Dramatic rise in the proportion of ESBL-producing Escherichia coli and Klebsiella pneumoniae among clinical isolates identified in Canadian hospital laboratories from 2007 to 2016

Ceftolozane/Tazobactam treatment for patients with hospital-acquired and ventilatory-associated bacterial pneumonia in Canada in 2022-2024: results from the CLEAR registry

BACKGROUND

We report results from the national CLEAR (Canadian Leadership on Antimicrobial Real-Life Usage) registry on the usage of ceftolozane/tazobactam in Canada from 2022 to 2024.

RESEARCH DESIGN AND METHODS

The authors reviewed the final data using the national ethics approved CLEAR study. Thereafter, the literature is surveyed regarding the usage of ceftolozane/tazobactam to treat patients with HABP and VABP via PubMed (up to May 2024).

RESULTS

Ceftolozane/tazobactam was primarily used as directed therapy to treat HABP and VABP caused by Pseudomonas aeruginosa. It was primarily used alone, or in combination with another agent, to treat resistant and multidrug-resistant (MDR) P. aeruginosa infections. Despite primarily being used to treat severely ill patients in intensive care units, its use was associated with relatively high microbiological/clinical cure rates, along with an excellent safety profile. Several reports attest to the microbiological/clinical efficacy and safety of using ceftolozane/tazobactam to treat HABP and VABP.

CONCLUSIONS

In Canada, ceftolozane/tazobactam is primarily used as directed therapy alone, or in combination, to treat MDR P. aeruginosa infections. Though mostly used to treat severely ill patients in the ICU, ceftolozane/tazobactam use in HABP and VABP is associated with relatively high microbiological/clinical cure rates and an excellent safety profile.

Antimicrobial resistance and AmpC production in ESBL-producing Klebsiella pneumoniae and Klebsiella quasipneumoniae: A retrospective study in Japanese clinical isolates

INTRODUCTION

The study of Klebsiella quasipneumoniae, Klebsiella variicola, and AmpC production in extended-spectrum β-lactamase (ESBL)-producing Klebsiella in Japan is limited, and existing data are insufficient. This study aims to characterize Klebsiella species, determine AmpC production rates, and analyze antimicrobial resistance patterns in ESBL-producing Klebsiella isolates in Japan.

METHODS

A total of 139 clinical isolates of ESBL-producing Klebsiella were collected in Japan, along with their corresponding antimicrobial susceptibility profiles. The isolates were identified using a web-based tool. ESBL genes within the isolates were identified using multiplex PCR. Screening for AmpC-producing isolates was performed using cefoxitin disks, followed by multiplex PCR to detect the presence of AmpC genes. Antimicrobial resistance patterns were analyzed across the predominant ESBL genotypes.

RESULTS

The web-based tool identified 135 isolates (97.1%) as Klebsiella pneumoniae and 4 (2.9%) as K. quasipneumoniae subsp. similipneumoniae, with no instances of K. variicola detected. Among K. pneumoniae, the CTX-M-1 group emerged as the predominant genotype (83/135, 61.5%), followed by K. quasipneumoniae subsp. similipneumoniae (3/4, 75.0%). The CTX-M-9 group was the second most prevalent genotype in K. pneumoniae (45/135, 33.3%). The high resistance rates were observed for quinolones (ranging from 46.7% to 63.0%) and trimethoprim/sulfamethoxazole (78.5%). The CTX-M-1 group exhibited higher resistance to ciprofloxacin (66/83, 79.5%) compared to the CTX-M-9 group (18/45, 40.0%), a trend also observed for levofloxacin and trimethoprim/sulfamethoxazole. Among the 16 isolates that tested positive during AmpC screening, only one K. pneumoniae isolates (0.7%) were confirmed to carry the AmpC gene.

CONCLUSION

Klebsiella pneumoniae with the CTX-M-1 group is the most common ESBL-producing Klebsiella in Japan and showed a low proportion of AmpC production. These isolates are resistant to quinolones and trimethoprim/sulfamethoxazole, highlighting the challenge of managing this pathogen. The findings underscore the importance of broader research and continuous monitoring to address the resistance patterns of ESBL-producing Klebsiella.

Phenotypic and Genotypic Characterization of Extended Spectrum Beta-Lactamase-Producing Clinical Isolates of Escherichia coli and Klebsiella pneumoniae in Two Kenyan Facilities: A National Referral and a Level Five Hospital

Background

The emergence of antimicrobial resistance (AMR) and multidrug resistance (MDR) among Escherichia coli and Klebsiella pneumoniae, especially through the production of extended spectrum β-lactamases (ESBLs), limits therapeutic options and poses a significant public health threat.

Objective

The aim of this study was to assess the phenotypic and genetic determinants of antimicrobial resistance of ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates from patient samples in two Kenyan Hospitals.

Methods

We collected 138 E. coli and 127 K. pneumoniae isolates from various clinical specimens at the two health facilities from January 2020 to February 2021. The isolates' ESBL production and antibiotic susceptibility were phenotypically confirmed using a standard procedure. Molecular analysis was done through conventional polymerase chain reaction (PCR) with appropriate primers for gadA, rpoB, blaTEM, blaSHV, blaOXA, blaCTX-M-group-1, blaCTX-M-group-2, blaCTX-M-group-9, and blaCTX-M-group-8/25 genes, sequencing and BLASTn analysis.

Results

Most E. coli (82.6%) and K. pneumoniae (92.9%) isolates were ESBL producers, with the highest resistance was against ceftriaxone (69.6% among E. coli and 91.3% among K. pneumoniae) and amoxicillin/clavulanic acid (70.9% among K. pneumoniae). The frequency of MDR was 39.9% among E. coli and 13.4% among K. pneumoniae isolates. The commonest MDR phenotypes among the E. coli isolates were CRO-FEP-AZM-LVX and CRO-AZM-LVX, while the FOX-CRO-AMC-MI-TGC-FM, FOX-CRO-FEP-AMC-TZP-AZM-LVX-MI and CRO-AMC-TZP-AZM-MI were the most frequent among K. pneumoniae isolates. Notably, the FOX-CRO-FEP-AMC-TZP-AZM-LVX-MI phenotype was observed in ESBL-positive and ESBL-negative K. pneumoniae isolates. The most frequent ESBL genes were blaTEM (42%), blaSHV (40.6%), and blaOXA (36.2%) among E. coli, and blaTEM (89%), blaSHV (82.7%), blaOXA (76.4%), and blaCTX-M-group-1 (72.5%) were most frequent ESBL genes among K. pneumoniae isolates. The blaSHV and blaOXA and blaTEM genotypes were predominantly associated with FOX-CRO-FEP-MEM and CRO-FEP multidrug resistance (MDR) and CRO antimicrobial resistance (AMR) phenotypes, among E. coli isolates from Embu Level V (16.7%) and Kenyatta National Hospital (7.0%), respectively.

Conclusions

The high proportion of ESBL-producing E. coli and K. pneumoniae isolates increases the utilization of last-resort antibiotics, jeopardizing antimicrobial chemotherapy. Furthermore, the antimicrobial resistance patterns exhibited towards extended-spectrum cephalosporins, beta-lactam/beta-lactamase inhibitor combinations, fluoroquinolones, and macrolides show the risk of co-resistance associated with ESBL-producing isolates responsible for MDR. Hence, there is a need for regular surveillance and implementation of infection prevention and control strategies and antimicrobial stewardship programs.

A Five-Year Analysis of Antibiotic Resistance Trends among Bacteria Identified in Positive Urine Samples in a Tertiary Care Hospital from Bucharest, Romania

The rise of multidrug-resistant bacteria (MDR) has resulted in limited treatment options and poorer outcomes for patients. The objective of this study was to analyze the overall antibiotic resistance trends and distribution for pathogens identified in urine samples at the National Institute of Infectious Diseases "Prof. Dr. Matei Balș" from Bucharest, Romania, over a 5-year period. Antibiotic susceptibility testing was performed using automatic systems and the disk diffusion method. ESBL- and carbapenemases-producing strains were identified using immunochromatography tests, and ROSCO Diagnostica kits were used for definitive confirmation. All results were interpreted according to EUCAST clinical breakpoints. Gram-negative rods (GNR) had overall resistance rates higher than 50% for penicillin and 40% for 3rd- and 4th-generation cephalosporins. Escherichia coli resistance to fosfomycin (3%) and nitrofurantoin (2%) remains low, and 33.30% of E. coli, 48% of Klebsiella spp., and 37% of Pseudomonas aeruginosa isolates were multidrug-resistant (MDR). All Acinetobacter baumannii isolates were MDR by the last year of the study. For Gram-positive cocci (GPC), 37% of all Enterococcus faecium strains and 2% of Enterococcus faecalis were vancomycin-resistant (VRE). E. coli's incidence in UTIs' etiology is on a downward trend. The incidence of Klebsiella spp. and GPCs is rising. Antibiotic stewardship strategies should be implemented after carefully considering regional variations in etiology and resistance trends.

Prevalence and distribution pattern of AmpC β-lactamases in ESBL producing clinical isolates of Klebsiella spp. in parts of Assam, India

The production of extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases is the most common explanation of multidrug resistance in clinical isolates of Klebsiella spp. In the present study, a total of 160 isolates of Klebsiella spp. were procured from the DBT-NER project with ethical clearance no. DU/Dib/ECBHR(Human)/2021-22/02). These were collected from various health settings of Assam and identified as drug-resistant. The isolates were screened for antibiotic susceptibility and phenotypic tests were performed on multidrug resistant isolates to confirm ESBL and AmpC β-lactamases production. The distribution pattern of ESBL and AmpC β-lactamase genotype was investigated by polymerase chain reaction (PCR). The results showed that among 107 multidrug-resistant (MDR) isolates of Klebsiella spp., 67.28% of isolates were ESBL producers and 56.07% were potential AmpC producers. The PCR results revealed that blaCTX-M was the most prevalent ESBL genotype. Among the ESBL producers, 11.11% of isolates showed co-occurrence with plasmid-mediated AmpC β lactamases genotype which indicated the high prevalence of ESBL and AmpC co-producers in K. pneumoniae and K. oxytoca, suggesting the possibility of serious public health concerns. Therefore, it is crucial to regularly monitor the spread of multidrug resistance among clinical isolates.

Impact of acquired broad-spectrum β-lactamases on susceptibility to oral penems/carbapenems (tebipenem, sulopenem, and faropenem) alone or in combination with avibactam and taniborbactam β-lactamase inhibitors in Escherichia coli

The impact of β-lactamases on susceptibility to oral penems/carbapenems (tebipenem, sulopenem, and faropenem) and other carbapenem molecules was evaluated in Escherichia coli, alone and in combination with avibactam or taniborbactam β-lactamase inhibitors. Tebipenem and sulopenem exhibited a similar spectrum of activity compared to the intravenous carbapenems and displayed lower MIC values than ceftibuten-avibactam against E. coli producing extended-spectrum β-lactamases or AmpC enzymes. Combined with taniborbactam, tebipenem and sulopenem exhibited low MIC values against almost all tested recombinant E. coli, including metallo-β-lactamase producers.

Hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP) in Canada: treatment update and the role of new IV antimicrobials

INTRODUCTION

Hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP) continue to be common infections causing significant morbidity and mortality worldwide. The timely initiation of empiric antimicrobial therapy is essential. In this paper, we provide a focused expert opinion on the current and potential empiric antimicrobial treatment options in HABP and VABP in Canada influenced by antimicrobial resistance impacting the use of older agents as well as available new intravenous (IV) antimicrobials.

AREAS COVERED

The authors discuss treatment options for HABP and VABP in Canada. In addition, we focus on the potential role of new IV antimicrobials recently introduced to Canada. A literature search of HABP and VABP treatments was performed via PubMed (up to March 2023), using the following key words: monotherapy, combination therapy, aminoglycosides, carbapenems, cephalosporins, fluoroquinolones, penicillins as well as amoxicillin/clavulanate, ceftobiprole, ceftolozane/tazobactam, dalbavancin, and fosfomycin.

EXPERT OPINION

Empiric antimicrobial treatment for HABP and VABP in Canada continues to focus on both the severity of illness and the presence/absence of patient risk factors for antimicrobial resistance. The role of new IV antimicrobials in the empiric treatment for HABP and VABP depends on their antimicrobial activity and published data on efficacy and safety and influenced by Health Canada-approved indications.

Phenotypic and molecular characterization of ESBL producing Escherichia coli and Klebsiella pneumoniae among Lebanese patients

Introduction

Antimicrobial resistance is a major public health issue worldwide and became one of the principal international healthcare crises of the 21st century. The production of ESBLs is one of the resistance mechanisms in Enterobacteriaceae, and they are increasingly detected in Escherichia coli and Klebsiella pneumoniae globally. Therefore, the aim of this study was to determine the phenotypic and molecular characteristics of ESBL-producing E. coli and K. pneumoniae among Lebanese patients.

Methods

A total of 152 ESBL-producing E. coli and K. pneumoniae were obtained from Geitaoui Hospital in Beirut between September 2019 and October 2020 from various clinical samples. The phenotype of ESBL producers was confirmed by a double-disc synergy test and antibiotic susceptibility was determined using the disc diffusion method. Genotypically, multiplex PCR was used to detect the ESBL genes (bla_TEM, bla_CTX-M and bla_SHV).

Results

All strains were confirmed to be ESBL producers (121 isolates were E. coli and 31 isolates were K. pneumoniae). All isolates showed resistance to cefotaxime, cefuroxime, ampicillin and piperacillin. On the other hand, they showed a low susceptibility rate to trimethoprim/sulfamethoxazole and ciprofloxacin. Almost all the isolates were susceptible to ertapenem, imipenem and amikacin. In our study, ESBL genes were detected among 48 (39.67%) E. coli isolates and 8 (58.06%) K. pneumoniae isolates, and the most prevalent gene was bla_TEM (25%), followed by bla_CTX-M (19.08%) and bla_SHV (16.45%).

Conclusion

Imipenem and ertapenem are the most effective drugs to treat ESBL producers. However, antibiotic stewardship programs must be implemented immediately to combat antibiotic resistance.

Drug resistance and susceptibility of amikacin in children with extended-spectrum beta-lactamase-producing Enterobacterales: a systematic review with meta-analysis

Antibiotic resistance surveillance may be essential to identify patterns of antibiotic resistance and guide treatment choices. Therefore, this systematic review and meta-analysis aimed to evaluate amikacin resistance and susceptibility in children with extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE). From inception to September 5, 2022, relevant studies were searched via PubMed, Embase, Cochrane Library, and Web of Science databases. A network meta-analysis was conducted to explore the sequencing of resistance rates in amikacin and other antibiotics. Totally, 26 studies with 2582 clusters of bacterial isolates were included. The resistance rate of amikacin in children with ESBL-PE was 10.1%, higher than the resistance rate of tigecycline (0.0%), ertapenem (0.4%), meropenem (0.7%), and imipenem (3.0%). For the drug susceptibility rate in children with ESBL-PE, the susceptibility rate of amikacin (89.7%) was lower than tigecycline (99.6%), imipenem (96.8%), meropenem (97.3%), and ertapenem (95.6%). Amikacin showed a low drug resistance and a high drug resistance in children with ESBL-PE infection, making it a good option for the treatment of the infection caused by ESBL-PE.

Trends in the Rates of Extended-Spectrum-β-Lactamase-Producing Enterobacterales Isolated from Urine Cultures during the COVID-19 Pandemic in Ontario, Canada

Worldwide, extended-spectrum β-lactamase (ESBL) rates are increasing at an alarming level with increasing rates of health care exposures, international travel, and antibiotic usage. In this study, we investigated whether enhanced social isolation, travel restrictions, and the reduced use of antibiotics in Ontario, Canada during coronavirus disease 2019 (COVID-19) pandemic had an impact on ESBL rates in urine cultures collected from the community and long-term-care (LTC) facilities across the province. Data from a total of 8.6 million urine cultures performed at LifeLabs Ontario from 2016 to 2021 were utilized for analysis. ESBL-producing Escherichia coli (ESBL Escherichia coli) and ESBL Klebsiella pneumoniae were identified using standard operating procedures. Data trends were estimated by interrupted time series (ITS) regression analysis. Among 2.3 million positive urine cultures, 48.9% and 7.2% grew E. coli and K. pneumoniae, of which 5.8% and 3.3% produced ESBLs, respectively. While the overall rate of ESBL isolation was higher in the pandemic period than in the prepandemic period, by ITS regression analysis of the monthly rates of ESBL isolation, decreasing trends were noted for ESBL E. coli in both the community and LTC facilities and for ESBL K. pneumoniae in the community. The ESBL K. pneumoniae rates in LTC facilities continued to increase throughout the COVID-19 period. By subgroup analysis for different genders, age groups, and local health integration network (LHIN) units, similar trends were seen in most cases (P < 0.05), except for a few densely populated LHINs where rate changes were not statistically significant. IMPORTANCE Community-onset urinary tract infections (UTIs) caused by ESBL-producing Enterobacterales, particularly E. coli and K. pneumoniae, are a major public health concern. In this study, we assessed the impact of COVID-19 on ESBL rates in urine cultures in Ontario, Canada. Our results show the recent epidemiology of ESBL-producing Enterobacterales in urine cultures from both the community and LTC facilities in Ontario, Canada, and the impact of COVID-19 restrictions on ESBL trends for the entire province as well as different subgroups of the population based on demographic and geographic characteristics. Our results may have important public health implications in the context of the gradual easing of COVID-19 restrictions.

Antimicrobial resistance patterns of bacterial pathogens recovered from the urine of patients at Canadian hospitals from 2009 to 2020

Objectives

To investigate in vitro susceptibility patterns of bacterial pathogens recovered from the urine of outpatients (isolates from outpatient clinics or emergency departments) and hospital inpatients across Canada from 2009 to 2020 as part of the CANWARD study.

Methods

Canadian hospital microbiology laboratories submitted bacterial pathogens cultured from urine to the CANWARD study coordinating laboratory on an annual basis (January 2009 to December 2020). Antimicrobial susceptibility testing was performed by CLSI broth microdilution, with MICs interpreted by current CLSI breakpoints.

Results

In total, 4644 urinary pathogens were included in this study. Escherichia coli was recovered most frequently (53.3% of all isolates), followed by Enterococcus faecalis, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa and Staphylococcus aureus. Together, these six species accounted for 84.2% of study isolates. Nitrofurantoin demonstrated excellent in vitro activity versus E. coli, with 97.6% of outpatient and 96.1% of inpatient isolates remaining susceptible. In contrast, E. coli susceptibility rates were lower for ciprofloxacin (outpatient 79.5%, inpatient 65.9%) and trimethoprim/sulfamethoxazole (outpatient 75.2%, inpatient 73.5%). The percentage of E. coli isolates that were phenotypically positive for ESBL production significantly increased from 4.2% (2009-11) to 11.3% (2018-20). A similar although less pronounced temporal trend was observed with ESBL-producing K. pneumoniae.

Conclusions

E. coli was the pathogen most frequently recovered from the urine of Canadian patients, and the proportion of isolates that were ESBL producers increased over time. Susceptibility data presented here suggest that ciprofloxacin and trimethoprim/sulfamethoxazole may be suboptimal for the empirical treatment of complicated urinary infections.

Cefepime pharmacodynamic targets against Enterobacterales employing neutropenic murine lung infection and in vitro pharmacokinetic models

BACKGROUND

Very limited studies, so far, have been conducted to identify the pharmacodynamic targets of cefepime, a well-established fourth-generation cephalosporin. As a result, conventional targets representing the cephalosporin class are used for cefepime target attainment analysis.

OBJECTIVES

We employed both a neutropenic murine lung infection model and an in vitro pharmacokinetic model (IVPM) to determine cefepime's pharmacodynamic target [percentage of the dosing interval during which unbound drug concentrations remain higher than the MIC (%fT>MIC)] for bacteriostatic and 1 log10 kill effects.

METHODS

Ten strains with cefepime MICs ranging from 0.03 to 16 mg/L were studied in the lung infection. In the IVPM, five cefepime-resistant strains with cefepime/tazobactam (fixed 8 mg/L) MICs ranging from 0.25 to 8 mg/L were included. Through 24 h dose fractionation, both in lung infection and IVPM (in the latter case, tazobactam 8 mg/L continuous infusion was used to protect cefepime), varying cefepime exposures and corresponding pharmacodynamic effect scenarios were generated to identify the pharmacodynamic targets.

RESULTS

Using a non-linear sigmoidal maximum-effect (Emax) model, the cefepime's plasma fT>MIC for 1 log10 kill in lung infection ranged from 17% to 53.7% and a combined exposure-response plot yielded 30%. In the case of IVPM, T>MIC ranged from 6.9% to 75.4% with a mean value of 34.2% for 1 log10 kill.

CONCLUSIONS

Both in vivo and in vitro studies showed that cefepime's pharmacodynamic requirements are lower than generally reported for cephalosporins (50%-70% fT>MIC). The lower requirement for cefepime could be linked with factors such as cefepime's better permeation properties and multiple PBP affinity-driven enhanced bactericidal action.

In vitro activity of sulopenem against 1880 bacterial pathogens isolated from Canadian patients with urinary tract infections (CANWARD, 2014-21)

INTRODUCTION

There are limited oral antimicrobial options for the treatment of urinary infections caused by ESBL-producing and MDR Enterobacterales. Sulopenem is an investigational thiopenem antimicrobial that is being developed as both an oral and IV formulation. The purpose of this study was to evaluate the in vitro activity of sulopenem versus bacterial pathogens recovered from the urine of patients admitted to or assessed at hospitals across Canada (CANWARD).

MATERIALS AND METHODS

The in vitro activity of sulopenem and clinically relevant comparators was determined for 1880 Gram-negative and Gram-positive urinary isolates obtained as part of the CANWARD study (2014 to 2021) using the CLSI broth microdilution method.

RESULTS

Sulopenem demonstrated excellent in vitro activity versus members of the Enterobacterales, with MIC90 values ranging from 0.06 to 0.5 mg/L for all species tested. Over 90% of ESBL-producing, AmpC-producing and MDR (not susceptible to ≥1 antimicrobial from ≥3 classes) Escherichia coli were inhibited by ≤0.25 mg/L of sulopenem. Sulopenem had an identical MIC90 to meropenem for ESBL-producing and MDR E. coli. The MIC90 of sulopenem and meropenem versus MSSA was 0.25 mg/L. Sulopenem was not active in vitro versus Pseudomonas aeruginosa (similar to ertapenem), and it demonstrated poor activity versus Enterococcus faecalis (similar to meropenem).

CONCLUSIONS

Sulopenem demonstrated excellent in vitro activity versus bacterial pathogens recovered from the urine of Canadian patients. These data suggest that sulopenem may have a role in the treatment of urinary infections caused by antimicrobial-resistant Enterobacterales, but additional clinical studies are required.

Characterization of Novel Bacteriophage vB_KpnP_ZX1 and Its Depolymerases with Therapeutic Potential for K57 Klebsiella pneumoniae Infection

A novel temperate phage vB_KpnP_ZX1 was isolated from hospital sewage samples using the clinically derived K57-type Klebsiella pneumoniae as a host. Phage vB_KpnP_ZX1, encoding three lysogen genes, the repressor, anti-repressor, and integrase, is the fourth phage of the genus Uetakevirus, family Podoviridae, ever discovered. Phage vB_KpnP_ZX1 did not show ideal bactericidal effect on K. pneumoniae 111-2, but TEM showed that the depolymerase Dep_ZX1 encoded on the short tail fiber protein has efficient capsule degradation activity. In vitro antibacterial results show that purified recombinant Dep_ZX1 can significantly prevent the formation of biofilm, degrade the formed biofilm, and improve the sensitivity of the bacteria in the biofilm to the antibiotics kanamycin, gentamicin, and streptomycin. Furthermore, the results of animal experiments show that 50 µg Dep_ZX1 can protect all K. pneumoniae 111-2-infected mice from death, whereas the control mice infected with the same dose of K. pneumoniae 111-2 all died. The degradation activity of Dep_ZX1 on capsular polysaccharide makes the bacteria weaken their resistance to immune cells, such as complement-mediated serum killing and phagocytosis, which are the key factors for its therapeutic action. In conclusion, Dep_ZX1 is a promising anti-virulence agent for the K57-type K. pneumoniae infection or biofilm diseases.

Antibiotic Exposure during the Preceding Six Months Is Related to Intestinal ESBL-Producing Enterobacteriaceae Carriage in the Elderly

Intestinal carriage of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE carriage) poses a health risk to the elderly. It was aimed to study the prevalence and the risk factors of intestinal ESBL-PE carriage in the elderly. An observational study of a 921-elderly cohort was examined at health checkup for intestinal ESBL-PE carriage at a tertiary medical center in Shanghai. The prevalence and risk factors of intestinal ESBL-PE carriage, especially antimicrobial use in the preceding 9 months, were studied. The prevalence of intestinal ESBL-PE carriage was 53.3% (491/921) in community-dwelling elderly people. A total of 542 ESBL-producing isolates, including E. coli (n = 484) and K. pneumoniae (n = 58), were obtained. On genotyping, the CTX-M-9 ESBL was the most prevalent for 66.0% (358/542) of all isolates. Multivariate analysis showed that antibiotic exposure, age (61–70 years), and nursing home residence were independent risk factors of the ESBL-PE carriage. The analysis on the monthly use of antimicrobials showed that antibiotic exposure during the 6 months prior to sample collection contributed to the high prevalence of ESBL-PE carriage. A single exposure to an antimicrobial increased the risk of the carriage significantly, and the risk increased with the frequency of antimicrobial exposure (RR, 1.825 to 5.255). Prior use of second or third generation cephalosporins, fluoroquinolones, and macrolides increased the risk of the carriage. The results of this study indicate the importance of using antimicrobials judiciously in clinical settings to reduce antimicrobial resistance. Further studies with multiple center surveillance and with comparison of ESBL-PE carriage in the elderly and in the general population simultaneously are needed.

One Health Genomic Analysis of Extended-Spectrum β-Lactamase‒Producing Salmonella enterica, Canada, 2012‒2016

Extended-spectrum β-lactamases (ESBLs) confer resistance to extended-spectrum cephalosporins, a major class of clinical antimicrobial drugs. We used genomic analysis to investigate whether domestic food animals, retail meat, and pets were reservoirs of ESBL-producing Salmonella for human infection in Canada. Of 30,303 Salmonella isolates tested during 2012–2016, we detected 95 ESBL producers. ESBL serotypes and alleles were mostly different between humans (n = 54) and animals/meat (n = 41). Two exceptions were bla_SHV-2 and bla_CTX-M-1 IncI1 plasmids_, which were found in both sources. A subclade of S. enterica serovar Heidelberg isolates carrying the same IncI1-bla_SHV-2 plasmid differed by only 1–7 single nucleotide variants. The most common ESBL producer in humans was Salmonella Infantis carrying bla_CTX-M-65, which has since emerged in poultry in other countries. There were few instances of similar isolates and plasmids, suggesting that domestic animals and retail meat might have been minor reservoirs of ESBL-producing Salmonella for human infection.

Gut colonisation by extended-spectrum β-lactamase-producing Escherichia coli and its association with the gut microbiome and metabolome in Dutch adults: a matched case-control study

BACKGROUND

Gut colonisation by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is a risk factor for developing overt infection. The gut microbiome can provide colonisation resistance against enteropathogens, but it remains unclear whether it confers resistance against ESBL-producing E coli. We aimed to identify a potential role of the microbiome in controlling colonisation by this antibiotic-resistant bacterium.

METHODS

For this matched case-control study, we used faeces from 2751 individuals in a Dutch cross-sectional population study (PIENTER-3) to culture ESBL-producing bacteria. Of these, we selected 49 samples that were positive for an ESBL-producing E coli (ESBL-positive) and negative for several variables known to affect microbiome composition. These samples were matched 1:1 to ESBL-negative samples on the basis of individuals' age, sex, having been abroad or not in the past 6 months, and ethnicity. Shotgun metagenomic sequencing was done and taxonomic species composition and functional annotations (ie, microbial metabolism and carbohydrate-active enzymes) were determined. Targeted quantitative metabolic profiling (proton nuclear magnetic resonance spectroscopy) was done to investigate metabolomic profiles and combinations of univariate (t test and Wilcoxon test), multivariate (principal coordinates analysis, permutational multivariate analysis of variance, and partial least-squares discriminant analysis) and machine-learning approaches (least absolute shrinkage and selection operator and random forests) were used to analyse all the molecular data.

FINDINGS

No differences in diversity parameters or in relative abundance were observed between ESBL-positive and ESBL-negative groups based on bacterial species-level composition. Machine-learning approaches using microbiota composition did not accurately predict ESBL status (area under the receiver operating characteristic curve [AUROC]=0·41) when using either microbiota composition or any of the functional profiles. The metabolome also did not differ between ESBL groups, as assessed by various methods including random forest (AUROC=0·61).

INTERPRETATION

By combining multiomics and machine-learning approaches, we conclude that asymptomatic gut carriage of ESBL-producing E coli is not associated with an altered microbiome composition or function. This finding might suggest that microbiome-mediated colonisation resistance against ESBL-producing E coli is not as relevant as it is against other enteropathogens and antibiotic-resistant bacteria.

FUNDING

None.

Sulopenem: An Intravenous and Oral Penem for the Treatment of Urinary Tract Infections Due to Multidrug-Resistant Bacteria

Sulopenem (formerly known as CP-70,429, and CP-65,207 when a component of a racemic mixture with its R isomer) is an intravenous and oral penem that possesses in vitro activity against fluoroquinolone-resistant, extended spectrum β-lactamases (ESBL)-producing, multidrug-resistant (MDR) Enterobacterales. Sulopenem is being developed to treat patients with uncomplicated and complicated urinary tract infections (UTIs) as well as intra-abdominal infections. This review will focus mainly on its use in UTIs. The chemical structure of sulopenem shares properties of penicillins, cephalosporins, and carbapenems. Sulopenem is available as an oral prodrug formulation, sulopenem etzadroxil, which is hydrolyzed by intestinal esterases, resulting in active sulopenem. In early studies, the S isomer of CP-65,207, later developed as sulopenem, demonstrated greater absorption, higher drug concentrations in the urine, and increased stability against the renal enzyme dehydropeptidase-1 compared with the R isomer, which set the stage for its further development as a UTI antimicrobial. Sulopenem is active against both Gram-negative and Gram-positive microorganisms. Sulopenem's β-lactam ring alkylates the serine residues of penicillin-binding protein (PBP), which inhibits peptidoglycan cross-linking. Due to its ionization and low molecular weight, sulopenem passes through outer membrane proteins to reach PBPs of Gram-negative bacteria. While sulopenem activity is unaffected by many β-lactamases, resistance arises from alterations in PBPs (e.g., methicillin-resistant Staphylococcus aureus [MRSA]), expression of carbapenemases (e.g., carbapenemase-producing Enterobacterales and in Stenotrophomonas maltophilia), reduction in the expression of outer membrane proteins (e.g., some Klebsiella spp.), and the presence of efflux pumps (e.g., MexAB-OprM in Pseudomonas aeruginosa), or a combination of these mechanisms. In vitro studies have reported that sulopenem demonstrates greater activity than meropenem and ertapenem against Enterococcus faecalis, Listeria monocytogenes, methicillin-susceptible S. aureus (MSSA), and Staphylococcus epidermidis, as well as similar activity to carbapenems against Streptococcus agalactiae, Streptococcus pneumoniae, and Streptococcus pyogenes. With some exceptions, sulopenem activity against Gram-negative aerobes was less than ertapenem and meropenem but greater than imipenem. Sulopenem activity against Escherichia coli carrying ESBL, CTX-M, or Amp-C enzymes, or demonstrating MDR phenotypes, as well as against ESBL-producing Klebsiella pneumoniae, was nearly identical to ertapenem and meropenem and greater than imipenem. Sulopenem exhibited identical or slightly greater activity than imipenem against many Gram-positive and Gram-negative anaerobes, including Bacteroides fragilis. The pharmacokinetics of intravenous sulopenem appear similar to carbapenems such as imipenem-cilastatin, meropenem, and doripenem. In healthy subjects, reported volumes of distribution (V_d) ranged from 15.8 to 27.6 L, total drug clearances (CL_T) of 18.9-24.9 L/h, protein binding of approximately 10%, and elimination half-lives (t_½) of 0.88-1.03 h. The estimated renal clearance (CL_R) of sulopenem is 8.0-10.6 L/h, with 35.5% ± 6.7% of a 1000 mg dose recovered unchanged in the urine. An ester prodrug, sulopenem etzadroxil, has been developed for oral administration. Initial investigations reported a variable oral bioavailability of 20-34% under fasted conditions, however subsequent work showed that bioavailability is significantly improved by administering sulopenem with food to increase its oral absorption or with probenecid to reduce its renal tubular secretion. Food consumption increases the area under the curve (AUC) of oral sulopenem (500 mg twice daily) by 23.6% when administered alone and 62% when administered with 500 mg of probenecid. Like carbapenems, sulopenem demonstrates bactericidal activity that is associated with the percentage of time that free concentrations exceed the MIC (%f T > MIC). In animal models, bacteriostasis was associated with %f T > MICs ranging from 8.6 to 17%, whereas 2-log₁₀ kill was seen at values ranging from 12 to 28%. No pharmacodynamic targets have been documented for suppression of resistance. Sulopenem concentrations in urine are variable, ranging from 21.8 to 420.0 mg/L (median 84.4 mg/L) in fasted subjects and 28.8 to 609.0 mg/L (median 87.3 mg/L) in those who were fed. Sulopenem has been compared with carbapenems and cephalosporins in guinea pig and murine systemic and lung infection animal models. Studied pathogens included Acinetobacter calcoaceticus, B. fragilis, Citrobacter freundii, Enterobacter cloacae, E. coli, K. pneumoniae, Proteus vulgaris, and Serratia marcescens. These studies reported that overall, sulopenem was non-inferior to carbapenems but appeared to be superior to cephalosporins. A phase III clinical trial (SURE-1) reported that sulopenem was not non-inferior to ciprofloxacin in women infected with fluoroquinolone-susceptible pathogens, due to a higher rate of asymptomatic bacteriuria in sulopenem-treated patients at the test-of-cure visit. However, the researchers reported superiority of sulopenem etzadroxil/probenecid over ciprofloxacin for the treatment of uncomplicated UTIs in women infected with fluoroquinolone/non-susceptible pathogens, and non-inferiority in all patients with a positive urine culture. A phase III clinical trial (SURE-2) compared intravenous sulopenem followed by oral sulopenem etzadroxil/probenecid with ertapenem in the treatment of complicated UTIs. No difference in overall success was noted at the end of therapy. However, intravenous sulopenem followed by oral sulopenem etzadroxil was not non-inferior to ertapenem followed by oral stepdown therapy in overall success at test-of-cure due to a higher rate of asymptomatic bacteriuria in the sulopenem arm. After a meeting with the US FDA, Iterum stated that they are currently evaluating the optimal design for an additional phase III uncomplicated UTI study to be conducted prior to the potential resubmission of the New Drug Application (NDA). It is unclear at this time whether Iterum intends to apply for EMA or Japanese regulatory approval. The safety and tolerability of sulopenem has been reported in various phase I pharmacokinetic studies and phase III clinical trials. Sulopenem (intravenous and oral) appears to be well tolerated in healthy subjects, with and without the coadministration of probenecid, with few serious drug-related treatment-emergent adverse events (TEAEs) reported to date. Reported TEAEs affecting ≥1% of patients were (from most to least common) diarrhea, nausea, headache, vomiting and dizziness. Discontinuation rates were low and were not different than comparator agents. Sulopenem administered orally and/or intravenously represents a potentially well tolerated and effective option for treating uncomplicated and complicated UTIs, especially in patients with documented or highly suspected antimicrobial pathogens to commonly used agents (e.g. fluoroquinolone-resistant E. coli), and in patients with documented microbiological or clinical failure or patients who demonstrate intolerance/adverse effects to first-line agents. This agent will likely be used orally in the outpatient setting, and intravenously followed by oral stepdown in the hospital setting. Sulopenem also allows for oral stepdown therapy in the hospital setting from intravenous non-sulopenem therapy. More clinical data are required to fully assess the clinical efficacy and safety of sulopenem, especially in patients with complicated UTIs caused by resistant pathogens such as ESBL-producing, Amp-C, MDR E. coli. Antimicrobial stewardship programs will need to create guidelines for when this oral and intravenous penem should be used.

Diversity of blaCTX-M-1-carrying plasmids recovered from Escherichia coli isolated from Canadian domestic animals

Conserved IncI1 and IncHI1 plasmids carrying blaCTX-M-1 have been found circulating in chickens and horses from continental Europe, respectively. In Canada, blaCTX-M-1 is overwhelmingly the most common blaCTX-M variant found in Escherichia coli from chicken and horses and can be recovered at lower frequencies in swine, cattle, and dogs. Whole-genome sequencing has identified a large genetic diversity of isolates carrying this variant, warranting further investigations into the plasmids carrying this gene. Therefore, the objective of this study was to describe the genetic profiles of blaCTX-M-1 plasmids circulating in E. coli from Canadian domestic animals and compare them to those recovered in animals in Europe. Fifty-one blaCTX-M-1 positive E. coli isolates from chicken (n = 14), horses (racetrack horses n = 11; community horses n = 3), swine (n = 7), turkey (n = 6), dogs (n = 5), beef cattle (n = 3), and dairy cattle (n = 2) were selected for plasmid characterization. Sequences were obtained through both Illumina and Oxford Nanopore technologies. Genomes were assembled using either Unicycler hybrid assembly or Flye with polishing performed using Pilon. blaCTX-M-1 was found residing on a plasmid in 45 isolates and chromosomally located in six isolates. A conserved IncI1/ST3 plasmid was identified among chicken (n = 12), turkey (n = 4), swine (n = 6), dog (n = 2), and beef cattle (n = 2) isolates. When compared against publicly available data, these plasmids showed a high degree of similarity to those identified in isolates from poultry and swine in Europe. These results suggest that an epidemic IncI1/ST3 plasmid similar to the one found in Europe is contributing to the spread of blaCTX-M-1 in Canada. A conserved IncHI1/FIA(HI1)/ST2 plasmid was also recovered from nearly all racetrack horse isolates (n = 10). Although IncHI1/ST2 plasmids have been reported among European horse isolates, IncHI1/ST9 plasmids appear to be more widespread. Further studies are necessary to understand the factors contributing to these plasmids' success in their respective populations.

Global Prevalence and Molecular Epidemiology of mcr-Mediated Colistin Resistance in Escherichia coli Clinical Isolates: A Systematic Review

BACKGROUND AND AIM

The continuing rise in infections caused by multi-drug resistant (MDR) bacteria is one of the most serious public health issues in today's societies. Colistin is a last-resort antimicrobial medication used to treat infections caused by MDR gram-negative bacteria; therefore resistance to this antibiotic is extremely hazardous. The current study aimed to evaluate the global prevalence and distribution of colistin resistance genes among human clinical isolates of Escherichia coli (E. coli) as a systematic review.

METHODS

PubMed, Embase, and Web of Science databases were systematically searched. For further evaluation, all original English-language articles that demonstrated colistin resistance in E. coli clinical isolates published between 2000 and 2020 were examined.

RESULTS

Out of 4857 initial articles, after various stages of review and evaluation, 190 related articles were selected. More than 79 % of the publications selected in this research were published from 2014 to 2020. In Asia, Europe, America, Africa, and Oceania, the prevalence of mobilized colistin resistance (mcr) producing colistin-resistant E. coli was 66.72%, 25.48%, 5.19%, 2.27%, and 0.32 %, respectively.

CONCLUSION

The recent widespread spreading of E. coli strains harboring mcr conferring colistin resistance, especially in Asia and Europe, is concerning and needs more attention.

Epidemiology and risk factors for pyogenic liver abscess in the Calgary Health Zone revisited: a population-based study

Background

Pyogenic liver abscess (PLA), although uncommon in North America, is associated with significant morbidity and mortality. We sought to re-examine the epidemiology, risk factors, and outcomes of PLA in a large, diverse Canadian health zone.

Methods

All Calgary Health Zone (CHZ) residents aged ≥20 with PLA between 2015 and 2017 were identified. Incidence and mortality rates were calculated using census data. Risk factors for PLA were identified using a multivariate analysis. Data was compared to 1999–2003 data, also collected in the CHZ.

Results

There were 136 patients diagnosed with PLA between 2015 and 2017. Incidence rate during this period increased significantly relative to 1999–2003 (3.7 vs 2.3 cases/100,000 population, p < 0.01), however, mortality rates remained similar. The microbiological composition of PLA did not change over this 15-year time period but the number of antimicrobial resistant isolates did increase (8% vs 1%, p = 0.04). The greatest risk factors for PLA relative to general populations included current malignancy, liver-transplant, end-stage renal disease, and cirrhosis. Thirty-day mortality was 7.4% and independent risk factors included polymicrobial bacteremia, absence of abscess drainage, congestive-heart failure, a history of liver disease, and admission bilirubin.

Conclusions

Pyogenic liver abscess is a health concern with rising incidence rate. The increasing prevalence of comorbidities in our population and factors that are associated with risk of PLA suggests this will continue to be an emerging diagnosis of concern. Increasing prevalence of antibiotic resistant organisms compounding unclear optimal treatment regimens is an issue that requires urgent study.

Comparison of phenotypic antimicrobial susceptibility testing results and WGS-derived genotypic resistance profiles for a cohort of ESBL-producing Escherichia coli collected from Canadian hospitals: CANWARD 2007-18

OBJECTIVES

To determine whether the genotypic resistance profile inferred from WGS could accurately predict phenotypic resistance for ESBL-producing Escherichia coli isolated from patient samples in Canadian hospital laboratories.

METHODS

As part of the ongoing CANWARD study, 671 E. coli were collected and phenotypically confirmed as ESBL producers using CLSI M100 disc testing criteria. Isolates were sequenced using the Illumina MiSeq platform, resulting in 636 high-quality genomes for comparison. Using a rules-based approach, the genotypic resistance profile was compared with the phenotypic resistance interpretation generated using the CLSI broth microdilution method for ceftriaxone, ciprofloxacin, gentamicin and trimethoprim/sulfamethoxazole.

RESULTS

The most common genes associated with non-susceptibility to ceftriaxone, gentamicin and trimethoprim/sulfamethoxazole were CTX-M-15 (n = 391), aac(3)-IIa + aac(6')-Ib-cr (n = 121) and dfrA17 + sul1 (n = 169), respectively. Ciprofloxacin non-susceptibility was most commonly attributed to alterations in both gyrA (S83L + D87N) and parC (S80I + E84V), with (n = 187) or without (n = 197) aac(6')-Ib-cr. Categorical agreement (susceptible or non-susceptible) between actual and predicted phenotype was 95.6%, 98.9%, 97.6% and 88.8% for ceftriaxone, ciprofloxacin, gentamicin and trimethoprim/sulfamethoxazole, respectively. Only ciprofloxacin results (susceptible or non-susceptible) were predicted with major error (ME) and very major error (VME) rates of <3%: ciprofloxacin (ME, 1.5%; VME, 1.1%); gentamicin (ME, 0.8%-31.7%; VME, 4.8%); ceftriaxone (ME, 81.8%; VME, 3.0%); and trimethoprim/sulfamethoxazole (ME, 0.9%-23.0%; VME, 5.2%-8.5%).

CONCLUSIONS

Our rules-based approach for predicting a resistance phenotype from WGS performed well for ciprofloxacin, with categorical agreement of 98.9%, an ME rate of 1.5% and a VME rate of 1.1%. Although high categorical agreements were also obtained for gentamicin, ceftriaxone and trimethoprim/sulfamethoxazole, ME and/or VME rates were ≥3%.

ESBL-positive Escherichia coli and Klebsiella pneumoniae isolates from across Canada: CANWARD surveillance study, 2007-18

OBJECTIVES

ESBL-producing Escherichia coli and Klebsiella pneumoniae are pathogens of increasing importance in Canada and elsewhere in the world. The purpose of this study was to phenotypically and molecularly characterize ESBL-producing E. coli and K. pneumoniae clinical isolates obtained from patients attending Canadian hospitals over a 12 year period.

METHODS

Isolates were collected between January 2007 and December 2018 as part of an ongoing national surveillance study (CANWARD). ESBL production was confirmed using the CLSI (M100) phenotypic method. Susceptibility testing was carried out using custom broth microdilution panels, and all isolates underwent WGS.

RESULTS

In total, 671 E. coli and 141 K. pneumoniae were confirmed to be ESBL producers. The annual proportion of ESBL-producing isolates increased for both E. coli (from 3.3% in 2007 to 11.2% in 2018; P < 0.0001) and K. pneumoniae (from 1.3% in 2007 to 9.3% in 2018; P < 0.0001). The most frequent STs were ST131 for E. coli [62.4% (419/671) of isolates] and ST11 [7.8% (11/141)] and ST147 [7.8% (11/141)] for K. pneumoniae. Overall, 97.2% of ESBL-producing E. coli and K. pneumoniae isolates were MDR. blaCTX-M-15 predominated in both ESBL-producing E. coli (62.3% of isolates) and ESBL-producing K. pneumoniae (48.9% of isolates).

CONCLUSIONS

The proportion of ESBL-producing E. coli, especially ST131, and K. pneumoniae, especially ST11 and ST147, in Canada increased significantly from 2007 to 2018. Continued prospective surveillance of these evolving MDR and at times XDR pathogens is imperative.

Epidemiology of extended-spectrum β-lactamase and metallo-β-lactamase-producing Escherichia coli in South Asia

Aim: To determine the prevalence of extended-spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL)-producing Escherichia coli in South Asia. Methodology: A systematic review and meta-analysis of data published in PubMed, EMBASE, Web of Science and Scopus. Results: The pooled prevalence of ESBL and MBL-producing E. coli in South Asia were 33% (95% CI: 27-40%) and 17% (95% CI: 12-24%), respectively. The prevalence of bla_CTX-M type was 58% (95% CI: 49-66%) with bla_CTX-M-15 being the most prevalent (51%, 95% CI: 40-62%) variant. The most prevalent MBL variant was bla_NDM-1 (33%, 95% CI: 20-50%). Conclusion: This study suggests a high prevalence of ESBLs and MBLs among E. coli clinical isolates. Comprehensive resistance surveillance is required to guide clinicians prescribing antibiotics in South Asia.

In vitro activity of imipenem-relebactam against various resistance phenotypes/genotypes of Enterobacterales and Pseudomonas aeruginosa isolated from patients across Canada as part of the CANWARD study, 2016-2019

Broth microdilution was used to determine the in vitro activities of imipenem-relebactam and comparators versus 4260 Enterobacterales and 1324 Pseudomonas aeruginosa clinical isolates. Excluding Serratia marcescens, 96.7% to 100% of Enterobacterales species were susceptible to imipenem-relebactam. Susceptibility of P. aeruginosa isolates to imipenem-relebactam and imipenem was 91.3% and 59.1%, respectively.

Multidrug-Resistant Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolated from Vegetable Farm Soil in South Korea

The populations of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) have increasingly disseminated in humans, animals, and the environment. This study aimed to determine the prevalence, antimicrobial susceptibilities, and molecular characteristics of ESBL-EC isolates obtained from vegetable farm soil. In total, 200 soil samples were collected from vegetable farms in Incheon, South Korea, between 2018 and 2019 and cultured on MacConkey screening plates supplemented with 2 μg/mL cefotaxime. Cefotaxime-resistant ESBL-EC isolates were recovered from 4.0% (8/200) of the soil samples. All eight isolates were nonsusceptible to ampicillin, piperacillin, cefazolin, cefotaxime, and cefepime and harbored bla_CTX-M-type ESBL genes, including bla_CTX-M-15 (50.0%), bla_CTX-M-55 (25.0%), and bla_CTX-M-14 (25.0%). Phylogenetic analysis showed that the B1 lineage was predominant (75.0%), followed by A (12.5%) and B2 (12.5%) lineages. Multilocus sequence typing revealed eight different E. coli sequence types (STs), including ST10, ST73, ST155, ST847, ST2521, ST3285, ST5173, and ST9479. Notably, ST10 and ST73 belong to the global extraintestinal pathogenic E. coli lineages. Our findings demonstrated that the farm soil environment may serve as a reservoir of human-associated multidrug-resistant ESBL-producing pathogens.

Extended-spectrum β-lactamase-producing Escherichia coli isolated from raw vegetables in South Korea

The increasing prevalence of oxyimino-cephalosporin-resistant Enterobacteriaceae has become a global concern because of their clinical impact on both human and veterinary medicine. The present study determined the prevalence, antimicrobial susceptibility, and molecular genetic features of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) isolates from raw vegetables. A total of 1324 samples were collected from two agricultural wholesale markets in Incheon, South Korea in 2018. The ESBL-EC strains were isolated from 0.83% (11/1324) samples, and all of them were resistant to ampicillin, piperacillin, cefazoline, cefotaxime, and nalidixic acid and yielded CTX-M-type ESBL, including CTX-M-14, CTX-M-15, CTX-M-55, CTX-M-27, and CTX-M-65. The isolates belonged to phylogenetic subgroups D (n = 5), A (n = 4), and B1 (n = 2). Multilocus sequence typing revealed nine known E. coli sequence types (STs), including ST10, ST38, ST69, ST101, ST224, ST349, ST354, ST2509, ST2847, and two new STs. Notably, ST69, ST10, ST38, and ST354 belong to the major human-associated extraintestinal pathogenic E. coli lineages. Our results demonstrate that ESBL-producing multidrug-resistant pathogens may be transmitted to humans through the vegetable intake, highlighting the importance of resistance monitoring and intervention in the One Health perspective.

Clinically Relevant Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolates From Food Animals in South Korea

Extended-spectrum β-lactam antimicrobials have been broadly used in food animals and humans to control infectious diseases. However, the emergence and rapid spread of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, mainly Escherichia coli, have seriously threatened global health in recent decades. In this study, we determined the prevalence, antimicrobial susceptibility, and genetic properties of ESBL-producing E. coli (ESBL-EC) strains isolated from food animals in South Korea. A total of 150 fecal samples from healthy chickens (n = 34), pigs (n = 59), and cattle (n = 57) were screened from January to July 2018. Among these, 77 non-duplicate cefotaxime-resistant ESBL-EC strains were isolated from 32 chicken, 41 pig, and 4 cattle samples, with the corresponding occurrence rates of 94.1, 69.5, and 7.0%, respectively. All the isolates showed multidrug resistance (MDR) and produced at least one type of β-lactamase, including CTX-M (98.7%) and TEM (40.3%). CTX-M-14 (53.1%), CTX-M-55 (53.7%), and CTX-M-65 (50.0%) were the predominant genotypes in the chicken, pig, and cattle samples, respectively. Multilocus sequence typing revealed 46 different sequence types (STs), including the human-associated extraintestinal pathogenic E. coli ST131 (n = 2), ST10 (n = 5), ST38 (n = 1), ST410 (n = 4), ST354 (n = 2), ST58 (n = 3), ST117 (n = 1), and ST457 (n = 1). To the best of our knowledge, this is the first report of pandemic E. coli ST131 in non-human isolates in South Korea. Our results demonstrate the high prevalence and diversity of MDR-ESBL-EC in food animals and highlight them as potential pathogenic ESBL-EC reservoirs that may pose a high risk to human health.

High Prevalence of CTX-M Type Extended-Spectrum Beta-Lactamase Genes and Detection of NDM-1 Carbapenemase Gene in Extraintestinal Pathogenic Escherichia coli in Cuba

Increase of extraintestinal pathogenic Escherichia coli (ExPEC) showing resistance to beta-lactams is a major public health concern. This study was conducted as a first molecular epidemiological study on ExPEC in Cuba, regarding prevalence of extended-spectrum beta-lactamases (ESBLs) and carbapenemase genes. A total of 306 ExPEC isolates collected in medical institutions in 16 regions in Cuba (2014–2018) were analyzed for their genotypes and presence of genes encoding ESBL, carbapenemase, plasmid-mediated quinolone resistance (PMQR) determinants by PCR and sequencing. The most common phylogenetic group of ExPEC was B2 (49%), followed by D (23%), A (21%), and B1 (7%). Among ESBL genes detected, bla_CTX-M was the most common and detected in 61% of ExPEC, with bla_CTX-M-15 being dominant and distributed to all the phylogenetic groups. NDM-1 type carbapenemase gene was identified in two isolates of phylogenetic group B1-ST448. Phylogenetic group B2 ExPEC belonged to mostly ST131 (or its single-locus variant) with O25b allele, harboring bla_CTX-M-27, and included an isolate of emerging type ST1193. aac (6’)-Ib-cr was the most prevalent PMQR gene (40.5%), being present in 54.5% of CTX-M-positive isolates. These results indicated high prevalence of CTX-M genes and the emergence of NDM-1 gene among recent ExPEC in Cuba, depicting an alarming situation.