Comparison by multilocus variable‐number tandem repeat analysis and antimicrobial resistance among atypical enteropathogenic Escherichia coli strains isolated from food samples and human and animal faecal specimens

• Published in: Journal of applied microbiology Vol. 122; no. 1; pp. 268 - 278
• Main Authors: Wang, L., Nakamura, H., Kage‐Nakadai, E., Hara‐Kudo, Y., Nishikawa, Y.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01-01-2017
• Subjects: Animals; Anti-Bacterial Agents - pharmacology; Antibiotics; Cattle; Diarrhea; Drug resistance; Drug Resistance, Bacterial; E coli; Enteropathogenic Escherichia coli - classification; Enteropathogenic Escherichia coli - drug effects; Enteropathogenic Escherichia coli - genetics; Enteropathogenic Escherichia coli - isolation & purification; Escherichia coli; Escherichia coli Infections - microbiology; Escherichia coli Infections - veterinary; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Feces; Feces - microbiology; Food Microbiology; food safety; Genotype; genotyping; Humans; Minisatellite Repeats; molecular epidemiology; Swine; food safety; molecular epidemiology; antibiotics; Escherichia coli; genotyping
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/jam.13322

Aim
This study assessed whether multilocus variable‐number tandem repeat analysis (MLVA) and antimicrobial susceptibility testing discriminated diarrhoeagenic atypical enteropathogenic Escherichia coli (aEPEC) from aEPEC indigenous to domestic animals or healthy people.
Methods and Results
MLVA genotyping of 142 aEPEC strains isolated from foods and faecal samples of domestic animals and humans revealed 126 distinct MLVA profiles that distributed to four clusters, yielding a Simpson's index of diversity (D) of 99·8%. Cluster 2 included 87% of cattle isolates and 67% of patient isolates. The plurality (15/34, 44%) of strains from healthy humans mapped to Cluster 1, while half (18/41, 44%) of the swine strains belonged to Cluster 4. Testing for antimicrobial susceptibility revealed that 52 strains (37%) of aEPEC were resistant to one or more agents; only 10 strains (7%) exhibited resistance to more than three agents. Strains isolated from swine or food exhibited a wider variety of resistance phenotypes than bovine or human strains.
Conclusions
MLVA assigned the aEPEC isolates from cattle and patients to Cluster 2, distinct from aEPEC from other sources. Hog yards may be a larger source of drug‐resistant strains than are cattle ranches.
Significance and Impact of the Study
MLVA suggests that human diarrhoeagenic aEPEC are derived from cattle and are distinct from strains carried by healthy people and other animals. Cattle appear to be reservoirs of human diarrhoeagenic aEPEC.