Escherichia coli is a significant pathogen in extraintestinal infections, and ESBL-producing E. coli poses a major clinical challenge due to its antibiotic resistance. This study comprehensively analyzed E. coli isolates from urine and blood samples of patients with urinary tract and bloodstream infections at three major tertiary hospitals in South Korea. The goal was to provide insights into the distribution, antibiotic resistance, and virulence factors of these strains. Our analysis identified CTX-M and TEM as the dominant ESBL types, found in 71.7% and 61.7% of isolates, respectively, with 46.7% showing co-occurrence. Multilocus sequence typing (MLST) revealed the predominance of high-risk clones such as ST131, ST69, ST73, and ST95, with rare sequence types like ST410 and ST405 also identified. The high prevalence of virulence factors, including iutA (80.8%) and kpsMII (74.2%), further highlights the complexity of these strains. In addition, 38.3% of clinical isolates contained a combination of siderophore, adhesin, protectin, and toxin-related genes. There was no significant difference between urinary tract and bloodstream infections or regional differentiation in Korea. This study highlights the importance of controlling ESBL-producing E. coli infections, especially given the increasing incidence among patients with underlying medical conditions and older adults who are more susceptible to urinary tract infections. These findings serve as valuable indicators for pathogen analysis, especially those harboring antibiotic resistance and toxin genes. The insights gained are expected to contribute significantly to the development of infectious disease prevention and control strategies.

• Klíčová slova
• Escherichia coli, Blood infection, Extended spectrum beta-lactamases (ESBLs), Extra-intestinal pathogenic (ExPEC), Multi-locus sequence typing (MLST), Urinary tract infection (UTI), Virulence factors,
• MeSH
• antibakteriální látky farmakologie   MeSH
• bakteriemie * mikrobiologie   epidemiologie   MeSH
• beta-laktamasy * genetika   metabolismus   MeSH
• dospělí MeSH
• Escherichia coli * genetika   izolace a purifikace   patogenita   enzymologie   účinky léků   klasifikace   MeSH
• faktory virulence genetika   MeSH
• infekce močového ústrojí * mikrobiologie   epidemiologie   MeSH
• infekce vyvolané Escherichia coli * mikrobiologie   epidemiologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mikrobiální testy citlivosti MeSH
• mladý dospělý MeSH
• multilokusová sekvenční typizace MeSH
• prevalence MeSH
• proteiny z Escherichia coli genetika   metabolismus   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• virulence MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Korejská republika epidemiologie   MeSH
• Názvy látek
• antibakteriální látky MeSH
• beta-laktamasy * MeSH
• faktory virulence MeSH
• proteiny z Escherichia coli MeSH

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.

• Klíčová slova
• colistin, livestock, mcr, resistance, screening,
• Publikační typ
• časopisecké články MeSH

Poultry represents a common source of bacteria with resistance to antibiotics including the critically important ones. Selective cultivation using colistin, cefotaxime and meropenem was performed for 66 chicken samples coming from 12 farms in Paraguay while two breeding companies supplied the farms. A total of 62 Escherichia coli and 22 Klebsiella pneumoniae isolates were obtained and representative isolates were subjected to whole-genome sequencing. Relatively high prevalence of phylogenetic group D and F was observed in E. coli isolates and several zoonotic sequence types (STs) including ST457 (14 isolates), ST38 (5), ST10 (2), ST117 (2) or ST93 (4) were detected. Isolates from three farms, which purchased chicken from a Paraguayan hatchery showed higher prevalence of mcr-5.1 and blaCTX-M-8 compared to the other nine farms, which purchased chickens from a Brazilian hatchery. Moreover, none of the K. pneumoniae isolates were linked to the Paraguayan hatchery. ESBL/AmpC and mcr-5-carrying multi-drug resistant (MDR) plasmids were characterized, and complete sequences were obtained for eight plasmids. The study shed light on Paraguayan poultry farms as a reservoir of antibiotic resistance commonly conferred via MDR plasmids and showed linkage between resistance and origin of the chickens at the hatcheries level.

• Klíčová slova
• E. coli, ESBL/AmpC, I1 plasmids, K. pneumoniae, colistin,
• Publikační typ
• časopisecké články MeSH

Silver gulls carry phylogenetically diverse Escherichia coli, including globally dominant extraintestinal pathogenic E. coli (ExPEC) sequence types and pandemic ExPEC-ST131 clades; however, our large-scale study (504 samples) on silver gulls nesting off the coast of New South Wales identified E. coli ST457 as the most prevalent. A phylogenetic analysis of whole-genome sequences (WGS) of 138 ST457 samples comprising 42 from gulls, 2 from humans (Australia), and 14 from poultry farmed in Paraguay were compared with 80 WGS deposited in public databases from diverse sources and countries. E. coli ST457 strains are phylogenetic group F, carry fimH145, and partition into five main clades in accordance to predominant flagella H-antigen carriage. Although we identified considerable phylogenetic diversity among the 138 ST457 strains, closely related subclades (<100 SNPs) suggested zoonotic or zooanthroponosis transmission between humans, wild birds, and food-producing animals. Australian human clinical and gull strains in two of the clades were closely related (≤80 SNPs). Regarding plasmid content, country, or country/source, specific connections were observed, including I1/ST23, I1/ST314, and I1/ST315 disseminating blaCMY-2 in Australia, I1/ST113 carrying blaCTX-M-8 and mcr-5 in Paraguayan poultry, and F2:A-:B1 plasmids of Dutch origin being detected across multiple ST457 clades. We identified a high prevalence of nearly identical I1/ST23 plasmids carrying blaCMY-2 among Australian gull and clinical human strains. In summary, ST457 is a broad host range, geographically diverse E. coli lineage that can cause human extraintestinal disease, including urinary tract infection, and displays a remarkable ability to capture mobile elements that carry and transmit genes encoding resistance to critically important antibiotics.

• Klíčová slova
• AmpC, ESBL, ExPEC, I1 plasmids, ST457,
• MeSH
• antibakteriální látky farmakologie   MeSH
• beta-laktamasy genetika   MeSH
• beta-laktamy MeSH
• divoká zvířata MeSH
• Escherichia coli * genetika   MeSH
• fylogeneze MeSH
• infekce vyvolané Escherichia coli * veterinární   MeSH
• lidé MeSH
• plazmidy genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Austrálie MeSH
• Názvy látek
• antibakteriální látky MeSH
• beta-laktamasy MeSH
• beta-laktamy MeSH