Coordinated Virulence in Acinetobacter baumannii: Mechanisms, Integration and Therapeutic Opportunities

Acinetobacter baumannii has emerged as a significant multi-drug-resistant (MDR) pathogen, particularly in healthcare environments, due to its large arsenal of virulence factors. This review organizes these virulence factors into three groups based primarily on location and functionality: (1) membrane-associated virulence factors, (2) outer envelope components and secreted virulence factors and (3) pili and fimbriae. Together, these factors drive motility, biofilm formation, abiotic and biotic surface adherence, cell invasion, immune evasion, and antimicrobial resistance, which all complicate infection management. Elucidation of the individual and coordinated mechanisms of bacterial virulence factors is essential for identifying targets that can be exploited by novel therapies. This review, therefore, synthesizes the literature to date describing A. baumannii virulence factors as well as their individual and concerted functionalities to provide groundwork for future studies that will hopefully aid in the discovery of novel therapeutics.