Assessment of bacteriological quality and handling of bovine raw milk collected from communal areas in Mahikeng, South Africa

Abstract

According to the literature from previously done investigations, there is limited data with regard to the dangers posed by the informal milk markets, and as a result, the prevalence of zoonosis as well as chemical or drug residues in most African countries including SA is not fully understood (Karimuribo et al., 2005; Mosalagae et al., 2011). The aim of this study was to investigate the occurrence, evolutionary relationships and antibiotic resistance profiles of pathogenic bacteria isolated from raw milk obtained from communal farms in Mahikeng, North-West Province of South Africa. The study also investigated milk handling practices and antibiotic use at farm level. One hundred and sixty-eight (n=168) raw milk samples were collected from communal farms/households with lactating cows in eight villages in Mahikeng between September 2017 and January 2018. Various bacterial species including Staphylococcus aureus, Staphylococcus equorum, Enterococcus faecium, Enterococcus faecalis, Enterococcus durans, Enterococcus casseliflavus, Enterobacter hormaechei, Enterobacter asburiae, Clostridium bifermentans, Clostridium species, Paraclostridium benzoelyticum, Salmonella Typhimurium , Escherichia coli, Shigella species, Bacillus sp., Alcaligenes faecalis, Citrobacter braakii, Proteus hauseri, Providencia species, Lactococcus garvieae, Lactococcus lactis and Weissella cibaria were isolated and identified using morphological (Gram-staining), biochemical (catalase, oxidase, indole, coagulase and Analytical Profile Index-API) and molecular (conventional Polymerase Chain Reaction-PCR) methods. The antibiotic resistance profiles of the isolates were determined using disc-diffusion method. All raw milk samples tested (n=168) had total bacterial count (TBC) higher than the recommended level of 5.0 x 104 cfu/ml. All the isolates were subjected for API tests, whereby 56 isolates were positively identified to species level and were then subjected to PCR. Following PCR, determination of antimicrobial resistance was done for all the isolates (n=56) and it was found that only one isolate (Weissella cibaria) was resistant to one antibiotic while the rest were resistant to more than one antibiotic. It was further found that, most (46.4%) of the bacterial isolates were susceptible to Norfloxacin while most (53.6%) were resistant to Streptomycin. It was observed that milk handling practices at farm level were poor with lack of proper hygiene practices, example being that only 3% of the respondents indicated that they wash their hands without using soap or disinfectants before milking and the rest of the respondents reported not to wash their hands at all. It was also found that a very high number (83%) of farmers made use of antibiotics without consulting with the veterinarians, and even a higher number (93%) indicated that they did not read the instructions on pamphlets before use. Based on the results of this study which demonstrated poor quality of raw milk produced by communal dairy farmers in Mahikeng, it was therefore concluded that such milk is not safe for human consumption.