[The increasing and expression of virulence factors of opportunistic microorganisms in blood serum under various alternatives of iron homeostasis].

Staphylococcus aureus and Pseudomonas aeruginosa are foregroundpathogens of bacteriemia and sepsis. They produce large spectrum of such factors of pathogenicity permitting them to proliferate and survive in bloodstream as hydrolytic enzymes, adenosine diphosphate-ribosylarginine toxins, plasmocoagulase, etc. The occurrence of alteration of growth and expression of virulence factors of S. aureus and P. aeruginosa at fermentation in LB-broth depending on iron concentration was demonstrated previously. The conditions in vivo significantly differ the laboratory conditions. The activity of growth and expression of pathogenicity factors of S. aureus and P. aeruginosa at fermentation in blood serum of donors with different alternative of iron homeostasis was analyzed. The study established expression of genes of hemolytic phospholipase C (plcH), alginate (algD), exotoxin A (exoA) for P. aeruginosa and genes of protein A (spA), virulence global regulator (RNAIII) for S. aureus. The iron-deficient serum and serum with normal iron homeostasis decreased activity of growth of S. aureus and P. aeruginosa. The growth rate and expression level of all analyzed genes turned out higher at fermentation of S. aureus and P. aeruginosa in serums containing excess of iron (more than 30 mkM). The fermentation of P. aeruginosa in iron-deficient serum resulted in decreasing of expression level of genes plcH, algD, exoA. The expression of RNA III and spaA S.aureus in iron-deficient serum increased towards normal content of iron in blood. The example of S. aureus and P. aeruginosa demonstrated that expression of many virulence factors of opportunistic microorganisms depends on iron homeostasis of host organism. The survival and proliferation of microorganisms in blood depend on both immune status of host organism and biological characteristics of pathogen.