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Annals of Laboratory Medicine, 2020.40(2), 180-183, DOI: https://doi.org/https://doi.org/10.3343/alm.2020.40.2.180
Whole-genome analysis of blaCTX-M-55 carrying Escherichia coli among pigs, farm environment, and farm workers
Young Ah Kim, Hyunsoo Kim; Min Hyuk Choi; Young Hee Seo; Hyukmin Lee; Kyoungwon Lee
Background: The aim of this study is to assess the prevalence and molecular epidemiology of ESBL-producing E. coli colonization in pigs, farm workers and farm environments to elucidate the transmission of multidrug-resistant clones from animal to human.
Methods: Nineteen pig farms were enrolled across the country in Korea from August to December 2017. ESBL-producing E. coli isolates were cultured in 190 pigs, 38 farm workers and 112 sites of farm environments, directly (stool or perirectal swab) or after enrichment (sewage). Antimicrobial susceptibility tests and blaTEM, blaSHV and blaCTX-M were detected. The genomes of the four CTX-M-55-producing E. coli isolates from various sources in one farm were entirely sequenced to assess the relatedness of the strains. Whole genome sequencing (WGS) was performed with the PacBio RS II system (Pacific Biosciences, Menlo Park, CA, USA).
Results: ESBL genotypes were 85 CTX-M-1 group (one CTX-M-3, 23 CTX-M-15, one CTX-M-28, 59 CTX-M-55, one CTX-M-69) and 60 CTX-M-9 group (41 CTX-M-14, one CTX-M-17, one CTX-M-27, 13 CTX-M-65, 4 CTX-M-102) in total 145 isolates. The rectal colonization rates were 53.2% (101/190) in pigs and 39.5% (15/38) in farm workers. In WGS, sequence types (STs) were determined as ST69 (E. coli PJFH115 isolate from a human carrier), ST457 (two E. coli isolates PJFE101 recovered from a fence and PJFA1104 from a pig) and ST5899 (E. coli PJFA173 isolate from the other pig). The four plasmids encoding CTX-M-55 (88,456 to 149, 674 base pair), whether it belonged to IncFIB or IncFIC-IncFIB type, shared IncF backbone furnishing the conjugal elements, suggesting of genes originated from the same ancestor.
Conclusions: In conclusion, the prevalence of ESBL-producing E. coli in swine farms was surprisingly high and many of them shared common ESBL genotypes of clinical isolates such as CTX-M-14, 15 and 55 in Korea. It could spread by horizontal transfer between isolates from different reservoirs (human-animal-environment).
- DOI: https://doi.org/https://doi.org/10.3343/alm.2020.40.2.180
- ISBN or ISSN: 2234-3806
- 본 연구는 질병관리본부 연구개발과제연구비를 지원받아 수행되었습니다.
- This research was supported by a fund by Research of Korea Centers for Disease Control and Prevention.