Fosfomycin Susceptibility among Extended-spectrum βeta Lactamase (Esbl)-Producing Escherichia coli and Klebsiella pneumoniae Isolates Causing Uti in a Tertiary Care Center in Western India

A BSTRACT Context: At present, commonly encountered infections like urinary tract infections (UTIs) are becoming more and more difficult to treat. UTIs caused by extended-spectrum β -lactamase (ESBL) organisms tend to lead to uncertain outcomes and prolong hospitalization as these organisms are multidrug resistant. Such a situation has forced clinicians to reconsider the use of old antibiotics like fosfomycin. Aims: To determine fosfomycin susceptibility among ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates causing UTI in a tertiary care center in Western India. Settings and Design: This is a cross-sectional study done in the Department of Microbiology between July 2021 and July 2022. Methods and Material: Urine samples from all outpatients and inpatients with suspected UTI which were received in the microbiology laboratory were inoculated in appropriate culture media. Pure growth of bacteria with a significant colony count was identified and antibiotic susceptibility testing was done as per standard guidelines. Statistical Analysis Used: The collected data were entered in a Microsoft Excel sheet and analyzed. Results: A total of 437 urine samples were collected from which 39 isolates of ESBL E. coli and 10 isolates of ESBL Klebsiella pneumoniae were obtained. All the E. coli isolates were sensitive to fosfomycin, while two of the Klebsiella pneumoniae isolates were resistant to fosfomycin. Conclusions: Older antibiotics like fosfomycin and nitrofurantoin attain high concentrations in the urinary tract, have a minimal impact on gastrointestinal flora, and do not develop resistance as compared to many other antibiotics. Therefore, fosfomycin should be preferred for the treatment of uncomplicated UTIs caused by resistant strains.