In vitro susceptibility of fosfomycin in uropathogens with emerging resistance in Enterococcus isolates

Background: Urinary tract infection is a very common clinical entity and are the leading causes of nosocomial infections. The options for antibiotics especially for nosocomial infections are very limited. Fosfomycin a good drug to be used in UTI and is recommend as first line agents for acute uncomplicated UTIs. The emergence of resistance to fosfomycin is a concern. Limited resistance data for fosfomycin is available from India. This study was conducted in order to monitor the trends of resistance to fosfomycin in E coli and Enterococcus faecalis causing UTI. Methods: Urine samples received in the laboratory from all patients were included in the study. Microscopy of uncentrifuged urine sample was done. Culture and sensitivity was done as per the CLSI guidelines. Susceptibility testing of the isolates to fosfomycin was performed interpretation done as per CLSI. Results: Total 150 isolates were taken for the study which included 100 isolates of E. coli and 50 isolates of Enterococcus faecalis. None of the E. coli isolates were resistant to fosfomycin and 82.0% of the isolates were found to be sensitive to nitrofurantoin. None of the Enterococcus faecalis isolates were resistant to linezolid. The percentage susceptibility was 52 % and 70 % for nitrofurantoin and fosfomycin respectively. Conclusions: The increasing resistance to fosfomycin is a matter of concern. An increased fosfomycin resistance rate in E. faecalis was observed. Performing antimicrobial susceptibility testing should be the most important criteria before starting the antibiotic to avoid undue usage and more such studies need to be conducted.