Management of Bacterial Conjunctivitis
For uncomplicated bacterial conjunctivitis in immunocompetent patients, prescribe a broad-spectrum topical antibiotic (such as moxifloxacin 0.5% three times daily or polymyxin B/trimethoprim four times daily) for 5–7 days, with no specific agent demonstrating superiority over others. 1
First-Line Topical Antibiotic Selection
No single topical antibiotic has proven superior for uncomplicated bacterial conjunctivitis, allowing selection based on dosing convenience, cost, and local resistance patterns. 1, 2
Fourth-generation fluoroquinolones (moxifloxacin 0.5%) are often preferred due to broad-spectrum coverage including enhanced gram-positive activity and some MRSA strains. 1, 2, 3
Alternative first-line options include polymyxin B/trimethoprim, erythromycin ointment, or older fluoroquinolones (ofloxacin 0.3%, ciprofloxacin), all administered four times daily for 5–7 days. 1, 4, 2
Topical antibiotics provide earlier clinical remission (68% cure rate versus 55% with placebo by days 4–9) and allow faster return to work or school. 1, 2
Standard Dosing Schedule
Moxifloxacin 0.5%: one drop three times daily for 7 days (FDA-approved regimen). 3
Most other topical antibiotics: one drop four times daily for 5–7 days. 1, 2
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 improvement, followed by standard three-times-daily dosing. 2
Hygiene Measures and Infection Control
Strict hand hygiene with soap and water is critical to prevent transmission to others or the unaffected eye. 4, 2
Avoid sharing towels, pillows, or personal items during the infectious period. 4
Discard multiple-dose eyedrop containers after infection resolves to avoid recontamination. 2
Contact lens wear must be discontinued during any form of infectious conjunctivitis. 4, 3
For viral conjunctivitis, patients should minimize close contact for 10–14 days from symptom onset due to high contagiousness. 4
Natural History and When Antibiotics May Be Unnecessary
Mild bacterial conjunctivitis in immunocompetent adults is self-limited, with approximately 64% of cases resolving spontaneously by days 6–10 without treatment. 1, 2
Despite self-resolution, topical antibiotics shorten symptom duration and reduce transmissibility, making treatment an individual decision balancing cost, convenience, and desire for faster recovery. 1, 5, 6
In children, topical antibiotics allow earlier return to school and reduce community spread. 1, 5
Indications for Second-Line Therapy
Suspected MRSA Conjunctivitis
If no clinical improvement within 48–72 hours of fluoroquinolone therapy, obtain conjunctival cultures and consider compounded topical vancomycin. 1, 2
MRSA isolates are increasingly common (42% of staphylococcal isolates in some regions) and are generally resistant to fluoroquinolones and aminoglycosides but susceptible to vancomycin. 1, 2
Risk factors for MRSA include nursing home residence, recent hospitalization, and community-acquired infections. 1
Geographic Resistance Patterns
In some regions, Pseudomonas aeruginosa resistance to moxifloxacin has increased from 19% to 52%, highlighting the importance of local resistance surveillance. 2
Individual risk factors for fluoroquinolone resistance include recent fluoroquinolone use, advanced age, and recent ocular surgery. 2
Alternative When Antibiotics Are Unavailable
- Povidone-iodine 1.25% ophthalmic solution may be as effective as topical antibiotics for bacterial conjunctivitis in settings with limited antibiotic access. 1, 2, 7
Indications for Ophthalmology Referral (Red Flags)
Immediate ophthalmology referral is required for: 1, 4, 2
- Visual loss or decreased vision
- Moderate to severe pain (beyond mild irritation)
- Severe purulent discharge (suggesting possible gonococcal infection)
- Corneal involvement (opacity, infiltrate, or ulcer on examination)
- Conjunctival scarring
- Lack of response to therapy after 3–4 days
- Recurrent episodes
- History of herpes simplex virus eye disease
- Immunocompromised state
Special Situations Requiring Systemic Antibiotics
Gonococcal Conjunctivitis
Systemic antibiotic therapy is mandatory; topical therapy alone is insufficient. 1, 2
Obtain conjunctival cultures and Gram staining before initiating treatment. 1
Daily ophthalmology follow-up is required until complete resolution to prevent corneal perforation, which can occur within 24 hours. 1, 2
Saline lavage may promote comfort and accelerate inflammation resolution. 1
Sexual partners must be treated, and sexually transmitted disease screening is mandatory. 1, 2
In children, sexual abuse must be considered and documented by standard culture. 1, 2, 7
Chlamydial Conjunctivitis
Systemic therapy is required because more than 50% of infants have concurrent infection at other sites (nasopharynx, genital tract, lungs). 1, 2
No evidence supports adding topical antibiotics to systemic therapy. 1
Re-evaluate after treatment completion, as treatment failure occurs in up to 19% of cases. 1, 2
Sexual partners must be treated simultaneously, and sexual abuse must be considered in children. 1, 2
Neonatal Conjunctivitis
All neonatal conjunctivitis requires immediate evaluation and systemic treatment due to risk of corneal perforation, septicemia, and meningitis. 2, 7
Gonococcal ophthalmia neonatorum: ceftriaxone 25–50 mg/kg IV or IM single dose (maximum 125 mg) plus topical antibiotics. 2, 7
Chlamydial conjunctivitis: erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into four doses for 14 days. 2, 7
Follow-Up Strategy
Instruct patients to return in 3–4 days if no improvement is noted with topical antibiotic therapy. 1, 4, 2, 7
At follow-up, perform interval history, visual acuity measurement, and slit-lamp biomicroscopy. 1, 2
Signs of positive response include reduced pain and discharge, decreased eyelid edema or conjunctival injection, and clearer demarcation of any infiltrate. 2
If infection worsens or fails to improve after 48–72 hours, obtain cultures and consider resistant organisms. 2
Common Pitfalls to Avoid
Do not prescribe topical antibiotics for viral conjunctivitis, as they provide no benefit, may cause toxicity, and promote antimicrobial resistance. 4, 2, 6
Never use topical corticosteroids without definitively excluding viral conjunctivitis (especially herpes simplex virus and adenovirus), as steroids can exacerbate HSV infection, prolong adenoviral shedding, and cause corneal perforation. 4, 2
Do not use combination antibiotic-steroid drops (e.g., Tobradex) empirically without ruling out viral etiology. 2
Do not prescribe oral antibiotics for routine bacterial conjunctivitis; they are reserved exclusively for gonococcal and chlamydial infections. 2
Avoid prolonged use of topical antibiotics beyond 7 days, as this increases risk of ocular toxicity and resistance. 2
Do not miss gonococcal conjunctivitis, which requires immediate systemic treatment to prevent corneal perforation and vision loss. 1, 2