Emerging Resistance among Uropathogens: Is Fosfomycin Revival the Best Hope?

Abstract

Introduction: Increasing bacterial resistance and the non-availability of newer antimicrobial agents have necessitated the re-evaluation of old antimicrobial agents. Although an old antibiotic, Fosfomycin gives a ray of hope as it has a unique property of not sharing structural similarity with other antibiotics and with no cross-resistance. Aim: To retrospectively evaluate the invitro activity of Fosfomycin against Extended-Spectrum Beta-Lactamase (ESBL) producing and Carbapenem Resistant Enterobacteriaceae (CRE). Materials and Methods: The study period was from December 2018 to November 2019. Antibiotic sensitivity was carried out according to the Clinical and Laboratory Standards Institute (CLSI) guidelines using the automated Vitek-2 Compact (Bio-Merieux, France). Fosfomycin susceptibility was determined by E-test (Biomereiux, India). The interpretive criteria according to CLSI for Fosfomycin is given only for E.coli and not for other Enterobacteriaceae, hence the results were interpreted as per CLSI criteria given for E. coli (i.e., susceptibility at a Minimum Inhibitory Concentration (MIC) of ≤64 μg). Results: Overall, 91.07% (102/112) isolates were susceptible to Fosfomycin with 91.67% (88/96) susceptibility for ESBL producing Enterobacteriaceae and 87.5% (14/16) for CRE. Fosfomycin has shown good invitro activity against ESBL producers as well as CRE. Conclusion: Fosfomycin showed promising results as a re-emerging antibiotic for the treatment of Urinary Tract Infection (UTI) because of its unique mechanism of action, low incidence of resistance, oral availability with single-dose administration and little tendency to display cross-resistance to other antibiotics.