Variations in antibiotic resistance and plasmid content in Escherichia coli isolates from the normal intestinal flora and clinical sources

INTRODUCTION: Escherichia coli is one of the most important bacteria in the normal intestinal flora. The current study aimed to investigate their possession of antibiotic resistance and plasmids compared with their clinical isolates to determine the extent of their risk and health importance. METHODS: For this purpose, 400 stool samples were collected from healthy individuals (newborns and healthy adults), as well as clinical samples. Microscopic, cultural, and biochemical diagnostic methods were used, and the diagnosis was confirmed using the Vitek 2 compact system to obtain 12 identified isolates of E. coli for each isolation source. RESULTS: Antibiotic susceptibility tests revealed that multidrug resistance existed in nearly all isolate sources; for example, multidrug resistance in newborn isolates was 25-100%, while in healthy adult isolates was 25 - 75%, and in patients, isolates were 33.33 - 100%. Moreover, the results showed that the studied isolates possess plasmid bands in varying numbers, in newborn isolates 1- 3 plasmid bands, in healthy adult isolates 0-4 plasmid bands, and patient isolates 0 - 3 plasmid bands. CONCLUSION: We conclude from the current study that E. coli isolated from the normal flora of either newborns or adults, possess high resistance to antibiotics, and they also possess plasmids that support the existence of this resistance, which makes these isolates of high risk as its pathogenic isolates.