Characterization Of Biofilm Formation By A Streptococcus Suis And Dispersion Using Bacteriophage Lysin

Streptococcus suis is an important zoonotic pathogen that causes meningitis, sepsis, arthritis, endocarditis and pneumonia in piglet or human meningitis, specifically, serotype 2 is the most popular and pathogenic, that is a big threaten to public hygiene and human life. The more serious problem is that the biofilm could be formed,, which could greatly increase the resistance and pathogenicity of bacteria. In this work, it is found that the significant biofilms were formed completely after 60 hours incubation by 10 out of 32 S. suis strains, and the capacity of biofilm formation was influenced by the concentration of glucose in the medium. Exopolysaccharide content in the biofilm was higher than those produced by the planktonic cells. The biofilm-grown bacteria were 2500 times more resistant to ampicillin or amoxicillin than planktonic bacteria. Scanning electron microscopy revealed a dense biofilm structure by S. suis. Bacteriophage lysin, designated LySMP, was used to degrade the dense biofilm as well as antibiotics and phage SMP. The results showed that the normal concentrations of antibiotic could not eradicate the biofilm; phage SMP had no significant effect on biofilm-grown bacteria and structure of biofilm; LySMP could almost kill all the biofilm-grown bacteria of SS2-4 and SS2-H, and the efficacy of biofilm removal by LySMP treatment was up to 80%. The investigation about the formation of S. suis biofilm will provide the basis for further research on pathogenic mechanism and our results suggest that bacteriophage lysin could provide effective strategies to remove S. suis biofilm.