Antibiotic Sensitivity and Plasmid Profiles of Escherichia coli Isolated from Pediatric Diarrhea

BACKGROUND: The emergence of drug resistance among diarrheagenic Escherichia coli (E. coli) in the pediatric population is an important cause of morbidity and mortality in developing countries. MATERIAL AND METHODS: Isolation and identification of E. coli strains from stool specimens are carried out according to standard techniques. Antibiotic susceptibility testing was performed using disc-diffusion method. Plasmid profiling and conjugation experiments were done to analyze the antibiotic resistance transfer from one bacterium cell to another through plasmid. RESULTS: Out of 170 pediatric diarrheal samples, 105 (61.76%) E. coli strains were isolated. About 90% of E. coli strains were resistant to most of the antimicrobial agents tested. All the isolates were resistant to ampicillin, imipenem and cotrimoxazole and were sensitive to amikacin. The resistance to antibiotics shows 29 different antibiotic resistance patterns. About 67 (64%) strains of E. coli isolates harbored plasmids, and 51 (76.1%) of them were able to transfer their plasmids. The plasmid sizes ranged from 1.0 to 25 kb, the most common plasmid of size 4.8 kb being detected in all the plasmid-harbored E. coli strains. The results of transconjugation show that all the transconjugant colonies were carrying 4.8-kb plasmid and were resistant to ampicillin, imipenem and cotrimoxazole. CONCLUSION: There is an increase in the prevalence of drug resistance among E. coli isolates, and conjugal transfer of plasmids has greatly contributed to the rapid spread of antibiotic resistance among E. coli isolates.