Community-acquired bloodstream infections caused by Acinetobacter baumannii: A matched case-control study.

Background: Acinetobacter baumannii is an important nosocomial pathogen worldwide. Its role in community-acquired infection remains controversial and has rarely been reported.

Methods: Patients with monobacterial bloodstream infections caused by genomic species identified A. baumannii, admitted to Taipei Veterans General Hospital between 1999 and 2010, were selected as cases. Controls were defined as patients acquiring infection in a healthcare setting and were matched for age and sex. The clinical, epidemiologic, and microbiological characteristics of cases and controls were compared.

Results: Cases presented with shock more frequently and had higher APACHE II scores (25 vs 19, p = 0.005). No significant differences between the two groups were noted in the sources of bloodstream infection and underlying diseases. Multidrug resistance rates were higher in nosocomial A. baumannii isolates then in those acquired in the community (81.5% vs 38.9%, p = 0.002). Patients infected in the community were more likely to receive appropriate antimicrobial therapy than those with hospital-acquired A. baumannii (10/18; 55.6% vs 11/54; 20.4%, p = 0.011). Acquisition in the community (odds ratio [OR] 5.716, 95% confidence interval [CI] 1.021-32.003, p = 0.047), respiratory tract as the infection source (OR 9.514, 95% CI 2.370-38.189, p = 0.001), and immunosuppressive therapy (OR 4.331, 95% CI 1.052-17.832, p = 0.042) were independently associated with increased 14-day mortality among patients with A. baumannii bacteremia in this cohort.

Conclusion: Community-acquired bacteremia caused by A. baumannii was rare but associated with a severe outcome. Further investigation of potential virulence factors of community-acquired A. baumannii is required.