What topical antibiotic eye drops are recommended for acute bacterial conjunctivitis in adults, and what are the alternative treatments for viral, allergic conjunctivitis or contact lens wearers?

Treatment of Conjunctivitis

For acute bacterial conjunctivitis in adults, prescribe topical moxifloxacin 0.5% three times daily for 5-7 days as first-line therapy, offering superior gram-positive coverage including activity against some MRSA strains. 1

Bacterial Conjunctivitis

First-Line Treatment

• Topical fluoroquinolones are the preferred agents for uncomplicated bacterial conjunctivitis, with no single antibiotic demonstrating superiority, allowing selection based on dosing convenience, cost, and local resistance patterns. 1
• Fourth-generation fluoroquinolones (moxifloxacin 0.5%, gatifloxacin) provide broader gram-positive coverage than earlier generations, including excellent activity against Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. 1, 2
• Alternative topical options include ciprofloxacin 0.3%, ofloxacin 0.3%, levofloxacin 1.5%, or besifloxacin 0.6% if moxifloxacin is unavailable. 1, 2

Dosing Regimen

• Apply one drop three to four times daily for 5-7 days to achieve earlier clinical and microbiological remission (68% cure rate versus 55% with placebo by days 4-9). 1, 3
• For severe bacterial conjunctivitis with copious purulent discharge, consider a loading dose of one drop every 5-15 minutes for the first hour, then hourly until clinical improvement, followed by standard three-times-daily dosing. 1, 2

Natural History Context

• Mild bacterial conjunctivitis in immunocompetent adults is self-limited, with approximately 64% of cases resolving spontaneously by days 6-10 without treatment. 1
• Topical antibiotics are recommended because they shorten symptom duration and allow faster return to work or school, despite the self-limited nature. 1, 4

Special Populations Requiring Different Management

Contact Lens Wearers

• Reserve fluoroquinolones (ofloxacin or ciprofloxacin) for contact lens wearers due to higher risk of Pseudomonas aeruginosa infection requiring more aggressive coverage. 1
• Discontinue contact lens use during treatment. 1

Suspected MRSA

• Consider MRSA in patients from nursing homes or with community-acquired infections who fail to respond to fluoroquinolones within 48-72 hours. 1
• MRSA isolates are generally resistant to fluoroquinolones and aminoglycosides but remain susceptible to vancomycin; compounded topical vancomycin may be required. 1, 2
• Geographic resistance patterns show 42% of MRSA isolates exhibit concurrent fluoroquinolone resistance. 1

Gonococcal Conjunctivitis

• Systemic antibiotics are mandatory—topical therapy alone is insufficient. 1
• Treat with ceftriaxone 250 mg IM single dose plus azithromycin 1 g oral single dose for concurrent chlamydial coverage. 1
• Obtain conjunctival cultures and Gram staining before initiating treatment. 1
• Requires daily ophthalmology monitoring until resolution to prevent corneal perforation. 1

Chlamydial Conjunctivitis

• Systemic therapy is required because more than 50% of patients have concurrent infection at other sites. 1
• Treat with azithromycin 1 g oral single dose or doxycycline 100 mg oral twice daily for 7 days. 1
• Screen for concurrent genital infections and treat sexual partners. 1

Viral Conjunctivitis

Adenoviral Conjunctivitis (Most Common)

• No proven effective antiviral treatment exists for adenovirus—management is supportive care only. 1
• Symptomatic treatment includes refrigerated preservative-free artificial tears four times daily, topical antihistamines for itch relief, and cold compresses. 1
• Avoid topical antibiotics as they provide no benefit, may cause ocular toxicity, and promote antimicrobial resistance. 1, 4
• Topical corticosteroids may be considered only in severe cases with marked chemosis, severe lid swelling, epithelial sloughing, or membranous conjunctivitis, but require close ophthalmology monitoring for elevated intraocular pressure and cataract. 1

HSV Conjunctivitis

• Treat with topical ganciclovir 0.15% gel three to five times daily or topical trifluridine 1% solution five to eight times daily. 1
• Add oral antivirals (acyclovir, valacyclovir, or famciclovir) for comprehensive coverage. 1
• Topical corticosteroids are absolutely contraindicated in HSV conjunctivitis as they potentiate viral replication and worsen infection. 1, 5

Herpes Zoster Ophthalmicus

• Treat with valacyclovir 1000 mg three times daily for 7 days (preferred) or acyclovir 800 mg five times daily for 7 days, initiated within 72 hours of rash onset. 5
• Apply topical antibiotics to vesicular lesions to prevent secondary bacterial infection. 5
• Topical antivirals alone are ineffective for varicella-zoster virus conjunctivitis and should not be used as monotherapy. 5

Allergic Conjunctivitis

First-Line Treatment

• Second-generation topical antihistamines with mast-cell stabilizing properties are first-line therapy for mild allergic conjunctivitis. 1
• Adjunctive measures include cold compresses, refrigerated preservative-free artificial tears, and sunglasses as an allergen barrier. 1
• Itching is the most consistent sign distinguishing allergic from infectious conjunctivitis. 1, 4

Second-Line Treatment

• Add a brief 1-2 week course of low side-effect profile topical corticosteroids (fluorometholone, rimexolone, or loteprednol) if symptoms persist. 1
• Monitor intraocular pressure and evaluate for cataract if corticosteroids are used. 1

Giant Papillary Conjunctivitis

• Discontinue contact lens use in conjunction with topical anti-inflammatory agents. 1

Red-Flag Criteria Requiring Immediate Ophthalmology Referral

• Visual loss or significant change in vision 1
• Moderate to severe eye pain (beyond mild irritation) 1
• Severe purulent discharge suggesting gonococcal infection 1
• Corneal involvement (opacity, infiltrate, or ulcer) 1
• Conjunctival scarring 1
• Lack of response to therapy after 3-4 days 1
• Recurrent episodes 1
• History of HSV eye disease 1
• Immunocompromised state 1
• Neonatal conjunctivitis (requires systemic treatment coordinated with pediatrician) 1

Critical Pitfalls to Avoid

• Never use combination antibiotic-steroid drops (e.g., Tobradex) without definitively ruling out viral conjunctivitis, especially HSV and adenovirus, by looking for watery discharge, follicular reaction, and preauricular lymphadenopathy. 1
• Do not use topical corticosteroids during active epithelial viral infection as they prolong adenoviral infections and worsen HSV infections. 1
• Avoid prolonged use of topical trifluridine beyond 2 weeks due to epithelial toxicity. 1
• Do not prescribe oral antibiotics for routine bacterial conjunctivitis—they are reserved exclusively for gonococcal and chlamydial infections. 1
• Consider sexual abuse in children presenting with gonococcal or chlamydial conjunctivitis. 1

Infection Control

• Strict hand hygiene with soap and water is critical to prevent transmission. 1
• Avoid close contact for 7-14 days from symptom onset in viral conjunctivitis. 1
• Discard multiple-dose eyedrop containers to avoid cross-contamination. 1