Bacteriological quality of Nono, a milk product sold at retail outlets in Federal Capital Territory, Nigeria

Abstract

Introduction: Milk handling in the Nigerian informal dairy sector is commonly done without observing hygienic practices, which is a threat to food safety and public health. The indiscriminate use of antibiotics in treatment of infections in animals has led to increasing resistance of pathogenic organisms to commonly used antibiotics. We determined the bacteriological quality of nono and the antimicrobial resistance of respective bacterial isolates. Methods: We conducted a cross-sectional study on 300 samples of ready-to-consume locally fermented milk product (nono) sold in the Federal Capital Territory, Nigeria between June and September 2018. We used a multistage sampling technique for sample collection. Culturing on appropriate media and conventional biochemical tests were carried out for identification and isolation of bacteria of interest while further confirmatory tests were carried out using Microbact/Mocrogen® kits. Serological test was conducted using Remel RIM™ Latex to confirm presence of E. coli 0157:H7 sero-group, while Kirby-Bauer disc diffusion method was used for antimicrobial susceptibility testing. Results: Total Aerobic Plate Count (±SD) ranged from 5.6 ± 1.7 - 7.0 ± 0.4 log10 cfu/ml while total coliform count ranged from 5.6 ± 0.5 - 6.5 ± 0.7 log10 cfu/ml. Out of the 300 samples, 37 (12.3%) tested positive for E. coli out of which 16% were of the 0157:H7 sero-group while 21(7%) were positive for Staphylococcus aureus. E. coli isolates were found to be totally resistant to Vancomycin and Methicillin, and almost totally resistant to Ampicillin (97%) and Tetracycline (95%). Staphylococcus aureus isolates on the other hand were totally resistant to Oxacillin, Ticarcillin and Amoxycillin. Conclusion: Total plate counts from this study is above the maximum permissible range of 4.6 log10 cfu/ml. The bacterial isolates showed multidrug resistance varying from 3 to 8 of the antibiotics used. We recommended health education and awareness creation on hygiene practices among local milk vendors and advocated for right use of antimicrobials in animals by veterinarians.