CRISPR-Cas9 modified bacteriophage for treatment of Staphylococcus aureus induced osteomyelitis and soft tissue infection

• Published in: PloS one Vol. 14; no. 11; p. e0220421
• Main Authors: Cobb, Leah H, Park, JooYoun, Swanson, Elizabeth A, Beard, Mary Catherine, McCabe, Emily M, Rourke, Anna S, Seo, Keun Seok, Olivier, Alicia K, Priddy, Lauren B
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22-11-2019; Public Library of Science (PLoS)
• Subjects: Alginates; Alginic acid; Animals; Anti-Bacterial Agents - pharmacology; Antibacterial agents; Antibiotic resistance; Antibiotics; Bacteria; Bacterial infections; Bactericidal activity; Bacteriophages - genetics; Biocompatibility; Bioengineering; Biofilms; Biology and Life Sciences; Biomedical materials; Clinical trials; CRISPR; CRISPR-Cas Systems; Development and progression; Diabetes; Disease Models, Animal; Drug resistance; E coli; Electron microscopy; Engineering; Female; Fluoroscopic imaging; Foot diseases; Fosfomycin; Fosfomycin - pharmacology; Gene Editing; Health aspects; Host range; Hydrogels; Infection; Infections; Infectious diseases; Leg ulcers; Longitudinal Studies; Medical research; Medicine and Health Sciences; Methicillin; Microbial drug resistance; Microscopy; Mitigation; Osteomyelitis; Osteomyelitis - microbiology; Osteomyelitis - pathology; Osteomyelitis - therapy; Phages; Physical Sciences; Rats; Rats, Sprague-Dawley; Scanning electron microscopy; Soft Tissue Infections - microbiology; Soft Tissue Infections - pathology; Soft Tissue Infections - therapy; Soft tissues; Staphylococcal infections; Staphylococcal Infections - pathology; Staphylococcal Infections - therapy; Staphylococcus aureus; Staphylococcus aureus infections; Staphylococcus infections; Strains (organisms); Tail fiber protein; Therapeutics; Tissues; Toxicity; Vancomycin; Vancomycin - pharmacology; Veterinary colleges; Veterinary medicine; Viruses; United States > US; Mississippi
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0220421

Osteomyelitis, or bone infection, is often induced by antibiotic resistant Staphylococcus aureus strains of bacteria. Although debridement and long-term administration of antibiotics are the gold standard for osteomyelitis treatment, the increase in prevalence of antibiotic resistant bacterial strains limits the ability of clinicians to effectively treat infection. Bacteriophages (phages), viruses that in a lytic state can effectively kill bacteria, have gained recent attention for their high specificity, abundance in nature, and minimal risk of host toxicity. Previously, we have shown that CRISPR-Cas9 genomic editing techniques could be utilized to expand temperate bacteriophage host range and enhance bactericidal activity through modification of the tail fiber protein. In a dermal infection study, these CRISPR-Cas9 phages reduced bacterial load relative to unmodified phage. Thus we hypothesized this temperate bacteriophage, equipped with the CRISPR-Cas9 bactericidal machinery, would be effective at mitigating infection from a biofilm forming S. aureus strain in vitro and in vivo. In vitro, qualitative fluorescent imaging demonstrated superiority of phage to conventional vancomycin and fosfomycin antibiotics against S. aureus biofilm. Quantitative antibiofilm effects increased over time, at least partially, for all fosfomycin, phage, and fosfomycin-phage (dual) therapeutics delivered via alginate hydrogel. We developed an in vivo rat model of osteomyelitis and soft tissue infection that was reproducible and challenging and enabled longitudinal monitoring of infection progression. Using this model, phage (with and without fosfomycin) delivered via alginate hydrogel were successful in reducing soft tissue infection but not bone infection, based on bacteriological, histological, and scanning electron microscopy analyses. Notably, the efficacy of phage at mitigating soft tissue infection was equal to that of high dose fosfomycin. Future research may utilize this model as a platform for evaluation of therapeutic type and dose, and alternate delivery vehicles for osteomyelitis mitigation.