Long-term control of hospital-wide, endemic multidrug-resistant Acinetobacter baumannii through a comprehensive "bundle" approach

Abstract

Background: Acinetobacter baumannii (Ab) is emerging as a multidrug-resistant (MDR) nosocomial pathogen of considerable clinical importance. Data on the efficacy of infection control measures in endemic situations are lacking. Here, we investigated the impact of a long-term multifaceted "bundle" approach in controlling endemic MDR Ab in a 950-bed tertiary care center.

Methods: Ongoing staff education, promotion of hand hygiene, strict Contact and Isolation Precautions, environmental cleaning, and targeted active surveillance in high-risk areas during periods of likely transmission and contamination were initiated in this program. To assess the efficacy of our interventions, we recorded (before and after the intervention) the epidemiologic and clinical features of MDR Ab infections and determined the clonal relationship among MDR Ab bloodstream isolates by pulsed-field gel electrophoresis.

Results: Before the "bundle" was instituted, the rate of colonization/infection was 0.82 cases per 100 admissions (1994-1995). Colonization/infection rates showed a sustained decrease after implementation of the control program in 1995 to 0.46 in 1996-1997 and to 0.21 in 1998-2003 (P < .001). Coincident with the institution of this program, the rate of bacteremia because of MDR Ab decreased 6-fold during the 8-year observation period. A notable change in the clonal distribution of the MDR Ab isolates was also demonstrated.

Conclusion: The implementation of a comprehensive and multifaceted infection control program ("bundle") in a tertiary care center effectively controlled the spread and clinical impact of MDR Ab.

Figure 1

Evolution of the rates of multi-drug resistant Acinetobacter baumannii during the study period. Data are expressed as number of new cases of colonization/infection (squares) and bacteremia (circles) per 100 admissions. The infection control program was implemented on September 1995 (arrow).

Figure 2

Consumption of antimicrobial agents during the study period. Data are presented as daily defined doses (DDD) per 1,000 patient-days. Aminoglycosides includes gentamicin, tobramycin, and amikacin. Extended-spectrum cephalosporins include cefotaxime, ceftriaxone, and ceftazidime. Fluoroquinolones includes ciprofloxacin, ofloxacin and levofloxacin. Carbapenems include imipenem and meropenem.

Figure 3

Evolution of the clonal relationship (PFGE profiles) among 191 multi-drug resistant Acinetobacter baumannii isolates from blood cultures. Data are presented as absolute numbers per year.