The Effects of Insulin and Glucose on Different Characteristics of a UPEC: Alterations in Growth Rate and Expression Levels of some Virulence Genes

Background: Host factors are known to modulate virulence, antibiotic susceptibility, and growth rate of bacteria. The effect of human insulin and glucose on growth rate and expression of virulence genes (usp, sfa/foc, cnf1) of a uropathogenic E. coli (UPEC) strain were investigated in this study. Methods: E. coli C7 was grown in tryptic soy broth (TSB-control) and TSB containing 20 mu U/mL insulin, 200 mu U/mL insulin, 0.1% glucose, and 200 mu U/mL insulin + 0.1% glucose. Growth rates were determined via optical density measurement in a spectrophotometer. Real-time polymerase chain reaction was used to determine the gene expression levels. Statistical analyses were performed via Tukey's post hoc-test. Results: Differences were found to be not statistically significant for bacterial growth rate in TSB and TSB with insulin and/or glucose. The expression levels of all three virulence genes were shown to be reduced significantly in the presence of insulin and/or glucose. The highest degree of repression was observed in 200 mu U/mL insulin added to TSB. Also, the repression level of the gene expression was revealed to be reduced in 0.1% glucose supplemented TSB. Conclusions: In the present study, it was shown that insulin and glucose can modulate UPEC's gene expression while the growth rate was not affected.