Chronic suppurative otitis media
Chronic suppurative otitis media (CSOM) is a persistent middle-ear infection with recurrent otorrhea through a perforated tympanic membrane, and it is a leading cause of acquired hearing loss in low- and middle-income countries. Its two dominant pathogens, Pseudomonas aeruginosa and Staphylococcus aureus, are notorious biofilm formers that shelter on the middle-ear mucosa and ossicles, making them poorly responsive to topical and systemic antibiotics and increasingly multidrug-resistant. Because the disease is anatomically accessible (the perforation allows direct topical instillation), localized, and biofilm-driven, it is an unusually attractive target for bacteriophage therapy. Lytic phages self-amplify at the infection site, penetrate biofilm, and kill antibiotic-resistant strains without disrupting the broader microbiome.
How phages act here
Mechanism
Lytic phages bind strain-specific surface receptors (e.g., P. aeruginosa LPS, type IV pili, or flagella; S. aureus wall teichoic acid), inject their genome, hijack the cell, and lyse it, releasing progeny that propagate through the infected ear so long as host bacteria persist. Many anti-Pseudomonas and anti-staphylococcal phages encode depolymerases and endolysins that degrade exopolysaccharide matrix and peptidoglycan, letting them erode the biofilms that make CSOM recalcitrant. Strain specificity is a double-edged sword: it spares commensals but demands cocktails of complementary phages (and ideally pre-treatment susceptibility/host-range matching) to cover heterogeneous, mixed P. aeruginosa/S. aureus infections and to suppress phage-resistant escape mutants. Phage-antibiotic synergy is well documented (sub-inhibitory antibiotics plus phages can clear biofilm better than either alone), and engineered/CRISPR-armed phages plus purified endolysins are emerging routes to broaden killing and add a sequence-targeted dimension, though these remain preclinical for ear infection.
Where it stands
Current evidence
The strongest human evidence remains the 2009 Wright et al. randomized, double-blind, placebo-controlled Phase I/II trial (UK MHRA-approved) of Biophage-PA, a six-phage cocktail against antibiotic-resistant P. aeruginosa in 24 patients with chronic otitis: phage-treated ears showed statistically significant improvement in clinical indicators and lower P. aeruginosa counts versus placebo, with no treatment-related adverse events. This is the first and still essentially the only controlled clinical trial of phage therapy for a chronic ear infection, and no large confirmatory RCT specific to CSOM has yet been completed as of 2026. More recent human data are anecdotal but encouraging: a 2025 US case report (Casazza et al., Otology & Neurotology) described intratympanic plus parenteral custom phage therapy resolving multidrug-resistant P. aeruginosa chronic mastoiditis in an immunosuppressed cystic-fibrosis lung-transplant patient. The richest contemporary work targeting the exact CSOM pathogen pair is veterinary: Kwon et al. (2024, Veterinary Microbiology) developed a formulated P. aeruginosa + Staphylococcus phage cocktail that reduced bacterial counts and clinical signs in a mouse otitis model and in dogs with chronic otitis externa. Overall the field is at the proof-of-concept/compassionate-use stage for ear infection, with broader registered phage trials (e.g., Armata's anti-Pseudomonas programs) advancing for related indications.
Evidence confidence: medium
The data
Key studies & trials
- Wright A, Hawkins CH, Anggård EE, Harper DR. A controlled clinical trial of a therapeutic bacteriophage preparation in chronic otitis due to antibiotic-resistant Pseudomonas aeruginosa; a preliminary report of efficacy. Clinical Otolaryngology. 2009;34(4):349-357. ↗
- Casazza J, Tan D, Newcomer M, Sakano H, Isaacson B, Hunter JB. Bacteriophage Therapy for Chronic Mastoiditis. Otology & Neurotology. 2025;46(4):e117-e119. ↗
- Kwon J, Kim SG, Kim SW, et al. Tailoring formulation for enhanced phage therapy in canine otitis externa: a cocktail approach targeting Pseudomonas aeruginosa and Staphylococcus pseudintermedius. Veterinary Microbiology. 2024;301:110354. ↗
- Wright A, Hawkins CH, Anggård EE, Harper DR. Biophage-PA Phase I/II trial — DOI record. Clinical Otolaryngology. 2009;34(4):349-357. doi:10.1111/j.1749-4486.2009.01973.x ↗
Who is working on it
Programs & centers
The possibility
CSOM may become one of the first mainstream indications for phage therapy precisely because the ear is reachable: a clinician could swab the draining ear, match it against a banked P. aeruginosa/S. aureus phage cocktail, and instill drops that self-amplify, dissolve biofilm, and clear strains that have shrugged off every available antibiotic. Pairing such cocktails with low-dose antibiotics or purified endolysins could turn months of refractory otorrhea into a short, microbiome-sparing topical course, sparing children in resource-limited settings from progressive hearing loss. If a properly powered modern RCT reproduces the 2009 Biophage-PA signal, point-of-care personalized phage drops for the chronically discharging ear are a credible near-term reality.