Mannitol-fermenting methicillin-resistant staphylococci (MRS) in pig abattoirs in Cameroon and South Africa: A serious food safety threat.

Food animals can be reservoirs of methicillin-resistant staphylococci (MRS) and are involved in their zoonotic transmission through the food chain. In Africa, there is a dearth of information about the food safety issues associated with their dissemination in the farm-to-plate continuum. This study sought to determine and compare the carriage, antimicrobial resistance profiles and clonal relatedness of circulating MRS strains among pigs and exposed workers in Cameroon and South Africa. A total of 288 nasal and rectal pooled samples collected from 432 pigs as well as nasal and hand swabs from 82 humans were cultured on mannitol salt agar supplemented with 6 mg/l cefoxitin. Presumptive MRS were screened for methicillin resistance using the cefoxitin disc test and confirmed with the VITEK 2 system. Selected isolates underwent genomic fingerprinting via REP-PCR. Univariate and multivariate logistic regression analyses were performed to identify risk factors for MRS carriage in humans from a questionnaire survey among slaughterhouse workers. Overall, 75% and 70% of nasal and rectal pooled samples were respectively positive for MRS. The MRS prevalence in all pooled pig samples from Cameroon was higher than that of South Africa. MRS prevalence of carriage (nasal and hand) was higher in Cameroonian exposed workers compared to those from South Africa, with high statistical significance. Nasal MRS colonization was highly statistically associated with hand MRS (31.58% vs 86.21%; p = 0.000; OR = 13.54; 95% CI 3.99-45.95; p = 0.015). Recent antibiotic use, previous hospitalization, occupation of relatives, years in the employment and contact with poultry were the main risk factors identified in the emergence and spread of MRS. MRS are emerging as serious foodborne pathogens and present a food safety threat. There is an urgent need to implement stringent and effective prevention and containment measures to curb antibiotic resistance in the farm-to-plate continuum in Cameroon and South Africa.