A rapid method for the detection of motility in Acinetobacter baumannii and its association to the existence of the virulence-associated genes pilA and algW

Abstract

Acinetobacter (A.) baumannii is one of the major nosocomial pathogens worldwide. It is associated with bloodstream infection, pneumonia, meningitis, urinary tract, soft tissue, and wound infections. Several factors contribute to its survival and spread as a nosocomial pathogen, and motility is often associated with the virulence, fitness, and tenacity of A. baumannii on surfaces. In the present study, the correlation between the presence of genes encoding for fimbrial protein PilA and periplasmic protease AlgW and motility was investigated in 87 clinical and non-clinical A. baumannii isolates from Germany. A. baumannii exhibited robust swimming, swarming, and twitching movement based on the percentage of agar in the medium, as well as the time and temperature of incubation. The swarm motility medium utilizing 2% agar with tetrazolium salts provided an efficient assay for the phenotypic characterization of A. baumannii and it was more efficient than the classical motility assays in terms of time, visibility, and biosafety. The presence of the pilA gene increased motility of A. baumannii but was not required for motility. The algW gene was found in 18 strains obtained from milk, all of them with proven phenotypic motility. The rapid detection of motility is essential to evaluate the virulence and fitness of A. baumannii. Further studies on the level of genome, transcriptome and proteome are needed to investigate the secrets behind different movement paths in each strain.