Assessment of Bovine Raw Milk Obtained from Selected Farms in Zaria Environs Nigeria for Toxigenic Strain of Escherichia Coli

The presence of E. coli in food or water became accepted as indicative of recent faecal contamination and the possible presence of pathogens. The study therefore aims at detecting the presence of E.coli and E. coli O157 and an indication of quality assessment of the raw milk samples sold to the open market. A total of 199 composite milk samples and 13 bulk milk samples were collected from selected farms in Zaria environs and analyzed for total aerobic and coliform counts using standard cultural methods. The total bacterial and were more than 105 in 95.48% while total coliform counts was more than 100 cell/ml in 47.24% of the composite milk analysed. All the bulk samples collected had 100% bacterial and 69.2% coliform contamination. The cleaned teats had a mean of 3.03�2.13log10cfu/ml which was not significantly different (t=1.574, p=0.117) when compared to the count obtained from the teats that were unclean (3.12�1.97log10cfu/ml). However, total coliform counts of composite milk samples from animals with cleaned teats had a mean of 1.42�1.05log10cfu/ml was significantly lower (t=6.418, p-0.001) than the counts of milk obtained from cows with unclean teats (2.78�1.95log10cfu/ml) The incidence of Escherichia coli in the milk samples was 7.5%, when isolates were tested for enterotoxin production using the VET-RPLA kit, 14.3% of the isolates were found to possess the heat-labile toxin. All the isolates were found to be susceptible to Ceftriaxone and Ammox-Clav (n=15; %=100), one isolate was resistant to gentamycin, ciprofloxacin and chloramphenicol (n=15, 6.7%). Eight isolates were found resistant to nalixidic (n=15, 53.3%) and nine were found to be resistant to Sulphamethazole and Trimethoprim (n=15, 60%).