Frequency, antimicrobial susceptibility and distribution of tetracycline resistance genes from diarrhogenic E. coli

Introduction:Diarrhea caused by multidrug-resistant Escherichia coli has been recognized as an important public health problem among children in developing countries. The main objective of this study was to study the susceptibilities of E. coli isolates to nine antimicrobial agents, as well as to determine the prevalence of tetracycline resistance genes. Materials and Methods: One hundred fifteen diarrhogenic E. coli samples were collected from patients in 3 hospitals in southwest Iran. Isolates were tested for susceptibility to antimicrobial drugs by disc diffusion methods as described by the CLSI. PCR amplification was used to detect tetracycline resistance genes. Results: The number of isolates showing resistance to each antimicrobial agent were: imipenem (n=6), tetracycline (n=73), ciprofloxacin (n=17), nalidixic acid (n=37), streptomycin (n=14), gentamycin (n=6), nitrofurantuin (n=4), amikacin (n=0). Of the tetracycline resistant isolates, 76.6% (115/150) were positive by PCR for tet genes, as follow: tetA (75%), tetB (64%) and tetC (12%). Conclusion: Antibiotic resistance and distribution of tetracycline resistance are widespread in diarrheagenic E. coli in patients with acute diarrhea in Shiraz, Iran. Hence studies to assess the role of antimicrobial agents in the treatment of E. coli infections in children are needed.

Diarrhogenic E. coli, Tetracycline resistance, Iran