Increasing antimicrobial resistance among Gram-negative bacteria necessitates evaluation of newer therapeutic options or reevaluation of outdated ones. There are limited data available from India on fosfomycin. The aim of this study was to evaluate the susceptibility of Gram-negative isolates (Klebsiella, Escherichia coli) to fosfomycin in a tertiary care oncology and neurosurgical center in India.
Susceptibility of 121 Gram-negative isolates (E. coli and Klebsiella) to carbapenems, cefoperazone sulbactam, and fosfomycin was analyzed. Identification of the isolates and sensitivity testing to carbapenem and cefoperazone-sulbactam were done on Vitek analyzer. Fosfomycin susceptibility was done using eTest. Minimum Inhibitory Concentration (MIC) of 64 μg or less was considered sensitive, 128 μg as intermediate, and 256 μg or more as resistant to fosfomycin as per the Clinical and Laboratory Standards Institute 2013 guideline for E. coli urinary isolates.
Of the 76 isolates, 43 were Klebsiella (56.5%) and 33 (43.4%) were E. coli. Of the 33 E. coli isolates, 32 (96.9%) were susceptible to fosfomycin, 27 (81.8%) to cefoperazone-sulbactam, and 31 (93.9%) to carbapenem. Of the 43 Klebsiella isolates, 34 (79%) were sensitive to fosfomycin, 19 (44%) to cefoperazone-sulbactam, and 26 (60.4%) to meropenem. MICs of E. coli isolates were very low; however, most Klebsiella isolates though sensitive had MICs at higher end of the sensitive range.
In the era of increasing antimicrobial resistance in Gram-negative bacteria, fosfomycin could be a promising option.