Isolation, drug resistance and molecular characterization of Salmonella isolates in northern Morocco

Abstract

Objectives: The objective of this investigation was to assess the methods for the characterization of Salmonella isolates and to identify relationships of Salmonella isolates from human and food sources in northern Morocco. Methodology: Several Salmonella serotypes were isolated from human and food samples and were characterized using conventional culture methods, biochemical, serological, antimicrobial testing, and phage typing. Molecular analyses such as enterobacterial repetitive intergenic consensus (ERIC)-PCR, macrorestriction profiling by pulsed-field gel electrophoresis (PFGE), and virulence gene analysis were also performed. Results: Sixteen Salmonella strains were isolated in our laboratory, serotyped and identified as S. Kottbus, S. Indiana, S. London, S. Typhi, S. Hadar, S. Corvallis, S. Mbandaka, S. Ouakam, S. Tm var. cop., S. Virchow, and S. Altona. The most common resistance profiles for the isolates was ATCFATSCGKSSS, belonging to phage type PT20, ATASCSS associated with strains DT104L/ad and ATATSS for isolates that were not typeable. The PFGE patterns were different for each Salmonella serotype. All strains were negative for the virulence gene spvR. Conclusions: To our knowledge, this is the first molecular characterization of Salmonella in food and humans from Morocco. Comparison of molecular techniques for differentiating between human and food isolates of Salmonella in north of Morocco shows that ERIC typing and PFGE were more discriminating than the other techniques used in this study.