Molecular Epidemiology of in Poultry in South Africa Using the Farm-to-Fork Approach.

The presence of the zoonotic pathogen in the food supply chain poses a serious public health threat. This study describes the prevalence, susceptibility profiles, virulence patterns, and clonality of from a poultry flock monitored over six weeks, using the farm-to-fork approach. was isolated using selective media and confirmed to the genus and species level by real-time polymerase chain reaction (RT-PCR) of the and genes, respectively. Antimicrobial susceptibility profiles were determined using Vitek-2 and the Kirby-Bauer disk diffusion method against a panel of 21 antibiotics recommended by the World Health Organisation Advisory Group on Integrated Surveillance of Antimicrobial Resistance (WHO-AGISAR). Selected virulence genes were identified by conventional PCR, and clonality was determined using enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). was present in 32.1% of the samples: on the farm (30.9%), at the abattoir (0.6%), and during house decontamination (0.6%). A total of 210 isolates contained the and genes. Litter, faeces, and carcass rinsate isolates were classified as resistant to cefuroxime (45.2%), cefoxitin (1.9%), chloramphenicol (1.9%), nitrofurantoin (0.4%), pefloxacin (11.4%), and azithromycin (11%). Multidrug resistance (MDR) was observed among 3.8% of the isolates. All wastewater and 72.4% of carcass rinsate isolates were fully susceptible. All isolates harboured the , and virulence genes, while , , , and were absent. In addition, was only present among the wastewater isolates. Various ERIC-PCR patterns were observed throughout the continuum with different subtypes, indicating the unrelated spread of . This study concluded that poultry and the poultry environment serve as reservoirs for resistant and pathogenic . However, there was no evidence of transmission along the farm-to-fork continuum.