Intrahospital dissemination of carbapenem-resistant Acinetobacter baumannii and analysis of the infected patients' prognosis.

Objective: To assess the genetic relationship of clinical isolates of carbapenem-resistant A. baumannii(resistant to both imipenem and meropenem) from January 2007 to March 2008 in Peking University Third Hospital for measures to decrease the isolates; to investigate the characteristics of patients with carbapenem-resistant A.baumannii colonization or infection and to evaluate antibiotic treatment for health care-associated infections caused by carbapenem-resistant A.baumannii.

Methods: The medical records of patients with carbapenem-resistant A. baumannii colonization or infection were reviewed. Antibiotic susceptibilities of the isolates were determined by the standardized disk-diffusion method and the clonal relationship of the isolates was analyzed by pulsed-field gel electrophoresis.

Results: A total of 49 carbapenem-resistant A. baumannii strains were isolated from the 49 patients hospitalized during the study period and pulsed-field gel electrophoresis typing yielded 7 different patterns. A total of 45 (91.8%) genotyped strains showed clonal relationship. The most frequently identified predisposing factors were intensive care unit stay, invasive procedures, and hypoalbuminemia. Chronic obstructive pulmonary disease (12 cases) and cerebrovascular disease (10 cases) were the most common comorbid conditions. The mortality of patients with carbapenem-resistant A. baumannii infection was 38.1% (8 of 21 patients), and the acute physiology and chronic health evaluation II score, initial antibiotic therapy failure rate and the presence of hypoalbuminemia were significantly increased in the death group. Combination therapy regimens had higher success rates than monotherapy regimens(11/13, 84.6% vs. 3/17, 17.6%).

Conclusion: There has been clonal spread of carbapenem-resistant A. baumannii strains among patients in our hospital since 2007. Intensive care unit stay, invasive procedures, hypoalbuminemia, chronic obstructive pulmonary disease and cerebrovascular disease were common in patients with carbapenem-resistant A. baumannii colonization or infection. Antibiotic combination therapy may be effective for carbapenem-resistant A. baumannii infection.