Increased resistance among Staphylococcus epidermidis isolates in a large teaching hospital over a 12-year period.

Abstract

The prevalence of drug resistance among clinically significant blood isolates of Staphylococcus epidermidis (n = 464) and consumption of antibiotics at a tertiary care teaching hospital (Meilahti Hospital, Helsinki) were analysed for the period 1983-1994. Resistance to methicillin increased from 28 to 77%. Simultaneously, usage of third-generation cephalosporins increased nearly sevenfold (from 8.6 kg/ to 56.4 kg/year). A significant correlation was found between percentages of methicillin resistance and usage of penicillinase-stable beta-lactam agents, including cloxacillin, imipenem, and first-, second-, and third-generation cephalosporins (r = 0.737, p < 0.0062). The increase in ciprofloxacin resistance occurred soon after the introduction of ciprofloxacin. Moreover, there was a remarkable increase in resistance to fusidic acid (from 10 to 40%) and rifampin (from 0 to 23%) despite the low usage of these agents. Overall, the rate of multiply resistant isolates roughly tripled (from 20 to 71%) and, by 1994, the frequency of isolates susceptible to vancomycin only was as high as 11%, which remarkably limits options for therapy.