SerratiaBacteremia in a Large University Hospital: Trends in Antibiotic Resistance During 10 Years and Implications for Antibiotic Use

Abstract

Objective:To identify antibiotic resistance trends and risk factors for resistance ofSerratiaspecies to third-generation cephalosporins.Design:Retrospective survey of medical records.Setting:A 2,200-bed, tertiary-care hospital.Patients:One hundred twenty-two patients withSerratiabacteremia between January 1991 and June 2001.Methods:Infectious disease physicians collected data from medical records regarding patient demographics, underlying disease or condition, portal of entry, microorganism, antibiogram, complications, antibiotics received, and outcome.Results:Among 122Serratiaisolates, 117 (95.9%) wereSerratiamarcescens and 110 (90.2%) were of nosocomial origin. During the study period, the 122 isolates showed a high rate of resistance to third-generation cephalosporins (45.9%) and extended-spectrum penicillins (56.6%). The resistance rate to ciprofloxacin was 32.0%. The resistance rate to third-generation cephalosporins increased from 31.7% for 1991 to 1995 to 54.9% for 1996 to 1998 and 50.0% for 1999 to 2001. In the multivariate analysis, prior use of a second-generation cephalosporin (adjusted odds ratio [OR], 5.90; 95% confidence interval [CI95], 1.41 to 24.6;P= .015) or a third-generation cephalosporin (OR, 3.26; CI95, 1.20 to 8.87;P= .020) was a strong independent risk factor for resistance to third-generation cephalosporins. The overall case-fatality rate was 25.4% (Serratiabacteremia-related case-fatality rate, 13.1%).Conclusion:Prior use of a second- or third-generation cephalosporin was the most important risk factor for bacteremia withSerratiaresistant to third-generation cephalosporins, suggesting the need for antibiotic control. The potential role of patient-to-patient spread could not be fully evaluated in this retrospective study.