Treatment of Bacterial Conjunctivitis
For mild to moderate bacterial conjunctivitis, prescribe a broad-spectrum topical fluoroquinolone (moxifloxacin 0.5% or gatifloxacin) one drop three times daily for 5-7 days, which accelerates clinical resolution, reduces transmissibility, and allows earlier return to work or school. 1, 2, 3
Initial Assessment and Culture Indications
- Obtain conjunctival cultures and Gram staining before initiating treatment if you suspect gonococcal infection or if the presentation is moderate to severe with copious purulent discharge, marked inflammation, or severe pain 1, 4, 5
- Examine for swollen preauricular or submandibular lymph nodes, which indicate bacterial rather than viral etiology 4
- Check visual acuity at baseline—any visual loss mandates immediate ophthalmology referral 1, 4
First-Line Antibiotic Selection
Preferred Agents: Fluoroquinolones
- Moxifloxacin 0.5%: One drop three times daily for 7 days (FDA-approved dosing) 2
- Gatifloxacin 0.3%: Alternative fluoroquinolone with similar efficacy 3
- Fluoroquinolones provide broad-spectrum coverage against the most common pathogens: Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae 1, 5, 2
- Moxifloxacin achieves microbiological eradication rates of 98.5% for H. influenzae, 86.4% for S. pneumoniae, and 94.1% for S. aureus 6
Alternative Agents
- Aminoglycosides (tobramycin or gentamicin): Effective alternatives if fluoroquinolones are unavailable or contraindicated 1, 4
- Polymyxin B/trimethoprim: Another option, though less effective than fluoroquinolones 1, 7
- Povidone-iodine 1.25%: May be as effective as topical antibiotics when access to antibiotics is limited 1, 4
Special Pathogen Considerations
Gonococcal Conjunctivitis (Neisseria gonorrhoeae)
- Topical antibiotics alone are insufficient—systemic antibiotic therapy is mandatory 1, 4, 5
- Add saline lavage to promote comfort and faster resolution 1
- Requires daily follow-up until complete resolution 5
- Hospitalization may be necessary for severe cases and is mandatory for neonatal gonococcal conjunctivitis 1, 5
Chlamydial Conjunctivitis (Chlamydia trachomatis)
- Requires systemic antibiotic therapy (oral azithromycin single dose or tetracycline for 7 days in adults) 1, 5
- Topical therapy alone is inadequate 1, 4, 5
- In children, consider the possibility of sexual abuse 1, 4
- Moxifloxacin has activity against C. trachomatis, but systemic therapy remains essential 2
Methicillin-Resistant Staphylococcus aureus (MRSA)
- MRSA occurs in approximately 42% of staphylococcal isolates with high concurrent fluoroquinolone resistance 8, 5
- Fluoroquinolones are generally poorly effective against MRSA 8
- May require compounded topical vancomycin based on culture results 1, 5
- Risk factors for fluoroquinolone resistance include recent fluoroquinolone use, hospitalization, advanced age, and recent ocular surgery 8, 5
Follow-Up Protocol
- Instruct patients to return if no improvement occurs after 3-4 days of treatment 1, 4, 5
- At follow-up, perform interval history, visual acuity measurement, and slit-lamp biomicroscopy 1, 4
- For gonococcal conjunctivitis, daily follow-up is mandatory until complete resolution 5
Critical Pitfalls to Avoid
- Do not use topical corticosteroids unless under close ophthalmologic supervision, as they may prolong bacterial shedding and worsen infection 4, 5
- Reserve fluoroquinolones for bacterial conjunctivitis to preserve their effectiveness given increasing resistance patterns 5
- Do not prescribe topical antibiotics alone for gonococcal or chlamydial conjunctivitis—systemic therapy is required 1, 4, 5
- Advise patients not to wear contact lenses during treatment 2
- Counsel on hygiene measures: frequent hand washing and avoiding sharing personal items to prevent transmission 4