The pandemic Escherichia coli sequence type 131 strain is acquired even in the absence of antibiotic exposure

Cobalt complexes modulate plasmid conjugation in Escherichia coli and Klebsiella pneumoniae

Antimicrobial resistance genes (ARG), such as extended-spectrum β-lactamase (ESBL) and carbapenemase genes, are commonly carried on plasmids. Plasmids can transmit between bacteria, disseminate globally, and cause clinically important resistance. Therefore, targeting plasmids could reduce ARG prevalence, and restore the efficacy of existing antibiotics. Cobalt complexes possess diverse biological activities, including antimicrobial and anticancer properties. However, their effect on plasmid conjugation has not been explored yet. Here, we assessed the effect of four previously characterised bis(N-picolinamido)cobalt(II) complexes lacking antibacterial activity on plasmid conjugation in Escherichia coli and Klebsiella pneumoniae. Antimicrobial susceptibility testing of these cobalt complexes confirmed the lack of antibacterial activity in E. coli and K. pneumoniae. Liquid broth and solid agar conjugation assays were used to screen the activity of the complexes on four archetypical plasmids in E. coli J53. The cobalt complexes significantly reduced the conjugation of RP4, R6K, and R388 plasmids, but not pKM101, on solid agar in E. coli J53. Owing to their promising activity, the impact of cobalt complexes was tested on the conjugation of fluorescently tagged extended-spectrum β-lactamase encoding pCTgfp plasmid in E. coli and carbapenemase encoding pKpQILgfp plasmid in K. pneumoniae, using flow cytometry. The complexes significantly reduced the conjugation of pKpQILgfp in K. pneumoniae but had no impact on pCTgfp conjugation in E. coli. The cobalt complexes did not have plasmid-curing activity, suggesting that they target conjugation rather than plasmid stability. To our knowledge, this is the first study to report reduced conjugation of clinically relevant plasmids with cobalt complexes. These cobalt complexes are not cytotoxic towards mammalian cells and are not antibacterial, therefore they could be optimised and employed as inhibitors of plasmid conjugation.

Anthropogenic contamination sources drive differences in antimicrobial-resistant Escherichia coli in three urban lakes

Antimicrobial resistance (AMR) is an ever-present threat to the treatment of infectious diseases. However, the potential relevance of this phenomenon in environmental reservoirs still raises many questions. Detection of antimicrobial-resistant bacteria in the environment is a critical aspect for understanding the prevalence of resistance outside of clinical settings, as detection in the environment indicates that resistance is likely already widespread. We isolated antimicrobial-resistant Escherichia coli from three urban waterbodies over a 15-month time series, determined their antimicrobial susceptibilities, investigated their population structure, and identified genetic determinants of resistance. We found that E. coli populations at each site were composed of different dominant phylotypes and showed distinct patterns of antimicrobial and multidrug resistance, despite close geographic proximity. Many strains that were genome-sequenced belonged to sequence types of international concern, particularly the ST131 clonal complex. We found widespread resistance to clinically important antimicrobials such as amoxicillin, cefotaxime, and ciprofloxacin, but found that all strains were susceptible to amikacin and the last-line antimicrobials meropenem and fosfomycin. Resistance was most often due to acquirable antimicrobial resistance genes, while chromosomal mutations in gyrA, parC, and parE conferred resistance to quinolones. Whole-genome analysis of a subset of strains further revealed the diversity of the population of E. coli present, with a wide array of AMR and virulence genes identified, many of which were present on the chromosome, including blaCTX-M. Finally, we determined that environmental persistence, transmission between sites, most likely mediated by wild birds, and transfer of mobile genetic elements likely contributed significantly to the patterns observed.IMPORTANCEA One Health perspective is crucial to understand the extent of antimicrobial resistance (AMR) globally, and investigation of AMR in the environment has been increasing in recent years. However, most studies have focused on waterways that are directly polluted by sewage, industrial manufacturing, or agricultural activities. Therefore, there remains a lack of knowledge about more natural, less overtly impacted environments. Through phenotypic and genotypic investigation of AMR in Escherichia coli, this study adds to our understanding of the extent and patterns of resistance in these types of environments, including over a time series, and showed that complex biotic and abiotic factors contribute to the patterns observed. Our study further emphasizes the importance of incorporating the surveillance of microbes in freshwater environments in order to better comprehend potential risks for both human and animal health and how the environment may serve as a sentinel for potential future clinical infections.

Plasmid-mediated colistin resistance from fresh meat and slaughtered animals in the Czech Republic: nation-wide surveillance 2020-2021

The aim of this study was to determine the occurrence of plasmid-mediated colistin resistance in domestic and imported meat and slaughter animals in the Czech Republic during 2020-2021 by using selective cultivation and direct PCR testing. A total of 111 colistin-resistant Escherichia coli isolates with mcr-1 gene were obtained from 65 (9.9%, n = 659) samples and subjected to whole-genome sequencing. Isolates with mcr were frequently found in fresh meat from domestic production (14.2%) as well as from import (28.8%). The mcr-1-positive E. coli isolates predominantly originated from meat samples (16.6%), mainly poultry (27.1%), and only minor part of the isolates came from the cecum (1.7%). In contrast to selective cultivation, 205 (31.1%) samples of whole-community DNA were positive for at least one mcr variant, and other genes besides mcr-1 were detected. Analysis of whole-genome data of sequenced E. coli isolates revealed diverse sequence types (STs) including pathogenic lineages and dominance of ST1011 (15.6%) and ST162 (12.8%). Most isolates showed multidrug-resistant profile, and 9% of isolates produced clinically important beta-lactamases. The mcr-1 gene was predominantly located on one of three conjugative plasmids of IncX4 (83.5%), IncI2 (7.3%), and IncHI2 (7.3%) groups. Seventy-two percent isolates of several STs carried ColV plasmids. The study revealed high prevalence of mcr genes in fresh meat of slaughter animals. Our results confirmed previous assumptions that the livestock, especially poultry production, is an important source of colistin-resistant E. coli with the potential of transfer to humans via the food chain. IMPORTANCE We present the first data on nation-wide surveillance of plasmid-mediated colistin resistance in the Czech Republic. High occurrence of plasmid-mediated colistin resistance was found in meat samples, especially in poultry from both domestic production and import, while the presence of mcr genes was lower in the gut of slaughter animals. In contrast to culture-based approach, testing of whole-community DNA showed higher prevalence of mcr and presence of various mcr variants. Our results support the importance of combining cultivation methods with direct culture-independent techniques and highlight the need for harmonized surveillance of plasmid-mediated colistin resistance. Our study confirmed the importance of livestock as a major reservoir of plasmid-mediated colistin resistance and pointed out the risks of poultry meat for the transmission of mcr genes toward humans. We identified several mcr-associated prevalent STs, especially ST1011, which should be monitored further as they represent zoonotic bacteria circulating between different environments.

Tackling Soil ARG-Carrying Pathogens with Global-Scale Metagenomics

Antibiotic overuse and the subsequent environmental contamination of residual antibiotics poses a public health crisis via an acceleration in the spread of antibiotic resistance genes (ARGs) through horizontal gene transfer. Although the occurrence, distribution, and driving factors of ARGs in soils have been widely investigated, little is known about the antibiotic resistance of soilborne pathogens at a global scale. To explore this gap, contigs from 1643 globally sourced metagnomes are assembled, yielding 407 ARG-carrying pathogens (APs) with at least one ARG; APs are detected in 1443 samples (sample detection rate of 87.8%). The richness of APs is greater in agricultural soils (with a median of 20) than in non-agricultural ecosystems. Agricultural soils possess a high prevalence of clinical APs affiliated with Escherichia, Enterobacter, Streptococcus, and Enterococcus. The APs detected in agricultural soils tend to coexist with multidrug resistance genes and bacA. A global map of soil AP richness is generated, where anthropogenic and climatic factors explained AP hot spots in East Asia, South Asia, and the eastern United States. The results herein advance this understanding of the global distribution of soil APs and determine regions prioritized to control soilborne APs worldwide.

Short- and Long-Read Sequencing Reveals the Presence and Evolution of an IncF Plasmid Harboring blaCTX-M-15 and blaCTX-M-27 Genes in Escherichia coli ST131

Escherichia coli sequence type 131 (ST131) has contributed to the spread of extended-spectrum beta-lactamase (ESBL) and has emerged as the dominant cause of hospital- and community-acquired urinary tract infections. Here, we report for the first time an in-depth analysis of whole-genome sequencing (WGS) of 4 ESBL-producing E. coli ST131 isolates recovered from patients in two hospitals in Armenia using Illumina short-read sequencing for accurate base calling to determine their genotype and to infer their phylogeny and using Oxford Nanopore Technologies long-read sequencing to resolve plasmid and chromosomal genetic elements. Genotypically, the four Armenian isolates were identified as part of the H30Rx/clade C2 (n = 2) and H41/clade A (n = 2) lineages and were phylogenetically closely related to isolates from the European Nucleotide Archive (ENA) database previously recovered from patients in the United States, Australia, and New Zealand. The Armenian isolates recovered in this study had chromosomal integration of the blaCTX-M-15 gene in the H30Rx isolates and a high number of virulence genes found in the H41 isolates associated with the carriage of a rare genomic island (in the context of E. coli ST131) containing the S fimbrial, salmochelin siderophore, and microcin H47 virulence genes. Furthermore, our data show the evolution of the IncF[2:A2:B20] plasmid harboring both blaCTX-M-15 and blaCTX-M-27 genes, derived from the recombination of genes from an IncF[F2:A-:B-] blaCTX-M-15-associated plasmid into the IncF[F1:A2:B20] blaCTX-M-27-associated plasmid backbone seen in two genetically closely related H41 Armenian isolates. IMPORTANCE Combining short and long reads from whole-genome sequencing analysis provided a genetic context for uncommon genes of clinical importance to better understand transmission and evolutionary features of ESBL-producing uropathogenic E. coli (UPEC) ST131 isolates recovered in Armenia. Using hybrid genome assembly in countries lacking genomic surveillance studies can inform us about new lineages not seen in other countries with genes encoding high virulence and antibiotic resistance harbored on mobile genetic elements.

Polyclonal Spread of Fosfomycin Resistance among Carbapenemase-Producing Members of the Enterobacterales in the Czech Republic

Fosfomycin (FOS) has been recently reintroduced into clinical practice, but its effectiveness against multidrug-resistant (MDR) Enterobacterales is reduced due to the emergence of FOS resistance. The copresence of carbapenemases and FOS resistance could drastically limit antibiotic treatment. The aims of this study were (i) to investigate fosfomycin susceptibility profiles among carbapenem-resistant Enterobacterales (CRE) in the Czech Republic, (ii) to characterize the genetic environment of fosA genes among the collection, and (iii) to evaluate the presence of amino acid mutations in proteins involved in FOS resistance mechanisms. During the period from December 2018 to February 2022, 293 CRE isolates were collected from different hospitals in the Czech Republic. FOS MICs were assessed by the agar dilution method (ADM), FosA and FosC2 production was detected by the sodium phosphonoformate (PPF) test, and the presence of fosA-like genes was confirmed by PCR. Whole-genome sequencing was conducted with an Illumina NovaSeq 6000 system on selected strains, and the effect of point mutations in the FOS pathway was predicted using PROVEAN. Of these strains, 29% showed low susceptibility to fosfomycin (MIC, ≥16 μg/mL) by ADM. An NDM-producing Escherichia coli sequence type 648 (ST648) strain harbored a fosA10 gene on an IncK plasmid, while a VIM-producing Citrobacter freundii ST673 strain harbored a new fosA7 variant, designated fosA7.9. Analysis of mutations in the FOS pathway revealed several deleterious mutations occurring in GlpT, UhpT, UhpC, CyaA, and GlpR. Results regarding single substitutions in amino acid sequences highlighted a relationship between ST and specific mutations and an enhanced predisposition for certain STs to develop resistance. This study highlights the occurrence of several FOS resistance mechanisms in different clones spreading in the Czech Republic. IMPORTANCE Antimicrobial resistance (AMR) currently represents a concern for human health, and the reintroduction of antibiotics such as fosfomycin into clinical practice can provide further option in treatment of multidrug-resistant (MDR) bacterial infections. However, there is a global increase of fosfomycin-resistant bacteria, reducing its effectiveness. Considering this increase, it is crucial to monitor the spread of fosfomycin resistance in MDR bacteria in clinical settings and to investigate the resistance mechanism at the molecular level. Our study reports a large variety of fosfomycin resistance mechanisms among carbapenemase-producing Enterobacterales (CRE) in the Czech Republic. Our study summarizes the main achievements of our research on the use of molecular technologies, such as next-generation sequencing (NGS), to describe the heterogeneous mechanisms that reduce fosfomycin effectiveness in CRE. The results suggest that a program for widespread monitoring of fosfomycin resistance and epidemiology fosfomycin-resistant organisms can aide timely implementation of countermeasures to maintain the effectiveness of fosfomycin.

A One Health Genomic Investigation of Gentamicin Resistance in Escherichia coli from Human and Chicken Sources in Canada, 2014 to 2017

We investigated whether gentamicin resistance (Gen^r) in Escherichia coli isolates from human infections was related to Gen^r E. coli in chicken and whether resistance may be due to coselection from use of lincomycin-spectinomycin in chickens on farms. Whole-genome sequencing was performed on 483 Gen^r E. coli isolates isolated between 2014 and 2017. These included 205 human-source isolates collected by the Canadian Ward (CANWARD) program and 278 chicken-source isolates: 167 from live/recently slaughtered chickens (animals) and 111 from retail chicken meat collected by the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS). The predominant Gen^r gene was different in human and chicken sources; however, both sources carried aac(3)-IId, aac(3)-VIa, and aac(3)-IVa. Forty-one percent of human clinical isolates of Gen^r E. coli contained a bla_CTX-M extended-spectrum beta-lactamase (ESBL) gene (84/205), and 53% of these were sequence type 131 (ST131). Phylogenomic analysis revealed a high diversity of Gen^r isolates; however, there were three small clusters of closely related isolates from human and chicken sources. Gen^r and spectinomycin resistance (Spec^r) genes were colocated in 148/167 (89%) chicken animal isolates, 94/111 (85%) chicken retail meat isolates, and 137/205 (67%) human-source isolates. Long-read sequencing of 23 isolates showed linkage of the Gen^r and Spec^r genes on the same plasmid in 14/15 (93%) isolates from chicken(s) and 6/8 (75%) isolates from humans. The use of lincomycin-spectinomycin on farms may be coselecting for gentamicin-resistant plasmids in E. coli in broiler chickens; however, Gen^r isolates and plasmids were mostly different in chickens and humans.

A Longitudinal Survey of Antibiotic-Resistant Enterobacterales in the Irish Environment, 2019-2020

The natural environment represents a complex reservoir of antibiotic-resistant bacteria as a consequence of different wastewater discharges including anthropogenic and agricultural. Therefore, the aim of this study was to examine sewage and waters across Ireland for the presence of antibiotic-resistant Enterobacterales. Samples were collected from the West, East and South of Ireland. Two periods of sampling took place between July 2019 and November 2020, during which 118 water (30 L) and 36 sewage samples (200 mL) were collected. Waters were filtered using the CapE method, followed by enrichment and culturing. Sewage samples were directly cultured on selective agars. Isolates were identified by MALDI-TOF and antibiotic susceptibility testing was performed in accordance with EUCAST criteria. Selected isolates were examined for bla_CTX-M, bla_VIM, bla_IMP, bla_OXA-48, bla_NDM, and bla_KPC by real time PCR and whole genome sequencing (n = 146). A total of 419 Enterobacterales (348 water, 71 sewage) were isolated from all samples. Hospital sewage isolates displayed the highest percentage resistance to many beta-lactam and aminoglycoside antibiotics. Extended-spectrum beta-lactamase-producers were identified in 78% of water and 50% of sewage samples. One or more carbapenemase-producing Enterobacterales were identified at 23 individual sampling sites (18 water, 5 sewage). This included the detection of bla_OXA-48 (n = 18), bla_NDM (n = 14), bla_KPC (n = 4) and bla_OXA-484 (n = 1). All NDM-producing isolates harbored the ble-MBL bleomycin resistance gene. Commonly detected sequence types included Klebsiella ST323, ST17, and ST405 as well as E. coli ST131, ST38 and ST10. Core genome MLST comparisons detected identical E. coli isolates from wastewater treatment plant (WWTP) influent and nursing home sewage, and the surrounding waters. Similarly, one Klebsiella pneumoniae isolated from WWTP influent and the surrounding estuarine water were identical. These results highlight the need for regular monitoring of the aquatic environment for the presence of antibiotic-resistant organisms to adequately inform public health policies.

Antimicrobial-Resistant Escherichia coli Distribution and Whole-Genome Analysis of Sequence Type 131 Escherichia coli Isolates in Public Restrooms in Taiwan

The threat of antibiotic-resistant bacteria to public health may originate from public restrooms. To better understand the community burden of antimicrobial-resistant Escherichia coli and sequence type complex 131 E. coli (STc131) in the public restroom, we performed a surveillance in public restrooms in southern Taiwan. Swabs were sampled from randomly selected public restrooms in Tainan, Taiwan in 2019. Antimicrobial susceptibility, phylogenetic grouping, and multiplex PCR were performed for the major ST complex in the B2 phylogenetic group. If STc131 isolates were identified, the whole-genome sequencing was performed. A total of 613 collection sites found 132 sites (21.5%) positive for E. coli. The most common phylogenetic group was A (30.9%) followed by B2 (30.3%). Ceftriaxone-resistant E. coli and extended-spectrum β-lactamases–producing E. coli were found in 2.4 and 1.0% of total public restrooms, respectively. The isolates in rural areas had higher ceftriaxone non-susceptibility than those in the city centers (3.9 vs. 1.2%, P = 0.038). Nine STc131 isolates were found in public restrooms, and most (77.8%) belonged to the subtype fimH41, whereas 22.2% belonged to fimH30. With the inclusion of STc131 isolates from human and dog fecal colonization in Taiwan, whole-genome sequencing was performed in 35 isolates. A large cluster of fimH41 in SNP-tree and GrapeTree was found from different sources (human, dog, and environment) and geographical areas. In conclusion, our surveillance of antimicrobial-resistant E. coli showed a higher prevalence of E. coli detected in public restrooms in the rural areas compared to those in city centers. The whole-genome sequence implies that fimH41 STc131 strains are successfully circulated in the community in Taiwan.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): antimicrobial‐resistant Escherichia coli in dogs and cats, horses, swine, poultry, cattle, sheep and goats

Escherichia coli (E. coli) was identified among the most relevant antimicrobial‐resistant (AMR) bacteria in the EU for dogs and cats, horses, swine, poultry, cattle, sheep and goats in previous scientific opinions. Thus, it has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on its eligibility to be listed, Annex IV for its categorisation according to disease prevention and control rules as in Article 9 and Article 8 for listing animal species related to the bacterium. The assessment has been performed following a methodology previously published. The outcome is the median of the probability ranges provided by the experts, which indicates whether each criterion is fulfilled (lower bound ≥ 66%) or not (upper bound ≤ 33%), or whether there is uncertainty about fulfilment. Reasoning points are reported for criteria with uncertain outcome. According to the assessment here performed, it is uncertain whether AMR E. coli can be considered eligible to be listed for Union intervention according to Article 5 of the AHL (33–66% probability). According to the criteria in Annex IV, for the purpose of categorisation related to the level of prevention and control as in Article 9 of the AHL, the AHAW Panel concluded that the bacterium does not meet the criteria in Sections 1, 2, 3 and 4 (Categories A, B, C and D; 0–5%, 5–10%, 10–33% and 10–33% probability of meeting the criteria, respectively) and the AHAW Panel was uncertain whether it meets the criteria in Section 5 (Category E, 33–66% probability of meeting the criteria). The animal species to be listed for AMR E. coli according to Article 8 criteria include mammals, birds, reptiles and fish.

Piperacillin/tazobactam-resistant, cephalosporin-susceptible Escherichia coli bloodstream infections are driven by multiple acquisition of resistance across diverse sequence types

Resistance to piperacillin/tazobactam (TZP) in Escherichia coli has predominantly been associated with mechanisms that confer resistance to third-generation cephalosporins. Recent reports have identified E. coli strains with phenotypic resistance to piperacillin/tazobactam but susceptibility to third-generation cephalosporins (TZP-R/3GC-S). In this study we sought to determine the genetic diversity of this phenotype in E. coli (n=58) isolated between 2014–2017 at a single tertiary hospital in Liverpool, UK, as well as the associated resistance mechanisms. We compare our findings to a UK-wide collection of invasive E. coli isolates (n=1509) with publicly available phenotypic and genotypic data. These data sets included the TZP-R/3GC-S phenotype (n=68), and piperacillin/tazobactam and third-generation cephalosporin-susceptible (TZP-S/3GC-S, n=1271) phenotypes. The TZP-R/3GC-S phenotype was displayed in a broad range of sequence types, which was mirrored in the same phenotype from the UK-wide collection, and the overall diversity of invasive E. coli isolates. The TZP-R/3GC-S isolates contained a diverse range of plasmids, indicating multiple acquisition events of TZP resistance mechanisms rather than clonal expansion of a particular plasmid or sequence type. The putative resistance mechanisms were equally diverse, including hyperproduction of TEM-1, either via strong promoters or gene amplification, carriage of inhibitor-resistant β-lactamases, and an S133G bla_CTX-M-15 mutation detected for the first time in clinical isolates. Several of these mechanisms were present at a lower abundance in the TZP-S/3GC-S isolates from the UK-wide collection, but without the associated phenotypic resistance to TZP. Eleven (19%) of the isolates had no putative mechanism identified from the genomic data. Our findings highlight the complexity of this cryptic phenotype and the need for continued phenotypic monitoring, as well as further investigation to improve detection and prediction of the TZP-R/3GC-S phenotype from genomic data.

Escherichia coli ST131 isolated from urological patients can acquire plasmid-mediated extended spectrum β-lactamase from other bacteria with high frequency

OBJECTIVES

To investigate the prevalence of the clonal group Escherichia coli ST131 in urologic patients, and to clarify the mechanisms underlying the high prevalence of the antimicrobial resistant genes in ST131.

METHODS

We used 65 Escherichia coli strains collected from the Department of Urology, Nagasaki University Hospital, between January 2018 and December 2018. All of them underwent multilocus sequence typing and were analyzed for genes associated with quinolone resistance and extended-spectrum β-lactamases. To compare ST131 and non-ST131 strains, bacterial conjugation experiments and intestinal colonization evaluations were performed.

RESULTS

ST131 was the most dominant among all the strains, along with levofloxacin resistant strains, and extended-spectrum β-lactamases positive strains (32%, 63%, and 73%, respectively). 12 out of 15 extended-spectrum β-lactamases-producing Escherichia coli strains harbored CTX-M-9. In particular, all extended-spectrum β-lactamases-producing ST131 strains possessed CTX-M-9. The proportions of ST131 strains with or without quinolone resistance-determining region mutations were significantly higher and lower, respectively, than that of non-ST131 strains (P = 0.0002 and P < 0.0001, respectively). When Klebsiella pneumoniae was used as a donor, three ST131 strains acquired extended-spectrum β-lactamases a total of 16 times (six, four, and six times each), which was significantly more than that in one of the non-ST131 strains (two times). The amount of bacteria was significantly lower in the ST131 strains than in the non-ST131 strains administered to mice. Both the ST131 and non-ST131 strains increased again after the administration of vancomycin, even after the colony was not detected.

CONCLUSIONS

These results support the mechanisms underlying the prevalence of ST131 strains in hospitals, particularly in urologic patients.

From Pathophysiological Hypotheses to Case–Control Study Design: Resistance from Antibiotic Exposure in Community-Onset Infections

Antimicrobial resistance is a global public health concern, at least partly due to the misuse of antibiotics. The increasing prevalence of antibiotic-resistant infections in the community has shifted at-risk populations into the general population. Numerous case–control studies attempt to better understand the link between antibiotic use and antibiotic-resistant community-onset infections. We review the designs of such studies, focusing on community-onset bloodstream and urinary tract infections. We highlight their methodological heterogeneity in the key points related to the antibiotic exposure, the population and design. We show the impact of this heterogeneity on study results, through the example of extended-spectrum β-lactamases producing Enterobacteriaceae. Finally, we emphasize the need for the greater standardization of such studies and discuss how the definition of a pathophysiological hypothesis specific to the bacteria–resistance pair studied is an important prerequisite to clarify the design of future studies.

Rare transmission of commensal and pathogenic bacteria in the gut microbiome of hospitalized adults

Bacterial bloodstream infections are a major cause of morbidity and mortality among patients undergoing hematopoietic cell transplantation (HCT). Although previous research has demonstrated that pathogens may translocate from the gut microbiome into the bloodstream to cause infections, the mechanisms by which HCT patients acquire pathogens in their microbiome have not yet been described. Here, we use linked-read and short-read metagenomic sequencing to analyze 401 stool samples collected from 149 adults undergoing HCT and hospitalized in the same unit over three years, many of whom were roommates. We use metagenomic assembly and strain-specific comparison methods to search for high-identity bacterial strains, which may indicate transmission between the gut microbiomes of patients. Overall, the microbiomes of patients who share time and space in the hospital do not converge in taxonomic composition. However, we do observe six pairs of patients who harbor identical or nearly identical strains of the pathogen Enterococcus faecium, or the gut commensals Akkermansia muciniphila and Hungatella hathewayi. These shared strains may result from direct transmission between patients who shared a room and bathroom, acquisition from a common hospital source, or transmission from an unsampled intermediate. We also identify multiple patients with identical strains of species commonly found in commercial probiotics, including Lactobacillus rhamnosus and Streptococcus thermophilus. In summary, our findings indicate that sharing of identical pathogens between the gut microbiomes of multiple patients is a rare phenomenon. Furthermore, the observed potential transmission of commensal, immunomodulatory microbes suggests that exposure to other humans may contribute to microbiome reassembly post-HCT.

Here, Siranosian et al. provide evidence for rare transmission of commensal and pathogenic bacteria between the microbiomes of hospitalized adults, with important factors being roommate overlap and exposure to broad-spectrum antibiotics.

Exploring temporal trends and risk factors for resistance in Escherichia coli-causing bacteraemia in England between 2013 and 2018: an ecological study

BACKGROUND

Escherichia coli are Gram-negative bacteria associated with an increasing burden of antimicrobial resistance (AMR) in England.

OBJECTIVES

To create a comprehensive epidemiological picture of E. coli bacteraemia resistance trends and risk factors in England by linking national microbiology data sources and performing a longitudinal analysis of rates.

METHODS

A retrospective observational study was conducted on all national records for antimicrobial susceptibility testing on E. coli bacteraemia in England from 1 January 2013 to 31 December 2018 from the UK Health Security Agency (UKHSA) and the BSAC Resistance Surveillance Programme (BSAC-RSP). Trends in AMR and MDR were estimated using iterative sequential regression. Logistic regression analyses were performed on UKHSA data to estimate the relationship between risk factors and AMR or MDR in E. coli bacteraemia isolates.

RESULTS

An increase in resistance rates was observed in community- and hospital-onset bacteraemia for third-generation cephalosporins, co-amoxiclav, gentamicin and ciprofloxacin. Among community-acquired cases, and after adjustment for other factors, patients aged >65 years were more likely to be infected by E. coli isolates resistant to at least one of 11 antibiotics than those aged 18-64 years (OR: 1.21, 95% CI: 1.18-1.25; P < 0.05). In hospital-onset cases, E. coli isolates from those aged 1-17 years were more likely to be resistant than those aged 18-64 years (OR: 1.33, 95% CI: 1.02-1.73; P < 0.05).

CONCLUSIONS

Antibiotic resistance rates in E. coli-causing bacteraemia increased between 2013 and 2018 in England for key antimicrobial agents. Findings of this study have implications for guiding future policies on a prescribing of antimicrobial agents, for specific patient populations in particular.

Mechanisms involved in the active secretion of CTX-M-15 β-lactamase by pathogenic E. coli ST131

Infections caused by antimicrobial resistant bacterial pathogens are fast becoming an important global health issue. Strains of Escherichia coli are common causal agents of urinary tract infection and can carry multiple resistance genes. This includes the gene bla_CTX-M-15 that encodes for an extended spectrum beta-lactamase (ESBL). While studying antimicrobial resistance (AMR) in the environment we isolated several strains of E. coli ST131 downstream of a waste water treatment plan (WWTP) in a local river. These isolates were surviving in the river sediment and characterisation proved that a multi-resistant phenotype was evident. Here, we show that E. coli strain 48 (river isolate ST131), provided a protective effect against a third-generation cephalosporin (cefotaxime) for a susceptible E. coli strain 33 (river isolate ST3576) through secretion of a functional ESBL into the growth medium. Furthermore, extracellular ESBL activity was stable for at least 24 h after secretion. Proteomic and molecular genetic analyses identified CTX-M-15 as the major secreted ESBL responsible for the observed protective effect. In contrast to previous studies, outer-membrane vesicles (OMVs) were not the route for CTX-M-15 secretion. Indeed, mutation of the Type I secretion system led to a significant reduction in the growth of the ESBL-producing strain as well as a significantly reduced ability to confer protective effect. We speculate that CTX-M-15 secretion, mediated through active secretion using molecular machinery provides a public goods service by facilitating the survival of otherwise susceptible bacteria in the presence of cefotaxime.

Prevalence and risks factors associated with ESBL-producing faecal carriage in a single long-term-care facility in Spain: emergence of CTX-M-24- and CTX-M-27-producing Escherichia coli ST131-H30R

OBJECTIVES

To address the faecal carriage prevalence of antibiotic-multiresistant bacteria and associated risk factors in a public long-term care facility (LTCF).

METHODS

A prospective study in a single government-funded LTCF of 300 residents in Ciudad Real, Spain. Residents' clinical and demographic data were collected, as well as recent antibiotic consumption in the institution. Each participant contributed a rectal swab, which was plated on selective and differential-selective media. Colonies were identified by MALDI-TOF and ESBL production was confirmed by the double-disc synergy method, with characterization of the molecular mechanism by PCR. Isolates were typed by PFGE and submitted for ST131 screening by PCR.

RESULTS

Faecal carriage of ESBL-producing Enterobacterales was detected in 58 (31%) of 187 participants and previous infection by MDR bacteria was identified as a risk factor. The genes characterized were: blaCTX-M-15 (40.6%); blaCTX-M-14 (28.8%); blaCTX-M-27 (13.5%); and blaCTX-M-24 (10.1%). Some 56.4% of the isolates were grouped into the E. coli ST131 clone; 70.9% of these corresponded to the O25b serotype, 51.6% of them to Clade C1 (H30) and 12.9% to Clade C2 (H30Rx). Clade C1 isolates were mostly C1-M27, whereas the C2 sublineage was mainly related to the production of CTX-M-15. ST131-CTX-M-24 isolates (n = 6) corresponded to Clade A with serotype O16.

CONCLUSIONS

A high prevalence of ESBL-producing Enterobacterales faecal carriage has been detected in a single LTCF, highlighting the emergence of ST131 Clade A-M24 and Clade C1-M27 lineages.

The Challenge of Global Emergence of Novel Colistin-Resistant Escherichia coli ST131

Escherichia coli ST131 is one of the high-risk multidrug-resistant clones with a global distribution and the ability to persist and colonize in a variety of niches. Carbapenemase-producing E. coli ST131 strains with the ability to resist last-line antibiotics (i.e., colistin) have been recently considered a significant public health. Colistin is widely used in veterinary medicine and therefore, colistin-resistant bacteria can be transmitted from livestock to humans through food. There are several mechanisms of resistance to colistin, which include chromosomal mutations and plasmid-transmitted mcr genes. E. coli ST131 is a great model organism to investigate the emergence of superbugs. This microorganism has the ability to cause intestinal and extraintestinal infections, and its accurate identification as well as its antibiotic resistance patterns are vitally important for a successful treatment strategy. Therefore, further studies are required to understand the evolution of this resistant organism for drug design, controlling the evolution of other nascent emerging pathogens, and developing antibiotic stewardship programs. In this review, we will discuss the importance of E. coli ST131, the mechanisms of resistance to colistin as the last-resort antibiotic against resistant Gram-negative bacteria, reports from different regions regarding E. coli ST131 resistance to colistin, and the most recent therapeutic approaches against colistin-resistance bacteria.

Hospital-diagnosed infections with Escherichia coli clonal group ST131 are mostly acquired in the community

The worldwide spread of E. coli ST131 has significantly contributed to the dissemination of E. coli producing extended-spectrum β-lactamases (ESBL). In a French University hospital, we assessed the molecular features of ESBL-producing E. coli and identified risk factors in patients for colonization or infection with E. coli ST131. Over a 2-year period (2015–2017), each patient with at least one clinical isolate or one screening isolate positive with ESBL-producing E. coli were included (n = 491). The ST131 clonal group accounted for 17.5% (n = 86) of all ESBL-producing E. coli and represented 57.3% isolates of phylogroup B2. FimH-based sub-typing showed that 79.1% (68/86) of ST131 isolates were fimH30, among which 67.6% (n = 46), 20.6% (n = 14) and 11.8% (n = 8) isolates harbored genes encoding the ESBL CTX-M-15, CTX-M-27, and CTX-M-14, respectively. The multivariate analysis identified two factors independently associated with ST131 ESBL-producing E. coli isolates: infection (Odds ratio [OR] = 1.887, 95% confidence interval [CI]: 1.143–3.115; p = 0.013) and community acquisition (OR = 2.220, 95% CI: 1.335–3.693; p = 0.002). In conclusion, our study confirmed the predominance of ST131 clonal group among ESBL-producing E. coli and the difficulty to identify common risk factors associated with carriage of this pandemic clonal group.

Caretaker knowledge, attitudes, and practices (KAP) and carriage of extended-spectrum beta-lactamase-producing E. coli (ESBL-EC) in children in Quito, Ecuador

Background

The rapid spread of extended-spectrum beta-lactamase-producing E. coli (ESBL-EC) is an urgent global health threat. We examined child caretaker knowledge, attitudes, and practices (KAP) towards proper antimicrobial agent use and whether certain KAP were associated with ESBL-EC colonization of their children.

Methods

Child caretakers living in semi-rural neighborhoods in peri-urban Quito, Ecuador were visited and surveyed about their KAP towards antibiotics. Fecal samples from one child (less than 5 years of age) per household were collected at two time points between July 2018 and May 2019 and screened for ESBL-EC. A repeated measures analysis with logistic regression was used to assess the relationship between KAP levels and child colonization with ESBL-EC.

Results

We analyzed 740 stool samples from 444 children living in households representing a range of environmental conditions. Of 374 children who provided fecal samples at the first household visit, 44 children were colonized with ESBL-EC (11.8%) and 161 were colonized with multidrug-resistant E. coli (43%). The prevalences of ESBL-EC and multidrug-resistant E. coli were similar at the second visit (11.2% and 41.3%, respectively; N = 366). Only 8% of caretakers knew that antibiotics killed bacteria but not viruses, and over a third reported that they “always” give their children antibiotics when the child’s throat hurts (35%). Few associations were observed between KAP variables and ESBL-EC carriage among children. The odds of ESBL-EC carriage were 2.17 times greater (95% CI: 1.18–3.99) among children whose caregivers incorrectly stated that antibiotics do not kill bacteria compared to children whose caregivers correctly stated that antibiotics kill bacteria. Children from households where the caretaker answered the question “When your child’s throat hurts, do you give them antibiotics?” with “sometimes” had lower odds of ESBL-EC carriage than those with a caretaker response of “never” (OR 0.48, 95% CI 0.27–0.87).

Conclusion

Caregivers in our study population generally demonstrated low knowledge regarding appropriate use of antibiotics. Our findings suggest that misinformation about the types of infections (i.e. bacterial or viral) antibiotics should be used for may be associated with elevated odds of carriage of ESBL-EC. Understanding that using antibiotics is appropriate to treat infections some of the time may reduce the odds of ESBL-EC carriage. Overall, however, KAP measures of appropriate use of antibiotics were not strongly associated with ESBL-EC carriage. Other individual- and community-level environmental factors may overshadow the effect of KAP on ESBL-EC colonization. Intervention studies are needed to assess the true effect of improving KAP on laboratory-confirmed carriage of antimicrobial resistant bacteria, and should consider community-level studies for more effective management.

Plasmids shape the diverse accessory resistomes of Escherichia coli ST131

The human gut microbiome includes beneficial, commensal and pathogenic bacteria that possess antimicrobial resistance (AMR) genes and exchange these predominantly through conjugative plasmids. Escherichia coli is a significant component of the gastrointestinal microbiome and is typically non-pathogenic in this niche. In contrast, extra-intestinal pathogenic E. coli (ExPEC) including ST131 may occupy other environments like the urinary tract or bloodstream where they express genes enabling AMR and host cell adhesion like type 1 fimbriae. The extent to which commensal E. coli and uropathogenic ExPEC ST131 share AMR genes remains understudied at a genomic level, and we examined this here using a preterm infant resistome. We found that individual ST131 had small differences in AMR gene content relative to a larger shared resistome. Comparisons with a range of plasmids common in ST131 showed that AMR gene composition was driven by conjugation, recombination and mobile genetic elements. Plasmid pEK499 had extended regions in most ST131 Clade C isolates, and it had evidence of a co-evolutionary signal based on protein-level interactions with chromosomal gene products, as did pEK204 that had a type IV fimbrial pil operon. ST131 possessed extensive diversity of selective type 1, type IV, P and F17-like fimbriae genes that was highest in subclade C2. The structure and composition of AMR genes, plasmids and fimbriae vary widely in ST131 Clade C and this may mediate pathogenicity and infection outcomes.

Emergence of Escherichia coli ST131 Causing Urinary Tract Infection in Western Asia: A Systematic Review and Meta-Analysis

Escherichia coli sequence type (ST) 131 is considered a high-risk pandemic clone and frequently extended-spectrum β-lactamase (ESBL)-producing clone that is strongly associated with the global dissemination of CTX-M-15 type. The emergence of ST131 has become a public health threat because this clonal group typically exhibits multiple virulence factors and antimicrobial resistance. Therefore, this study aimed to analyze the literature published on the estimation of the prevalence of clone ST131 among E. coli strains isolated from patients with urinary tract infections in western Asia. A systematic search was carried out to identify eligible articles in the Web of Science, PubMed, Scopus, Embase, and Google Scholar electronic databases from January 2010 to December 2018. Next, 13 articles meeting the inclusion criteria were selected for data extraction and analysis by Comprehensive Meta-Analysis Software. The included studies were conducted in Iran, Jordan, Kuwait, Pakistan, Saudi Arabia, Turkey, and Yemen. In all studies, the pooled prevalence of ST131 was 24.6% (95% CI: 13.5%-40.4%) in wild type isolates, 42.7% (95% CI: 32.5%-53.5%) among ESBLs-producing isolates, and 64.8% (95% CI: 36%-85.5%) among multiple-drug resistant (MDR) isolates. Moreover, the prevalence of ST131 isolates carrying CTX-M-15 type was 68% (95% CI: 48.4%-82.8%). Our study indicated the high prevalence of broadly disseminated ST131 clone among MDR and ESBLs isolates in western Asia. Moreover, O25b was the predominant ST131 clone type, which was mostly associated with CTX-M-15 type.

The evolutionary puzzle of Escherichia coli ST131

The abrupt expansion of Escherichia coli sequence type (ST) 131 is unmatched among Gram negative bacteria. In many ways, ST131 can be considered a real-world model for the complexities involved in the evolution of a multidrug resistant pathogen. While much progress has been made on our insights into the organism's population structure, pathogenicity and drug resistance profile, significant gaps in our knowledge remain. Whole genome studies have shed light on key mutations and genes that have been selected against the background of antibiotics, but in most cases such events are inferred and not supported by experimental data. Notable examples include the unknown fitness contribution made by specific plasmids, genomic islands and compensatory mutations. Furthermore, questions remain like why this organism in particular achieved such considerable success in such a short time span, compared to other more pathogenic and resistant clones. Herein, we document what is known regarding the genetics of this organism since its first description in 2008, but also highlight where work remains to be done for a truly comprehensive understanding of the biology of ST131, in order to account for its dramatic rise to prominence.