Characterization of Salmonellae isolated from different animal and human sources by PCR and resistance trends

Abstract

Salmonella is one of the most important zoonotic pathogens with many virulence factors playing a major role in its pathogenesis. The aims of this study were to detect spvA, int2 and invC virulence genes of different Salmonella serotypes isolated from various clinical animal and human sources, and to investigate antibiotic resistance patterns among these serotypes. Using a PCR assay, a total of 64 Salmonella isolates were evaluated for the presence of virulence genes. Results revealed that spvA, int2 and invC genes were found in 65.6%, 39.1%, and 76.6% of the Salmonella isolates, respectively. Seven different serotypes were differentiated according to the specific antisera. Antibiotic susceptibility results showed that isolates were susceptible to all tested antibiotics (31.25%), Amikacin (84.4%), Co-Amoxiclav (81.2%), Cefepime (73.4%), Ceftizoxime (76.6%), Ceftriaxone (60.9%), Meropenem (50%), Norfloxacin (82.8%), and Piperacillin (75%). SpvA is a plasmid gene and the int2 gene has been identified on mobile elements. In addition, the chromosomal invC gene is associated with type III secretion systems (TTSS; not present in all Salmonellae). Hence, the detection of these genes could be used to identify the Salmonella genus. High prevalence of int2 and spvA genes was also observed in multidrug resistance Salmonella isolates which might play an important role in the dissemination of antimicrobial resistance in multidrug resistance (MDR) Salmonella isolates.