Received: June24, 2004, Accepted: November 30, 2004, Published online: July 1, 2005.

STUDY ON THE SUSCEPTIBILITY OF Enterococcus faecalis FROM INFECTIOUS PROCESSES TO CIPROFLOXACIN AND VANCOMYCIN

GENARO A. (1), CUNHA M. L. R. S. (2), LOPES C. A. M. (2)

(1) Department of Tropical Diseases and Imaging Diagnosis, Botucatu School of Medicine, UNESP, São Paulo State University, São Paulo, Brazil; (2) Department of Microbiology and Immunology, Botucatu Institute of Biosciences, UNESP, São Paulo State University, Botucatu, São Paulo, Brazil.

ABSTRACT: Enterococcus faecalis is considered a pathogen responsible for hospital infections and, due to its frequent multi-resistant profile, has caused preoccupations among many medical authorities. The objective of this study was to determine the antimicrobial susceptibility of 74 strains isolated from blood cultures and purulent secretions to vancomycin and ciprofloxacin through the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) by using the Microdilution test. The results showed a greater efficacy of vancomycin compared to ciprofloxacin (98.6% of the strains were inhibited by vancomycin at lower concentrations: 0.06 - 1 g/ml). However, in the MBC analysis 73% of the strains showed a MBC of vancomycin only at high concentrations (equal to or higher than 64 g/ml. For ciprofloxacin, the strains showed a broad sensitivity with MICs and MBCs distributed along all the MIC classes. Results also revealed a probability that some strains are tolerant to vancomycin, which indicates the need of other tests to confirm this characteristic.

KEY WORDS: Enterococcus faecalis, vancomycin, ciprofloxacin, resistance, spontaneous mutation.

CORRESPONDENCE TO:

A. GENARO, Department of Tropical Diseases and Imaging Diagnosis, Botucatu School of Medicine, UNESP, Distrito de Rubião Júnior, 18618-000, Botucatu, SP, Brazil. Phone: 14 3811 6212. Email: angelmagenaro@hotmail.com