P158: Use of a Bacteriophage-encoded Lysin, PlyC, as an Enzyme Eliminator against Streptococcus pyogenes Biofilm-related Contamination

Streptococcus pyogenes (Group A Streptococcus, or GAS) is a highly-sophisticated human pathogen associated with extensive morbidity and mortality worldwide. GAS is often found in the throat, on the skin, and on the prepared food frequently related with foodborne outbreaks. Formation of a streptococcal biofilm-structure has been shown to play a role in protection of bacterial cells by antimicrobial agents, intensifying the need for a better alternative to control GAS biofilm-related contamination. Bacteriophage-encoded peptidoglycan hydrolases, or lysins, have been investigated as therapeutic agents against bacterial pathogens due to their ability to lyse the bacterial cell wall.  Here we show the efficacy of PlyC, a streptococcal-specific lysin, for disruption of GAS static and dynamic biofilms. Experiments revealed that planktonic GAS were susceptible to penicillin (Minimum Inhibitory Concentration, MIC = 0.016 mg/L) and PlyC (MIC = 0.02 mg/L). However, static GAS biofilms were resistant to penicillin (Minimum Biofilm Eradication Concentration, MBEC = 100 mg/L) whereas treatment with PlyC (MBEC = 1 mg/L) eliminated 99.9% of biofilm biomass as supported by quantitative fluorescence staining. Finally, the action of PlyC against dynamic GAS biofilms was visualized in a flow cell system by time-lapse microscopy. Biofilm-structure remained intact following penicillin treatment, while PlyC completely disrupted the multilayer biofilm structure (~ 200 micron) and sterilized the entire chamber within 15 minutes. Our study demonstrates that unlike the conventional antibiotics, PlyC displays powerful anti-biofilm activity in vitro. These results support further investigation of industrial application of PlyC and other lysins for developing a better and environmentally safe “green” disinfectant.