Molecular Detection of Shiga Toxin-Producing O177 Isolates, Their Antibiotic Resistance, and Virulence Profiles From Broiler Chickens.

The World Health Organization (WHO) describes Shiga toxin-producing (STEC) as a bacterium that can cause severe food-borne diseases. Common sources of infection include undercooked meat products and faecal contamination in vegetables. This study aimed to isolate, identify and assess the virulence and antibiotic resistance profiles of STEC isolates from broiler chicken faeces. Faecal samples were cultured, and polymerase chain reaction (PCR) was utilized to identify the isolates. Subsequently, the confirmed isolates were screened for seven virulence markers using PCR. The antibiotic susceptibility of the isolates to 13 different antibiotics was determined using the disk diffusion method. PCR was also employed to screen for antibiotic resistance genes. The gene, which encodes the beta-glucuronidase enzyme, was detected in 62 (64.6%) of the 91 presumptively identified isolates. Of these, 23 isolates (37.1%) were confirmed to be O177 serogroup through amplification of gene. All O177 isolates possessed the virulence gene, while 65% carried the gene. Among the O177 isolates, three harboured a combination of genes, while one isolate contained a combination of genes. All O177 isolates carried one or more antimicrobial resistance (AMR) genes, with 17 isolates (73.7%) identified as multidrug resistance (MDR). This is the first study to report the presence of O177 serotype from broiler chickens in South Africa. The findings reveal that broiler chicken faeces are a significant reservoir for MDR O177 and a potential source of AMR genes. These results underscore the importance of continuous surveillance and monitoring of the spread of AMR infectious bacteria in food-producing animals and their environments. The study also emphasizes that monitoring and control of poultry meat should be considered a major public health concern.