Staphylococcal Phage Lysate
**Staphylococcal Phage Lysate (SPL)** is an injectable biologic and immune stimulant primarily utilized in veterinary dermatology. It is specifically indicated for the management of **recurrent, idiopathic staphylococcal pyodermas** in dogs, often used alongside appropriate antimicrobial therapy. > **Clinical Pearl:** In an era of increasing antimicrobial resistance (e.g., MRSP - Methicillin-Resistant *Staphylococcus pseudintermedius*), immunomodulators like SPL offer a valuable adjunctive approach to reduce the frequency and duration of systemic antibiotic use. The product is prepared by lysing cultures of *Staphylococcus aureus* (Cowan serologic types I & III; human strains) using a staphylococcal bacteriophage. The prepared solution contains *S. aureus* components (protein A extracts), bacteriophage, and unfiltered beef heart infusion broth. It is ultrafiltered to achieve bacteriologic sterility.
Mechanism: SPL functions as an immunomodulator that specifically enhances **cell-mediated immunity** (Th1 immune response). * **Cytokine Stimulation:** It stimulates the production of key pro-inflammatory and immunoregulatory cytokines, including **Tumor Necrosis Factor (TNF-α)**, **Interleukin-6 (IL-6)**, and **Interferon-gamma (IFN-γ)**. * **Mechanism:** By upregulating IFN-γ and TNF-α, SPL enhances the phagocytic and bactericidal activities of macrophages and neutrophils → leading to improved clearance of intracellular and extracellular staphylococcal organisms from the skin. * **Protein A Role:** The presence of staphylococcal Protein A acts as a potent B-cell superantigen and immunogen, further stimulating a robust host immune response against staphylococcal antigens.
Dosing by species
- Labeled indications (Highly allergic patients) · Skin test with 0.05-0.1 mL intradermally. Therapy: Initially, 0.2 mL SC, then incremental increases of 0.2 mL once a week to 1 mL (a total of 5 injections). Then continue at 1 mL SC weekly for approximately 10-12 weeks. · SC/ID · Weekly · 10-12 weeks · Concomitant antibiotic therapy is recommended for an initial 4-6 week period. Maximum dose should be decreased in small dogs and can be increased cautiously, if necessary, in large dogs to 1.5 mL.
- Labeled indications (Non-allergic patients) · 0.5 mL SC twice weekly for 10-12 weeks, then 0.5-1 mL every 1-2 weeks. · SC · Twice weekly then every 1-2 weeks · 10-12 weeks initial, then maintenance · Concomitant antibiotic therapy is recommended for an initial 4-6 week period.
- Idiopathic, recurrent pyoderma · 0.5 mL SC twice weekly for 10-12 weeks, then tapered to effect. · SC · Twice weekly · 10-12 weeks then tapered · This agent is rarely needed, because in most cases, an underlying cause can be identified and treated.
- Chronic recurrent idiopathic pyoderma · Injections are administered twice weekly (0.5 mL) and slowly reduced to 0.5 mL every 2 weeks. · SC · Twice weekly then reduced · Ongoing · Pyoderma needs to be under control as this product is not a substitute for antibiotics.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Prior systemic hypersensitivity reactions to SPL
- Documented hypersensitivity reactions to beef products (contains unfiltered beef heart infusion broth)
Adverse effects
- Post vaccine-type reactions (fever, malaise)
- Injection site reactions (redness, itching, swelling occurring 2-3 hours post-injection and persisting up to 3 days)
- Systemic hypersensitivity reactions (weakness, vomiting, diarrhea, severe itching, rapid breathing, fatigue/lassitude)
Drug interactions
- Cell-mediated immunosuppressive drugs (e.g., corticosteroids, cyclosporine) · May reduce the efficacy of SPL
Monitoring
- Clinical efficacy (resolution of pyoderma)
- Local injection site reactions (redness, swelling, itching)
- Systemic hypersensitivity reactions (anaphylaxis, vomiting, weakness)
Overdose
No specific information was located regarding acute toxicity. Other than an increased risk for local or systemic hypersensitivity reactions, significant morbidity appears unlikely. Should an anaphylactic-type reaction occur, treat supportively; the manufacturer recommends **epinephrine** and **atropine** as antidotes.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.