Effect of Negative Pressure on Proliferation, Virulence Factor Secretion, Biofilm Formation, and Virulence-Regulated Gene Expression of In Vitro.

. To investigate the effect of negative pressure conditions induced by NPWT on . . was cultured in a Luria-Bertani medium at negative pressure of -125 mmHg for 24 h in the experimental group and at atmospheric pressure in the control group. The diameters of the colonies of were measured after 24 h. ELISA kit, orcinol method, and elastin-Congo red assay were used to quantify the virulence factors. Biofilm formation was observed by staining with Alexa Fluor® 647 conjugate of concanavalin A (Con A). Virulence-regulated genes were determined by quantitative RT-PCR. . As compared with the control group, growth of was inhibited by negative pressure. The colony size under negative pressure was significantly smaller in the experimental group than that in the controls ( < 0.01). Besides, reductions in the total amount of virulence factors were observed in the negative pressure group, including exotoxin A, rhamnolipid, and elastase. RT-PCR results revealed a significant inhibition in the expression level of virulence-regulated genes. . Negative pressure could significantly inhibit the growth of . It led to a decrease in the virulence factor secretion, biofilm formation, and a reduction in the expression level of virulence-regulated genes.