Differential Diagnosis for a 30-year-old Male with Worsening Conjunctivitis Symptoms
- Single most likely diagnosis:
- Toxicity or hypersensitivity reaction to polymyxin B: This is likely because the patient's symptoms worsened after treatment with polymyxin B drops, which can cause allergic reactions or toxicity, especially with prolonged use.
- Other Likely diagnoses:
- Bacterial resistance or inadequate treatment: The lack of improvement and worsening of symptoms could indicate that the causative bacteria are resistant to polymyxin B, or the treatment duration was insufficient.
- Viral conjunctivitis: Although initially treated for bacterial conjunctivitis, the absence of purulent drainage and worsening symptoms could suggest a viral etiology, which would not respond to polymyxin B.
- Fungal infection: The brown spot on the inner line of the upper eyelid could be a sign of a fungal infection, which might have been opportunistic or secondary to the initial bacterial infection.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Scleritis or episcleritis: These are inflammatory conditions of the sclera or episclera that can present with severe eye pain, redness, and swelling, and can lead to serious complications if not promptly treated.
- Endophthalmitis: Although rare, this is a severe infection of the inner eye that can occur after trauma, surgery, or even topical medication use, and requires immediate medical attention to preserve vision.
- Rare diagnoses:
- Phlyctenular keratoconjunctivitis: An immune-mediated condition that can cause conjunctivitis and corneal lesions, often associated with a hypersensitivity reaction to antigens such as staphylococcal toxins.
- Parasitic infections (e.g., acanthamoebiasis): These are rare causes of conjunctivitis, especially in immunocompetent individuals, but can present with atypical symptoms and require specific diagnostic tests and treatments.