Abstract
The emergence of third-generation cephalosporin resistance in Escherichia coli is increasing at an alarming rate in many countries. Thus, the aim of this study was to analyze co-infecting blaCTX-M-producing pathogenic E. coli isolates linked to three school outbreaks. Among 66 E. coli isolates, 44 were identified as ETEC O25, an ETEC isolate serotype was O2, and the other 21 were confirmed as EAEC O44. Interestingly, six patients were co-infected with EAEC O44 and ETEC O25. For these isolates, molecular analysis [antibiotic susceptibility testing, identification of the β-lactamase gene, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE)] was performed for further characterization. In addition, the transmission capacity of blaCTX-M genes was examined by conjugation experiments. Whole-genome sequencing (WGS) was performed on representative EAEC O44 and ETEC O25 isolates associated with co-infection and single-infection. All isolates were resistant to cefotaxime and ceftriaxone. All EAEC isolates carried the blaCTX-M-14 gene and all ETEC isolates the blaCTX-M-15 gene, as detected by multiplex PCR and sequencing analysis. Sequence type and PFGE results indicated three different patterns depending on the O serotype. WGS results of representative isolates revealed that the ETEC O25 strains harbored blaCTX-M-15 located on IncK plasmids associated with the ΔblaTEM-blaCTX-M-15-orf477 transposon. The representative EAEC O44 isolates carried blaCTX-M-14 on the chromosome, which was surrounded by the ISEcp1-blaCTX-M-14-IS903 transposon. To the best of our knowledge, this is the first report of co-infection with chromosomally located blaCTX-M-14 and plasmid-encoding blaCTX-M-15 in pathogenic E. coli. Our findings indicate that resistance genes in clinical isolates can spread through concurrent combinations of chromosomes and plasmids.
Highlights
Pathogenic Escherichia coli is a cause of gastroenteritis, including foodborne outbreaks, worldwide
A total of 44 enterotoxigenic E. coli (ETEC) strains were classified as O-type O25, and the serotype of one ETEC strain was O2; the other 21 strains were confirmed as O44
We confirmed that six patients were co-infected with ETEC O25 and enteroaggregative E. coli (EAEC) O44
Summary
Pathogenic Escherichia coli is a cause of gastroenteritis, including foodborne outbreaks, worldwide. Most E. coli infections are self-limiting, and sometimes require antimicrobial treatment. For treatment of E. coli infections, antibiotics such as thirdgeneration cephalosporins and fluoroquinolones are prescribed (Kim et al, 2014b). The emergence of antimicrobial resistance is increasing at an alarming rate in many countries. Thirdgeneration cephalosporin resistance, including resistance against cefotaxime and ceftriaxone, has been steadily reported in recent years. Many countries have rapidly experienced the dissemination of extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae isolates, E. coli (Oteo et al, 2012)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
