Enterococci are part of the indigenous microbiota of human gastrointestinal tract and food of animal origin. Enterococci inhabiting non-human reservoirs play a critical role in the acquisition and dissemination of antimicrobial resistance determinants. The aim of this work was to investigate the antimicrobial resistance in Enterococcus faecalis and Enterococcus faecium strains recovered from artisanal food of animal origin. Samples of goat cheese (n = 42), cow cheese (n = 40), artisanal salami (n = 30), and minced meat for the manufacture of hamburgers (n = 60) were analyzed. Phenotypic and genotypic tests for species-level identification of the recovered isolates were carried out. Minimum inhibitory concentration (MIC) study for in vitro quantitative antimicrobial resistance assessment was performed, and 71 E. faecalis and 22 E. faecium were isolated. The recovered enterococci showed different multi-drug resistance patterns that included tretracycline, erythromycin, ciprofloxacin, linezolid, penicillin, ampicillin, vancomycin, teicoplanin, gentamicin (high-level resistance), and streptomycin (high-level resistance). VanA-type E. faecium were detected. β-lactamase activity was not observed. Artisanal foods of animal origin act as a non-human reservoir of E. faecalis and E. faecuim strains, expressing multi-resistance to antimicrobials. In conclusion, the implementation of a continuous antimicrobial resistance surveillance in enterococci isolated from artisanal food of animal origin is important.

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Enterococci often acquire antimicrobial resistance through horizontal gene transfer. Relatedness between enterococci with high level resistance to gentamicin and vancomycin isolated from humans, food and hospital environment in Tandil County (Argentina) was investigated. PCR amplification for species determination was carried out. Resistance to seven antimicrobials was studied; virulence genes (esp, cylA), vancomycin and gentamicin resistance genes were investigated. In the isolates with high level antimicrobial resistance (gentamicin, vancomycin), pulse-field gel electrophoresis was performed. Vancomycin-resistant E. faecium (n:13) were recovered from human, food and hospital environment samples. All the isolates expressed high-level vancomycin and teicoplanin (vanA genotype), as well high-level gentamicin and streptomycin resistance. Vancomycin-resistant E. faecium were distributed among seven clonal types; esp gene was detected in clinical strains. There was no clonal relationship with food vanA E. faecium, but these strains could pose a risk in intra/inter genus transfer of vanA determinant to human-adapted strains. High-level gentamicin resistant E. faecalis (n:7) were recovered from human and food samples. Glycopeptide resistance was not observed; cylA gene was detected in most of the clinical high-level gentamicin resistant E. faecalis isolates. PFGE patterns showed four clonal types in high-level gentamicin resistant E. faecalis strains; there was demonstrated clonal relatedness between isolates from different origin. In Argentina, this is the first study showing a clonal relationship between high-level gentamicin resistant E. faecalis isolated from food and humans. These results encourage the study of dissemination of clonal complexes with mobile resistance genes.

The study’s aim was to analyze the population structure of enterococci causing human invasive infections in a medium-sized Argentinian Hospital coincidental with a 5 year-period of increased recovery of antibiotic resistant enterococci (2010–2014). Species identification (biochemical testing/MALDI-TOF-MS), antimicrobial susceptibility (disk-diffusion) and clonal relatedness (PFGE/MLST/BAPS) were determined according to standard guidelines. β-lactamase production was determined by a nitrocefin test and confirmed by PCR/sequencing. The isolates were identified as Enterococcus faecalis and Enterococcus faecium at a 2:1 ratio. Most of the E. faecalis isolates, grouped in 25 PFGE-types (ST9/ST179/ST236/ST281/ST388/ST604/ST720), were resistant to high-levels (HLR) of gentamicin/streptomycin. A ST9 clone (bla+/HLR-gentamicin) was detected in patients of different wards during 2014. E. faecium isolates were grouped in 10 PFGE-types (ST25/ST18/ST19/ST52/ST792), with a low rate of ampicillin resistance. Five vancomycin-resistant E. faecium, three vanA (ST792/ST25) and two vanB (ST25) were detected. The ST25 clone carried either vanA or vanB. The recovery of a bla+-ST9-E. faecalis clone similar to that described in the late 1980s in Argentina suggests the possibility of a local hidden reservoir. These results reflect the relevance of local epidemiology in understanding the population structure of enterococci as well as the emergence and spread of antimicrobial resistance in predominant enterococcal clonal lineages.