Co-isolates of Acinetobacter baumannii complex in polymicrobial infections: a meta-analysis

Background. Acinetobacter baumannii complex (ABC) infections are commonly polymicrobial. Examining which pathogens are most commonly co-isolated with ABC is an important first step for assessing disease potential due to pathogen-pathogen interactions. Methods. Based on a systematic search of PubMed, Scopus and CENTRAL, we estimated percent proportions of co-isolates in polymicrobial pulmonary and bloodstream ABC infections using random-effects meta-analysis. RESULTS. Twenty-eight eligible studies were analysed reporting 575 polymicrobial bloodstream and 290 polymicrobial pulmonary infections. Common co-isolates in pulmonary infections were P. aeruginosa (36%, 95% CI 24–49%, I(2) 71%), S. aureus (28%, 95% CI 19–38%, I(2) 44%) and Klebsiella spp. (11%, 95% CI 6–20 %, I(2) 56%), while the prevalence of other co-pathogens did not exceed 5%. Most common co-isolates in bloodstream infections were coagulase-negative Staphylococci (21%, 95% CI 12–34 %, I(2) 84%), Enterococci (15%, 95% CI 9–26%, I(2) 73%), P. aeruginosa (12%, 95% CI 6–22%, I(2) 74%), Klebsiella spp. (10%, 95% CI 6–16%, I(2) 42%), Enterobacter spp. (10%, 95% CI 6–16 %, I(2) 38%) and S. aureus (8%, 95% CI 4–15%, I(2) 58%). CONCLUSION. The common co-isolation of certain pathogens (especially P. aeruginosa ) with ABC suggests potential beneficial between-pathogen interactions, which may have treatment implications for polymicrobial infections and requires further study.