Vaccination with Acinetobacter baumannii adhesin Abp2D provides protection against catheter-associated urinary tract infection.

Catheter-associated urinary tract infections (CAUTIs) contribute greatly to the burden of healthcare-associated infections. Acinetobacter baumannii is a Gram-negative bacterium with high levels of antibiotic resistance that is of increasing concern as a CAUTI pathogen. A. baumannii expresses fibrinogen-binding adhesins (Abp1D and Abp2D) that mediate biofilm formation on catheters, which become coated with fibrinogen upon insertion. Here we develop a protein subunit vaccine against the Abp1D and Abp2D receptor binding domains (RBD) and show that vaccination significantly reduces bacterial titers in a female mouse model of CAUTI. We further demonstrate that immunity to Abp2D(RBD) alone is sufficient for protection. Mechanistically, we define the B cell response to Abp2D(RBD) vaccination, demonstrate that passive immunization with Abp2D(RBD)-immune serum transfers immunity to naïve mice, and show that Abp2D(RBD)-immune serum inhibits bacterial binding to fibrinogen-coated catheters. This work represents an antibiotic-sparing strategy for the prevention of A. baumannii CAUTI which has an important role in the global fight against antimicrobial resistance.