Antimicrobial Resistance of Non-O157 Shiga Toxin-Producing Escherichia coli Isolated from Humans and Domestic Animals

Abstract

Non-O157 Shiga toxin-producing Escherichia coli (STEC) is an important pathogen that can cause zoonotic diseases. To investigate the antimicrobial resistance of STEC in China, non-O157 STEC isolates, recovered from domestic animals and humans from 12 provinces, were analyzed using antimicrobial susceptibility testing and whole genome characterization. Out of the 298 isolates tested, 115 strains showed resistance to at least one antimicrobial and 85 strains showed multidrug resistance. The highest resistance rate was to tetracycline (32.6%), followed by nalidixic acid (25.2%) and chloramphenicol and azithromycin (both 18.8%). However, imipenem and meropenem were effective against all isolates. Antimicrobial resistance patterns varied among strains from different sources. Strains from pig, sheep, humans, and cattle showed resistance rates of 100.0%, 46.9%, 30.3%, and 6.3% to one or more antimicrobials, respectively. Forty-three genes related to 11 antimicrobial classes were identified among these strains. The colistin-resistance gene mcr was only carried by strains from pigs. A new fosfomycin-resistant gene, fosA7, was detected in strains from humans, cattle, and sheep. Whole genome phylogenetic analysis showed that strains from the four sources were genetically diverse and scattered throughout the phylogenetic tree; however, some strains from the same source had a tendency to cluster closely. These results provide a reference to monitor the emergence and spread of multidrug resistant STEC strains among animals and humans. Furthermore, with a better understanding of antimicrobial genotypes and phenotypes among the diverse STEC strains obtained, this study could guide the administration of antimicrobial drugs in STEC infections when necessary.

Antimicrobial resistance, virulence genes, and phylogenetic characteristics of pathogenic Escherichia coli isolated from patients and swine suffering from diarrhea

“…In this study, we found high rates of multidrug resistance (swine: 93.8%; patients: 86.0%). Evidently, in our results, values obtained were higher than those obtained in other studies (Pig -Netherland: 34.2% [4], China: 84.2% [28], Thailand: 84.6% [14]; Humans -Netherland: 7.1% [29], China: 15.2% [28], Thailand: 45.7% [14]) In Korea, antimicrobial use in veterinary (33.2 defined daily doses (DDD) per 1000 inhabitants per day) and human medicine (31.7 DDD per 1000 inhabitants per day) is relatively higher as compared to that in other member countries of the Organization for Economic Co-operation and Development (OECD) (21.3 and 23.7 DDD per 1000 inhabitants per day, respectively) [30,31]. Besides the possible role of increased selective pressure by repeated exposure to therapeutic agents, this is a likely cofactor in the increased frequency of antimicrobial resistance observed among pathogens [32].…”

Chromosomally Located fosA7 in Salmonella Isolates From China

“…On the other hand, it has the potential to be a reservoir of a mobilized fosfomycin resistance gene. The emergence of fosA7 with a transposase gene downstream on the chromosome of E. coli or fosA7.5 flanked by insertion sequences located on plasmid further supports this hypothesis (Milner et al, 2020;Pan et al, 2021). The fosA7 gene can confer high-level fosfomycin resistance once it is captured by a high copy plasmid or the mobile elements that bring stronger promoters that enhance its expression.…”

High prevalence and pathogenic potential of Shiga toxin-producing Escherichia coli strains in raw mutton and beef in Shandong, China

“…The minimal inhibitory concentrations of all STEC isolates were performed using broth microdilution method as previously described ( Pan et al, 2021 ). The qualitative interpretations of susceptible (S), intermediate (I), resistant (S) strains were determined according to the standard of the Clinical Laboratory Standards Institute guidelines (CLSI 2020).…”