Biologia, Bratislava, 56/Suppl. 9: 31-35, 2001.

ISSN 0006-3088 (Biologia). ISSN 1335-6399 (Biologia. Section Cellular and Molecular Biology).


Full Paper

The impact of antibiotic selective pressure on vancomycin-resistant enterococci occurrence.


Milan Kolar1*, Iva Vagnerova1 & Karel Urbanek2

1 Department of Microbiology, Faculty of Medicine, Palacky University, Olomouc, Hnevotinska 3, CZ-77515 Olomouc, Czech Republic; fax: ++ 420 68 5632966, e-mail:

2 Department of Pharmacology, Faculty of Medicine, Palacky University, Olomouc, Czech Republic

* corresponding author

Received: December 28, 2000 / Accepted: April 23, 2001



A very negative feature in hematological patients is the occurrence of vancomycin-resistant enterococci (VRE). Three phenotypes of vancomycin resistance (types A, B and C) are now well described. The VanA phenotype with high level of inducible resistance to vancomycin and teicoplanin, the VanB phenotype with a lower level of inducible resistance to vancomycin and susceptibility to teicoplanin and the VanC phenotype due to the chromosomal vanC resistance gene in certain species. In the period of observation (1997-2000), we isolated in total 1918 Enterococcus strains in the Department of Hemato-oncology of the University Hospital in Olomouc (Czech Republic), and 138 (7.2%) strains were identified as VRE. The percentage of VRE in the mentioned department was within the interval 1.7-15.1%. The VRE were most frequently identified as Enterococcus faecium VanA (77%) and Enterococcus faecalis VanB (12%). Comparing the development of the selective pressure of the antimicrobial drugs and percentage of VRE in each period of observation, the effect of the application of 3rd generation cephalosporins, glycopeptides and fluoroquinolones on the VRE occurrence can be suspected. A distinct reduction of the application of these antimicrobial agents influenced the occurrence of VRE which decreased from 15.1% in the 2nd half of 1998, to 6.1% in the 1st half of 2000.


Key words: vancomycin-resistant enterococci, antibiotic selective pressure.