Excellent fosfomycin and linezolid susceptibility among multidrug resistant urinary Enterococcus isolates in Eastern India

Urinary tract infection (UTI) is one of the most common infectious diseases. Enterococcus spp. is an important causative agent of UTI. Emergence of resistance is high among enterococcus isolates. Fosfomycin has emerged as a novel oral therapeutic option for urinary isolates. A prospective study was done in Medical College, Kolkata for a period of 6 months (from January to June 2018). After obtaining ethical clearance from the Institutional Review Board (IRB) urine samples with significant growth of enterococcus were included in the study. Identification of Enterococcus species was preliminary done by Gram stain and conventional biochemical tests along with automated identification by VITEK 2 Compact. These isolates were tested for antimicrobial susceptibility to different antibiotics like ampicillin/ penicillin, tetracycline, ciprofloxacin, levofloxacin, vancomycin, teicoplanin, linzolid, fosfomycin and nitrofurantoin by Kirby Bauer disc diffusion method and minimum inhibitory concentration (MIC) by VITEK 2 Compact. MIC for fosfomycin was done by E-test method. Interpretation of susceptibility was done according to the Clinical and Laboratory Standards Institute (CLSI) 2017 guidelines. During the period of 6 months (from January to June 2018) there were 194 isolates of Enterococcus spp. from 2732 urine samples showing a prevalence of 7.1%. Among these 194 isolates there were 148 Enterococcus faecalis, 40 Enterococcus faecium, 2 Enterococcus casseliflavus, 2 Enterococcus gallinarum and 2 Enterococcus avium. All isolates were highly susceptible to vancomycin, teicoplanin, linezolid and fosfomycin. There were total of 8 (4.12%) isolates of vancomycin resistant enterococcus. Resistance to ampicillin and high level gentamicin was significantly related in Enterococcus faecium. Fosfomycin is a highly susceptible for urinary enterococcus isolates. However, larger prospective in vivo studies are required to determine the efficacy.