Antibiotic Resistance Pattern and Plasmid Curing of Escherichia coli Isolated from Soil Samples in Girei, Nigeria

In this study, seventy five (75) soil samples were collected from farmlands, riverbanks and dumpsites and screened for the presence of Escherichia coli via inoculation on EMB, Gram’s staining and some biochemical tests. Overall, 15 E. coli isolates were identified. Dumpsite has the highest number of isolates with 9(60%), followed by farmland with four 4(26.7%) isolates, and lastly riverbank with two 2(13.3%) isolates. Subculture on Sorbitol-MacConkey agar revealed that 2 isolates from dumpsite were EHEC O157:H7. Most of the isolates were resistant to Amoxicillin and Augmentin (66.7% and 73.3% respectively). One of the EHEC strains was found to be resistant to Pefloxacin. Multidrug resistant isolates later became susceptible to previously resisted antibiotics after plasmid curing using 10% sodium dodecyl sulphate (SDS). The outcome of this study suggests that EHEC O157:H7 is not common in the soil environment in comparison with other E. coli strains and it is found to be associated with dumpsites. Resistance to some of the antibiotics was plasmid-borne; therefore, indiscriminate use of antibiotics should be avoided to minimize rapid development of resistant bacterial strains. Dumping of refuse close to households should also be avoided so as to minimize the risk of infection with EHEC O157:H7.