Molecular Monitoring of Fosfomycin Resistance in Escherichia coli Strains Isolated from Patients with Urinary Catheters in north-east of Iran

Introduction: Urinary tract infection is a common nosocomial infection that has recently become difficult to treat because of the increased emergence of multi-drug resistant strains. This study aims to determine the minimum inhibitory concentration, and molecular pattern of resistance to fosfomycin in Escherichia coli isolates originated from patients hospitalized with urinary tract infection in the intensive care unit (ICU) and coronary care unit (CCU). Methods: Urine samples were obtained from 106 patients in three hospitals of Gorgan, northeast of Iran. After isolation and identification of E. coli isolates, the Kirby-Bauer disk diffusion test was performed to evaluate the antibiotic susceptibility pattern. Minimum inhibitory concentrations (MICs) of isolates to fosfomycin were determined using the agar dilution method over a concentration range of 0.5-1024 μg/mL. Also, the presence of murA and glpT genes were investigated using polymerase chain reaction with specific primers. Results: Frequency of E. coli isolates was 62.3%, most of which originated from ICU patients (56.5%). The rate of susceptibility to fosfomycin was 85%. Moreover, the MIC of 80.3% of the isolates was less than or equal to 64 μg/mL. We also detected the murA and glpT genes in 77.8% and 22.2% of fosfomycin-resistant isolates, respectively. Conclusion: Our results indicated a high bactericidal activity of fosfomycin against uropathogenic E. coli isolates. In agreement with similar studies, we concluded that the presence of murA is significantly associated with the development of resistance to fosfomycin. J Med Microbiol Infec Dis, 2018, 6 (4): 112-117.