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.

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%, I² 71%), S. aureus (28%, 95% CI 19-38%, I² 44%) and Klebsiella spp. (11%, 95% CI 6-20 %, I² 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 %, I² 84%), Enterococci (15%, 95% CI 9-26%, I² 73%), P. aeruginosa (12%, 95% CI 6-22%, I² 74%), Klebsiella spp. (10%, 95% CI 6-16%, I² 42%), Enterobacter spp. (10%, 95% CI 6-16 %, I² 38%) and S. aureus (8%, 95% CI 4-15%, I² 58%).

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.