High Susceptibility of Fosfomycin to Uropathogenic Escherichia coli Isolated at Tertiary Care Hospital of Nepal

Background: Antibiotic resistance in uropathogens is a worldwide problem. Empirical therapy of urinary tract infection (UTI) is based on the susceptibility patterns of locally isolated bacteria in a given time period. Escherichia coli (E.coli), the most common pathogen causing UTI has developed resistance against most of the antibiotics for empirical use. Fosfomycin is one of the best antibiotics to treat UTI, however very little information is available about the susceptibility rate of E. coli to fosfomycin in Nepal.

Aim: The aim of this study was to determine the fosfomycin susceptibility pattern against uropathogenic E. coli isolated from January to June 2016 in a tertiary care hospital of Nepal. Methods: A total of 242 E.coli urinary isolates were included in this study. The isolated organisms were identified by conventional methods. The antimicrobial susceptibility was performed by modified disc diffusion method. Minimum inhibitory concentration (MIC) of fosfomycin was performed by E-test. Extended spectrum β-lactamase (ESBL) and AmpC β-lactamase production was screened and confirmed by double disc synergy test.

Results: E. coli were the most common pathogen isolated and were highly resistant to common antibiotics for oral use such as fluoroquinolones, cephalosporins and cotrimoxazole. However, 98% of E. coli isolates were found susceptible to fosfomycin.

Conclusions: E. coli urinary isolates revealed a high level of resistance to all the antibiotics tested with the exception of fosfomycin. Fosfomycin showed the highest efficacy against E. coli and is the best choice for empirical treatment in Nepal. This study revealed that quinolones, cephalosporins and cotrimoxazole cannot be used for empirical treatment of UTI in Nepal.