Abstract:
This cross-sectional study determined the occurrence of virulence and antimicrobial
resistance genes in Salmonella strains recovered from chicken obtained from informal
markets in Gauteng province, South Africa. The study also assessed the relationship
between these characteristics, the source, the type of samples, and the serotypes of
Salmonella isolates. A total of 151 samples (cloacal swabs, chicken carcasses, and carcass
drips) were randomly collected from 47 informal market outlets in six townships
in Gauteng province. Salmonella spp. was isolated and identified based on ISO
6579:2002 methods and confirmed by polymerase chain reaction (PCR) targeting
invA gene fragment. Conventional PCR was used to detect 12 virulence and 18 antimicrobial
resistance (AMR) genes in Salmonella spp. The most frequently detected virulence
genes were invA (100%), shdA (91%), mgtB (87.7%), and sopE (81%), but
considerably low for spvC (2.2%), sefC (1.5%), and pefC (0.4%). The differences in
detection frequency were statistically significant (p < 0.05). Tetracycline-resistant
genes tetA (34.7%) and tetB (16%) were the most frequently detected, while Betalactam-
resistant genes blaTEM (0.4%), blaCMY-2 (0.4%) and quinolones resistant gene
qnrS (0.4%) were detected in low frequency (p < 0.05). The locations of the outlets
and the types of samples were significantly associated with detecting some virulence
and AMR genes. Significant but moderately to substantial positive correlations were
observed for qnrS, sul2; shdA, and mgtB genes. The pipA and spiC were, however, substantially
negatively correlated. Our findings show that detecting these virulence and
AMR genes in Salmonella isolates serves as a potential health hazard to the public,
environment, and poultry farming in Gauteng, South Africa.
