Assessment of microbial contamination of raw cow milk and antimicrobial resistance of salmonella spp isolated in Ilala district, Dar es salaam, Tanzania

Dissertation

The current cross sectional study was conducted to determine factors influencing microbial contamination, proportion and antimicrobial susceptibility profiles of Salmonella spp isolated from raw cow milk in Ilala district, Dar Es Salaam, Tanzania. A total of 138 smallholder dairy farmers were randomly selected and interviewed, and subsequently, milk samples were aseptically collected from Kivule, Kitunda, Magole and Ukonga between July and October 2020. Identification was done by conventional culture method, biochemical tests and serotyping. Disc diffusion method was used for antimicrobial sensitivity testing. Reference organisms used in the study included; Salmonella typhimurium (ATCC 14028) and E. coli (ATCC 25922). Results showed that, majority of smallholder dairy farmers were males with primary education, 8% of respondents consume milk from animals under medication and 23.9% did not adhere to withdrawal periods. Furthermore, results indicated that, 34.8% and 57.1% reported not to wash hands before milking and between milking different cows and 30.4% reported to milk sick cows practices which were found to significantly predispose milk to microbial contamination (p=0.000; p=0.001 and p=0.042) respectively. Out of 138 samples, 8 (5.8%) samples confirmed to be Salmonella whereby 3 were S. typhimurium, 3 were S. enteriditis and 2 were S. typhi. Kivule ward showed high prevalence (14.6%) of Salmonella than the other wards with no statistical difference (P>0.05) between them. Antimicrobial susceptibility results showed all isolates were resistant to ampicillin, amoxicillin/clavulanic acid and penicillin but susceptible to gentamycin, tetracycline, chloramphenicol, ciprofloxacin and trimethoprim-sulfamethoxazole and 100% of isolates showed multi-drug resistant against three antibiotics. This study revealed the presence of Salmonella in apparently healthy dairy cows in Ilala district with antimicrobial resistances. Improvement in animal husbandry practices and public education on general milk hygiene are recommended. Additionally, extension officers, veterinarians and all other stakeholders should play a part in ensuring that consumers receive safe, high-quality milk.