Plasmid Profile of Antibiotics Heteroresistant Escherichia coli Isolates from Diarrhoeic Children Attending Ahmadu Bello University Teaching Hospital, Shika, Zaria, Nigeria

In this study, 100 Escherichia coli (E. coli) isolates were obtained from the stool of 222 diarrhoeic children attending Ahmadu Bello University Teaching Hospital, Shika, Zaria. Out of the 100 isolates of E. coli obtained, five (5) were found to be heteroresistant to different antibiotics. The isolation and biochemical identification were performed using standard microbiological procedures. The antimicrobial susceptibility testing and the determination of the heteroresistance were performed using modified Bauer-Kirby sensitivity testing technique. The isolation of plasmid DNA was performed using the protocol described in the plasmid extraction kit (Thermo Scientific, UK). Multiplex PCR assay was performed to identify the different diarrhoeagenic groups of the antibiotics heteroresistant E. coli isolates. The results of antimicrobial susceptibility testing shows that 5 (100%) of the isolates are resistant to amoxicillin, 4 (80%) to trimethoprim/sulfamethoxazole, 2 (40%) to ciprofloxacin and chloramphenicol, 1(20%) to gentamicin and none was resistant to amoxicillin-clavulanic acid and ceftriaxone. Multiple antibiotic resistance (MAR) indexing of the E. coli isolates in this study showed that 80% have MAR index above 0.2, at such a MAR index, there is a significant level of misuse of these antibiotics within a particular environment. Among the five (5) heteroresistant E. coli isolates, 2 (40%) were found to be β-lactamase positive while 3 (60%) were found to be β-lactamase negative. The plasmid analysis showed that, four (4) of the five (5) E. coli isolates were found to harbor plasmids. However, there was no correlation between β-lactamase production and possession of plasmid by the antibiotics heteroresistant E. coli isolates. Following the Multiplex PCR assay, none of the antibiotics heteroresistant E. coli isolates harbor the virulence gene for any of the diarrhoeagenic E. coli.