Introduction: Enterococci are important hospital-acquired pathogens. The most commonly isolated species of the genus, Enterococcus faecalis and Enterococcus faecium are the third to fourth-most prevalent nosocomial pathogens worldwide. The aim of this study was to determine the frequency of resistance to vancomycin and other antimicrobial agents of Enterococcus spp strains isolated from blood cultures of hospitalized patients.
Material and methods: During the three-year period, from 2008 to 2010, 132 strains of Enterococcus spp isolated from blood cultures of hospitalized patients were tested for their susceptibility to ampicillin, vancomycin, gentamycin (high-level resistance), erythromycin, chloramphenicol, teicoplanin, ciprofloxacin by disc diffusion method according to the Clinical and Laboratory Standards Institute recommendations. Susceptibility of vancomycin resistant E. faecium to the same antibiotics and to linezolid, quinopristin/dalfopristin and tigecyclin was determined using VITEK system.
Results and discussion: Resistance to vancomycin was detected in 21 (15.9%) Enterococcus spp strains. The percentage of resistance to other antimicrobial agents varied from 23. l% for chloramphenicol to 81.3% for ciproflxacin. All vancomycin resistant enterococci were identified as E. faecium and belonged to phenotype VanA. The resistance to other antibiotics was very high, except for linezolid and quinopristin/dalfopristin (4.7%). The high-level aminoglycoside resistance was 87.6% for gentamycin and 95.2% for streptomycin. All isolates were resistant to ampicillin, teicoplanin and ciprofloxacin.
Conclusion: The detected high frequency of multidrug-resistant isolates among vancomycin resistant enterococci is of great importance and suggests the need for further monitoring of susceptibility in order to take adequate measures to prevent and control spreading of resistant strains.