Detection of Metallo-ß-lactamases in Aeromonas isolated from alheira: a tradicional portuguese meat product
Data
2010
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International Association for Food Protection
Resumo
Introduction: Members of the genus Aeromonas are facultative anaerobic gram-negative rods, oxidase-positive that are widely distributed in aquatic environments and have also been isolated from different kinds of food. Gastroenteritis is considered the most common Aeromonas clinical presentation. Susceptibility patterns of these species revealed an increase in resistance to ß-lactam antibiotics, which is attributed to the presence of ß-lactamases. Zinc-dependent class B metallo-ß-lactamases (MBLs), chromosomally mediated and those encoded by transferable genes, are of special importance because display an extremely wide spectrum of hydrolysis that includes also carbapenems.
Rationale: The aim of this study was to determine the susceptibility patterns, to ß-lactam antibiotics, of Aeromonas strains isolated from alheira, a traditional Portuguese meat sausage and the occurrence of CphA, a chromosomally mediated MBL, and VIM, an acquired MBL.
Results: Thirty-two samples purchased in different local markets were analysed. A total of 84 presumptive Aeromonas spp. were obtained and subjected to genotyping ERIC-PCR analysis. The 20 strains showing differences in the ERIC-pattern were identified by gyrB gene sequencing and tested against 15 ß-lactam antibiotics. Metallo-beta-lactamases encoding genes were detected by PCR and positive results were confirmed by sequencing. All the strains studied belonged to the species A. hydrophila (5), A. caviae (6), A. media (6), A. salmonicida (2) and A. allosaccharophila (1). Tested antibiotic susceptibilities in these strains indicated a noticeable level of multiresistance. blaCphA gene was detected in 8 strains (40%). There was no evidence for the presence of blaVIM genes in any isolate.
Conclusion: In this study a high percentage of resistance to cephalotin and ticarcillin and low percentage to other ß-lactam antibiotics have been detected in Aeromonas spp. from alheira. Despite blaCphA gene was detected in all strains of the species A. hydrophila, A. salmonicida and A. allosaccharophila, only one strain of A. salmonicida showed resistence to imipenem.