A Comparative Analysis of Virulence Factors in Klebsiella Species

Abstract

Klebsiella is a genus of bacteria frequently associated with nosocomial infections due to their multi‐drug resistant properties. Klebsiella pneumoniae accounts for a large majority of hospital‐acquired pneumonia, urinary tract infections, and septicemia. The pathogenicity of K. pneumoniae clinical isolates has been greatly established to better understand and treat these infections. Klebsiella oxytoca is also primarily healthcare associated and is considered to be an emerging nosocomial pathogen, as it causes the second most frequent infections from the Klebsiella genus. Although it shares many characteristics with K. pneumoniae, its virulence factors have not been well studied due to its lesser degree of incidence. As an emerging pathogen, more information must be gathered in order to learn how to best treat this infectious, antibiotic‐resistant bacteria. This study aims to first determine if the pathogenic factors found in clinical Klebsiella pneumoniae isolates are also present in Klebsiella oxytoca and then compare the production of these virulence factors under normal and inducing conditions. This work compares the expression of pathogenic factors in five isolates of K. oxytoca, three isolates of K. pneumoniae, and one strain of Escherichia coli. The pathogenic factors chosen for this study include antibiotics resistance, siderophore production, biofilm formation abilities, and reactive oxygen species (ROS) detoxification. To determine antibiotic resistance, the minimum inhibitory concentration of nine different antibiotics was calculated for each isolate. Siderophore production was measured using a Chrome Azurol Sulfonate colorimetric test in both the absence and presence of 2,2’‐dipyridyl, an iron chelator. Biofilm formation was detected with Crystal Violet dye in both the absence and presence of acetaminophen and hydrochlorothiazide, both of which are commonly used therapeutic pharmaceuticals in nosocomial settings, as well as 2,2’‐dipyridyl. ROS detoxification via superoxide dismutase enzyme activity was measured through native gel activity assays. Our findings indicate that K. pneumoniae has resistance to more antibiotics than K. oxytoca, but the two species have comparable siderophore production, biofilm formation capabilities, and ROS detoxification capabilities. In conclusion, Klebsiella pneumoniae and Klebsiella oxytoca share several mechanisms of pathogenicity under normal and inducing conditions and drug resistance is the most notable difference among the strains tested in this work.