What is the recommended treatment for bacterial conjunctivitis?

Treatment of Bacterial Conjunctivitis

For mild bacterial conjunctivitis, prescribe a 5-7 day course of broad-spectrum topical antibiotic applied 4 times daily, choosing the most convenient or least expensive option such as polymyxin B/trimethoprim, as no evidence demonstrates superiority of any particular agent in uncomplicated cases. 1, 2

Severity-Based Treatment Algorithm

Mild Bacterial Conjunctivitis

• Topical antibiotic therapy accelerates clinical and microbiological remission by days 2-5, reduces transmissibility, and allows earlier return to school/work, even though most cases are self-limited. 1, 2, 3
• Apply any broad-spectrum topical antibiotic 4 times daily for 5-7 days 1, 2
• Acceptable first-line options include:
  • Polymyxin B/trimethoprim 1
  • Erythromycin 1
  • Tobramycin 1
  • Gentamicin 1
• Reserve fluoroquinolones (ofloxacin, ciprofloxacin, moxifloxacin) for moderate-to-severe cases or contact lens wearers to preserve effectiveness and minimize resistance. 1, 4

Moderate to Severe Bacterial Conjunctivitis

Characterized by copious purulent discharge, pain, and marked inflammation 4, 2:

• Obtain conjunctival cultures and Gram staining immediately before initiating treatment, especially if gonococcal infection is suspected. 1, 4
• Prescribe fluoroquinolones as first-line empiric therapy due to broad-spectrum coverage against common pathogens including Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Pseudomonas. 4
• Specific fluoroquinolone options:
  • Ciprofloxacin 0.3%: 1-2 drops every 2 hours while awake for 2 days, then every 4 hours while awake for 5 days 5
  • Moxifloxacin 0.5% or ofloxacin 0.3% 4
• Alternative: Aminoglycosides (tobramycin or gentamicin) 4

Special Pathogen Considerations

Gonococcal Conjunctivitis

• Requires systemic antibiotic therapy; topical treatment alone is insufficient. 1, 4
• Add saline lavage for comfort and faster resolution 1
• Mandatory daily follow-up until complete resolution 4, 2
• Hospitalization may be necessary for severe cases and is mandatory for neonatal cases 1

Chlamydial Conjunctivitis

• Requires systemic antibiotic therapy (oral azithromycin single dose or tetracycline for 7 days in adults); topical therapy alone is inadequate. 1, 4
• For neonates: erythromycin base or ethylsuccinate 50 mg/kg/day divided into 4 doses for 14 days 1
• Follow-up evaluation is critical as treatment failure occurs in up to 19% of cases 2

MRSA Conjunctivitis

• MRSA has been isolated with increasing frequency and may require compounded topical vancomycin, as MRSA is resistant to many commercially available topical antibiotics including aminoglycosides. 1, 4
• Microbiology laboratory testing should guide therapy 4

Contact Lens Wearers

• Higher risk for Pseudomonas infection; prescribe fluoroquinolones regardless of severity. 1, 4

Alternative Treatment Option

• Povidone-iodine 1.25% ophthalmic solution may be as effective as topical antibiotics and can be considered when access to antibiotics is limited. 1, 2

Follow-Up Protocol

• Advise patients to return in 3-4 days if no improvement is noted. 1, 4
• At follow-up, perform interval history, visual acuity measurement, and slit-lamp biomicroscopy 1, 4
• For gonococcal conjunctivitis, daily follow-up is mandatory until resolution 4, 2

Immediate Ophthalmology Referral Indications

Refer immediately for: 1, 4

• Visual loss or decreased visual acuity
• Moderate or severe pain
• Severe purulent discharge
• Corneal involvement (infiltrate, ulceration, opacity)
• Conjunctival scarring
• Lack of response to therapy after 3-4 days
• Recurrent episodes

Critical Pitfalls to Avoid

Antibiotic Resistance

• Bacterial resistance is a growing concern, particularly with MRSA infections and fluoroquinolone-resistant organisms. 1, 4
• Individual risk factors for fluoroquinolone resistance include recent fluoroquinolone use, hospitalization, advanced age, and recent ocular surgery 4
• Approximately 42% of staphylococcal isolates show methicillin resistance with high concurrent fluoroquinolone resistance 4

Inappropriate Corticosteroid Use

• Avoid topical corticosteroids unless under close ophthalmologic supervision, as they may prolong bacterial shedding and worsen infection. 4
• If severe inflammation requires corticosteroids, perform baseline and periodic intraocular pressure measurements 1

Misdiagnosis of Viral Conjunctivitis

• Avoid prescribing antibiotics for viral conjunctivitis, which accounts for unnecessary costs and promotes resistance. 1
• Viral conjunctivitis is the most common overall cause of infectious conjunctivitis and usually does not require treatment 6

Special Populations

• In children with gonococcal or chlamydial conjunctivitis, consider the possibility of sexual abuse. 1, 2
• For children with blepharitis where tetracyclines are contraindicated, use topical antibiotics like tobramycin 1