Treatment of Bacterial Conjunctivitis
For bacterial conjunctivitis, prescribe a 5-7 day course of broad-spectrum topical antibiotic applied 4 times daily, with fluoroquinolones (moxifloxacin or gatifloxacin) or aminoglycosides (tobramycin) as first-line options. 1
Initial Assessment and Diagnosis
- Bacterial conjunctivitis typically presents with purulent discharge, marked inflammation, and sometimes pain 1, 2
- Obtain conjunctival cultures and Gram staining only in moderate to severe cases with copious purulent discharge, or when gonococcal infection is suspected 1, 3
- Examine for swollen preauricular or submandibular lymph nodes, which indicate bacterial rather than viral etiology 2, 3
First-Line Antibiotic Selection
Fluoroquinolones are the preferred agents for moderate to severe bacterial conjunctivitis:
- Moxifloxacin or gatifloxacin provide excellent coverage against common pathogens including Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae 2, 4, 5
- Fourth-generation fluoroquinolones (moxifloxacin, gatifloxacin) have superior gram-positive coverage, including some methicillin-resistant S. aureus strains 4
- Gatifloxacin 0.5%: instill one drop every 2 hours while awake (up to 8 times) on Day 1, then one drop 2-4 times daily on Days 2-7 5
Aminoglycosides are effective alternatives:
- Tobramycin provides broad-spectrum coverage and is particularly useful for rotating antibiotic classes to prevent resistance 2, 3, 4
- Apply 4 times daily for 5-7 days 1, 4
For mild cases, choose the most convenient or least expensive option:
- Polymyxin B/trimethoprim is effective for uncomplicated bacterial conjunctivitis 1, 4
- Povidone-iodine 1.25% ophthalmic solution may be as effective as topical antibiotics when access is limited 1, 4
Special Situations Requiring Systemic Therapy
Gonococcal conjunctivitis requires immediate systemic antibiotics:
- Adults: Ceftriaxone 1 g IM single dose PLUS azithromycin 1 g orally single dose (to cover concurrent chlamydial infection) 1
- Add saline lavage to promote comfort and faster resolution 4
- Topical antibiotics alone are completely inadequate 1, 4
Chlamydial conjunctivitis requires systemic therapy:
- Adults: Azithromycin 1 g orally single dose OR doxycycline 100 mg orally twice daily for 7 days 1
- Infants: Erythromycin base or ethylsuccinate 50 mg/kg/day divided into 4 doses for 14 days 1, 4
- Topical therapy provides no additional benefit beyond systemic treatment 4
MRSA conjunctivitis may require compounded vancomycin:
- MRSA organisms are resistant to most commercially available topical antibiotics including fluoroquinolones and aminoglycosides 1, 4
- Microbiology testing should guide therapy when MRSA is suspected 1
Critical Follow-Up Instructions
- Instruct patients to return if no improvement occurs after 3-4 days of treatment 1, 2, 3, 4
- At follow-up, perform visual acuity measurement and slit-lamp biomicroscopy 3, 4
- For severe cases with corneal involvement or membranous conjunctivitis, schedule follow-up within 1 week 2
Important Pitfalls to Avoid
Do not use topical corticosteroids routinely:
- Corticosteroids may prolong bacterial shedding and worsen infection 2, 3
- Consider only for severe inflammation with marked chemosis or eyelid swelling, and only with close follow-up 2
Reserve fluoroquinolones appropriately:
- Use fluoroquinolones for moderate to severe cases or suspected resistant organisms, particularly in contact lens wearers at higher risk for Pseudomonas infection 4
- Overuse contributes to resistance development 4, 6, 7
Recognize when referral is mandatory:
- Visual loss, moderate or severe pain, or severe purulent discharge 3, 4
- Corneal involvement, conjunctival scarring, or lack of response to therapy 3, 4
- Neonatal conjunctivitis requires immediate consultation 3