Effect of Cell-Free Culture Fluid of Staphylococcus aureus on the Structure and Biochemical Composition of Klebsiella pneumoniae and Pseudomonas aeruginosa Biofilms

Recently, there has been increasing evidence that many infections are associated with the formation of multispecies biofilms, in which there is a change in the sensitivity of bacteria to antibiotics and a change in the permeability of the extracellular matrix compared to monocultures. In this work, we show that the addition of cell-free culture liquid (CFCL) of Staphylococcus aureus to Klebsiella pneumoniae and Pseudomonas aeruginosa biofilms increases the content of α-, and β-polysaccharides in the matrix up to 2 times, which likely affects the structure of the biofilm. The increase in the polysaccharide component is also confirmed by a significant rise in the expression level of the K. pneumoniae pgaA and P. aeruginosa pelA, pslA genes in the presence of S. aureus culture liquid.