In vitro susceptibility of enterococci strains isolated from urine samples to fosfomycin and other antibiotics

Enterococci are mostly isolated from urinary tract infections (UTIs). Increasing antibiotic resistance affects the success rate in empirical treatment, thus makes antibiotic susceptibility tests important. The aim of this study was to determine the species distribution and resistance patterns of Enterococcus strains isolated from urine samples to antibacterial agents including fosfomycin in a teaching hospital, Istanbul. The identification of 100 Enterococcus strains were determined by using conventional methods and API 20 Strep (bioMerieux France). The susceptibility testing was performed by disk diffusion and Etest. The majority of isolates were E. faecalis (67%), followed by E. faecium (33%). The ratio of E. faecalis to E. faecium was 2.03/1. E. faecalis and E. faecium strains were resistant to penicillin (38.8, 93.9%), ampicillin (4.8, 84.8%), vancomycin (1.5, 18.2%), teicoplanin (1.5, 18.2%), gentamicin (13.4, 58%), ciprofloxacin (34.3, 84.8%), levofloxacin (34.3, 87.9%), norfloxacin (38.8, 84.8%), tetracycline (89.6, 48.5%), nitrofurantoin (1.5, 39.4%), and fosfomycin (2.3, 0%) (p < 0.0001), respectively. Resistance to fosfomycin was observed in neither E. faecium strains, nor vancomycine-resistant enterococci strains. It was concluded that, enterococci are important pathogens for UTI; species identification and periodic evaluation of antibiotic susceptibility pattern would be guide for early empirical treatment and in uncomplicated UTI, fosfomycin could be an alternative option for therapy.