Genomic characterization of antimicrobial resistance in mcr-carrying ESBL-producing Escherichia coli from pigs and humans.

Whole-genome sequencing (WGS) was conducted to characterize mcr-carrying extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (n=7). These E. coli isolates originated from two pigs (TH2 and TH3) and two humans (TH8 and TH9) from Thailand, and three pigs from Lao PDR (LA1, LA2 and LA3). Four E. coli sequence types/serotypes - ST6833/H20 (TH2 and TH3), ST48/O160:H40 (TH8 and TH9), ST5708/H45 (LA1) and ST10562/O148:H30 (LA2 and LA3) - were identified. The plasmid replicon type IncF was identified in all isolates. The point mutations Ser31Thr in PmrA and His2Arg in PmrB were found concurrently in all isolates (colistin MIC=4-8 µg ml-1). LA1 contained up to five point mutations in PmrB, and the colistin MIC was not significantly different from that for the other isolates. All mcr-1.1 was located in the ISApl1-mcr-1-pap2 element, while all mcr-3.1 was located in the TnAs2-mcr-3.1-dgkA-ISKpn40 element. The mcr-3.1 and blaCTX-M-55 genes were co-localized on the same plasmid, which concurrently contained cml, qnrS1 and tmrB. The blaCTX-M-55 and mcr-3.1 genes were located on conjugative plasmids and could be transferred horizontally under selective pressure from ampicillin or colistin. In conclusion, comprehensive insights into the genomic information of ESBL-producing E. coli harbouring mcr were obtained. As mcr-carrying ESBL-producing E. coli were detected in pigs and humans, a holistic and multisectoral One Health approach is required to contain antimicrobial resistance (AMR).

Colistin resistance and plasmid-mediated mcr genes in Escherichia coli and Salmonella isolated from pigs, pig carcass and pork in Thailand, Lao PDR and Cambodia border provinces.

BACKGROUND: Colistin and carbapenem-resistant bacteria have emerged and become a serious public health concern, but their epidemiological data is still limited. OBJECTIVES: This study examined colistin and carbapenem resistance in Escherichia coli and Salmonella from pigs, pig carcasses, and pork in Thailand, Lao PDR, and Cambodia border provinces. METHODS: The phenotypic and genotypic resistance to colistin and meropenem was determined in E. coli and Salmonella obtained from pigs, pig carcasses, and pork (n = 1,619). A conjugative experiment was performed in all isolates carrying the mcr gene (s) (n = 68). The plasmid replicon type was determined in the isolates carrying a conjugative plasmid with mcr by PCR-based replicon typing (n = 7). The genetic relatedness of mcr-positive Salmonella (n = 11) was investigated by multi-locus sequence typing. RESULTS: Colistin resistance was more common in E. coli (8%) than Salmonella (1%). The highest resistance rate was found in E. coli (17.8%) and Salmonella (1.7%) from Cambodia. Colistin-resistance genes, mcr-1, mcr-3, and mcr-5, were identified, of which mcr-1 and mcr-3 were predominant in E. coli (5.8%) and Salmonella (1.7%), respectively. The mcr-5 gene was observed in E. coli from pork in Cambodia. Two colistin-susceptible pig isolates from Thailand carried both mcr-1 and mcr-3. Seven E. coli and Salmonella isolates contained mcr-1 or mcr-3 associated with the IncF and IncI plasmids. The mcr-positive Salmonella from Thailand and Cambodia were categorized into two clusters with 94%-97% similarity. None of these clusters was meropenem resistant. CONCLUSIONS: Colistin-resistant E. coli and Salmonella were distributed in pigs, pig carcasses, and pork in the border areas. Undivided-One Health collaboration is needed to address the issue.

Presence and Transfer of Antimicrobial Resistance Determinants in Escherichia coli in Pigs, Pork, and Humans in Thailand and Lao PDR Border Provinces.

This study aimed to investigate antimicrobial resistance (AMR) characteristics of Escherichia coli isolates from pig origin (including pigs, pig carcass, and pork) and humans in Thailand and Lao People's Democratic Republic (PDR) border provinces. The majority of the E. coli isolates from Thailand (69.7%) and Lao PDR (63.3%) exhibited multidrug resistance. Class 1 integrons with resistance gene cassettes were common (n = 43), of which the most predominant resistance gene cassette was aadA1. The percentage of extended-spectrum beta-lactamase (ESBL) producers was 3.4 in Thailand and 3.2 in Lao PDR. The ESBL genes found were blaCTX-M14, blaCTX-M27, and blaCTX-M55, of which blaCTX-M55 was the most common (58.6%). Ser-83-Leu and Asp-87-Asn were the predominant amino acid changes in GyrA of ciprofloxacin-resistant isolates. Twenty-two percent of all isolates were positive for qnrS. Class 1 integrons carrying aadA1 from pigs (n = 1) and ESBL genes (blaCTX-M55 and blaCTX-M14) from pigs (n = 2), pork (n = 1), and humans (n = 7) were located on conjugative plasmids. Most plasmids (29.3%) were typed in the IncFrepB group. In conclusion, AMR E. coli are common in pig origin and humans in these areas. The findings confirm AMR as One Health issue, and highlight the need for comprehensive and unified collaborations within and between sectors on research and policy.