[Trend of antimicrobial drug-susceptibility of blood isolates at an oncological center (1998-2003)].

Objective: To describe the patterns of antimicrobial resistance organisms isolated in blood cultures from patients detected in a tertiary level of care, teaching oncological hospital.

Material And Methods: All strains obtained from blood cultures from 1998 to 2003 were included and processed using the Bactec and Microscan system to determinate isolates and susceptibility to antimicrobials. The percent difference (increase or decrease) was obtained by comparing the frequency of resistance at baseline and at the end of the study.

Results: A total of 2071 positive blood cultures were obtained; 59.7% of isolates were Gram negative bacteria, 35.7% Gram-positive bacteria and 4.6% were yeasts. E. coli was the most frequent isolated (18.6%), followed by. Staphylococcus epidermidis (12.7%) and Klebsiella spp (9%). Throughout the study the susceptibility of Gram negative bacteria was stable and over 88% for most of the antimicrobials tested (except for Pseudomonas aeruginosa). Ciprofloxacin susceptibility for Escherichia coli stayed around 50%. Susceptibility to amikacin was higher than that to gentamicin. Staphylococcus aureus susceptibility for oxacillin was 96% and that for vancomycin 100%. S. epidermidis susceptibility for oxacillin was 14% and for vancomycin was 98.6%. No strains of vancomycin-resistant enterococci were found. All Streptococcus pneumoniae strains were penicillin susceptible.

Conclusions: The drug-resistance found in this hospital is the result of the control in the use of antimicrobials, the hospital nosocomial infection program and the use of drug combination in all patients with bacteremia.