Defining Gene-Phenotype Relationships in Acinetobacter baumannii through One-Step Chromosomal Gene Inactivation
ABSTRACTRates of infection with hospital-acquiredAcinetobacter baumanniihave exploded over the past decade due to our inability to limit persistence and effectively treat disease.A. baumanniiquickly acquires antibiotic resistance, and its genome encodes mechanisms to tolerate biocides and desiccation, which enhance its persistence in hospital settings. With depleted antibiotic options, new methods to treatA. baumanniiinfections are desperately needed. A comprehensive understanding detailingA. baumanniicellular factors that contribute to its resiliency at genetic and mechanistic levels is vital to the development of new treatment options. Tools to rapidly dissect theA. baumanniigenome will facilitate this goal by quickly advancing our understanding ofA. baumanniigene-phenotype relationships. We describe here a recombination-mediated genetic engineering (recombineering) system for targeted genome editing ofA. baumannii. We have demonstrated that this system can perform directed mutagenesis on wide-ranging genes and operons and is functional in various strains ofA. baumannii, indicating its broad application. We utilized this system to investigate key gene-phenotype relationships inA. baumanniibiology important to infection and persistence in hospitals, including oxidative stress protection, biocide resistance mechanisms, and biofilm formation. In addition, we have demonstrated that both the formation and movement of type IV pili play an important role inA. baumanniibiofilm.IMPORTANCEAcinetobacter baumanniiis the causative agent of hospital-acquired infections, including pneumonia and serious blood and wound infections.A. baumanniiis an emerging pathogen and has become a threat to public health because it quickly develops antibiotic resistance, making treatment difficult or impossible. While the threat ofA. baumanniiis well recognized, our understanding of even its most basic biology lags behind. Analysis ofA. baumanniicellular functions to identify potential targets for drug development has stalled due in part to laborious genetic techniques. Here we have pioneered a novel recombineering system that facilitates efficient genome editing inA. baumanniiby single PCR products. This technology allows for rapid genome editing to quickly ascertain gene-phenotype relationships. To demonstrate the power of recombineering in dissectingA. baumanniibiology, we use this system to establish key gene-phenotype relationships important to infection and persistence in hospitals, including oxidative stress protection, biocide resistance, and biofilm formation.