Treatment of Bacterial Conjunctivitis
For uncomplicated bacterial conjunctivitis, prescribe a 5-7 day course of topical moxifloxacin 0.5% three times daily without adding a steroid, as topical antibiotics alone accelerate clinical resolution and steroids are generally not indicated unless severe inflammation is present under close ophthalmologic supervision. 1, 2
First-Line Antibiotic Selection
Topical fluoroquinolones are the preferred first-line agents due to superior coverage of common pathogens including Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae 1, 2
Moxifloxacin 0.5% administered three times daily for 5-7 days is the optimal choice, offering fourth-generation fluoroquinolone coverage with enhanced gram-positive activity including some methicillin-resistant S. aureus strains, achieving 81% complete resolution at 48 hours 3, 4
Alternative fluoroquinolones include ofloxacin 0.3%, ciprofloxacin, gatifloxacin, or levofloxacin if moxifloxacin is unavailable or cost-prohibitive 1, 3
For mild cases where cost is a primary concern, the American Academy of Ophthalmology states that no clinical evidence demonstrates superiority of any particular antibiotic, so the most convenient or least expensive broad-spectrum option (gentamicin, tobramycin, polymyxin B/trimethoprim) can be selected 1, 3
When Steroids Are Indicated (Rare)
Topical corticosteroids should generally be avoided in bacterial conjunctivitis and are explicitly not recommended for routine use 1, 3
The only indication for adding a brief course of topical corticosteroids is severe inflammation with marked chemosis, lid swelling, or membranous conjunctivitis, and this requires close ophthalmologic supervision with baseline and periodic intraocular pressure monitoring 1, 3
Critical contraindications to steroid use include: any suspicion of viral conjunctivitis (especially HSV or adenovirus), as steroids potentiate HSV infection and prolong adenoviral shedding 1, 3, 5
If considering combination antibiotic/steroid therapy (e.g., tobramycin/dexamethasone), you must definitively rule out viral etiology by confirming purulent (not watery) discharge, absence of follicular reaction, and no preauricular lymphadenopathy 1, 3
Special Pathogen Considerations Requiring Different Approaches
Gonococcal conjunctivitis requires systemic antibiotics: ceftriaxone 1 g IM single dose plus azithromycin 1 g orally single dose for adults, with daily monitoring until resolution—topical antibiotics alone are insufficient 1, 2
Chlamydial conjunctivitis requires systemic therapy: azithromycin 1 g orally single dose or doxycycline 100 mg twice daily for 7 days—topical therapy alone is inadequate 1, 2
MRSA conjunctivitis may require compounded topical vancomycin if cultures confirm resistance to fluoroquinolones and aminoglycosides, as MRSA isolates are increasingly common (42% of staphylococcal isolates) 1, 2
Contact lens wearers are at higher risk for Pseudomonas infection and should receive fluoroquinolones specifically 1, 3
Critical Follow-Up and Referral Criteria
Advise patients to return in 3-4 days if no improvement occurs, at which point perform visual acuity measurement and slit-lamp examination 1, 2
Immediate ophthalmology referral is mandatory for: visual loss, moderate-to-severe pain, severe purulent discharge, corneal involvement (infiltrate/ulcer/opacity), conjunctival scarring, lack of response to therapy, recurrent episodes, history of HSV eye disease, or immunocompromised state 1, 2, 3
Obtain conjunctival cultures and Gram staining before treatment if gonococcal infection is suspected based on hyperacute presentation with copious purulent discharge 1, 2
Common Pitfalls to Avoid
Do not prescribe antibiotics for viral conjunctivitis, which is the most common overall cause of infectious conjunctivitis and does not respond to antibacterial agents—this promotes unnecessary resistance 1, 6
Do not use combination antibiotic/steroid drops (e.g., Tobradex) empirically without definitively ruling out viral etiology, as this can worsen HSV infections and prolong adenoviral shedding 1, 3, 5
Reserve fluoroquinolones for moderate-to-severe cases when possible to preserve their effectiveness against resistant organisms, though they remain first-line for typical outpatient bacterial conjunctivitis 1, 2
Consider sexual abuse in children with gonococcal or chlamydial conjunctivitis and ensure sexual partners are treated in adults 1, 3
Neonatal conjunctivitis requires systemic treatment coordinated with pediatrics and often hospitalization—topical therapy alone is insufficient 1, 3