Occurrence, genetic diversities and antibiotic resistance profiles of Salmonella serovars isolated from chickens

Abstract

Purpose: Contamination with Salmonella on food products and poultry in particular has been linked to foodborne infections and/or death in humans. This study investigated the occurrence, genetic diversities and antibiotic resistance profiles of Salmonella strains isolated from chickens. Patients and methods: Twenty each duplicate faecal swab samples were collected from five different poultry pens of broilers, layers and indigenous chickens in the North-West Province, South Africa. Isolates identities were confirmed through amplification and sequence analysis of 16S rRNA and the invA gene fragments after which phylogenetic tree was constructed. Salmonella enteritidis (ATCC:13076™), Salmonella Typhimurium (ATCC:14028™) and E. coli (ATCC:259622™) were used as positive and negative controls, respectively. The serotypes of Salmonella isolates were determined. Antibiotic-resistant profiles of the isolates against eleven antimicrobial agents were determined. Results: Eighty-four (84%) of representative isolates possessed the invA genes. The percent occurrence and diversity of Salmonella subspecies in chickens were 1.81-30.9% and was highest in Salmonella enterica subsp. enterica. Notably, the following serotypes Salmonella bongori (10.09%), Salmonella Pullorum (1.81%), Salmonella Typhimurium (12.72%), Salmonella Weltevreden, Salmonella Chingola, Salmonella Houten and Salmonella Bareily (1.81%). Isolates (96.6%) displayed multidrug resistance profiles and the identification of isolates with more than nine antibiotic resistance was a cause for concern. Conclusion: This study indicates that isolates had pre-exposure histories to the antibiotics tested and may pose severe threats to food security and public health.