[Characteristic of clinical fluoroquinolone resistant isolates E. faecalis]

In presented study we have characterized phenotype of clinical E. faecalis strains, fluoroquinolone susceptibility and the presence of two potential virulence factors--hemolysin/cytolysin and gelatinase. Eighty three of E. faecalis strains were isolated from clinical samples from patients of five Warsaw hospitals. Susceptibility to 18 antibiotics was assessed by the disk diffusion method (ace. NCCLS). The MIC of ciprofloxacin was determineted by agar dilution method and the MIC of sparfloxacin and moxifloxacin by the E-test (AB BIODISK). Hemolysin production was evaluated on Columbia agar medium supplemented with 5% horse blood. Gelatinase production was determinated by using two different methods: I - on the Todd-Hewitt agar containing gelatin (30 g/l) and II--on the trypticase soy agar supplemented with 1,5% skim milk. Fourty nine (59%) of the 83 isolates E. faecalis were ciprofloxacin resistant and 14 (16,9%) were ciprofloxacin intermediate. The majority of E. faecalis strains (57,8%) were higly resistant to ciprofloxacin (MIC > or = 32 microg/ml). All of ciprofloxacin resistant E. faecalis isolates were cross-resistant to the other fluoroquinolones, as well. Production of hemolysin was more frequent among ciprofloxacin resistant E. faecalis strains. The dependence between gelatinase production and fluoroquinolone:resistance was not observed. Both investigated methods of gelatinase activity detection gave the same results and can be used exchangeably. Hemolytic strains were more frequently isolated from urine (47,8%), however gelatinase producing strains were more frequently isolated from wounds (31,6%).