The epidemiology of multidrug-resistant Acinetobacter baumannii: does the community represent a reservoir?

Abstract

Objective: To explore the role of the community as a potential reservoir for Acinetobacter baumannii.

Design: Antimicrobial resistance patterns and genotypes of A. baumannii isolates from patients in two Manhattan hospitals were compared with those of A. baumannii isolates from the hands of community members.

Results: A total of 103 isolates from two hospitals (hospital A, 81; hospital B, 22) and 23 isolates from community residents were studied. Of the hospital isolates, 36.6% were multidrug resistant (hospital A, 68.2%; hospital B, 27.8%). In contrast, there were no multidrug-resistant isolates from the community (P < .005 between hospital and community). The prevalence of A. baumannii on the hands of community residents was 10.4% (23 of 222). By molecular typing, 42 strains of A. baumannii were identified. Of the isolates from hospital A and hospital B, 55.6% (45 of 81) and 68.2% (15 of 22), respectively, were indistinguishable or closely related. In contrast, most community (83.3%) isolates were unrelated (P = .001 between hospital and community).

Conclusion: Acinetobacter isolates from the community, characterized by a large variety of unrelated strains (83.3%), were distinct from the hospital isolates, of which 58.3% were closely related. The absence of multidrug-resistant strains in the community compared with 36.8% prevalence among hospital isolates suggests that the reservoir for epidemic strains resides in the hospital environment itself. To our knowledge, this is the first study to examine the community as a potential reservoir for hospital strains of A. baumannii.