Antimicrobial Resistant pattern of E. coli O157 Isolated from Human, Cattle and Surface Water Samples in Northeast Nigeria

This study evaluated antimicrobial resistant pattern of E. coli O157 in human faeces, cattle products and water in Northeast, Nigeria. A total of 18 E. coli O157 isolates from human stool (n=12), cattle (faeces and unpasteurized cow milk) (n=5) and water (n=1) were studied. Using the agar disk diffusion method, none of the E. coli O157 strains exhibited resistance to ciprofloxacin and ofloxacin. Neither cattle nor aquatic strain showed any resistance against gentamycin, streptomycin and chloramphenicol. Resistant rate among human strains was low against gentamycin(8.3%), streptomycin(8.3%), chloramphenicol(25.0%) and sulphamethoxazole-trimethoprim(25.0%). Increasing resistant pattern against tetracycline, ampicillin, cephalexin and clavulanic acid-potentiated amoxicillin was observed in about 50% to 80% of human and cattle isolates. The only aquatic strain was resistant to amoxicillin/clavulanic acid, ampicillin, tetracycline and sulphamethoxazole-trimethoprim. One human strain exhibited similar resistant pattern to two cattle strains comprising cephalexin, amoxicillin/clavulanic acid and ampicillin. About 44.4% of all the strains shared similar resistotype. More than 75% of E. coli O157 isolates from both human and animal sources exhibited MDR pattern in the combination of ?3 antibiotics. However, 4 human strains expressed highest level of MDR involving 6 antibiotics. The high frequency of antibiotic resistance among tetracycline, ampicillin, cephalexin and amoxicillin/clavulanic acid in both man and animal has raised serious public health concern.