Diversity of serine-ß-lactamase genes among Aeromonas isolates from pigs slaughtered for consumption

Fontes, M. C.
Saavedra, M. J.
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International Association of Food Protection
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Introduction: Antimicrobial resistance in foodborne pathogens has become a public health issue. The intense and indiscriminate use of antibiotics is undoubtedly the major force associated with the high bacteria resistance worldwide. Some Aeromonas species cause both gastrointestinal and extraintestinal infectious diseases in humans. Many studies suggest members of Aeromonas developed multiple antibiotic resistances which constitutes a limitation to the treatment of infections associated to these bacteria. Rationale: The aim of this work was to evaluate the susceptibility patterns of the isolates obtained from pigs slaughtered for consumption and to assess the occurrence and diversity of ß-lactamase genes. Results: A total of 106 Aeromonas strains were isolated from 50 (73%) of the 69 samples of pig carcasses and diaphragm muscle analysed. The strains, identified by gyrB gene sequencing, belong to eight different species (A. hydrophila, A. bestiarum, A. salmonicida, A.caviae, A. media, A. veronii, A. allosaccharophila and A. aquariorum) and were tested against 8 families of antibiotics (27 antimicrobial agents). The β-Lactamases encoding genes blaTEM, blaSHV, blaCTX-M, blaOXA, blaFOX and blaMOX were detected by PCR. The susceptibilities profiles revealed a high level of resistance to several groups of antibiotics. The genes blaOXA-B (1) and blaOXA-C (1) were detected in strains of A. hydrophila and the gene blaCTX-M (1) was presented in A. media. In A. aquariorum and in one A. caviae the gene blaMOX was presented. The genes blaFOX and blaOXA-aer were detected in 71% and 49% respectively of the strains tested. There was no evidence for the presence of blaTEM and blaSHV genes. Conclusion: In the present work we verified multiresistance mainly to the cephalotin (ß-lactam) and erythromycin (macrolide) in different Aeromonas strains. In several strains, the presence of more than one β-Lactamase gene, from different classes, was detected. The genes blaFOX and blaOXA-aer showed a high dispersal in some species of the Aeromonas genus.