Staphylococcal proliferation and biofilm formation in vitro under the influence of cell-free extracts of probiotic origin

Abstract

The paper presents the results of the study on proliferation and biofilm formation by Staphylococcus aureus and Staphylococcus epidermidis under the influence of cell-free extracts obtained by the author’s method and containing derivatives of probiotic strains Вifidobacterium bifidum and Lactobacillus reuteri.The aim of this work was to study the ability of cell-free extracts containing derivatives of probiotics Bifidobacterium bifidum and Lactobacillus reuteri to influence proliferation and biofilm formation by staphylococci in vitro, to evaluate the prospects of their use for the correction of microecological disorders and adjuvant therapy of staphylococcal infection.Materials and methods. Cell-free extracts were obtained from commercial strains B. bifidum and L. reuteri by the authors’ method. Reference strain of S. aureus AТСС 25923 and clinical isolate of S. epidermidis were used as a test cultures. The investigation of the proliferation and biofilm formation by staphylococci was carried out by spectrophotometric method using a microtiter-plate reader “Lisa Scan EM” (Erba Lachema s.r.o., Czech Republic).Results. It has been established that the effect of cell-free extract on proliferation and biofilm formation depends on the type of extract and on the species of staphylococcus. Among the five studied extracts, only one significantly inhibits the proliferation and biofilm formation of both staphylococci species. It is the cell-free extract, obtained from L. reuteri culture, grown in its own disintegrate supplemented with glycerol and glucose. The proliferative activity of S. aureus is sensitive to the L. reuteri derivatives while the proliferative activity of S. epidermidis is sensitive to the B. bifidum derivatives. The filtrates of disintegrates have stimulatory effect, while the filtrates of cultures have inhibitory effect on the staphylococcal proliferation. The biofilm formation by S. aureus is significantly inhibited by B. bifidum derivatives and is stimulated by L. reuteri derivatives. The biofilm formation by S. epidermidis is stimulated by derivatives of bifidobacteria and does not change in the presence of derivatives of lactobacteria in the growth medium.Conclusions. Obtained results indicate a high bioregulatory potential of cell-free extracts of probiotic origin and the possibility of drugs development for microecological disorders correction on their basis. They also confirm that the method of obtaining probiotic derivatives with bacteriotropic activity through precursor-directed biosynthesis is promising. Cell-free extract, obtained from L. reuteri culture, grown in its own disintegrate supplemented with glycerol and glucose, exhibits pronounced anti-staphylococcal activity in vitro. After confirming efficacy in vivo, it can be recommended for the adjuvant therapy of staphylococcal infections.