Thesis

Role for Rpos Gene Of Klebsiella Pneumoniae in Antibiotic Tolerance and Virulence

Klebsiella pneumoniae is a problematic gram-negative bacterium which commonly causes nosocomial infections such as pneumonia, urinary tract infections, burn wound infections, and bacteremia. K. pneumoniae is particularly virulent due to its ability to form biofilms within its host. Recent studies have revealed an upward trend of nosocomial infections caused by multidrug resistant (MDR) strains of K. pneumoniae. Most worrisome are extensively drug resistant strains (XDR), as they can withstand treatment with carbapenems, which are considered the most effective antibiotics in treating microbial infections caused by gram-negative organisms. RNA-sequencing of a biofilm of an MDR strain of K. pneumoniae (BAMC) treated with carbapenems for two hours demonstrated significant differential gene expression in treated biofilms compared to untreated controls. One gene of interest was the alternative sigma factor rpoS which controls the cells’ entry into stationary phase. In this study we attempted to identify the role of RpoS in antibiotic tolerance, virulence, and heat tolerance in K. pneumoniae. A rpoS knockout mutant was generated in the BAMC background. We found that the mutant was not defective in antibiotic or heat tolerance. We believe these responses may be modulated through another mechanism. Our rpoS knockout strain was found to be deficient in virulence in our infection model, Galleria mellonella. This research may provide potential drug targets for MDR or XDRorganisms.

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