Characteristics of strains of Escherichia coli isolated from locally-fermented milk ("Nono") in Zaria, Nigeria

Abstract

Of a total of 200 fermented milk ("Nono") samples collected, 79 (40%) were positive for Escherichia coli, all isolates being of fecal origin. The mean pH was 4.41 and the values ranged from 4.03 to 4.81. Thirty-three (42%) isolates produced alpha hemolysin while two (3%) had beta hemolytic pattern. Eight (26%) of 31 randomly selected isolates produced heat-labile (LT) enterotoxin as detected by the rabbit ileal loop test. On testing the susceptibility of 50 isolates to antimicrobial agents, resistance was high to nitrofurantoin (100%), furadantoin (98%), Co-trimoxazole (98%), tetracycline (90%), and sulphafurazole (98%). Only 17 (34%) and 16 (32%) isolates were resistant to gentamycin and Colistin sulfate, respectively. It was concluded that E. coli of fecal origin in "nono" could be a health risk as gastro-enteritis may result. Furthermore, the presence of other enteric pathogens cannot be ignored.