SEROTYPING AND ANTIMICROBIAL RESISTANCE OF SALMONELLA ISOLATES FROM FOOD MATRICES AND CLINICAL SPECIMENS FROM LEBANON

Abstract

Salmonella is a genus of bacteria responsible for the most frequently reported cases of foodborne illnesses worldwide. In this study, serotyping was done by using highly specific manufactured antisera, to identify circulating Salmonella serovars isolated from food samples and clinical specimens. Antibiotic susceptibility testing was also performed to determine the level of resistance of these serotypes. This was done by using the disk diffusion method by testing 14 clinically important antibiotics on the Salmonella isolates. A total of 85 Salmonella strains, preidentified by biochemical testing, were collected over the course of one year. Serotyping of the isolates revealed the presence of 14 serotypes in the food samples with S. Infantis and S. Enteritidis, being the most common and 6 serotypes in the clinical samples with S. Enteritidis and S. Typhimurium being the most common. Antimicrobial susceptibility testing results showed resistance of isolates from both sample types to conventional antibiotics like ampicillin and piperacillin, and almost total resistance of the food isolates to a broad-spectrum antibiotic imipenem, belonging to the carbapenem class. Higher resistance was observed in food samples than in clinical ones. Moreover, 13 and 3 multidrug resistant serotypes of Salmonella were identified for the first time in Lebanon in the food and clinical samples respectively, with three of them isolated from imported food samples.