Plasmid Profile Analysis of Aminoglycoside-Resistant Escherichia coli Isolated From Urinary Tract Infections

Background: Uropathogenic E. coli (UPEC) is the primary cause of humanurinary tract infections (UTIs) worldwide. Moreover, there has been renewed and growing interest in using older antibiotics for treatment, such as aminoglycosides. Objectives: The goal of this study was to determine the plasmid profile patterns of UPEC isolates harboring the aminoglycoside resistance gene aac(3)-IIa. PatientsandMethods: Atotal of 276 uropathogenic E. coli (UPEC) samples were isolated from UTI patients at the Tehran heart center in Tehran, Iran. Antimicrobial susceptibility testing against five aminoglycosides was performed by the disk diffusion method, and the aac(3)-IIa gene was detected via PCR. Moreover, plasmid profiling was carried out on those UPEC isolates harboring the aac(3)-IIa gene. Finally, the similarities among these isolates were determined on the basis of their plasmid profiles. Results: The highest level of resistance was seen for tobramycin (24.6%), and the aac(3)-IIa gene was found in 51 isolates. Twentyseven different plasmid profiles were identified among the isolates harboring the aac(3)-IIa gene, with the 15 kb plasmid being the most common. Moreover, no significant correlation was found between the resistance patterns and the number of plasmids. The cluster analysis based on the plasmid profiles grouped the isolates into five different clusters, of which cluster one was the largest (containing 14 of 51 isolates). Conclusions: Ourdata suggest the monitoring of aminoglycoside resistance, andits consideration in the empirical therapy of UPEC infections.