Extended-spectrum beta-lactamase-producing Enterobacteriaceae: an emerging public-health concern

Comparative genomic analysis of ESBL-selected and non-selected Escherichia coli in Australian wastewater: Elucidating differences in diversity, antimicrobial resistance, and virulence profiles

Extended-spectrum β-lactamases (ESBLs)-producing E. coli have been proposed as an indicator bacterium for antimicrobial resistance (AMR) surveillance within a OneHealth framework. However, it is important to understand the effects and potential biases ESBL-selection has on E. coli populations. Utilising whole genome sequencing, this study compared 80 ESBL-selected E. coli isolates with 201 non-selected isolates from Australian wastewater. The findings revealed significant variations between these cohorts in genetic diversity, AMR profiles, and carriage of virulence-associated genes (VAGs), plasmids, and the transmissible Locus of Stress Tolerance (tLST), a genomic island that imparts resistance to extreme heat and chlorination. The study highlights the predominance of certain sequence types (STs), particularly ST131 (75 % clade A), in ESBL-selected isolates (40 % vs 2 %) and overall the ESBL-selected isolates were largely multidrug-resistant (MDR), predominantly carrying genes for resistance to aminoglycosides, extended-spectrum β-lactams, fluoroquinolone, macrolides, sulphonamides/trimethoprim, and tetracyclines. The ESBLs identified were almost exclusively blaCTX-M genes, most commonly blaCTX-M-15 > blaCTX-M-27 > blaCTX-M-14. These were predominately carried on IncF plasmids or chromosomally (always ISEcp1 associated), in equal numbers. In contrast, 80 % of non-selected isolates carried no acquired ARGs, and none carried blaCTX-M genes. In both cohorts, extraintestinal pathogenic E. coli (ExPEC) was the dominate pathotype (35 % total) with few (4 % total) intestinal pathogenic E. coli pathotypes identified (aEPEC > ETEC > EAEC). Nevertheless, some clinically important genes were only identified in the non-selected group, namely tigecycline-resistance gene tet(X4) and AmpC ESBL blaCMY-2. Additionally, the presence of tLST, associated with higher metal resistance gene carriage (Ag, As, Cu, Hg, Ni), in a substantial portion of non-selected isolates (20 % vs 0 %), underscores environmental pressures shaping bacterial populations in wastewater ecosystems. These insights are important for developing comprehensive, less biased genomic surveillance strategies to understand and manage public health threats posed by pathogenic E. coli and AMR.

Newly isolated Drexlerviridae phage LAPAZ is physically robust and fosters eradication of Klebsiella pneumoniae in combination with meropenem

Due to the spread of multidrug resistance there is a renewed interest in using bacteriophages (briefly: phages) for controlling bacterial pathogens. The objective of this study was the characterization of a newly isolated phage (i.e. phage LAPAZ, vB_KpnD-LAPAZ), its antimicrobial activity against multidrug resistant Klebsiella pneumoniae and potential synergistic interactions with antibiotics. LAPAZ belongs to the family Drexlerviridae (genus: Webervirus) and lysed 30 % of tested strains, whereby four distinct capsular types can be infected. The genome consists of 51,689 bp and encodes 84 ORFs. The latent period is 30 min with an average burst size of 27 PFU/cell. Long-term storage experiments show that LAPAZ is significantly more stable in wastewater compared to laboratory media. A phage titre of 90 % persists up to 30 min at 50 ˚C and entire phage loss was seen only at temperatures > 66 ˚C. Besides stability against UV-C, antibacterial activity in liquid culture medium was consistent at pH values ranging from 4 to 10. Unlike exposure to phage or antibiotic alone, synergistic interactions and a complete bacterial eradication was achieved when combining LAPAZ with meropenem. In addition, synergism with the co-presence of ciprofloxacin was observed and phage resistance emergence could be delayed. Without co-addition of the antibiotic, phage resistant mutants readily emerged and showed a mixed pattern of drug sensitivity alterations. Around 88 % became less sensitive towards ceftazidime, meropenem and gentamicin. Conversely, around 44 % showed decreased resistance levels against ciprofloxacin. Whole genome analysis of a phage-resistant mutant with a 16-fold increased sensitivity towards ciprofloxacin revealed one de novo frameshift mutation leading to a gene fusion affecting two transport proteins belonging to the major facilitator-superfamily (MFS). Apparently, this mutation compromises ciprofloxacin efflux efficiency and further studies are warranted to understand how the non-mutated protein might be involved in phage-host adsorption.

Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae: insights from a tertiary hospital in Southern Thailand

Broad-spectrum ampicillin-resistant and third-generation cephalosporin-resistant Enterobacteriaceae, particularly Escherichia coli and Klebsiella pneumoniae that have pathological features in humans, have become a global concern. This study aimed to investigate the prevalence, antimicrobial susceptibility, and molecular genetic features of extended-spectrum beta-lactamase (ESBL)-producing E. coli and K. pneumoniae isolates in Southern Thailand. Between January and August 2021, samples (n = 199) were collected from a tertiary care hospital in Southern Thailand. ESBL and AmpC-lactamase genes were identified using multiplex polymerase chain reaction (PCR). The genetic relationship between ESBL-producing E. coli and K. pneumoniae was determined using the enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction. ESBL-producing E. coli and K. pneumoniae isolates were mostly collected from catheter urine samples of infected female patients. The ESBL production prevalence was highest in the medical wards (n = 75, 37.7%), followed by that in surgical wards (n = 64, 32.2%) and operating rooms (n = 19, 9.5%). Antimicrobial susceptibility analysis revealed that all isolates were resistant to ampicillin, cefotaxime, ceftazidime, ceftriaxone, and cefuroxime; 79.4% were resistant to ciprofloxacin; and 64.3% were resistant to trimethoprim-sulfamethoxazole. In ESBL-producing K. pneumoniae and E. coli, blaTEM (n = 57, 72.2%) and blaCTX-M (n = 61, 50.8%) genes were prominent; however, no blaVEB, blaGES, or blaPER were found in any of these isolates. Furthermore, only ESBL-producing K. pneumoniae had co-harbored blaTEM and blaSHV genes at 11.6%. The ERIC-PCR pattern of multidrug-resistant ESBL-producing strains demonstrated that the isolates were clonally related (95%). Notably, the presence of multidrug-resistant and extremely resistant ESBL producers was 83.4% and 16.6%, respectively. This study highlights the presence of blaTEM, blaCTX-M, and co-harbored genes in ESBL-producing bacterial isolates from hospitalized patients, which are associated with considerable resistance to beta-lactamase and third-generation cephalosporins.

IMPORTANCE

We advocate for evidence-based guidelines and antimicrobial stewardship programs to encourage rational and appropriate antibiotic use, ultimately reducing the selection pressure for drug-resistant bacteria and lowering the likelihood of ESBL-producing bacterial infections.

Antimicrobial Resistance in Uropathogenic Escherichia coli Strains Isolated from Relapses from Recurrent Urinary Tract Infections

Little is known about the characteristics of uropathogenic Escherichia coli (UPEC) associated with recurrent urinary tract infections (RUTIs). The present study aimed to analyze the phenotypic antimicrobial resistance of recurrent UPEC isolates attributable to either relapse or reinfection. A total of 140 E. coli strains were isolated from 70 outpatients with RUTIs. All isolates were analyzed by random amplified polymorphic DNA-polymerase chain reaction to evaluate genetic similarity between the first and second isolates. We found that 64.2% (45/70) of outpatients had a relapse with the primary infecting E. coli strain and 35.7% (25/70) had reinfection with a new E. coli strain. Compared with reinfecting strains, relapse UPEC isolates exhibited much higher antimicrobial resistance; 89% of these isolates were multidrug-resistant and 46.6% were extended-spectrum β-lactamase producers. Our study provides evidence that RUTIs are mainly driven by the persistence of the original strain in the host (relapses) despite appropriate antibiotic treatments, and only RUTIs attributed to relapses seem to favor multidrug resistance in UPEC isolates.

First Report on the Occurrence and Antibiotic Resistance Profile of Colistin-Resistant Escherichia coli in Raw Beef and Cow Feces in Vietnam

Colistin-resistant Escherichia coli (COE) has been recently recognized as a serious threat to animal and human health. This study aimed to determine the prevalence and antibiotic resistance profile of COE isolated from raw beef and cow feces in Vietnam. Our results showed that 16% (16/100) and 32% (32/100) of raw beef and cow feces samples were positive for COE, respectively. A total of 48 COE strains were isolated, with 16 originating from raw beef and 32 from cow feces samples. The antibiotic susceptibility test revealed that the COE isolates were highly resistant to ampicillin, tetracycline, florfenicol, trimethoprim/sulfamethoxazole, streptomycin, and nalidixic acid, with resistance rates ranging from 66.67% to 87.5%. In addition, 87.5% of the isolates were identified to be multidrug-resistant strains. Further molecular characterization indicated that all COE isolates carried the mcr-1 gene, with 16 of them also harboring blaCTX-M-55 genes. Taken together, the findings in this study demonstrate that raw beef and cow feces are important sources of COE, which can be potentially transmitted to humans through the food chain.

Antimicrobial resistance and phylogenetic relatedness of extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli in peridomestic rats (Rattus norvegicus and Rattus tanezumi) linked to city areas and animal farms in Hong Kong

Extended-spectrum β-lactamase-producing Escherichia (E.) coli (ESBL-EC) in the clinical setting have emerged as a major threat to public and animal health. Wildlife, including Rattus spp. may serve as reservoirs and spreaders of ESBL-EC in the environment. Peridomestic rats are well adapted to living in proximity to humans and animals in a variety of urban and agricultural environments and may serve as sentinels to identify variations of ESBL-EC within their different habitats. In this study, a set of 221 rats (Rattus norvegicus, R. tanezumi, R. andamanensis, and Niviventer huang) consisting of 104 rats from city areas, 44 from chicken farms, 52 from pig farms, and 21 from stables of horse-riding schools were screened for ESBL-EC. Overall, a total of 134 ESBL-EC were isolated from the caecal samples of 130 (59%) rats. The predominant blaESBL genes were blaCTX-M-14, blaCTX-M-15, blaCTX-M-55, and blaCTX-M-65. Phylogenetic analysis revealed a total of 62 sequence types (STs) and 17 SNP clusters. E. coli ST10 and ST155 were common to ESBL-EC from city areas and chicken farms, and ST44 were found among ESBL-EC from city areas and pig farms. Extra-intestinal pathogenic E. coli (ExPEC) ST69, ST131 and ST1193 were found exclusively among rats from city areas, and avian pathogenic E. coli (APEC) ST177 was restricted to ESBL-EC originating from chicken farms. Phylogenetic analysis showed that the populations of rodent ESBL-EC from city areas, chicken farms and pig farms were genetically different, suggesting a certain degree of partitioning between the human and animal locations. This study contributes to current understanding of ESBL-EC occurring in rats in ecologically diverse locations.

Effectiveness of oral antibiotics in managing extended-spectrum B-lactamase urinary tract infections: A retrospective analysis

Background

Urinary tract infections caused by extended-spectrum beta-lactamase organisms pose a significant concern worldwide. Given the escalating prevalence of drug resistance and the limited data on the effectiveness of oral antibiotics in treating these infections, this study aimed to assess the clinical outcomes in adult patients with extended-spectrum beta-lactamase urinary tract infections treated with oral antibiotics.

Methods

A retrospective observational cohort study was conducted at King Abdulaziz Medical City, Saudi Arabia, from January 2018 to December 2021. It included patients ⩾18 years with complicated or uncomplicated urinary tract infections from extended-spectrum beta-lactamase Enterobacterales and treated with oral antibiotics as step-down or mainstay therapy. All-cause clinical failure within 30 days post-discharge was evaluated as the efficacy outcome. Statistical analyses were performed using SPSS software.

Results

Out of 643 screened patients, 152 patients met the inclusion criteria. The patients were divided into oral step-down therapy (51.3%) and oral-only (48.7%) groups. The majority (69.1%) were females, with a mean age of 62 years. Complicated urinary tract infections were diagnosed in (75.5%) of cases, and the predominant pathogen was E. coli (79.6%). Clinical failure was observed in 23.1% in the oral step-down group and 13.5% in the oral-only group, with no significant difference (p = 0.128). Total antibiotics duration was significantly lower in the oral-only group (8 days vs. 12.2 days; p < 0.001). Binary logistic regression identified elder age, diabetes mellitus history, and prior extended-spectrum beta-lactamase infection as predictors of clinical failure.

Conclusion

This study suggests that both step-down or primary oral antibiotic treatment yielded similar clinical outcomes in managing patients with extended-spectrum beta-lactamase urinary tract infections. Further prospective studies are required to validate these findings.

Type IV-A3 CRISPR-Cas systems drive inter-plasmid conflicts by acquiring spacers in trans

Plasmid-encoded type IV-A CRISPR-Cas systems lack an acquisition module, feature a DinG helicase instead of a nuclease, and form ribonucleoprotein complexes of unknown biological functions. Type IV-A3 systems are carried by conjugative plasmids that often harbor antibiotic-resistance genes and their CRISPR array contents suggest a role in mediating inter-plasmid conflicts, but this function remains unexplored. Here, we demonstrate that a plasmid-encoded type IV-A3 system co-opts the type I-E adaptation machinery from its host, Klebsiella pneumoniae (K. pneumoniae), to update its CRISPR array. Furthermore, we reveal that robust interference of conjugative plasmids and phages is elicited through CRISPR RNA-dependent transcriptional repression. By silencing plasmid core functions, type IV-A3 impacts the horizontal transfer and stability of targeted plasmids, supporting its role in plasmid competition. Our findings shed light on the mechanisms and ecological function of type IV-A3 systems and demonstrate their practical efficacy for countering antibiotic resistance in clinically relevant strains.

Urinary Tract Infections among Febrile Infants in Qatar: Extended-Spectrum-Beta-Lactamase (ESBL)-Producing Versus Non-ESBL Organisms

BACKGROUND

The escalating prevalence of ESBL-producing Enterobacteriaceae in Qatar's pediatric population, especially in community-onset febrile urinary tract infections (FUTIs), necessitates a comprehensive investigation into this concerning trend.

RESULTS

Over the course of one year, a total of 459 infants were diagnosed and subsequently treated for UTIs. Cases primarily occurred in infants aged over 60 days, predominantly non-Qatari females born from term pregnancies. Notably, E. coli and K. pneumoniae were the most frequently identified organisms, accounting for 79.7% and 9.8% in the ESBL group and 57.2% and 18.7% in the non-ESBL group, respectively. Interestingly, hydronephrosis emerged as the most prevalent urological anomaly detected in both ESBL (n = 10) and other organism (n = 19) groups.

METHODS

In this retrospective cohort study conducted in Qatar, we meticulously evaluated the prevalence of pediatric FUTIs. Our study focused on febrile infants aged less than 1 year, excluding those with urine samples not obtained through a catheter.

CONCLUSIONS

E. coli and K. pneumoniae prevailed as the predominant causative agents in febrile children in Qatar, with hydronephrosis being identified as the most common urological anomaly. Moreover, our findings suggested that gentamicin served as a viable non-carbapenem option for hospitalized ESBL cases, while oral nitrofurantoin showed considerable promise for uncomplicated ESBL UTIs.

Infrared spectroscopy-based machine learning algorithms for rapid detection of Klebsiella pneumoniae isolated directly from patients' urine and determining its susceptibility to antibiotics

Among the most prevalent and detrimental bacteria causing urinary tract infections (UTIs) is Klebsiella (K.) pneumoniae. A rapid determination of its antibiotic susceptibility can enhance patient treatment and mitigate the spread of resistant strains. In this study, we assessed the viability of using infrared spectroscopy-based machine learning as a rapid and precise approach for detecting K. pneumoniae bacteria and determining its susceptibility to various antibiotics directly from a patient's urine sample. In this study, 2333 bacterial samples, including 636 K. pneumoniae were investigated using infrared micro-spectroscopy. The obtained spectra (27996spectra) were analyzed with XGBoost classifier, achieving a success rate exceeding 95 % for identifying K. pneumoniae. Moreover, this method allows for the simultaneous determination of K. pneumoniae susceptibility to various antibiotics with sensitivities ranging between 74 % and 81 % within approximately 40 min after receiving the patient's urine sample.

Genome Sequences of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Recovered from Mid-Stream Urine Samples in Accra, Ghana

Escherichia coli, a member of the commensal intestinal microbiota, is a significant aetiology of urinary tract infections (UTIs) and has a propensity for acquiring multidrug resistance characteristics, such as extended-spectrum beta-lactamases (ESBLs). Despite the increase in the incidence of ESBL-producing E. coli infections in sub-Saharan Africa, routine ESBL detection in Ghana is often absent, and molecular data on ESBL genotypes is scarce. Eleven ESBL-producing E. coli recovered from mid-stream urine samples were subjected to antimicrobial susceptibility testing and whole-genome sequence analyses. All isolates exhibited multidrug resistance, demonstrating phenotypic resistance to third-generation cephalosporins, such as cefotaxime, ceftazidime, and cefpodoxime. Three isolates demonstrated resistance to norfloxacin (a fluoroquinolone), and one isolate demonstrated intermediate resistance to ertapenem (a carbapenem). Analysis of the draft genomes identified multiple antimicrobial resistance genes including ESBL genotypes blaTEM-1B/TEM-190 (6/11 and 1/11, respectively), blaCTX-M-15/CTX-M-3 (7/11 and 1/11) and blaOXA-1/OXA-181 (3/11 and 1/11). The strains belong to 10 different serotypes and 10 different multilocus sequence types. This study provides information on phenotypic resistance in 11 ESBL E. coli from Ghana and AMR genotypes within their genomes.

Protocol for surveillance of antimicrobial-resistant bacteria causing community-acquired urinary tract infections in low-income countries

The spread of drug-resistant bacteria into the community is an urgent threat. In most low-middle-income countries (LMICs) settings, community-acquired infection (CAI) is empirically treated with no data to support the choice of antibiotics, hence contributing to resistance development. Continuous antimicrobial resistance (AMR) data on community-acquired pathogens are needed to draft empirical treatment guidelines, especially for areas with limited culture and susceptibility testing. Despite the importance of addressing antibiotic-resistant pathogens in the community setting, protocols for the surveillance of AMR bacterial infections are lacking in most (LMICs). We present a protocol for surveillance of AMR in LMICs using urinary tract infection (UTI) as a proxy for CAI to enable users to quantify and establish the drivers of AMR bacteria causing UTI. The protocol intends to assist users in designing a sustainable surveillance program for AMR in the community involving children above two years of age and adults presenting to a primary health facility for healthcare. Implementation of the protocol requires initial preparation of the laboratories to be involved, surveillance areas, selection of priority bacteria and antimicrobials to be used, and the design of a coordinated sampling plan. Recruitment should occur continuously in selected health facilities for at least 12 months to observe seasonal trends of AMR. At least 10 mL of clean-catch mid-stream urine must be collected into 20 mL calibrated sterile screw-capped universal bottles lined with 0.2 mg boric acid and transported to the testing laboratory. Utilise the data system that generates standard reports for patient care to be shared internally and externally in the regions and the world through global platforms such as the Global Antimicrobial Resistance Surveillance System.

Monitoring ESBL-Escherichia coli in Swiss wastewater between November 2021 and November 2022: insights into population carriage

Antimicrobial resistance (AMR) poses a global health threat, causing millions of deaths annually, with expectations of increased impact in the future. Wastewater surveillance offers a cost-effective, non-invasive tool to understand AMR carriage trends within a population. We monitored extended-spectrum β-lactamase producing Escherichia coli (ESBL-E. coli) weekly in influent wastewater from six wastewater treatment plants (WWTPs) in Switzerland (November 2021 to November 2022) to investigate spatio-temporal variations, explore correlations with environmental variables, develop a predictive model for ESBL-E. coli carriage in the community, and detect the most prevalent ESBL-genes. We cultured total and ESBL-E. coli in 300 wastewater samples to quantify daily loads and percentage of ESBL-E. coli. Additionally, we screened 234 ESBL-E. coli isolates using molecular methods for the presence of 18 ESBL-gene families. We found a population-weighted mean percentage of ESBL-E. coli of 1.9% (95% confidence interval: 1.8-2%) across all sites and weeks, which can inform ESBL-E. coli carriage. Concentrations of ESBL-E. coli varied across WWTPs and time, with higher values observed in WWTPs serving larger populations. Recent precipitations (previous 24/96 h) showed no significant association with ESBL-E. coli, while temperature occasionally had a moderate impact (P < 0.05, correlation coefficients approximately 0.40) in some locations. We identified blaCTX-M-1, blaCTX-M-9, and blaTEM as the predominant ESBL-gene families. Our study demonstrates that wastewater-based surveillance of culturable ESBL-E. coli provides insights into AMR trends in Switzerland and may also inform resistance. These findings establish a foundation for long term, nationally established monitoring protocols and provide information that may help inform targeted public health interventions.

IMPORTANCE

Antimicrobial resistance (AMR) is a global health threat and is commonly monitored in clinical settings, given its association with the risk of antimicrobial-resistant infections. Nevertheless, tracking AMR within a community proves challenging due to the substantial sample size required for a representative population, along with high associated costs and privacy concerns. By investigating high resolution temporal and geographic trends in extended-spectrum beta-lactamase producing Escherichia coli in wastewater, we provide an alternative approach to monitor AMR dynamics, distinct from the conventional clinical settings focus. Through this approach, we develop a mechanistic model, shedding light on the relationship between wastewater indicators and AMR carriage in the population. This perspective contributes valuable insights into trends of AMR carriage, emphasizing the importance of wastewater surveillance in informing effective public health interventions.

Comparison of CTX-M encoding plasmids present during the early phase of the ESBL pandemic in western Sweden

Plasmids encoding blaCTX-M genes have greatly shaped the evolution of E. coli producing extended-spectrum beta-lactamases (ESBL-E. coli) and adds to the global threat of multiresistant bacteria by promoting horizontal gene transfer (HGT). Here we screened the similarity of 47 blaCTX-M -encoding plasmids, from 45 epidemiologically unrelated and disperse ESBL-E. coli strains, isolated during the early phase (2009-2014) of the ESBL pandemic in western Sweden. Using optical DNA mapping (ODM), both similar and rare plasmids were identified. As many as 57% of the plasmids formed five ODM-plasmid groups of at least three similar plasmids per group. The most prevalent type (28%, IncIl, pMLST37) encoded blaCTX-M-15 (n = 10), blaCTX-M-3 (n = 2) or blaCTX-M-55 (n = 1). It was found in isolates of various sequence types (STs), including ST131. This could indicate ongoing local HGT as whole-genome sequencing only revealed similarities with a rarely reported, IncIl plasmid. The second most prevalent type (IncFII/FIA/FIB, F1:A2:B20) harboring blaCTX-M-27, was detected in ST131-C1-M27 isolates, and was similar to plasmids previously reported for this subclade. The results also highlight the need for local surveillance of plasmids and the importance of temporospatial epidemiological links so that detection of a prevalent plasmid is not overestimated as a potential plasmid transmission event in outbreak investigations.

The risk factors, antimicrobial resistance patterns, and outcomes associated with extended-spectrum β-lactamases-Producing pathogens in pediatric urinary tract infection

BACKGROUND

Extended-spectrum β-lactamases-producing Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis (ESBL-producing-EKP) are an increasingly common cause of childhood urinary tract infection (UTI) worldwide. Recognizing the risk factors and antimicrobial resistance patterns may guide new management in this population.

METHODS

This is a retrospective cohort study of over 5 years in Taiwan (2017-2021). Inclusion criteria are hospitalized pediatric patients with the discharge diagnosis of UTI caused by E. coli, Klebsiella pneumoniae, or Proteus mirabilis. ESBL-producing-EKP and non-ESBL-producing-EKP UTI cases were reviewed for characteristics, urinary isolate antibiotics resistance, and clinical outcomes.

RESULTS

The incidence rate of ESBL-producing-EKP UTI increased over the study period (Overall incidence rate: 14.1 %, 46/327 patients). Recent antibiotic therapy in ≤6 months (X2 = 11.83, p < 0.01) and a preterm gestational history (X2 = 8.11, p < 0.05) were associated with an increased risk. The proportion of patients with these two risk factors for ESBL acquisition were 37.5 % (X2 = 9.08, p < 0.05). The co-resistance rate of ESBL-producing-EKP to other antimicrobial agents was 63.0 % for gentamicin, 56.5 % for trimethoprim-sulfamethoxazole, 52.2 % for ciprofloxacin, 4.3 % for amikacin, and 2.2 % for imipenem. The generalized linear model analysis identified a significantly longer length of stay (β: 2.85; 95 % confidence interval [CI]: 1.14-4.56; p < 0.01) and intensive care unit duration (β: 5.86; 95 % CI: 1.59-10.12; p < 0.01) among patients with ESBL-producing-EKP UTI.

CONCLUSION

Amikacin should be considered as an alternative antimicrobial choice beyond carbapenems for ESBL-producing-EKP UTI, especially in the context of carbapenem-resistant E. coli/Klebsiella pneumoniae (CRE/CRKP) emergence.

Extended-spectrum beta-lactamases in clinical isolates of Escherichia coli and Klebsiella pneumoniae recovered from patients at the Tamale Teaching Hospital, Ghana

INTRODUCTION

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae are pathogens of significant public health interest for which new antibiotics are urgently needed.

AIM

To determine the prevalence of ESBLs in E. coli and K. pneumoniae isolates from patients attending the Tamale Teaching Hospital (TTH) in Ghana.

METHODOLOGY

The study was a cross-sectional study involving convenience sampling of E. coli and K. pneumoniae isolates from consenting patients' clinical specimens, between April and June 2015. Antimicrobial susceptibility test was performed, and ESBL-producer phenotypes were further screened for BlaTEM, BlaSHV, and BlaCTX-M genes. Patients' clinical data were additionally collected using a structured questionnaire.

RESULTS

Of the 150 non-duplicate E. coli and K. pneumoniae isolates identified, 140 were confirmed as E. coli (84%, n = 117) and K. pneumoniae (16%, n = 23). Of these, sixty-two (44%) [E. coli (84%; n = 52); K. pneumoniae (16%; n = 10)] phenotypically expressed ESBLs. The proportion of ESBL-producing isolates was higher in adults (15-65 years) than in neonates (< 28 days) (p = 0.14). Most of the isolates showed a high percentage resistance to ampicillin (96%) and tetracycline (89%), but a relatively lower resistance to amikacin (36%). No isolate was resistant to meropenem. More ESBL producers were multidrug resistant compared to non-ESBL-producers [23% (14/62) versus 18% (14/78); p = 0.573]. Overall, 74% (n = 46) of the ESBL genotypes expressed BlaCTX-M-1 genes, followed by 63% (n = 39) BlaTEM, and 16% (n = 10) BlaSHV. The study showed a high prevalence of ESBL-positive E. coli and K. pneumoniae, mostly CTX-M-1 producers at TTH.

CONCLUSION

Routine laboratory ESBL screening is warranted to inform patient management.

Phenotypic and molecular characterization of multi-drug resistant Klebsiella spp. isolates recovered from clinical settings

Klebsiella pneumoniae is a Gram-negative bacterium that colonizes the gastrointestinal tract and nasopharynx with many being linked to nosocomial infections. Extended-spectrum β-lactamases (ESBL)-producing and carbapenem-resistant K. pneumoniae is recognized by the World Health Organization (WHO) as a critical public health concern. In this study, whole-genome sequencing (WGS) - based analysis was performed to understand the molecular epidemiology of multi-drug resistant Klebsiella spp. clinical isolates. Genome comparison, multi-locus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and whole-genome-SNP-based phylogenetic analysis (wg-SNP) were used for in-depth molecular characterization. in silico typing was used to determine the resistance genes, virulence factors, Inc. groups, and capsular types. All except one isolate were non-susceptible to meropenem and 89% were non-susceptible to ertapenem and imipenem. blaNDM, blaOXA-48, and blaKPC were the detected carbapenemases with blaNDM-1 found in half of the sequenced genomes. Resistance to colistin was detected in one isolate and was linked to several genetic alterations in crrB, pmrB, and pmrC genes. The most common plasmid type was IncFIB followed by IncR, and the Type 3 fimbriae, encoded by the mrkABCDF operon, was conserved among all isolates. The most common sequence- (ST) and K-type detected were ST147 and K64. The prevelance and the genomic relatedness of ST147 isolates, as shown by the data from SNP-based phylogenetic analysis, PFGE, and genomic clustering, may be an outbreak marker. However, this can only be validated through a more comprehensive study encompassing a wider sampling scheme and over an extended timeframe.

Carbapenem-resistant Gram-negative bacteria (CR-GNB) in ICUs: resistance genes, therapeutics, and prevention - a comprehensive review

Intensive care units (ICUs) are specialized environments dedicated to the management of critically ill patients, who are particularly susceptible to drug-resistant bacteria. Among these, carbapenem-resistant Gram-negative bacteria (CR-GNB) pose a significant threat endangering the lives of ICU patients. Carbapenemase production is a key resistance mechanism in CR-GNB, with the transfer of resistance genes contributing to the extensive emergence of antimicrobial resistance (AMR). CR-GNB infections are widespread in ICUs, highlighting an urgent need for prevention and control measures to reduce mortality rates associated with CR-GNB transmission or infection. This review provides an overview of key aspects surrounding CR-GNB within ICUs. We examine the mechanisms of bacterial drug resistance, the resistance genes that frequently occur with CR-GNB infections in ICU, and the therapeutic options against carbapenemase genotypes. Additionally, we highlight crucial preventive measures to impede the transmission and spread of CR-GNB within ICUs, along with reviewing the advances made in the field of clinical predictive modeling research, which hold excellent potential for practical application.

Unusual and complicated peritonitis: Your questions answered

Effective treatment of infections is a growing challenge owing to antimicrobial resistance. Peritoneal dialysis (PD) patients experience more frequent hospitalisations than the general population and have greater exposure to antibiotics, making them particularly vulnerable to this threat. Over the last decade, we have noted a surge in cases of complicated peritoneal dialysis-associated peritonitis (PD peritonitis) caused by antimicrobial-resistant organisms, including extended-spectrum beta-lactamase (ESBL), AmpC beta-lactamase-producing Enterobacterales, Pseudomonas aeruginosa and fungi. Practitioners must be alert to these organisms, seek early recognition of these resistance patterns and make timely adjustments in order to avoid delay in treatment that may increase risk of PD catheter removal and technique failure. We present a case of successful treatment of ESBL peritonitis, highlight its challenges, while providing guidance on management of other unusual and complicated PD peritonitis.

Multidrug resistance plasmids commonly reprogram the expression of metabolic genes in Escherichia coli

Multidrug-resistant Escherichia coli is a leading cause of global mortality. Transfer of plasmids carrying genes encoding beta-lactamases, carbapenamases, and colistin resistance between lineages is driving the rising rates of hard-to-treat nosocomial and community infections. Multidrug resistance (MDR) plasmid acquisition commonly causes transcriptional disruption, and while a number of studies have shown strain-specific fitness and transcriptional effects of an MDR plasmid across diverse bacterial lineages, fewer studies have compared the impacts of different MDR plasmids in a common bacterial host. As such, our ability to predict which MDR plasmids are the most likely to be maintained and spread in bacterial populations is limited. Here, we introduced eight diverse MDR plasmids encoding resistances against a range of clinically important antibiotics into E. coli K-12 MG1655 and measured their fitness costs and transcriptional impacts. The scale of the transcriptional responses varied substantially between plasmids, ranging from >650 to <20 chromosomal genes being differentially expressed. However, the scale of regulatory disruption did not correlate significantly with the magnitude of the plasmid fitness cost, which also varied between plasmids. The identities of differentially expressed genes differed between transconjugants, although the expression of certain metabolic genes and functions were convergently affected by multiple plasmids, including the downregulation of genes involved in L-methionine transport and metabolism. Our data show the complexity of the interaction between host genetic background and plasmid genetic background in determining the impact of MDR plasmid acquisition on E. coli.

IMPORTANCE

The increase in infections that are resistant to multiple classes of antibiotics, including those isolates that carry carbapenamases, beta-lactamases, and colistin resistance genes, is of global concern. Many of these resistances are spread by conjugative plasmids. Understanding more about how an isolate responds to an incoming plasmid that encodes antibiotic resistance will provide information that could be used to predict the emergence of MDR lineages. Here, the identification of metabolic networks as being particularly sensitive to incoming plasmids suggests the possible targets for reducing plasmid transfer.

Antimicrobials: An update on new strategies to diversify treatment for bacterial infections

Ninety-five years after Fleming's discovery of penicillin, a bounty of antibiotic compounds have been discovered, modified, or synthesised. Diversification of target sites, improved stability and altered activity spectra have enabled continued antibiotic efficacy, but overwhelming reliance and misuse has fuelled the global spread of antimicrobial resistance (AMR). An estimated 1.27 million deaths were attributable to antibiotic resistant bacteria in 2019, representing a major threat to modern medicine. Although antibiotics remain at the heart of strategies for treatment and control of bacterial diseases, the threat of AMR has reached catastrophic proportions urgently calling for fresh innovation. The last decade has been peppered with ground-breaking developments in genome sequencing, high throughput screening technologies and machine learning. These advances have opened new doors for bioprospecting for novel antimicrobials. They have also enabled more thorough exploration of complex and polymicrobial infections and interactions with the healthy microbiome. Using models of infection that more closely resemble the infection state in vivo, we are now beginning to measure the impacts of antimicrobial therapy on host/microbiota/pathogen interactions. However new approaches are needed for developing and standardising appropriate methods to measure efficacy of novel antimicrobial combinations in these contexts. A battery of promising new antimicrobials is now in various stages of development including co-administered inhibitors, phages, nanoparticles, immunotherapy, anti-biofilm and anti-virulence agents. These novel therapeutics need multidisciplinary collaboration and new ways of thinking to bring them into large scale clinical use.

Quantification of β-lactamase producing bacteria in German surface waters with subsequent MALDI-TOF MS-based identification and β-lactamase activity assay

Environmental oligotrophic bacteria are suspected to be highly relevant carriers of antimicrobial resistance (AMR). However, there is a lack of validated methods for monitoring in the aquatic environment. Since extended-spectrum β-lactamases (ESBLs) play a particularly important role in the clinical sector, a culturing method based on R2A-medium spiked with different combinations of β-lactams was applied to quantify β-lactamase-producing environmental bacteria from surface waters. In German surface water samples (n = 28), oligotrophic bacteria ranging from 4.0 × 103 to 1.7 × 104 CFU per 100 mL were detected on the nutrient-poor medium spiked with 3rd generation cephalosporins and carbapenems. These numbers were 3 log10 higher compared to ESBL-producing Enterobacteriales of clinical relevance from the same water samples. A MALDI-TOF MS identification of the isolates demonstrated, that the method leads to the isolation of environmentally relevant strains with Pseudomonas, Flavobacterium, and Janthinobacterium being predominant β-lactam resistant genera. Subsequent micro-dilution antibiotic susceptibility tests (Micronaut-S test) confirmed the expression of β-lactamases. The qPCR analysis of surface waters DNA extracts showed the presence of β-lactamase genes (blaTEM, blaCMY-2, blaOXA-48, blaVIM-2, blaSHV, and blaNDM-1) at concentrations of 3.7 (±1.2) to 1.0 (±1.9) log10 gene copies per 100 mL. Overall, the results demonstrate a widespread distribution of cephalosporinase and carbapenemase enzymes in oligotrophic environmental bacteria that have to be considered as a reservoir of ARGs and contribute to the spread of antibiotic resistance.

Detection of CTX-M-15 ESBL in XDR Haemophilus parainfluenzae from a urethral swab

OBJECTIVES

Haemophilus parainfluenzae is an opportunistic pathogen causing respiratory tract infection and sexually transmitted diseases. The emergence of multidrug resistance in this species is particularly worrisome, especially since the recent description of CTX-M-15 ESBL-producing isolates in Spain. The aim of this study was to characterize a CTX-M-15-producing H. parainfluenzae clinical isolate, HP01, obtained from a urethral swab.

METHODS

MICs were determined with gradient strips for this isolate. Hydrolysis assays were performed with the β LACTA test. Genomic DNA from HP01 was subjected to Illumina and Oxford Nanopore sequencing to investigate the genetic environment of blaCTX-M-15. Phylogenetic analysis was performed with available H. parainfluenzae genomes from the NCBI database, including CTX-M-15 producers.

RESULTS

HP01, an XDR isolate, was resistant to penicillin, third-generation cephalosporins, fluoroquinolones, macrolides, cyclines and co-trimoxazole and susceptible only to carbapenems and rifampicin. HP01 carried blaTEM-1, blaCTX-M-15, tet(M), catS and mef(E)/mel and harboured amino acid substitutions in PBP3, PBP5, GyrA, ParC and FolA implicated in resistance. Genomic analysis revealed that blaCTX-M-15 was carried by a Tn3-like transposon inserted into a novel integrative and conjugative element (ICE), ICEHpaSLS, present on the chromosome and belonging to the ICEHin1056 family described in Haemophilus influenzae. The tet(M)-MEGA element was also detected on the chromosome. No plasmid was found. The phylogenetic analysis showed that four H. parainfluenzae producing CTX-M-15 clustered in the same clade.

CONCLUSIONS

Here we report the description of an XDR H. parainfluenzae producing blaCTX-M-15 isolated from a urethral swab. The blaCTX-M-15 gene was inserted into an ICE structure similar to those recently described in CTX-M-15 producers in Spain. The emergence of XDR H. parainfluenzae producing blaCTX-M-15 is a matter of great concern. Careful surveillance is required to prevent its spread.

Epidemiology and molecular characterization of CTX-M-type ESBLs producing Escherichia coli isolated from clinical settings

OBJECTIVES

Recently, blaCTX-Ms have become the dominant ESBLs for E. coli strains worldwide. We aim to provide a systematic study on the relationships between sequence types (STs), clinical origins, and the blaCTX-Ms genotypes of E. coli strains.

METHODS

Totally, 1005 complete sequences of clinical E. coli were collected from NCBI. Multilocus sequence typing (MLST) and antibiotic resistance genes screening were performed.

RESULTS

Faeces (26.27%), urine (16.02%), and blood (8.26%) were shown to be the main sources of clinical E. coli isolates. The isolates belong to 153 STs and 26 clonal complexes (CCs). The most prevalent STs were ST2 (11.3%), ST43 (8.6%), and ST8 (5.7%). The positive rate for blaCTX-Ms was 34.7%. Different samples showed significantly different blaCTX-Ms positive rates (P<0.05). The main genotypes were blaCTX-M-55-like (47.6%), blaCTX-M-1-like (31.8%), and blaCTX-M-2-like (22.1%). The majority of ST2 strains had blaCTX-M-55-like genes. In ST8 strains, there was a homogeneous distribution of blaCTX-M-9, blaCTX-M-65, blaCTX-M-55, blaCTX-M-2, and blaCTX-M-1. Only ST43 strains exhibited the presence of blaCTX-M-79. The blaCTX-Ms showed a pattern of cross-continental transmission with intra-regional spread. Among the 349 blaCTX-Ms-producing E. coli strains, 148 strains also carried carbapenem resistance genes, including blaNDM (119, 34.1%), blaKPC (16, 4.6%), blaOXA-48 (9, 2.6%) and blaIMP (4, 1.1%). Also, 81 strains carried the mcr gene (23.2%).

CONCLUSIONS

E. coli has become increasingly rich in blaCTX-Ms genotypes. Our findings about the connection between E. coli STs and blaCTX-Ms can be utilized to identify E. coli strains with high potential to spread drug resistance in the future.

Efficacy of cefoperazone/sulbactam for ESBL-producing Escherichia coli and Klebsiella pneumoniae bacteraemia and the factors associated with poor outcomes

OBJECTIVE

We aimed to assess the efficacy of cefoperazone/sulbactam (CPZ/SUL) in extended-spectrum β-lactamase (ESBL)-producing Enterobacterales infections and identify factors influencing outcomes.

METHODS

This retrospective multicentre study was conducted in Taiwan (January 2015 to December 2020) and examined the efficacy of CPZ/SUL treatment in ESBL-producing Enterobacterales bacteraemia. The minimum inhibitory concentrations (MICs) were determined using agar dilution; ESBL/AmpC genes were detected using polymerase chain reaction. The primary outcome was clinical success, whereas the secondary outcome was 30-day mortality. Clinical success was defined as the complete resolution of clinical signs and symptoms of K. pneumoniae or E. coli infection, with no evidence of persistent or recurrent bacteraemia. The factors influencing outcomes were identified using a multivariate analysis.

RESULTS

CPZ/SUL demonstrated a clinical success rate of 82.7% (91/110) in treating ESBL-producing Enterobacterales bacteraemia, with a 30-day mortality rate of 9.1% (10/110). Among 110 ESBL-producing isolates, a high clinical success rate was observed at an MIC of ≤32/32 mg/L. Multivariate analysis revealed that a Charlson comorbidity index (CCI) of ≥6 was associated with lower clinical success [odds ratio (OR): 5.80, 95% confidence interval (CI): 1.15-29.14, P = 0.033]. High Sequential Organ Failure Assessment scores (≥6) were significantly associated with increased 30-day mortality (OR: 14.34, 95% CI: 1.45-141.82, P = 0.023).

DISCUSSION

CPZ/SUL demonstrated a clinical success rate of 82.7% (91/110) in treating ESBL-producing Enterobacterales bacteraemia. Treatment success was evident when the CPZ and SUL MIC was ≤32/32 mg/L. Comorbidities (CCI ≥6) were associated with lower clinical success, while disease severity (Sequential Organ Failure Assessment score ≥6) correlated with higher mortality.

Molecular characterization of Escherichia coli producing extended-spectrum β-lactamase CTX-M-14 and CTX-M-28 in Mexico

The spread of ESBL-producing Escherichia coli has constantly increased in both clinical and community infections. Actually, the main ESBL reported is the CTX-M family, which is widely disseminated between the Enterobacteriaceae family. The epidemiology of the CTX-M family shows the CTX-M-15 variant dominating worldwide, followed by CTX-M-14 and CTX-M-27. The specific ESBL-producing E. coli clones included mainly the sequence types ST131, ST405, and ST648. In this report, we present the molecular characterization of ESBL-producing E. coli clinical isolates from eight hospitals in Mexico. From a collection of 66 isolates, 39 (59%) were identified as blaCTX-M-14 and blaCTX-M-27 belonging to the group CTX-M-9. We identified 25 (38%) isolates, producing blaCTX-M-28 belonging to the group CTX-M-1. blaCTX-M-2 and blaTEM-55 were identified in one isolate, respectively. Fourteen isolates (21%) were positive for blaCTX-M-14 (13%) and blaCTX-M-28 (7.3%) that were selected for further analyses; the antimicrobial susceptibility showed resistance to ampicillin (> 256 µg/mL), cefotaxime (> 256 µg/mL), cefepime (> 64 µg/mL), and ceftazidime (16 µg/mL). The ResFinder analysis showed the presence of the antimicrobial resistance genes aacA4, aadA5, aac(3)lla, sul1, dfrA17, tet(A), cmlA1, and blaTEM-1B. PlasmidFinder analysis identified in all the isolates the replicons IncFIB, which were confirmed by PCR replicon typing. The MLST analysis identified isolates belonging to ST131, ST167, ST405, and ST648. The ISEcp1B genetic element was found at 250 pb upstream of blaCTX-M-14 and flanked by the IS903 genetic element at 35 pb downstream. The IS1380-like element ISEc9 family transposase was identified at 250 pb upstream of blaCTX-M-14 and flanked downstream by the IS5/IS1182 at 80 pb. Our study highlights the significant prevalence of CTX-M-14 and CTX-M-28 enzymes as the second-most common ESBL-producing E. coli among isolates in Mexican hospitals. The identification of specific sequence types in different regions provides valuable insights into the correlation between ESBL and E. coli strains. This contribution to understanding their epidemiology and potential transmission routes is crucial for developing effective strategies to mitigate the spread of ESBL-producing E. coli in healthcare settings.

Beta-lactamase genes in bacteria from food animals, retail meat, and human surveillance programs in the United States from 2002 to 2021

The spread of beta-lactamase-producing bacteria is a global public-health concern. This study aimed to explore the distribution of beta-lactamases reported in three sampling sources (cecal, retail meat, and human) collected as part of integrated surveillance in the United States. We retrieved and analyzed data from the United States National Antimicrobial Resistance Monitoring Systems (NARMS) from 2002 to 2021. A total of 115 beta-lactamase genes were detected in E. coli, Salmonella enterica, Campylobacter, Shigella and Vibrio: including 35 genes from cecal isolates, 32 genes from the retail meat isolates, and 104 genes from the human isolates. Three genes in E. coli (blaCMY-2,blaTEM-1A, and blaTEM-1B), 6 genes in Salmonella enterica (blaCARB-2, blaCMY-2, blaCTXM-65, blaTEM-1A, blaTEM-1B, and blaHERA-3), and 2 genes in Campylobacter spp. (blaOXA-61 and blaOXA-449) have been detected across food animals (cattle, chicken, swine, and turkey) and humans over the study period. blaCTXM-55 has been detected in E. coli isolates from the four food animal sources while blaCTXM-15 and blaCTXM-27 were found only in cattle and swine. In Salmonella enterica, blaCTXM-2, blaCTXM-9, blaCTXM-14, blaCTXM-15, blaCTXM-27, blaCTXM-55, and blaNDM-1 were only detected among human isolates. blaOXAs and blaCARB were bacteria-specific and the only beta-lactamase genes detected in Campylobacter spp. and Vibrio spp respectively. The proportions of beta-lactamase genes detected varies from bacteria to bacteria. This study provided insights on the beta-lactamase genes detected in bacteria in food animals and humans in the United States. This is necessary for better understanding the molecular epidemiology of clinically important beta-lactamases in one health interface.

Rapid Phenotypic Antibiotic Susceptibility Profiling of Clinical Escherichia coli and Klebsiella pneumoniae Blood Cultures

Bloodstream infections (BSI) are defined by the presence of viable bacteria or fungi, accompanied by systemic signs of infection. Choosing empirical therapy based solely on patient risk factors and prior antibiotic susceptibility test (AST) may lead to either ineffective treatment or unnecessarily broad-spectrum antibiotic exposure. In general, Clinical & Laboratory Standards Institute guideline-approved ASTs have a turnaround time of 48-72 h from sample to answer, a period that may result in a critical delay in the appropriate selection of therapy. Therefore, reducing the time required for AST is highly advantageous. We have previously shown that our novel rapid AST method, MAPt (Micro-Agar-PCR-test), accurately identifies susceptibility profiles for spiked bioterrorism agents like Bacillus anthracis, Yersinia pestis and Francisella tularensis directly from whole-blood and blood culture samples, even at low bacterial levels (500 CFU/mL). This study evaluated the performance of MAPt on routine bloodstream infection (BSI), focusing on Escherichia coli and Klebsiella pneumoniae isolates from clinical cultures, including resistant strains to some of the six tested antibiotics. Notably, MAPt yielded results exceeding 95% agreement with the standard hospital method within a significantly shorter timeframe of 6 h. These findings suggest significant potential for MAPt as a rapid and reliable BSI management tool.

Prevalence of extended-spectrum beta-lactamase and molecular detection of blaTEM, blaSHV, and blaCTX-M genotypes among gram-negative Bacilli isolates from hospital acquired infections in pediatrics, one institutional study

BACKGROUND

Gram-negative bacilli represents an important pathogen in hospital-acquired infections (HAIs) worldwide. The emergence of antibiotic resistance in these pathogens warrants attention for the proper management of infections. Extended-spectrum beta-lactamase (ESBL) resistance represents a major therapeutic problem in infections due to Gram-negative bacilli. The present study aimed to study the extended-spectrum beta-lactamase genes blaTEM, blaSHV, and blaCTX-M by multiplex polymerase reaction in isolated Gram-negative bacilli from HAIs in pediatric patients.

METHODS

The study included one hundred-five isolates of Gram-negative bacilli from pediatric patients with different types of HAIs. The isolates were subjected to full microbiological identification, antibiotics susceptibility by disc diffusion method, the phenotypic study of ESBL, and the genetic study of ESBL genes by multiplex PCR.

RESULTS

Fifty isolates of Gram-Negative bacilli showed ESBL activity by a phenotypic study by double disc diffusion method (50/105). All ESBL producers' isolates were positive by PCR for ESBL genes. The most frequent gene was blaTEM (64%), followed by blaSHV (30%) and CTX-M (22%). Mixed genes were found in 4 isolates (8%) for blaTEM and blaSHV, blaTEM and CTX-M. There was a significant association between PCR for ESBL genes and phenotypic ESBL detection (P = 0.001). There was significant detection of ESBL genes in E. coli (28%), followed by Enterobacter spp. (26%), Klebsiella spp. (24%), Serratia (14%), Pseudomonas spp. (6%) and Proteus (2%), P = 0.01. There Seventy percent of isolates positive for ESBL production had an insignificant association between MDR and PCR for ESBL genes (P = 0.23).

CONCLUSION

The present study highlights the prevalence of ESBL activity among clinical isolates of Gram-negative bacilli isolated from hospital-acquired infections in pediatric patients. The most common gene responsible for this activity was blaTEM gee followed by blaSHV and blaCTX-M. There was a high prevalence of multiple antibiotic resistance among isolates with ESBL activity. The finding of the present study denotes the importance of screening extended beta-lactamase among Gram-negative bacilli associated with HAIs in pediatric patients.

Escherichia coli sequence type 410 with carbapenemases: a paradigm shift within E. coli toward multidrug resistance

Escherichia coli sequence type ST410 is an emerging carbapenemase-producing multidrug-resistant (MDR) high-risk One-Health clone with the potential to significantly increase carbapenem resistance among E. coli. ST410 belongs to two clades (ST410-A and ST410-B) and three subclades (ST410-B1, ST410-B2, and ST410-B3). After a fimH switch between clades ST410-A and ST410-B1, ST410-B2 and ST410-B3 subclades showed a stepwise progression toward developing MDR. (i) ST410-B2 initially acquired fluoroquinolone resistance (via homologous recombination) in the 1980s. (ii) ST410-B2 then obtained CMY-2, CTX-M-15, and OXA-181 genes on different plasmid platforms during the 1990s. (iii) This was followed by the chromosomal integration of blaCMY-2, fstl YRIN insertion, and ompC/ompF mutations during the 2000s to create the ST410-B3 subclade. (iv) An IncF plasmid "replacement" scenario happened when ST410-B2 transformed into ST410-B3: F36:31:A4:B1 plasmids were replaced by F1:A1:B49 plasmids (both containing blaCTX-M-15) followed by blaNDM-5 incorporation during the 2010s. User-friendly cost-effective methods for the rapid identification of ST410 isolates and clades are needed because limited data are available about the frequencies and global distribution of ST410 clades. Basic mechanistic, evolutionary, surveillance, and clinical studies are urgently required to investigate the success of ST410 (including the ability to acquire successive MDR determinants). Such information will aid with management and prevention strategies to curb the spread of carbapenem-resistant E. coli. The medical community can ill afford to ignore the spread of a global E. coli clone with the potential to end the carbapenem era.

Pharmacokinetics/pharmacodynamics analysis and establishment of optimal dosing regimens using unbound cefmetazole concentration for patients infected with Extended-Spectrum β-lactamase producing Enterobacterales (ESBL-E)

STUDY OBJECTIVE

Establish methods for measuring cefmetazole (CMZ) concentrations conduct a pharmacokinetic/pharmacodynamic (PK/PD) analysis using unbound CMZ concentrations for extended-spectrum β-lactamase producing enterobacterales (ESBL-E) and investigate optimal dosing regimens for not undergoing hemodialysis (non-HD) and undergoing hemodialysis (HD) patients.

DESIGN

Prospective observational study.

PATIENTS

Included patients treated with CMZ who provided written informed consent and were admitted to the Tokyo Bay Urayasu Ichikawa Medical Center between August 2021 and July 2022.

MEASUREMENTS

Total and Unbound CMZ concentration was measured by high-performance liquid chromatography (HPLC) with solid-phase extraction and ultrafiltration.

SETTING

Determining the CMZ dosing regimen involved modified creatinine clearance (CLCR ) with measured body weight (BW) using the Cockcroft-Gault equation. For non-HD patients, blood samples were collected during at least three points. For patients undergoing HD, 1 g was administered via intravenous infusion, or rapid intravenous injection after HD, or 30 min before the end of HD. Blood samples were collected before HD (pre-HD), and 1 and 3 h after starting HD and post-HD. All blood samples were collected at steady-state. Patient information was collected from electronic medical records. An unbound PK model was constructed for the non-HD patients. A nomogram was constructed using Monte Carlo simulations with a 90% probability of target attainment at 70% free time above the minimum inhibitory concentration (MIC). For the HD patients, a nomogram was used to determine the optimal dosing regimen for each HD schedule.

MAIN RESULTS

CMZ measurement methods were established. A model analysis of unbound PK in 37 non-HD patients incorporated creatinine clearance (CLCR ) using the Cockcroft-Gault equation, albumin (ALB) for clearance and body weight (BW) for the volume of distribution. In Monte Carlo simulations, nomograms corresponding to the MIC (known and unknown) were generated for each covariate. Using the nomogram, non-HD patients with an ESBL-E MIC of 8 mg/L, a BW of 60 kg, an ALB of 25 g/L, and a CLCR of 60 mL/min required administration of 2 g every 6 h (1- and 3-h infusions). Unbound PK model parameters were calculated for 7 HD patients, and the optimal dosing regimens following PK/PD were determined for each HD schedule. In HD patients, the regimen after and during HD was established using a treatment that was effective up to an ESBL-E MIC of 4 mg/L.

CONCLUSIONS

The nomogram for CMZ regimens established by PK/PD analysis of measured CMZ concentrations enables optimal CMZ dosing for ESBL-E-infected patients.

Association of piperacillin/tazobactam MIC and mortality in a cohort of ceftriaxone-resistant Escherichia coli bloodstream infections treated with piperacillin/tazobactam and carbapenems: a multicentric propensity score-weighted observational cohort study

OBJECTIVES

To assess the impact of piperacillin/tazobactam MICs on in-hospital 30 day mortality in patients with third-generation cephalosporin-resistant Escherichia coli bloodstream infection treated with piperacillin/tazobactam, compared with those treated with carbapenems.

METHODS

A multicentre retrospective cohort study was conducted in three large academic hospitals in Italy between 2018 and 2022. The study population comprised patients with monomicrobial third-generation cephalosporin-resistant E. coli bloodstream infection, who received either piperacillin/tazobactam or carbapenem therapy within 48 h of blood culture collection. The primary outcome was in-hospital 30 day all-cause mortality. A propensity score was used to estimate the likelihood of receiving empirical piperacillin/tazobactam treatment. Cox regression models were performed to ascertain risk factors independently associated with in-hospital 30 day mortality.

RESULTS

Of the 412 consecutive patients included in the study, 51% received empirical therapy with piperacillin/tazobactam, while 49% received carbapenem therapy. In the propensity-adjusted multiple Cox model, the Pitt bacteraemia score [HR 1.38 (95% CI, 0.85-2.16)] and piperacillin/tazobactam MICs of 8 mg/L [HR 2.35 (95% CI, 1.35-3.95)] and ≥16 mg/L [HR 3.69 (95% CI, 1.86-6.91)] were significantly associated with increased in-hospital 30 day mortality, while the empirical use of piperacillin/tazobactam was not found to predict in-hospital 30 day mortality [HR 1.38 (95% CI, 0.85-2.16)].

CONCLUSIONS

Piperacillin/tazobactam use might not be associated with increased mortality in treating third-generation cephalosporin-resistant E. coli bloodstream infections when the MIC is <8 mg/L.

Occurrence and characteristics of extended-spectrum-β-lactamase- and pAmpC-producing Klebsiella pneumoniae isolated from companion animals with urinary tract infections

This study examined 70 Klebsiella pneumoniae isolates derived from companion animals with urinary tract infections in Taiwan. Overall, 81% (57/70) of the isolates carried extended-spectrum β-lactamase (ESBL) and/or plasmid-encoded AmpC (pAmpC) genes. ESBL genes were detected in 19 samples, with blaCTX-M-1, blaCTX-M-9, and blaSHV being the predominant groups. pAmpC genes were detected in 56 isolates, with blaCIT and blaDHA being the predominant groups. Multilocus sequence typing revealed that sequence types (ST)11, ST15, and ST655 were prevalent. wabG, uge, entB, mrkD, and fimH were identified as primary virulence genes. Two isolates demonstrated a hypermucoviscosity phenotype in the string test. Antimicrobial susceptibility testing exhibited high resistance to β-lactams and fluoroquinolones in ESBL-positive isolates but low resistance to aminoglycosides, sulfonamides, and carbapenems. Isolates carrying pAmpC genes exhibited resistance to penicillin-class β-lactams. These findings provide valuable insights into the role of K. pneumoniae in the context of the concept of One Health.

Molecular characterization of extended-spectrum β-lactamase-producing Escherichia coli isolated from lower respiratory tract samples between 2002 and 2019 in the Central Slovenia region

BACKGROUND

Antibiotic resistance is one of the most serious global health problems and threatens the effective treatment of bacterial infections. Of greatest concern are infections caused by extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC). The aim of our study was to evaluate the prevalence and molecular characteristics of ESBL-EC isolated over an 18-year pre-COVID period from lower respiratory tract (LRT) samples collected from selected Slovenian hospitals.

OBJECTIVES AND METHODS

All isolates were identified by MALDI-TOF and phenotypically confirmed as ESBLs by a disk diffusion assay. Using a PCR approach, 487 non-repetitive isolates were assigned to phylogroups, sequence type groups, and clonal groups. Isolates were also screened for virulence-associated genes (VAGs) and antimicrobial resistance genes.

RESULTS

The prevalence of ESBL-EC isolates from LRT in a large university hospital was low (1.4%) in 2005 and increased to 10.8% by 2019. The resistance profile of 487 non-repetitive isolates included in the study showed a high frequency of group 1 blaCTX-M (77.4%; n = 377), blaTEM (54.4%; n = 265) and aac(6')-Ib-cr (52%; n = 253) genes and a low proportion of blaSHV and qnr genes. Isolates were predominantly assigned to phylogroup B2 (73.1%; n = 356), which was significantly associated with clonal group ST131. The ST131 group accounted for 67.6% (n = 329) of all isolates and had a higher number of virulence factor genes than the non-ST131 group. The virulence gene profile of ST131 was consistent with that of other extraintestinal pathogenic E. coli (ExPEC) strains and was significantly associated with ten of sixteen virulence factor genes tested. Using ERIC-PCR fingerprinting, isolates with the same ERIC-profile in samples from different patients, and at different locations and sampling dates were confirmed, indicating the presence of "hospital-adapted" strains.

CONCLUSION

Our results suggest that the ESBL-EC isolates from LRT do not represent a specific pathotype, but rather resemble other ExPEC isolates, and may be adapted to the hospital environment. To our knowledge, this is the first study of ESBL-EC isolated from LRT samples collected over a long period of time.

Inactivation of antibiotic-resistant bacteria in hospital wastewater by ozone-based advanced water treatment processes

The emergence and spread of antimicrobial resistance (AMR) continue on a global scale. The impacts of wastewater on the environment and human health have been identified, and understanding the environmental impacts of hospital wastewater and exploring appropriate forms of treatment are major societal challenges. In the present research, we evaluated the efficacy of ozone (O3)-based advanced wastewater treatment systems (O3, O3/H2O2, O3/UV, and O3/UV/H2O2) for the treatment of antimicrobials, antimicrobial-resistant bacteria (AMRB), and antimicrobial resistance genes (AMRGs) in wastewater from medical facilities. Our results indicated that the O3-based advanced wastewater treatment inactivated multiple antimicrobials (>99.9%) and AMRB after 10-30 min of treatment. Additionally, AMRGs were effectively removed (1.4-6.6 log10) during hospital wastewater treatment. The inactivation and/or removal performances of these pollutants through the O3/UV and O3/UV/H2O2 treatments were significantly (P < 0.05) better than those in the O3 and O3/H2O2 treatments. Altered taxonomic diversity of microorganisms based on 16S rRNA gene sequencing following the O3-based treatment showed that advanced wastewater treatments not only removed viable bacteria but also removed genes constituting microorganisms in the wastewater. Consequently, the objective of this study was to apply advanced wastewater treatments to treat wastewater, mitigate environmental pollution, and alleviate potential threats to environmental and human health associated with AMR. Our findings will contribute to enhancing the effectiveness of advanced wastewater treatment systems through on-site application, not only in wastewater treatment plants (WWTPs) but also in medical facilities. Moreover, our results will help reduce the discharge of AMRB and AMRGs into rivers and maintain the safety of aquatic environments.

The Challenges of The Diagnostic and Therapeutic Approach of Patients with Infectious Pathology in Emergency Medicine

The emergency department (ED) represents an important setting for addressing inappropriate antimicrobial prescribing practices because of the time constraints and the duration of microbiological diagnosis. The purpose of this study is to evaluate the etiology and antimicrobial resistance (AMR) pattern of the community-acquired pathogens, as well as the epidemiological characteristics of patients admitted through the ED, in order to guide appropriate antibiotic therapy.

METHODS

A retrospective observational study was performed on 657 patients, from whom clinical samples (urine, purulent secretions, blood cultures, etc.) were collected for microbiological diagnosis in the first 3 days after presentation in the ED. The identification of pathogens and the antimicrobial susceptibility testing with minimum inhibitory concentration determination were carried out according to the laboratory protocols.

RESULTS

From the 767 biological samples analyzed, 903 microbial isolates were identified. E. coli was most frequently isolated (24.25%), followed by Klebsiella spp., S. aureus (SA), and non-fermentative Gram-negative bacilli. E. coli strains maintained their natural susceptibility to most antibiotics tested. In the case of Pseudomonas spp. and Acinetobacter spp., increased rates of AMR were identified. Also, 32.3% of SA strains were community-acquired MRSA.

CONCLUSIONS

The introduction of rapid microbiological diagnostic methods in emergency medicine is imperative in order to timely identify AMR strains and improve therapeutic protocols.

Distribution and antimicrobial resistance analysis of gram-negative bacilli isolated from a tertiary hospital in Central China: a 10-year retrospective study from 2012 to 2021

Background

Gram-negative bacilli are one of the most common causes of various infections in clinical. The emergence and global spread of multi-drug resistant gram-negative bacilli has become a major challenge in the global public health field.

Methods

A total of 51,189 non-repetitive strains of gram-negative bacilli were isolated in clinical settings. The antimicrobial susceptibility testing was conducted by using the automated VITEK 2 compact system and the matched AST susceptibility test card, complemented by the disk diffusion method. The antimicrobial susceptibility results were interpreted by CLSI. Rates of MDR and XDR in Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa were investigated. Used the chi-square test to determine whether the antimicrobial resistance rates of four major gram-negative bacilli isolated from ICU and non-ICU department have statistical differences.

Results

Escherichia coli (31.4%), Klebsiella spp. (21.2%), Acinetobacter spp. (13.8%), and P. aeruginosa (11.0%) were the most frequently isolated gram-negative bacilli. Escherichia coli was the top one organism isolated from urinary tract (68.4%), bloodstream (39.9%), body fluid (33.2%), wound and pus (37%), except for respiratory tract (8.8%). Whereas Acinetobacter baumannii and K. pneumoniae were the major isolated organisms from respiratory tract. Acinetobacter baumannii showed high resistance to fluoroquinolones, β-lactam/β-lactamase inhibitor combinations class, ceftazidime, cefepime, imipenem, and meropenem, the resistance rates reached more than 70%. Ceftazidime showed a lower resistance rate to E. coli than ceftriaxone. For E. coli, fluoroquinolones showed a high resistance rate (ciprofloxacin 61.36% and levofloxacin 53.97%), whereas amikacin, carbapenems exhibited a lower resistance rate fluctuating at 2%. Acinetobacter baumannii and K. pneumoniae showed rapid increases in carbapenem resistance whereas E. coli had the lowest resistance rate and remain stable at 2%. Acinetobacter baumannii exhibited the highest rate of MDR and XDR, reaching 60-80 and 45-55%, respectively. Compared to non-ICU departments, the resistance rates of four major gram-negative bacilli in the ICU department were much higher and the differences were statistically significant (p < 0.05).

Conclusion

Amikacin, carbapenems, and piperacillin/tazobactam exhibited relatively high sensitivity, whereas fluoroquinolones showed high resistance rate whether they can be the first-line antimicrobials for empirical treatment of UTI should take more consideration. The gram-negative bacilli in ICU were more resistance than that in non-ICU. These findings are helpful for clinicians using antimicrobials reasonably.

Current status of β-lactam antibiotic use and characterization of β-lactam-resistant Escherichia coli from commercial farms by integrated broiler chicken operations in Korea

β-Lactam antibiotics are one of the most clinical importance in human and veterinary medicine because they are used for both preventive and therapeutic purposes against several gram-positive, gram-negative, and anaerobic organisms. In this study, it was confirmed that β-lactams (81.1%) were found to be significantly prescribed the most among 74 farms in 5 integrated broiler operations, and single prescription (84.6%), 2-day (41.5%) or 3-day (40.0%) administration, and 15 to 22 d of age (67.7%) administration was significantly higher in the farms (P < 0.05). Among the E. coli isolated from 74 farms in 5 integrated broiler operations, β-lactam-resistant E. coli isolates were detected more frequently in fecal sample (94.6%) than in dust sample (60.8%) (P < 0.05). The prevalence of MDR in β-lactam-resistant isolates, ranging from 88.1 to 96.5%, was significantly higher than that in non-β-lactam-resistant isolates (P < 0.05), without significant differences among operations. Of 466 β-lactam-resistant isolates, 432 (92.7%) isolates harbored β-lactamase genes. The non-extended-spectrum β-lactamase (ESBL) gene blaTEM-1 (81.8%) showed the highest prevalence among isolates, followed by the non-ESBL gene blaTEM-135 (6.4%) (P < 0.05). Five ESBL genes, SHV-12, OXA-1, CTX-M-27, CTX-M-55, and CTX-M-65, were found in 0.9 to 6.0% of the isolates. The pAmpC gene blaCMY-2 was detected in 17 isolates (3.6%). These results suggest that feces and dust are important reservoirs of antimicrobial-resistant bacteria, highlighting the need to strengthen farm management regulations, such as cleaning, disinfection, and litter disposal and to reduce the use of antibiotics in broiler operations.

Epidemiology, clinical outcomes and risk factors of third-generation cephalosporin-resistant Escherichia coli hospitalized infections in remote Australia-a case-control study

Background

Incidence of third-generation cephalosporin-resistant (3GCR) Escherichia coli infections has increased in remote Australia from 2012 to 2018.

Objectives

To describe the epidemiology of 3GCR E. coli in Central Australia.

Methods

A case-control study was conducted in the primary Central Australian hospital. Patient characteristics, antibiotic usage and clinical outcomes were compared between adult hospitalizations with 3GCR and susceptible E. coli isolates in 2018-19. Poisson regression was used to compare the incidence of 3GCR hospitalizations between Indigenous and non-Indigenous individuals. Patient characteristics and antibiotic usage were tested for associations with 3GCR isolates using univariate analysis.

Results

A total of 889 E. coli isolates were identified, of which 187 (21%) were 3GCR. The incidence of 3GCR E. coli infection was 2.15 per 1000 person-years, with an incidence rate ratio of 6.8 (95% CI 4.6-10.1) between Indigenous and non-Indigenous individuals. When compared with the control group, 3GCR E. coli infections were associated with a higher Charlson comorbidity index (CCI ≥3 in 30.7% versus 15.0%, P < 0.001) and were more commonly healthcare associated (52.4% versus 26.7%, P < 0.001). A higher 1 year mortality was observed in the 3GCR group after adjustment for comorbidity (OR = 4.43, P = 0.002), but not at 30 days (2.4% versus 0.0%, P = 0.2). The 3GCR group used more antibiotics in the past 3 months (OR = 5.75, P < 0.001) and 12 months (OR = 3.65, P < 0.001).

Conclusions

3GCR E. coli infections in remote Australia disproportionally affect Indigenous peoples and are associated with a high burden of comorbidities and antibiotic use. Strategies to enhance antimicrobial stewardship should be considered in this remote setting.

A randomized, controlled trial of prulifloxacin as conversion therapy after intravenous carbapenem in the treatment of acute pyelonephritis caused by third generation cephalosporin resistant pathogens: A pilot study

The efficacy of converting to oral fluoroquinolones after initial intravenous antibiotics for the treatment of acute pyelonephritis (APN) caused by the third-generation cephalosporin resistant Enterobacteriaceae (3-GCrEC) needs to be investigated. The objective was to compare the clinical and bacteriological outcome of oral prulifloxacin with intravenous ertapenem for the treatment of APN caused by 3-GCrEC. A pilot, randomized controlled trial of patients with APN caused by 3-GCrEC was conducted at two hospitals from August 2015 to December 2020. Any intravenous antimicrobial drug was initially permitted for empirical therapy. On day 4, adult patients (aged >18 years) with either non-bacteremic or bacteremic APN were eligible for the study if their infection was caused by 3-GCrEC susceptible to the study drugs. The patients were randomly assigned to receive either oral prulifloxacin or intravenous ertapenem. The total duration of antimicrobial therapy was 14 days. Of the 21 enrolled patients, 11 were treated with prulifloxacin, and 10 were treated with ertapenem. At the test of cure visit, there was no statistically significant difference between the patients with overall clinical success who were treated with prulifloxacin (90.9%) and those treated with ertapenem (100%, p = 0.999). In addition, there was no statistically significant difference in microbiological eradication between the prulifloxacin and ertapenem groups (100% vs. 100%, p = 0.999). The converting to oral prulifloxacin after intravenous antibiotics therapy appears to be an alternative option for treatment of APN caused by 3-GCrEC. A further large randomized controlled trial should be investigated.

Predictors for onset of extended-spectrum beta-lactamase-producing Escherichia coli-induced bacteraemia: a systematic review and meta-analysis

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli bacteraemia can induce unfavourable clinical outcomes due to delay in appropriate antimicrobial treatment and limited therapeutic options. Therefore, elucidating the predictors of ESBL-producing E. coli-induced bacteraemia is crucial to improve clinical outcomes. However, a literature search did not reveal any studies that incorporate a meta-analysis of the predictors of ESBL-producing E. coli-induced bacteraemia. As such, this review was undertaken to assess current evidence on the predictors of ESBL-producing E. coli-induced bacteraemia. PubMed, Web of Science and Cochrane Library databases were searched for all relevant publications from January 2000 to September 2021. This systematic review evaluated 10 observational studies, comprising a total of 2325 patients with E. coli-induced bacteraemia and 850 (36.6%) ESBL-producing strains. In the meta-analysis, previous antibiotic therapy [pooled risk ratio (RR) 2.72; P<0.001], especially with cephalosporins (pooled RR 4.66; P<0.001) and quinolones (pooled RR 5.47; P<0.001), and urinary catheter use (pooled RR 3.79; P<0.001) were predictive of ESBL-producing E. coli-induced bacteraemia. Antibiotic therapy for patients with the above-mentioned risk factors should be selected considering the possibility of ESBL-producing E. coli-induced bacteraemia compared with non-ESBL-producing E. coli-induced bacteraemia. It is important to elucidate whether appropriate modulation of the identified risk factors can potentially mitigate the risk of ESBL-producing E. coli-induced bacteraemia compared with non-ESBL-producing E. coli-induced bacteraemia.

Fecal carriage of extended-spectrum β-lactamase-producing enterobacterales from hospitals and community settings in Gaza Strip, Palestine

BACKGROUND

The fecal carriage of extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE) is a major driver of the global spread of these antibiotic resistance determinants. Here we determined the rate of fecal ESBL-PE carriage in pediatric hospitals and community-serving healthcare centers serving adults and children in the Gaza Strip, Palestine.

METHODS

A total of 373 fecal and rectal samples were collected from different hospitals and clinics in Gaza. The antibiotic susceptibility was determined using the disk diffusion method and interpreted according to CLSI guidelines. The bacterial isolates were tested for ESBL production using phenotypic methods (double disk synergy test and growth on selective chromogenic media). BlaCTX-M, blaSHV, and blaTEM genes were sought by PCR.

RESULTS

Out of the 373 isolates tested, 138 (37%) were considered ESBL positive as revealed by phenotypic tests. The prevalence of ESBLs among hospitalized patients was 39.1% (hospital setting) whereas, among outpatients attending community healthcare centers, it was 35.1% (community setting). ESBL production among Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii, Proteus mirabilis, and Klebsiella aerogenes isolates was 52.8%, 39.1%, 26.7%, 2.8%, and 2.1% respectively. Meropenem and amikacin were the most effective antibiotics against ESBL producers (68.9% and 73.6% susceptibility, respectively), while only 15.2%, 22.5%, and 24.6% remained susceptible to ceftazidime, cefotaxime, and ceftriaxone, respectively. Out of 138 phenotypically ESBL-positive isolates, 98 randomly chosen were screened for blaCTX-M, blaTEM, and blaSHV genes. The prevalence rate of blaCTX-M was 45.9%, while blaTEM and blaSHV genes were detected in 16.8% and 5.2% of CTX-M-negative isolates (corresponding mostly for K. pneumoniae isolates in the case of SHV-PCR), respectively.

CONCLUSIONS

The study revealed an alarmingly high prevalence of fecal carriage of ESBL-producing Enterobacterales among hospitalized children but also in the community of the Gaza Strip. In addition, 30% of ESBL-producers were already resistant to carbapenems, the treatment of choice of infections with ESBL-producers.

A multicentre study to determine the in vitro efficacy of flomoxef against extended-spectrum beta-lactamase producing Escherichia coli in Malaysia

Background

The high burden of extended-spectrum beta-lactamase-producing (ESBL)-producing Enterobacterales worldwide, especially in the densely populated South East Asia poses a significant threat to the global transmission of antibiotic resistance. Molecular surveillance of ESBL-producing pathogens in this region is vital for understanding the local epidemiology, informing treatment choices, and addressing the regional and global implications of antibiotic resistance.

Methods

Therefore, an inventory surveillance of the ESBL-Escherichia coli (ESBL-EC) isolates responsible for infections in Malaysian hospitals was conducted. Additionally, the in vitro efficacy of flomoxef and other established antibiotics against ESBL-EC was evaluated.

Results

A total of 127 non-repetitive ESBL-EC strains isolated from clinical samples were collected during a multicentre study performed in five representative Malaysian hospitals. Of all the isolates, 33.9% were isolated from surgical site infections and 85.8% were hospital-acquired infections. High rates of resistance to cefotaxime (100%), cefepime (100%), aztreonam (100%) and trimethoprim-sulfamethoxazole (100%) were observed based on the broth microdilution test. Carbapenems remained the most effective antibiotics against the ESBL-EC, followed by flomoxef. Antibiotic resistance genes were identified by PCR. The blaCTX-M-1 was the most prevalent ESBL gene, with 28 isolates (22%) harbouring blaCTX-M-1 only, 27 isolates (21.3%) co-harbouring blaCTX-M-1 and blaTEM, and ten isolates (7.9%) co-harbouring blaCTX-M-1, blaTEM and blaSHV. A generalised linear model showed significant antibacterial activity of imipenem against different types of infection. Besides carbapenems, this study also demonstrated a satisfactory antibacterial activity of flomoxef (81.9%) on ESBL-EC, regardless of the types of ESBL genes.

Prevalence of Extended Spectrum β-Lactamase Producers (ESBLs) with antibiotic resistance pattern of Gram negative pathogenic bacteria isolated from door handles in hospitals of Pokhara, Western Nepal

BACKGROUND

The presence of drug-resistant Gram-negative pathogenic bacteria and Extended Spectrum β-Lactamase Producers (ESBLs) in hospital associated fomites like door handles can serve as vehicles in transmission and may be the key factor in epidemiology of ESBL producing bacterial infection not only in a hospital setting but also in the community. The aim of this study was to determine the prevalence of ESBLs and antibiotic resistance of Gram-Negative pathogenic Bacteria isolated from door-handles in two selected hospitals in Pokhara Metropolitan City, Nepal. The study was conducted in selected hospitals in Pokhara Metropolitan City, Western Nepal. A cross-sectional study design was used. The hospitals were selected randomly. A total of 100 swab samples were taken from door-handles. Isolation and identification of bacteria were done using standard microbiological procedures. An antibiotic susceptibility test, screening and confirmation of ESBLs were performed using the Clinical Laboratory Standard Institute's guidelines.

RESULTS

Out of the 100 swab samples cultured, 96 (96%) showed bacterial growth. A total of one hundred and forty isolates were isolated in this study which were further identified based on cultural, morphological and biochemical characteristics. The study also found that door handles/knobs had higher level of contamination in Outpatient Departments (OPDs), Emergency, Laboratory, General wards and Toilets, in that order as compared to Radiology Room, Staff rooms, Intensive Care Unit and Operation Theatre which were lower. The level of contamination varies depending on the traffic exposure and the environment. The most prevalent Gram-negative bacteria identified was Escherichia coli 28.85%, followed by Klebsiella spp 21.15%, Pseudomonas aeruginosa 15.38%, Proteus spp 11.54%, Enterobacter spp 9.62%, Acenetobacter spp 7.69%, Citrobacter spp 5.77%. The most effective drug of choice was Amikacin, Nitrofurantoin, Norfloxacin, Ciprofloxacin, Tetracycline and Imipenem for many Gram-negative isolates. The overall prevalence of ESBLs in this study was 27.14%. Out of total 15 Escherichia coli isolated, 11(73.3%), Klebsiella spp 9/11 (81.8%); Pseudomonas spp 7/8 (87.5%), Proteus spp 4/6 (66.6%); Enterobacter spp 3/5 (60%), Acenetobacter spp 3/4 (75%) and Citrobacter spp 1/3 (33.3%) were found to be Extended β-Lactamase Producers (ESBLs).

CONCLUSION

The isolation of of pathogenic Gram-negative bacteria and ESBLs in hospital environments and subsequent detection of high drug resistance patterns indicates a potentially serious public health challenge that strengthens the need for the effective and routine cleaning of door-handles in hospitals.

Efficacy and safety of ceftazidime/avibactam in patients with infections caused by β-lactamase-producing Gram-negative pathogens: a pooled analysis from the Phase 3 clinical trial programme

OBJECTIVES

This post hoc pooled analysis evaluated clinical and microbiological outcomes and safety in patients with infections caused by β-lactamase-producing Gram-negative pathogens across five Phase 3, randomized, controlled, multicentre trials of ceftazidime/avibactam in adults with complicated intra-abdominal infection (cIAI), complicated urinary tract infection (cUTI)/pyelonephritis and nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP).

METHODS

In each trial, RECLAIM/RECLAIM 3 (cIAI), REPRISE (cIAI/cUTI), RECAPTURE (cUTI) and REPROVE (NP, including VAP) patients were randomized 1:1 to IV ceftazidime/avibactam (plus metronidazole for patients with cIAI) or comparators (carbapenems in >97% patients) for 5-21 days. Clinical and microbiological responses at the test-of-cure visit were assessed for patients with ESBLs, and/or plasmidic and/or overexpression of chromosomal AmpC, and/or serine carbapenemases without MBLs identified in baseline Gram-negative isolates by phenotypic screening and molecular characterization in the pooled microbiological modified ITT (mMITT) population.

RESULTS

In total, 813 patients (ceftazidime/avibactam, n = 389; comparator, n = 424) had ≥1 β-lactamase-producing baseline pathogen identified, amongst whom 792 patients (ceftazidime/avibactam, n = 379; comparator, n = 413) had no MBLs. The most frequent β-lactamase-producing pathogens across treatment groups were Escherichia coli (n = 381), Klebsiella pneumoniae (n = 261) and Pseudomonas aeruginosa (n = 53). Clinical cure rates in the pooled non-MBL β-lactamase-producing mMITT population were 88.1% (334/379) for ceftazidime/avibactam and 88.1% (364/413) for comparators; favourable microbiological response rates were 76.5% (290/379) and 68.8% (284/413), respectively. The safety profile of ceftazidime/avibactam was consistent with previous observations.

CONCLUSIONS

This analysis provides supportive evidence of the efficacy and safety of ceftazidime/avibactam in patients with infections caused by ESBLs, AmpC and serine carbapenemase-producing Gram-negative pathogens.

TRIAL REGISTRATION

NCT01499290; NCT01726023; NCT01644643; NCT01595438/NCT01599806; NCT01808092.

Distribution of Antibiotic Resistance in a Mixed-Use Watershed and the Impact of Wastewater Treatment Plants on Antibiotic Resistance in Surface Water

The aquatic environment has been recognized as a source of antibiotic resistance (AR) that factors into the One Health approach to combat AR. To provide much needed data on AR in the environment, a comprehensive survey of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and antibiotic residues was conducted in a mixed-use watershed and wastewater treatment plants (WWTPs) within the watershed to evaluate these contaminants in surface water. A culture-based approach was used to determine prevalence and diversity of ARB in surface water. Low levels of AR Salmonella (9.6%) and Escherichia coli (6.5%) were detected, while all Enterococcus were resistant to at least one tested antibiotic. Fewer than 20% of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (17.3%) and carbapenem-resistant Enterobacteriaceae (CRE) (7.7%) were recovered. Six ARGs were detected using qPCR, primarily the erythromycin-resistance gene, ermB. Of the 26 antibiotics measured, almost all water samples (98.7%) had detectable levels of antibiotics. Analysis of wastewater samples from three WWTPs showed that WWTPs did not completely remove AR contaminants. ARGs and antibiotics were detected in all the WWTP effluent discharges, indicating that WWTPs are the source of AR contaminants in receiving water. However, no significant difference in ARGs and antibiotics between the upstream and downstream water suggests that there are other sources of AR contamination. The widespread occurrence and abundance of medically important antibiotics, bacteria resistant to antibiotics used for human and veterinary purposes, and the genes associated with resistance to these antibiotics, may potentially pose risks to the local populations exposed to these water sources.

Anti-microbial resistance and aging-A design for evolution

The emergence of resistance to anti-infective agents poses a significant threat to successfully treating infections caused by bacteria. Bacteria acquire random mutations due to exposure to environmental stresses, which may increase their fitness to other selection pressures. Interestingly, for bacteria, the frequency of anti-microbial resistance (AMR) seems to be increasing in tandem with the human lifespan. Based on evidence from previous literature, we speculate that increased levels of free radicals (Reactive Oxygen Species-ROS and Reactive Nitrosative Species-RNS), elevated inflammation, and the altered tissue microenvironment in aged individuals may drive pathogen mutagenesis. If these mutations result in the hyperactivation of efflux pumps or alteration in drug target binding sites, it could confer AMR, thus rendering antibiotic therapy ineffective while leading to the selection of novel drug-resistant variants. This article is categorized under: Immune System Diseases > Genetics/Genomics/Epigenetics Infectious Diseases > Environmental Factors Metabolic Diseases > Environmental Factors.

ESBL-producing Enterobacteriaceae in a rural Rwandan community: Carriage among community members, livestock, farm products and environment

OBJECTIVES

Extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) are spreading globally. However, respective data from African communities including livestock and environmental specimens are rare. In a rural community of southern Rwanda, we assessed intestinal carriage of ESBL-PE among residents and livestock as well as presence in household specimens and examined associated factors.

METHODS

Samples of humans and livestock (both rectal swabs), soil, water, vegetables and animal products were collected within 312 community households in Sovu, Southern Rwanda. Specimens were screened for ESBL-PE on chromogenic agar, and susceptibility to common antibiotics was determined by disc diffusion assays. Socio-demographic information was collected with questionnaires focusing on the socio-economic background, alimentation, living conditions, hygiene measures and medical history of the participants.

RESULTS

Data and specimens from 312 randomly selected households including 617 human beings, 620 livestock and of approximately each 300 kitchen vegetables, animal products, soil and drinking water were analysed. Overall, 14.8% of 2508 collected samples were positive for ESBL-PE; figures were highest for humans (37.9%) and livestock (15.6%), lower for vegetables (3.8%) and animal products (3.3%), and lowest for soil (1.6%) and water (0.6%). Most detected ESBL-PE were Escherichia coli (93.5%) in addition to Klebsiella pneumoniae (6.5%). Cross-resistance to ampicillin-sulbactam, ciprofloxacin and co-trimoxazole was common. Logistic regression identified increasing age, another ESBL-PE positive household member, prolonged time for fetching water, current diarrhoea and the ability to pay school fees as independent predictors of intestinal ESBL-PE carriage among community members.

CONCLUSIONS

ESBL-PE carriage is common in a rural Rwandan farming community. Carriage in livestock is not associated with human carriage. Associated factors suggest few addressable risk factors. The data indicate that in southern Rwanda, ESBL-PE are no longer primarily hospital-based but circulate in the community.

Fecal Carriage of Extended-Spectrum β-Lactamase and Carbapenemase-Producing Enterobacteriaceae Among Oncology and Non-Oncology Patients at Jimma Medical Center in Ethiopia: A Comparative Cross-Sectional Study

Purpose

Extended-spectrum β-lactamase (ESBL) and carbapenemase-producing Enterobacteriaceae (CPE) are among the major threats to global health because of their encoded protection against key antibiotics.

Methods

A comparative cross-sectional study was conducted among oncology and non-oncology patient groups (1:1; n = 214) on a consecutive sampling approach. Stool or rectal swab was collected from June 2021 to November 2021 and screened for ESBL-PE and CPE using ChromID-ESBL media. Confirmation for the enzymes was made by using combination disc and modified carbapenem inactivation methods, respectively. Disk diffusion method was used to determine antimicrobial susceptibility testing following the recommendations of CLSI 2022. SPSS software version 23 was used for data analysis.

Results

Fecal carriage prevalence of ESBL-PE was found in 90 (84.1%) of oncology participants and in 77 (71.9%) of non-oncology patients (p = 0.032). Escherichia coli was the most common ESBL-PE isolate in 82 (62.5%) and 68 (88.3%) of oncology and non-oncology patients, followed by Klebsiella oxytoca [15 (11.5%) versus 6 (7.8%)], respectively. Out of the total ESBL-PE isolates from both oncology and non-oncology patient groups, the maximum level of resistance was observed against ciprofloxacin 177 (86.3%), trimethoprim-sulfamethoxazole 103 (80.3%), tetracycline 97 (75.8%), whereas enhanced susceptibility was appreciated to tigecycline 200 (97.6%), meropenem 162 (79.0%), and ertapenem 145 (70.7%) with no significant difference between oncology and non-oncology group. Carbapenemase-producing isolates from oncology patients were 12 (11.2%), whereas it was 4 (3.7%) (p = 0.611) from non-oncology group. Bacterial isolates from oncology in this study showed a trend of multiple drug resistance of 113 (88.3%).

Conclusion

The results revealed alarmingly high carriage rates of ESBL and CPE among all study participants. Moreover, the isolates showed increased resistance rates to alternative drugs and had multiple antibiotic-resistant patterns. Hence, it is important to emphasize strict adherence to antimicrobial stewardship program as well as infection prevention and control practices.

Six-year analysis of key monitoring for bacterial strain distribution and antibiotic sensitivity in a hospital

BACKGROUND

With the widespread use of antimicrobial drugs, bacterial resistance has become a significant problem, posing a serious threat to public health. The prevalence of clinical infection strains in hospitals and their drug sensitivities are key to the appropriate use of antibiotics in clinical practice.

AIM

To identify prevalent bacteria and their antibiotic resistance profiles in a hospital setting, thereby guiding effective antibiotic usage by clinicians.

METHODS

Specimens from across the institution were collected by the microbiology laboratory. The VITEK 2 compact fully automatic analyzer was used for bacterial identification and antibiotic sensitivity testing, and the WHONET5.6 software was utilized for statistical analysis.

RESULTS

A total of 12062 bacterial strains of key monitoring significance were detected. Staphylococcus aureus demonstrated widespread resistance to penicillin, but none of the strains were resistant to vancomycin or linezolid. Moreover, 219 strains of methicillin-resistant coagulase-negative staphylococci and 110 strains of methicillin-resistant Staphylococcus aureus were detected. Enterococcus faecalis showed moderate resistance to the third-generation quinolones ciprofloxacin and levofloxacin, but its resistance to nitrofurantoin and tetracycline was low. Enterococcus faecium displayed significantly lower resistance to third- and fourth-generation quinolones than Enterococcus faecalis. The resistance of two key monitoring strains, Escherichia coli and Klebsiella pneumoniae, to piperacillin/tazobactam was 5%-8%. However, none of the Escherichia coli and Klebsiella pneumoniae strains were resistant to meropenem. The resistance of Acinetobacter baumannii to piperacillin/sulbactam was nearly 90%. Nonetheless, the resistance to tigecycline was low, and Pseudomonas aeruginosa demonstrated minimal resistance in the antibiotic sensitivity test, maintaining a resistance of < 10% to the cephalosporin antibiotics cefotetan and cefoperazone over the last 6 years. The resistance to amikacin remained at 0.2% over the past 3 years.

CONCLUSION

Our hospital's overall antibiotic resistance rate was relatively stable from 2017 to 2022. The detection rates of key monitoring strains are reported quarterly and their resistance dynamics are monitored and communicated to the entire hospital, which can guide clinical antibiotic selection.