Modulation of Virulent Factors in Klebsiella pneumoniae Exposed to Different Hydrogen Ion Concentrations

The current investigation wasaimedat determining the levels of some virulent factors that evolve inKlebsiella pneumoniaethat are treated with different temperatures (-5, 4, 25 and 37 °C), pH (4 and 11.7) and oxygen level. The growth response of K. pneumoniae under these conditions was analyzed quantitatively by measuring the optical densities of the cultures. Biofilm formation was analyzed using the crystal violet method. Secreted metabolites were qualitatively observed onthin-layer chromatographywhile isolates were subjected to disk diffusion-based antibiotic susceptibility testing. Under the acidic condition, a significant reduction in bacterial growth in comparison to the control cultures were observedat all tested temperatures 37 °C (p=0.0088), 25 °C and 4 °C (p=0.0006) and -5 °C (p=0.0022). Similarly, there was a significant decrease in K. pneumoniae growth under basal conditions compared to 37 °C p<0.05. Biofilm formation was significantly reduced in acidic media under the aerobic condition (p=0.0259) while the basic media showed a similar significant reduction in the anaerobic condition (p=0.0150). Thin-layer chromatography showed the formation of bands at -5 °C and 4 °C with Rf of 0.6 and 0.9 both in acidic media. Antibiotic susceptibility tests demonstrated different patterns of the clearance zoneswith multiple antibiotic resistance (MAR) indices that fluctuate with increasing temperatures. Acidic and basic media also induced higher MAR indices of 0.6 while the control exhibited a lesser value of 0.0. The acidic medium under the anaerobic condition also induced a similar MAR index of 0.6 while basic media had 0.2.Conclusively, the exposure of K. pneumoniae to different conditions of pH, temperatures, and oxygen showed increases in growth, biofilm, secretion of metabolites, antibiotic resistance and susceptibility in some conditions, suggesting that these conditions promote virulence.