Multidrug resistant (MDR) infections caused by the bacterial pathogen Acinetobacter baumannii (Ab) are increasing at alarming rates. Ab has become the Gram-negative bacterium with the highest rate of multidrug resistance. As such, it is categorized by the World Health Organization as a critical priority for the research and development of new antimicrobial therapies. Ab is largely associated with healthcare-acquired infections in immunocompromised or critically ill patients. As a group, Ab strains are currently regarded as opportunistic, “niche-unspecific” pathogens capable of causing pneumonia, septicemia, and soft tissue and urinary tract infections (UTIs), including catheter-associated UTI (CAUTI). Challenging this paradigm, we have identified an Ab strain that acts as a “niche-specific” pathogen, displaying the specific ability to colonize the urinary tract but not the lungs of a susceptible host. We show that certain “uropathogenic Ab (UPAb)” strains are equipped with specific virulence factors that facilitate their adhesion and survival in the human bladder.
