The Phage Lysin PlySs2 Decolonizes Streptococcus suis from Murine Intranasal Mucosa

Abstract

Streptococcus suis infects pigs worldwide and may be zoonotically transmitted to humans with a mortality rate of up to 20%. S. suis has been shown to develop in vitro resistance to the two leading drugs of choice, penicillin and gentamicin. Because of this, we have pursued an alternative therapy to treat these pathogens using bacteriophage lysins. The bacteriophage lysin PlySs2 is derived from an S. suis phage and displays potent lytic activity against most strains of that species including serotypes 2 and 9. At 64 μg/ml, PlySs2 reduced multiple serotypes of S. suis by 5 to 6-logs within 1 hour in vitro and exhibited a minimum inhibitory concentration (MIC) of 32 μg/ml for a S. suis serotype 2 strain and 64 μg/ml for a serotype 9 strain. Using a single 0.1-mg dose, the colonizing S. suis serotype 9 strain was reduced from the murine intranasal mucosa by >4 logs; a 0.1-mg dose of gentamicin reduced S. suis by <3-logs. A combination of 0.05 mg PlySs2 + 0.05 mg gentamicin reduced S. suis by >5-logs. While resistance to gentamicin was induced after systematically increasing levels of gentamicin in an S. suis culture, the same protocol resulted in no observable resistance to PlySs2. Thus, PlySs2 has both broad and high killing activity against multiple serotypes and strains of S. suis, making it a possible tool in the control and prevention of S. suis infections in pigs and humans.

Revisiting Antibiotic Resistance Spreading in Wastewater Treatment Plants – Bacteriophages as a Much Neglected Potential Transmission Vehicle

“…While many of these alternatives show promise in theoretical and experimental settings, it remains to be investigated how they can be part of a global strategy to reduce antibiotic resistance spreading. Furthermore, such a change in therapy is likely to also suffer from development of resistance, though possibly at a lower rate as has been indicated for a few substances ( Gilmer et al, 2017 ). Thus, a general approach to limit spread of resistance is of need.…”

Postantibiotic and Sub-MIC Effects of Exebacase (Lysin CF-301) Enhance Antimicrobial Activity against Staphylococcus aureus

“…Recent in vitro studies also demonstrate that MRSA isolates surviving short (and sub-MIC) exposures to CF-301 undergo phenotypically stable increases in oxacillin susceptibility, consistent with resensitization (13,14) and likely mediated by cell wall perturbations (15). The potent in vivo efficacy of CF-301 has also been reported using multiple different animal infection models and includes demonstrations of antimicrobial activity at very low (possibly sub-MIC) concentrations when tested in addition to conventional antistaphylococcal antibiotics (12,(16)(17)(18). In the rabbit infective endocarditis (IE) model, for example, a single bolus dose of CF-301 at a concentration as low as 0.09 mg/kg administered in addition to 4 daily doses of daptomycin (DAP; 4 mg/kg, twice a day [BID]) resulted in significantly reduced MRSA densities of Ͼ6 log 10 CFU/g within heart valve vegetations, kidney, and spleen compared to 2 log 10 to 3 log 10 CFU/g for DAP alone after 5 days (16).…”

“…To test this, we examined in vitro pharmacodynamic (PD) parameters, including the postantibiotic effect (PAE), postantibiotic sub-MIC effect (PA-SME), and sub-MIC effect (SME), which enable an understanding of the impact of short-duration and/or sub-MIC exposures on bacterial growth (19)(20)(21)(22). These exposures are of particular interest considering the initial intended therapeutic use of CF-301 is via the administration of a single intravenous dose over a 2-h infusion in addition to standard-of-care antistaphylococcal antibiotics (17). By definition, the PAE is a suppressed phase of bacterial growth that persists after the initial exposure to an antimicrobial agent (often at supra-MIC levels) until normal bacterial growth resumes after the removal of the antibacterial agent.…”

Csl2, a novel chimeric bacteriophage lysin to fight infections caused by Streptococcus suis, an emerging zoonotic pathogen

“…The resulting chimera, Csl2, displays a strong bactericidal activity against some S. suis strains, and moderate to low activity against a few other streptococcal species belonging to the mitis group, with the noticeable exception of being ineffective against S. pneumoniae . The lethality of Csl2 against S. suis parallels those of PlySs2 21 , Ly7917 23 and the Art-240 artilysin 46 , and surpasses those of LySMP, Ply30, λSa2lys and the ClyR chimera 9 , 22 , 46 , 47 . However, it is less active against S. suis than the parental Cpl-7 (it requires three times more enzyme to reach nearly the same killing activity against the strain tested).…”

“…The PlySs2 lysin, from a prophage of a serotype 2 S. suis strain, has an N-terminal cysteine-histidine aminopeptidase (CHAP; PF05257) catalytic domain and a C-terminal SH3 type 5 (PF08460) cell wall binding domain (CWBD) 20 . PlySs2 is active against a broad range of Gram-positive bacteria in vitro and in vivo 21 . With identical modular composition, the Ply30 and Ly7917 lysins kill S. suis strains of various serotypes as well as Streptococcus equi subsp.…”