Abstract
Motility plays an essential role in the host–parasite relationship of pathogenic bacteria, and is often associated with virulence. While many pathogenic bacteria use flagella for locomotion, Acinetobacter baumannii strains do not have flagella, but have other features that aid in their motility. To study the genes involved in motility, transposon mutagenesis was performed to construct A. baumannii mutant strains. Mutant strain MR14 was found to have reduced motility, compared to wild-type ATCC 17978. NCBI BLAST analysis revealed that the Tn10 transposon in the MR14 genome is integrated into the gene that encodes for carboxy-terminal processing protease (Ctp). Additionally, MR14 exhibits a mucoidy, sticky phenotype as the result of increased extracellular DNA (eDNA) caused by bacterial autolysis. Transmission and scanning electron microscopy revealed cytoplasmic content leaving the cell and multiple cell membrane depressions, respectively. MR14 showed higher sensitivity to environmental stressors. Mutation of the ctp gene reduced invasion and adhesion of A. baumannii to airway epithelial cells, potentially due to increased hydrophobicity. In the zebrafish model of infection, MR14 increased the survival rate by 40% compared to the wild-type. Taken together, the ctp gene in A. baumannii has a pivotal role in maintaining membrane integrity, adaptation to environmental stress, and controlling virulence.
Highlights
Acinetobacter baumannii is a multi-drug resistant (MDR), nosocomial human pathogen causing serious infections among critically ill individuals worldwide
Tn10 transposon mutagenesis of the ctp gene was found to contribute to significantly reduced motility
The carboxy-terminal processing protease (Ctp) mutant becomes mucoidy, which we found is due to the accumulation of extracellular deoxypentose nucleic acid (DNA) (eDNA) caused by bacterial autolysis
Summary
Acinetobacter baumannii is a multi-drug resistant (MDR), nosocomial human pathogen causing serious infections among critically ill individuals worldwide. This microorganism is usually involved in various hospital and community-associated diseases, with MDR rates being higher among nosocomial isolates than strains causing community-associated infections [1]. A. baumannii can cause diverse infections, including bacteremia, meningitis, urinary tract infections, wound infections, septic shock, ventilator-associated pneumonia, and systemic infections leading to multi-organ failure and death among critically ill and immunocompromised individuals [2,3]. A. baumannii is resistant to almost all presently available antibiotics, and is termed a “red-alert” pathogen [4]. Treatment of infections caused by this pathogen is challenging, and there is an urgent need for the development of novel antimicrobial therapeutic strategies.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
