Novel Bacteriophage Lysin with Broad Lytic Activity Protects against Mixed Infection by Streptococcus pyogenes and Methicillin-Resistant Staphylococcus aureus

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pyogenes (group A streptococcus [GrAS]) cause serious and sometimes fatal human diseases. They are among the many Gram-positive pathogens for which resistance to leading antibiotics has emerged. As a result, alternative therapies need to be developed to combat these pathogens. We have identified a novel bacteriophage lysin (PlySs2), derived from a Streptococcus suis phage, with broad lytic activity against MRSA, vancomycin-intermediate S. aureus (VISA), Streptococcus suis, Listeria, Staphylococcus simulans, Staphylococcus epidermidis, Streptococcus equi, Streptococcus agalactiae (group B streptococcus [GBS]), S. pyogenes, Streptococcus sanguinis, group G streptococci (GGS), group E streptococci (GES), and Streptococcus pneumoniae. PlySs2 has an N-terminal cysteine-histidine aminopeptidase (CHAP) catalytic domain and a C-terminal SH3b binding domain. It is stable at 50°C for 30 min, 37°C for >24 h, 4°C for 15 days, and ؊80°C for >7 months; it maintained full activity after 10 freeze-thaw cycles. PlySs2 at 128 g/ml in vitro reduced MRSA and S. pyogenes growth by 5 logs and 3 logs within 1 h, respectively, and exhibited a MIC of 16 g/ml for MRSA. A single, 2-mg dose of PlySs2 protected 92% (22/24) of the mice in a bacteremia model of mixed MRSA and S. pyogenes infection. Serially increasing exposure of MRSA and S. pyogenes to PlySs2 or mupirocin resulted in no observed resistance to PlySs2 and resistance to mupirocin. To date, no other lysin has shown such notable broad lytic activity, stability, and efficacy against multiple, leading, human bacterial pathogens; as such, PlySs2 has all the characteristics to be an effective therapeutic.

Endolysins of Bacteriophages as an Anti-Methicillin Resistant Staphylococcus aureus Infection in Children: A Narrative Review

“…Similar results were also reported by Daniel B et al (51)(52)(53). Gilmer et al in 2016, reported bacteriophage lysin PlySs2 with broad lytic activity against MRSA1 and Streptococcus strains (54).…”

Antimicrobial bacteriophage-derived proteins and therapeutic applications

“…61 In this pioneering study, Nelson et al showed that the oral administration of 24 ng (of a group C streptococcal phage endolysin PlyC, could eliminate the streptococcal burden from heavy colonized murine oral cavities within 2 h. 61 In a follow-up study, a single 2 mg (»80 mg/kg) intraperitoneal injection of PlyC could rescue S. pyogenes bacteremic mice from death if given 3 h after bacterial challenge. 62 Similarly, a 2 mg intraperitoneal injection of the Streptococcus suis phage endolysin PlySs2, that was known to lyse several serotypes of S. pyogenes, could also rescue 95% of S. pyogenes bacteremic mice from death. Further study found that PlySs2 could also lyse methicillin-resistant S. aureus (MRSA), and is potent enough to protect mice from bacteremic death caused by mixtures of MRSA and GAS, whereas PlyC could not.…”

“…Further study found that PlySs2 could also lyse methicillin-resistant S. aureus (MRSA), and is potent enough to protect mice from bacteremic death caused by mixtures of MRSA and GAS, whereas PlyC could not. 62 However, PlyC and PlySs2 are not endolysins encoded by S. pyogenes phages. The only S. pyogenes phage endolysin reported to be tested in an animal model is PlyPy, the gene for which was identified from within a silent prophage.…”

Lysibodies are IgG Fc fusions with lysin binding domains targetingStaphylococcus aureuswall carbohydrates for effective phagocytosis

“…For AtlA lysibody and ClyS lysibody, slight to no signal was observed for nonstaphylococcal species (AtlA lysibody bound weakly to Bacillus cereus and Enterococcus faecalis, exclusively at the septum). PlySs2 lysibody, on the other hand, displayed a broad range of host binding, including staphylococci, E. faecalis, Enterococcus faecium, Streptococcus pyogenes, and Streptococcus agalactiae, consistent with the wider lytic activity range of the PlySs2 lysin (36). PlyG lysibody specifically bound B. anthracis (Fig.…”

“…Placing such domains at the N terminus of an antibody Fc region (directly replacing the Fab) results in an unnatural orientation for the lysin binding domain, potentially interfering with its function. As there are numerous examples of functional antibodies with C-terminal fusions (34), we created lysibodies using the binding domains of the S. aureus-specific lysins ClyS (35) and PlySs2 (36) fused to the C terminus of human IgG1 Fc region (Fig. 1B).…”