pulsed-field gel electrophoresis was used to analyze the relatedness between the maternal and neonatal isolates. Virulence factors for the isolates were determined using polymerase chain reaction.

RESULTS

We enrolled 421 premature infants born to 382 mothers. The rate of colonization in mothers was 47.6%, comprising 5.9% extended-spectrum beta-lactamase-producing E. coli (ESBL-E) and 20.0% ampicillin-resistant strains. Ten (2.4%) infants exhibited colonization; ESBL-E and ampicillin-resistant strains colonized three and four infants, respectively. Three antibiotic-resistant, strain-positive infants developed EOS. Pulsed-field gel electrophoresis revealed vertical transmission of bacteria in four infants. Multivariate logistic regression analysis revealed that ESBL-E-positive mothers [odds ratio (OR), 19.2; 95% confidence interval (CI), 2.5-145.7)] and vaginal delivery (OR, 9.4; 95% CI, 1.7-50.7) were risk factors for neonatal colonization. The infant isolates possessed numerous virulence factors.

CONCLUSIONS

Although the prevalence of E. coli-colonized premature infants at birth was low, the rate of antibiotic resistance and the attack rate for EOS were high. Infants with ESBL-E positive mothers should be closely monitored for EOS.

Frequency of infections caused by ESBL-producing bacteria in a pediatric ward - single-center five-year observation

INTRODUCTION

Infections caused by Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs) are a serious therapeutic and clinical problem. An increasing role of ESBL(+) pathogens is observed in both community- and hospital-acquired infections. The aim of the study was to assess the incidence and the risk factors for ESBL(+) bacteria infection in a pediatric ward during a 5-year period.

MATERIAL AND METHODS

The medical documentation data of patients hospitalized in the Department of Pediatrics, Pediatric Nephrology and Allergology between 2011 and 2015 were subjected to a retrospective analysis. Cases of ESBL(+) bacterial infections were analyzed in detail.

RESULTS

0.57% (46) of all the hospitalizations (8015) during the 5-year observation period in our department were caused by ESBL (+) pathogens. It constituted 8.5% of all positive microbiological cultures obtained. The analysis revealed an increasing trend in the number of ESBL (+) infections throughout the observed period. 43.5% of patients were only asymptomatic carriers. In 71.7% urinary tract structural and functional abnormalities were present. 76.1% of patients had been hospitalized previously and 60.9% had undergone urinary tract invasive procedures.

CONCLUSIONS

The results confirm the rising trend of ESBL (+) infections during the observed period. ESBL (+) bacteria were isolated primarily in previously hospitalized children with particular reference to urinary tract invasive procedures during hospitalizations. Moreover, the study showed that patients with urogenital disorders and non-urinary chronic diseases are more susceptible to these priority pathogen infections.

Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Meningitis and Cerebral Abscess in a Neonate: Therapeutic Challenge

We report a case of a 12-day-old term neonate with extended-spectrum beta-lactamase (ESBL) producing Escherichia coli (E. coli) meningitis and cerebral abscess. The patient received a 7-day course of antibiotics just few days prior to the infection. The incidence of infections from ESBL-producing E. coli is increasingly emerging. Antimicrobial agents must be vigilantly utilized to prevent the new highly resistant bacteria.

Reassessing the need for active surveillance of extended-spectrum beta-lactamase-producing Enterobacteriaceae in the neonatal intensive care population

OBJECTIVE

To determine the continued need for active surveillance to prevent extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) transmission in a neonatal intensive care unit (NICU).

DESIGN

This retrospective observational study included patients with ESBL-E colonization or infection identified during their NICU stay at our institution between 1999 and March 2018. Active surveillance was conducted between 1999 and March 2017 by testing rectal swab specimens collected upon admission and weekly thereafter. The overall incidence rates, of ESBL-E colonization or infection (including hospital acquired) before and after active surveillance were calculated. The cost associated with active surveillance was then estimated.

RESULTS

Overall, 171 NICU patients were found to have ESBL-E colonization or infection, and 150 of those patients (87.7%) were detected by active surveillance. The overall incidence rate was 1.4 per 100 patient admissions. The hospital-acquired incidence rate was 0.41 per 1,000 patient days, and this rate had decreased since 2002, with an average of 6 cases detected annually. A significant decrease was observed in 2009 when the unit moved to a new single-bed unit featuring private rooms. Active surveillance was discontinued with no increase in the number of infections. Of the 150 ESBL-E colonized patients, 14 (9.3%) subsequently developed an infection. Active surveillance resulted in a total of 50,950 specimen collections and a cost of $127,187 for processing, an average of $848 to detect 1 ESBL-E colonized patient.

CONCLUSION

ESBL-E transmission and infection in our NICU remains uncommon. Active surveillance may have contributed to the decline of ESBL-E transmission when used in conjunction with contact precautions and private rooms, but its relatively high cost could be prohibitive.

Molecular characterization, antimicrobial resistance and clinico-bioinformatics approaches to address the problem of extended-spectrum β-lactamase-producing Escherichia coli in western Saudi Arabia

The goal of this study was to genotypically characterize extended-spectrum β-lactamase-producing Escherichia coli isolates from the western region of Saudi Arabia and to identify active antibiotics against these isolates using phenotypic and molecular modeling. In total, 211 ESBL-producing E. coli isolates recovered from heterogeneous clinical specimens were identified by MALDI-TOF. Thirty-two sequence types (STs) were identified from a multilocus sequence typing (MLST) analysis of ESBL-producing E. coli, including a novel ST (ST8162). The most common ST in the Saudi and expatriate population was ST131, followed by ST38. All the isolates were multidrug resistant (MDR), and >95% of the isolates were resistant to third-generation (ceftriaxone and ceftazidime) and fourth-generation (cefepime) cephalosporins. The ESBL-positive E. coli isolates primarily harbored the bla_CTX-M and bla_TEM genes. No resistance was observed against the carbapenem antibiotic group. All the ESBL-producing E. coli isolates were observed to be susceptible to a ceftazidime/avibactam combination. Molecular interaction analyses of the docked complexes revealed the amino acid residues crucial for the binding of antibiotics and inhibitors to the modeled CTX-M-15 enzyme. Importantly, avibactam displayed the most robust interaction with CTX-M-15 among the tested inhibitors in the docked state (∆G = −6.6 kcal/mol). The binding free energy values for clavulanate, tazobactam and sulbactam were determined to be −5.7, −5.9 and −5.2 kcal/mol, respectively. Overall, the study concludes that ‘ceftazidime along with avibactam’ should be carefully used as a treatment option against only carbapenem-resistant MDR ESBL-producing E. coli in this region.

Genetic diversity study of various β-lactamase-producing multidrug-resistant Escherichia coli isolates from a tertiary care hospital using ERIC-PCR

BACKGROUND & OBJECTIVES

The prevalence of multidrug-resistant (MDR) Escherichia coli isolates producing β-lactamase enzyme is a growing problem across the globe. Strain typing is an epidemiologically important tool not only for detecting the cross transmission of nosocomial pathogens but also for determining the source of infection. The present study was conducted to understand the clonal relationship among various β-lactamase-producing MDR E. coli isolates using enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction (PCR).

METHODS

A total of 41 MDR E. coli isolates were randomly collected from various clinical samples and processed. Isolated organisms were tested for antibiotics resistance pattern. Phenotypic detection of metallo β-lactamases (MBL) was carried out by the imipenem-ethylenediaminetetraacetic acid disc diffusion/double-disc synergy test. AmpC enzyme production was tested by a modified three-dimensional extract test.

RESULTS

Almost all isolates were found sensitive to colistin. A high percentage of drug resistance was observed in these isolates against ceftazidime (100%), cefotaxime (100%), cefepime (100%), ofloxacin (97.56%), amoxicillin/clavulanic acid (97.56%) and norfloxacin (85.36%). Of the 41 isolates, ESBL producers were found to be predominant, i.e., 22 (53.65%), followed by AmpC (6, 14.63%) and MBL (5, 12.19%).

INTERPRETATION & CONCLUSIONS

At 60 per cent similarity cut-off value, the dendrogram analysis showed that there were a total of 14 unique clusters of ERIC (CL-1 - CL-14) within the 41 E. coli isolates, which revealed the genetic diversity existing between them.

Colonization With Antimicrobial-Resistant Gram-Negative Bacilli at Neonatal Intensive Care Unit Discharge

BACKGROUND

The epidemiology of the colonization of infants with antimicrobial-resistant Gram-negative bacilli (GNB) at discharge from the neonatal intensive care unit (NICU) is not well understood.

METHODS

A multicenter study in which rectal surveillance samples for culture were obtained at NICU discharge from infants hospitalized ≥14 days was performed. Factors associated with colonization with GNB resistant to gentamicin, third/fourth-generation cephalosporin agents, or carbapenem agents were assessed by using a fixed-effects model.

RESULTS

Of these infants, 9% (119 of 1320) were colonized with ≥1 antimicrobial-resistant GNB. Prolonged treatment (≥10 days) with meropenem or third/fourth-generation cephalosporin agents or treatment for ≥5 days with a β-lactam/β-lactamase combination agent were associated with an increased risk of colonization with GNB resistant to gentamicin. Surgery and ≥5 days of treatment with third/fourth-generation cephalosporin agents, a β-lactam/β-lactamase combination agent, or metronidazole were associated with an increased risk of colonization with GNB resistant to third/fourth-generation cephalosporin agents. Female sex and prolonged treatment (≥10 days) with meropenem were associated with colonization with GNB resistant to carbapenem agents.

CONCLUSIONS

Prolonged treatment with broad-spectrum antibiotics was associated with the colonization of infants with antimicrobial-resistant GNB within 7 days of NICU discharge. These findings suggest the potential for dissemination of resistant GNB from colonized infants to other NICUs, the community, or pediatric long-term care facilities. Antimicrobial stewardship efforts aimed at improving appropriate antibiotic use could have a beneficial effect on the emergence of antimicrobial-resistant GNB in the NICU population.

Clinical and Molecular Characteristics of Neonatal Extended-Spectrum β-Lactamase-Producing Gram-Negative Bacteremia: A 12-Year Case-Control-Control Study of a Referral Center in Taiwan

Extended-spectrum β-lactamase (ESBL)-producing Gram-negative bacteremia (GNB) in the neonatal intensive care unit was characterized by comparison with two control groups: a susceptible control group and a general base population group over 2001 to 2012. The influence of ESBL production on mortality was studied in all study subjects and ESBL-GNB isolates were microbiologically characterized. We identified 77 episodes of ESBL-GNB (14.2% of all neonatal late-onset GNB), which were caused by Klebsiella spp. (62.3%), E. coli (20.8%) and Enterobacter spp. (16.9%). Most ESBL-GNB strains were genetically unrelated and the SHV-type ESBLs were the most prevalent (67% of isolates). Comparison with both control groups disclosed previous usage of 3^rd generation cephalosporin (odds ratio [OR], 4.72; 95% confidence interval [CI], 2.03–10.97; P < 0.001), and underlying renal disease (OR, 4.07; 95% CI, 1.10–15.08; P = 0.035) as independent risk factors for ESBL-GNB. Inadequate empiric antibiotics, a higher illness severity, higher rates of infectious complications and sepsis-attributable mortality were more frequently seen in neonates with ESBL-GNB than those with non-ESBL GNB (20.8% and 15.6% vs. 9.2% and 7.9%, respectively; P = 0.008 and 0.049, respectively). Neonates with underlying secondary hypertension (OR, 7.22; 95% CI, 2.17–24.06) and infectious complications after bacteremia (OR, 6.66; 95% CI, 1.81–19.31) were identified as independent risk factor for in-hospital mortality. ESBL-GNB accounted for one-seventh of all neonatal gram-negative bacteremia, especially in neonates exposed to broad-spectrum cephalosporins. Neonates with ESBL-GNB bacteremia more frequently received inadequate empirical antibiotic therapy, which were associated with a higher rate of infectious complications and an adverse outcome.

High Prevalence of Antimicrobial-resistant Gram-negative Colonization in Hospitalized Cambodian Infants

BACKGROUND

Antimicrobial-resistant Gram-negative infections are a significant cause of mortality in young infants. We aimed to determine characteristics of, and risk factors for, colonization and invasive infection caused by 3rd generation cephalosporin (3GC) or carbapenem-resistant organisms in outborn infants admitted to a neonatal unit (NU) in Cambodia.

METHODS

During the first year of operation, patients admitted to the Angkor Hospital for Children NU, Siem Reap, Cambodia, underwent rectal swabbing on admission and twice weekly until discharge. Swabs were taken also from 7 environmental sites. Swabs were cultured to identify 3GC or carbapenem-resistant Acinetobacter sp., Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa.

RESULTS

The study included 333 infants with a median age at NU admission of 10 days (range, 0-43). Colonization by ≥1 3GC-resistant organism was detected in 85.9% (286/333). Admission swabs were collected in 289 infants: 61.9% were colonized by a 3GC-resistant organism at the time of admission, and a further 23.2% were colonized during hospitalization, at a median of 4 days [95% confidence interval: 3-5]. Probiotic treatment (hazard ratio: 0.58; 95% confidence interval: 0.35-0.98) was associated with delayed colonization. Colonization by a carbapenem-resistant organism occurred in 25 (7.5%) infants. Six infants had NU-associated K. pneumoniae bacteremia; phenotypically identical colonizing strains were found in 3 infants. Environmental colonization occurred early.

CONCLUSIONS

Colonization by antimicrobial-resistant Gram-negative organisms occurred early in hospitalized Cambodian infants and was associated with subsequent invasive infection. Trials of potential interventions such as probiotics are needed.

Role of Non-Active-Site Residue Trp-93 in the Function and Stability of New Delhi Metallo-β-Lactamase 1

New Delhi metallo-β-lactamase-1 (NDM-1) is expressed by various members of Enterobacteriaceae as a defense mechanism to hydrolyze β-lactam antibiotics. Despite various studies showing the significance of active-site residues in the catalytic mechanism, there is a paucity of reports addressing the role of non-active-site residues in the structure and function of NDM-1. In this study, we investigated the significance of non-active-site residue Trp-93 in the structure and function of NDM-1. We cloned blaNDM-1 from an Enterobacter cloacae clinical strain (EC-15) and introduced the mutation of Trp-93 to Ala (yielding the Trp93Ala mutant) by PCR-based site-directed mutagenesis. Proteins were expressed and purified to homogeneity by affinity chromatography. The MICs of the Trp93Ala mutant were reduced 4- to 8-fold for ampicillin, cefotaxime, ceftazidime, cefoxitin, imipenem, and meropenem. The poor hydrolytic activity of the Trp93Ala mutant was also reflected by its reduced catalytic efficiency. The overall catalytic efficiency of the Trp93Ala mutant was reduced by 40 to 55% (the Km was reduced, while the kcat was similar to that of wild-type NDM-1 [wtNDM-1]). Heat-induced denaturation showed that the ΔGD (o) and Tm of Trp93Ala mutant were reduced by 1.8 kcal/mol and 4.8°C, respectively. Far-UV circular dichroism (CD) analysis showed that the α-helical content of the Trp93Ala mutant was reduced by 2.9%. The decrease in stability and catalytic efficiency of the Trp93Ala mutant was due to the loss of two hydrogen bonds with Ser-63 and Val-73 and hydrophobic interactions with Leu-65, Val-73, Gln-123, and Asp-124. The study provided insight into the role of non-active-site amino acid residues in the hydrolytic mechanism of NDM-1.

Resistance to Cotrimoxazole and Other Antimicrobials among Isolates from HIV/AIDS and Non-HIV/AIDS Patients at Bugando Medical Centre, Mwanza, Tanzania

Bacterial resistance has increased in the AIDS era and is attributed to the widespread use of cotrimoxazole prophylaxis against opportunistic infections in HIV/AIDS patients. In Tanzania, cotrimoxazole prophylaxis has been used for more than ten years. Little is known, however, about its impact on the spread of antibiotic resistance in HIV positive patients. This cross-sectional study was done to compare magnitude of bacterial resistance to cotrimoxazole and other antimicrobials among isolates from HIV infected patients on cotrimoxazole prophylaxis and those not on prophylaxis and non-HIV patients attending Bugando Medical Centre (BMC). Susceptibility testing on obtained urine and swab specimens followed Clinical Laboratory Standard Institute, 2010, Guidelines. Of 945 samples collected, 155 had positive bacterial growth after 24 hours of incubation. Of the positive samples (72), 46.4% were from HIV positive patients. The common isolates were E. coli 41.3% (64/155), Klebsiella pneumoniae 17.5% (27/155), and Staphylococcus aureus 16.1% (25/155). Overall, bacterial resistance to cotrimoxazole was 118 (76.1%); among isolates from HIV patients bacterial resistance was 54 (75%), and for isolates from HIV patients on prophylaxis bacterial resistance was 36 (81.3%). HIV seropositivity and cotrimoxazole prophylaxis are not associated with antibiotic resistance observed in bacteria infecting patients attending BMC, Mwanza, Tanzania.

Extended-spectrum β-lactamase-producing Enterobacteriaceae in children: old foe, emerging threat

Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae present an ever-growing burden in the hospital and community settings, across all ages and demographics. Infections due to ESBL-containing pathogens continue to be associated with significant morbidity and mortality worldwide. With widespread empiric broad-spectrum β-lactam use creating selective pressure, and the resultant emergence of stable, rapidly proliferating ESBL-producing clones with continued horizontal gene transfer across genera, addressing this issue remains imperative. Although well characterized in adults, the epidemiology, risk factors, outcomes, therapies, and control measures for ESBL-producing bacteria are less appreciated in children. This analysis provides a brief summary of ESBL-producing Enterobacteriaceae in children, with a focus on recent clinical and molecular data regarding colonization and infection in nonoutbreak settings.

A five-year experience of carbapenem resistance in Enterobacteriaceae causing neonatal septicaemia: predominance of NDM-1

Treatment of neonatal sepsis has become a challenge with the emergence of carbapenemase-producing bacteria. This study documents the trend of carbapenem susceptibility in Enterobacteriaceae that caused septicaemia in neonates over a five year period (2007-2011) and the molecular characterisation of Enterobacteriaceae resistant to carbapenems and cephalosporins. Hundred and five Enterobacteriaceae including Escherichia coli (n = 27), Klebsiella pneumoniae (n = 68) and Enterobacter spp. (n = 10) were isolated from blood of septicaemic neonates followed by antibiotic susceptibility tests, determination of MIC values, phenotypic and genotypic detection of β-lactamases. Carbapenem was the most active antimicrobial tested after tigecycline. CTX-M type was the most prevalent ESBL throughout the period (82%). New Delhi Metallo-β-lactamase-1 (NDM-1), which is a recent addition to the carbapenemase list, was the only carbapenemase identified in our setting. Fourteen percent of the isolates possessed blaNDM-1. Carbapenem non-susceptibility was first observed in 2007 and it was due to loss of Omp F/Ompk36 in combination with the presence of ESBLs/AmpCs. NDM-1 first emerged in E. coli during 2008; later in 2010, the resistance was detected in K. pneumoniae and E. cloacae isolates. NDM-1-producing isolates were resistant to other broad-spectrum antibiotics and possessed ESBLs, AmpCs, 16S-rRNA methylases, AAC(6')-Ib-cr, bleomycin resistant gene and class 1 integron. Pulsed field gel electrophoresis of the NDM-1-producing isolates indicated that the isolates were clonally diverse. The study also showed that there was a significantly higher incidence of sepsis caused by NDM-1-harbouring isolates in the male sex, in neonates with low birth weight and neonates born at an extramural centre. However, sepsis with NDM-1-harbouring isolates did not result in a higher mortality rate. The study is the first to review the carbapenem resistance patterns in neonatal sepsis over an extended period of time. The study highlights the persistence of ESBLs (CTX-Ms) and the emergence of NDM-1 in Enterobacteriaceae in the unit.

Mode of delivery and other risk factors for Escherichia coli infections in very low birth weight infants

Background

Infections in newborns remain one of the most significant problems in modern medicine. Escherichia coli is an important cause of neonatal bloodstream and respiratory tract infections and is associated with high mortality. The aim of our study was to investigate the epidemiology of E. coli infection in Polish neonatal intensive care units (NICUs) and resistance to antibiotics, with particular reference to the safety of very low birth weight infants.

Methods

Continuous prospective infection surveillance was conducted in 2009–2012 in five NICUs, including 1,768 newborns whose birth weight was <1.5 kg. Escherichia coli isolates from different diagnostic specimens including blood, tracheal/bronchial secretions and others were collected. All isolates were tested using disk diffusion antimicrobial susceptibility methods. Pulsed-field gel electrophoresis was used to determine the possible horizontal transfer of E. coli among patients.

Results

The incidence of E. coli infections was 5.4% and 2.0/1,000 patient-days. The occurrence of E. coli infections depended significantly on the NICU and varied between 3.9% and 17.9%. Multivariate analysis that took into account the combined effect of demographic data (gender, gestational age and birth weight) and place of birth showed that only the place of hospitalisation had a significant effect on the E. coli infection risk. The highest levels of resistance among all E. coli isolates were observed against ampicillin (88.8%) and amoxicillin/clavulanic acid (62.2%). Among E. coli isolates, 17.7% were classified as multidrug resistant. Escherichia coli isolates showed different pulsotypes and dominant epidemic clones were not detected.

Conclusions

Our data indicate that antibiotic prophylaxis in the presence of symptoms such as chorioamnionitis and premature rupture of membranes did not help reduce the risk of E. coli infection. Multivariate analysis demonstrated only one significant risk factor for E. coli infection among infants with a birth weight <1.5 kg, that is, the impact of the NICU, it means that both neonatal care and care during pregnancy and labour were found to be significant.

Risk factors for acquisition of extended spectrum beta lactamase producing Escherichia coli and Klebsiella pneumoniae in North-Indian hospitals

Multidrug resistance and production of extended spectrum β-lactamases (ESBLs) by enteric gram negative rods in hospitals and community continue to be a matter of scientific concern. This retrospective study was executed to assess the prevalence of ESBL-producing Escherichia coli and Klebsiella pneumoniae at two North Indian hospitals and to determine the risk factors associated with the acquisition of these organisms. A total of 346 bacterial isolates were obtained. Of these, 48.27% (n = 167) were confirmed to be ESBL producers while 51.73% (n = 179) were non ESBL-producers. Among the ESBL producers, 55.69% (n = 93) were E. coli and 44.31% (n = 74) were K. pneumoniae. ESBL producing isolates showed co-resistance to multitude of antibiotics tested. Length of hospital stay (>3 days) and previous exposure to antibiotics were found as significant risk factors (p = 0.01 and 0.02) associated with the acquisition of ESBL-producing E. coli and K. pneumoniae isolates. Imipenem and meropenem can be suggested as drugs of choice in our study.

The mother as most important risk factor for colonization of very low birth weight (VLBW) infants with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E)

OBJECTIVES

This study aimed to determine the prevalence of and risk factors for colonization with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) and methicillin-resistant Staphylococcus aureus (MRSA) in very low birth weight (VLBW; <1500 g) infants and their mothers.

METHODS

This investigation was conducted in the perinatal centre at the Charité Berlin between May 2012 and June 2013. VLBW infants and their mothers were screened for colonization with ESBL-E and MRSA. Demographic and clinical data were obtained from the German nationwide surveillance system for nosocomial infections in VLBW infants (NEO-KISS) and used to perform univariate and multivariate analyses.

RESULTS

Of 209 VLBW infants, 12 (5.7%) were colonized with ESBL-E. Eighteen of 209 (8.6%) ESBL-E-tested neonates were related to an ESBL-E-positive mother. Univariate analysis, strain typing and multivariate analysis (OR 7.4, 95% CI 2.1-26.7, P = 0.002) identified an ESBL-E-positive mother and maternal-neonatal transmission as a main source of colonization. The prevalence of MRSA was 2.3% (5 of 221) among VLBW infants. One of the 221 (0.5%) MRSA-tested neonates was related to an MRSA-positive mother. No risk factors for transmission of MRSA could be detected in this study.

CONCLUSIONS

Our study demonstrated that maternal-neonatal transmission of ESBL-E from mother to child is an important risk factor for colonization of VLBW infants. As a consequence, routine ESBL-E screening of neonates and mothers should be considered as a means of reducing neonatal morbidity and mortality.

Novel combinations of antibiotics to inhibit extended-spectrum β-lactamase and metallo-β-lactamase producers in vitro: a synergistic approach

Aim: To determine the synergistic effect of different antibiotics, alone and in combination, against extended-spectrum β-lactamase and metallo-β-lactamase producers. Materials & methods: MIC values of different antibiotics were determined for a total of 12 strains, of which nine strains were of clinical origin and the remainder were reference strains. In vitro synergy testing was performed for all the isolates using microdilution, chequerboard techniques and time-kill assays. Results: Out of the all the combinations, cefoxitin gave the highest rate of synergy by pairing up with streptomycin and cefotaxime to form effective combinations against multidrug-resistant strains of bacteria. However, the combination of cefotaxime and cefoxitin showed synergistic activity against both NDM-1-producing strains. Conclusion: Novel synergistic combinations were observed against different resistant strains, including NDM-1 producers.

Characterization of extended-spectrum-beta-lactamase-producing Escherichia coli strains involved in maternal-fetal colonization: prevalence of E. coli ST131

Maternal-fetal Escherichia coli infections, such as neonatal bacteremia and meningitis, are important causes of morbidity and mortality. From 2006 to 2010, we studied newborns and their mothers who were colonized with E. coli in a French hospital in order to document (i) the epidemiology and genetic characteristics of extended-spectrum-beta-lactamase (ESBL)-producing E. coli strains, (ii) the prevalence of associated virulence genes, (iii) the prevalence of clone sequence type 131 (ST131), and (iv) the genetic relationship among ESBL-producing strains. Among the 2,755 E. coli cultures recovered from vaginal or neonatal samples, 68 were ESBL producers (2.46%). We found a wide diversity of ESBL genes, with the majority being bla(CTX-M-14), bla(CTX-M-1), and bla(CTX-M-15), distributed among the 4 main phylogenetic groups. Genes encoding virulence factors were found in 90.7% of the isolates, with ≥ 2 virulence genes present in 76% of cases. The prevalence of ST131 among ESBL-producing E. coli isolates was 9.4% (6/64). Five of these 6 ST131 isolates possessed bla(CTX-M-15) enzymes (and also were resistant to quinolones), and one possessed bla(CTX-M-2) enzymes. Two possessed virulence genes, suggesting the presence of pathogenicity island IIJ96 (PAI IIJ96)-like domains. Pulsed-field gel electrophoresis (PFGE) revealed a high level of genomic diversity overall, except for 3 closely related isolates belonging to clonal group ST131. Repetitive PCR showed that the six ST131 isolates were closely related to ST131 control strains (>95% similarity). This study shows a high prevalence of ESBL-producing E. coli strains and clonal group ST131 in the French maternal-fetal population. These results suggest a widespread distribution of ESBL enzymes in the community and highlight the early transmission between mothers and neonates. These findings are worrisome, especially for this particularly vulnerable population.

Biochemical characterization of CTX-M-15 from Enterobacter cloacae and designing a novel non-β-lactam-β-lactamase inhibitor

The worldwide dissemination of CTX-M type β-lactamases is a threat to human health. Previously, we have reported the spread of bla_CTX-M-15 gene in different clinical strains of Enterobacteriaceae from the hospital settings of Aligarh in north India. In view of the varying resistance pattern against cephalosporins and other β-lactam antibiotics, we intended to understand the correlation between MICs and catalytic activity of CTX-M-15. In this study, steady-state kinetic parameters and MICs were determined on E. coli DH5α transformed with bla_CTX-M-15 gene that was cloned from Enterobacter cloacae (EC-15) strain of clinical background. The effect of conventional β-lactamase inhibitors (clavulanic acid, sulbactam and tazobactam) on CTX-M-15 was also studied. We have found that tazobactam is the best among these inhibitors against CTX-M-15. The inhibition characteristic of tazobactam is defined by its very low IC₅₀ value (6 nM), high affinity (K_i = 0.017 µM) and better acylation efficiency (k₊₂/K′ = 0.44 µM⁻¹s⁻¹). It forms an acyl-enzyme covalent complex, which is quite stable (k₊₃ = 0.0057 s⁻¹). Since increasing resistance has been reported against conventional β-lactam antibiotic-inhibitor combinations, we aspire to design a non-β-lactam core containing β-lactamase inhibitor. For this, we screened ZINC database and performed molecular docking to identify a potential non-β-lactam based inhibitor (ZINC03787097). The MICs of cephalosporin antibiotics in combination with this inhibitor gave promising results. Steady-state kinetics and molecular docking studies showed that ZINC03787097 is a reversible inhibitor which binds non-covalently to the active site of the enzyme through hydrogen bonds and hydrophobic interactions. Though, it’s IC₅₀ (180 nM) is much higher than tazobactam, it has good affinity for CTX-M-15 (K_i = 0.388 µM). This study concludes that ZINC03787097 compound can be used as seed molecule to design more efficient non-β-lactam containing β-lactamase inhibitor that could evade pre-existing bacterial resistance mechanisms.

New Delhi metallo-β-lactamase (NDM-1): an update

New Delhi metallo-β-lactamase (NDM-1) is a novel broad spectrum carbapenemase with ability to inactivate all β-lactams except aztreonam. However, most of the NDM-1-producers also produce aztreonam hydrolysing-β-lactamases thereby making these pathogens absolutely resistant to all β-lactams. The bla(NDM-1) gene encodes a 27.5 kDa protein of 269 amino acids. It shares very little identity with other metallo-β-lactamases. Maximum identity has been observed to VIM-1/VIM-2 (32.4%). This mini-review is an update of the scientific literature for the said enzyme. Following the recommendation of David livermore, we further propose to combine "aztreonam" and "inhibitor of the most frequently encountered aztreonam hydrolysing-β-lactamases in a given setting" as a possible strategy against NDM-1-producers. The inhibitor should be 'versatile' as well, i.e. it should have the ability to inhibit most of the variants of aztreonam hydrolysing-β-lactamases prevalent in the concerned setting. We strongly recommend surveillance studies using aztreonam/NXL-104-combination against NDM-1-producing pathogens in different geographical regions across the globe.

Prevalence and characterization of multidrug-resistant and extended-spectrum beta-lactamase-producing Escherichia coli from pediatric wards of a Malaysian hospital

The emergence of Escherichia coli resistant to extended-spectrum cephalosporins (ESCs) is of concern as ESC is often used to treat infections by Gram-negative bacteria. One-hundred and ten E. coli strains isolated in 2009-2010 from children warded in a Malaysian tertiary hospital were analyzed for their antibiograms, carriage of extended-spectrum beta-lactamase (ESBL) and AmpC genes, possible inclusion of the beta-lactamase genes on an integron platform, and their genetic relatedness. All E. coli strains were sensitive to carbapenems. About 46% of strains were multidrug resistant (MDR; i.e., resistant to ≥3 antibiotic classes) and almost half (45%) were nonsusceptible to ESCs. Among the MDR strains, high resistance rates were observed for ampicillin (98%), tetracycline (75%), and trimethoprim/sulfamethoxazole (73%). Out of 110 strains, bla(TEM-1) (49.1%), bla(CTX-M) (11.8%), and bla(CMY-2) (6.4%) were detected. Twenty-one strains were ESBL producers. CTX-M-15 was the predominant CTX-M variant found and this is the first report of a CTX-M-27-producing E. coli strain from Malaysia. Majority (3.1%) of the strains harbored class 1 integron-encoded integrases with a predominance of aadA and dfr genes within the integron variable region. No gene cassette encoding ESBL genes was found and integrons were not significantly associated with ESBL or non-ESBL producers. Possible clonal expansion was observed for few CTX-M-15-positive strains but the O25-ST131 E. coli clone known to harbor CTX-M-15 was not detected while CMY-2-positive strains were genetically diverse.

Prevalence of integrons, blaCTX-M and blaTEM resistance markers among ESBL-producing uropathogenic Escherichia coli isolates: first report of genomic blaCTX-M from India

Integrons have been observed to be frequently associated with uropathogenic bacteria. This study aimed at 1) determining the prevalence of class 1 integrons among ESBLl-producing uropathogenic Escherichia coli, and 2) analyzing resistance genes associated with different phylogenetic groups of the integron-positive isolates with special reference to bla(CTX-M) and bla(TEM). Twenty-three ESBL-producing E. coli were studied. Enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) displayed 14 major patterns. Pulse field Gel electrophoresis-typing of 8 randomly selected integron-positive strains ruled out any correlation between genotype and antibiotype. Genomic DNA from 14 strains was PCR-positive for class 1 integrons, bla(CTX-M-15) and bla(TEM-1)-like genes. Integron-sequencing revealed "aadA5-dfrA17-dfrA7" as the most prevalent gene cassette. Our findings unveil the increasing role of the bla(CTX-M) genes in antibiotic resistance and emphasize on the significance of appropriate empirical treatment for Urinary tract infections. Moreover, this is the first study which reports bla(CTX-M) located on genomic DNA of bacteria from India.

Extended-spectrum-β-lactamase-producing Escherichia coli as a cause of pediatric infections: report of a neonatal intensive care unit outbreak due to a CTX-M-14-producing strain

Little information is available about pediatric infections caused by extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli. We characterized an outbreak caused by a CTX-M-14-producing E. coli isolate in a neonatal intensive care unit (NICU) and studied other infections caused by ESBL-producing E. coli in non-NICU pediatric units. All children ≤4 years old who were infected or colonized by ESBL-producing E. coli isolates between January 2009 and September 2010 were included. Molecular epidemiology was studied by phylogroup analysis, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing. Antibiotic resistance genes were analyzed by PCR and sequencing. Plasmids were studied by PFGE with S1 nuclease digestion and by incompatibility group analysis using a PCR-based replicon-typing scheme. Of the ESBL-producing E. coli isolates colonizing or infecting the 30 newborns, identical PFGE results were observed for 21 (70%) isolates, which were classified as CTX-M-14-producing E. coli of ST23 phylogroup A. bla(CTX-M-14a) was linked to ISEcp1 and was carried on an ∼80-bp IncK plasmid. A smaller ongoing outbreak due to SHV-12-producing ST131 E. coli was also identified in the same NICU. Fifteen additional infections with ESBL-producing E. coli were identified in non-NICU pediatric units, but none was caused by the CTX-M-14-producing E. coli epidemic clone. Overall, CTX-M-14 (71.1%), CTX-M-15 (13.3%), and SHV-12 (13.3%) were the most important ESBLs causing pediatric infections in this study. Infections of newborns with CTX-M-14-producing E. coli were caused by both clonal and nonclonal isolates.