A Physiochemical Investigation of the Role of Pili Forming Genes in Mediating Acinetobacter baumannii Multidrug Resistance to Model Antibiotics

The impact of pili forming genes from the Type IV Pili system on the multidrug resistance and biofilm formation of Acinetobacter baumannii, a bacterium responsible for numerous hospital-acquired infections, was investigated. Utilizing the AB5075 wildtype strain and its pili mutants, the growth kinetics, electrophoretic mobilities, surface wettabilities, and biofilm formation were quantified. These properties were used to predict bacterial interactions with common hospital materials. Techniques such as disk diffusion assay, minimum inhibitory concentration (MIC) assays, checkerboard assays, contact angle measurements, electrophoresis, and Derjaguin-Landau-Verwey-Overbeek (DLVO) modeling were employed to quantify the effects of pili genes and antibiotic treatment on bacterial adhesion and biofilm formation. Our findings revealed that pili genes significantly influenced the physicochemical properties and antibiotic resistance of A. baumannii. Furthermore, the type of material and antibiotic used can influence bacterial adhesion to common hospital materials and biofilm inhibition. Our results can be used to inform the development of new strategies to combat A. baumannii infections and enhance infection control measures in clinical settings.