Abstract
Shiga toxin-producing Escherichia coli (STEC) and Listeria monocytogenes are worldwide recognized zoonotic pathogens. Recent reports have emerged about the circulation of antimicrobial-resistant STEC and L. monocytogenes isolates. To assess the frequency of antimicrobial resistance and related genes in these pathogens, we studied 45 STEC and 50 L. monocytogenes isolates locally recovered from different sources. Antimicrobial susceptibility testing was performed by disk-diffusion method, and the genomic sequences of three selected STEC and from all 50 L. monocytogenes isolates were analyzed for antibiotic resistance genes. Four STEC and three L. monocytogenes isolates were phenotypically resistant to at least one of the antibiotics tested. Resistance genes aph(3″)-Ib, aph(3′)-Ia, aph(6)-Id, blaTEM−1B, sul2, mef (A), and tet(A) were found in a human STEC ampicillin-resistant isolate. All L. monocytogenes isolates harbored fosX, lin, mdrL, lde fepA, and norB. Overall resistance in L. monocytogenes and STEC was low or middle. However, the high load of resistance genes found, even in susceptible isolates, suggests that these pathogens could contribute to the burden of antimicrobial resistance.
Highlights
Shiga toxin-producing Escherichia coli (STEC) and Listeria monocytogenes are well-recognized zoonotic pathogens circulating in Uruguay [1, 2]
Serogroup Distribution, Antimicrobial Resistance, and Resistance Genes Found in STEC
Resistance genes found in the only sequenced resistant STEC isolate were aph(3′′)-Ib, aph(3′)-Ia, aph[6]-Id, blaTEM−1B, sul2, and tet(A)
Summary
Shiga toxin-producing Escherichia coli (STEC) and Listeria monocytogenes are well-recognized zoonotic pathogens circulating in Uruguay [1, 2]. STEC can produce watery or bloody diarrhea (WD, BD) or even more severe conditions such as hemorrhagic colitis (HC) or hemolytic–uremic syndrome (HUS). Cattle and other food production animals are the main known reservoir for STEC, and the transmission to humans occurs by direct contact with them or through the ingestion of foods or water contaminated with its feces [5]. Controversial, antibiotics such as gentamicin, azithromycin, fosfomycin, and meropenem are recommended to the treatment of human STEC infections to avoid the development of most severe diseases [6]
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