Antibiotic use and development of resistance in blood culture isolates: 8 years of experience from a cancer referral center.

The consumption of antimicrobial agents in a Slovakian national cancer institute from 1989-1996 was compared with resistance rates in clinically significant blood culture isolates. We observed an increase in resistance of viridans streptococci to penicillin and of enterococci to ampicillin. Resistance to vancomycin and teicoplanin was stable over the entire period despite a 20-fold increase in vancomycin consumption. Nor did we observe increased resistance to ofloxacin despite a 10-fold increase in consumption. Consumption of aminoglycosides and resistance levels were both stable. A different situation was observed with third-generation cephalosporins, where resistance of Pseudomonas aeruginosa, Stenotrophomonas maltophilia and Acinetobacter spp. to ceftazidime and cefotaxime increased with increasing consumption. Resistance of Enterobacteriaceae to cefotaxime and ceftazidime was stable. Resistance to imipenem did not change significantly. However, the number of Stenotrophomonas maltophilia bacteremias increased significantly after imipenem was introduced in 1991. Because of improved outcome in bacteremia, an increased incidence of both gram-negative and gram-positive bacteremia led to only a slight increase in associated mortality.