Is Erythromycin (erythromycin) eye ointment effective for treating coliform infections of the eye?

Erythromycin Eye Ointment for Coliform Infections

Erythromycin eye ointment is not recommended as first-line therapy for coliform (gram-negative) ocular infections as fluoroquinolones are more effective against these pathogens. 1

Recommended Treatment Approach for Coliform Eye Infections

First-line Treatment Options

• Topical fluoroquinolones are recommended as first-line therapy for bacterial keratitis caused by gram-negative organisms like coliforms due to their broad-spectrum coverage 1
• Fourth-generation fluoroquinolones (moxifloxacin, gatifloxacin) provide excellent coverage against gram-negative pathogens while offering improved gram-positive coverage compared to earlier generations 1
• Fluoroquinolones have been shown to be as effective as combination fortified antibiotic therapy for bacterial keratitis in multiple clinical trials 1, 2

Alternative Treatment Options

• For severe infections or cases unresponsive to initial therapy, combination fortified-antibiotic therapy should be considered 1
• Aminoglycosides (gentamicin, tobramycin) provide good coverage against gram-negative bacteria including coliforms and may be used in combination with other agents 1, 3
• For multidrug-resistant Pseudomonas (a gram-negative organism), topical colistin 0.19% may be considered 1

Treatment Administration

• For severe or central corneal infections, aggressive dosing is required - loading doses every 5-15 minutes followed by hourly applications 2
• Frequency of reevaluation depends on severity - severe cases should be followed daily initially until clinical improvement is confirmed 1
• For lesions close to the limbus, consider additional use of systemic antibiotics 1

Efficacy Considerations

• A Cochrane review found no evidence of difference in corneal perforation rates between different classes of topical antibiotics 1
• Fluoroquinolones are associated with reduced eye discomfort compared to aminoglycoside-cephalosporin combinations 1
• Single-drug therapy using fluoroquinolones has been shown to be as effective as combination therapy utilizing fortified antibiotics 2

Important Caveats

• Resistance patterns should be considered - there has been increasing resistance to fluoroquinolones in some regions (e.g., P. aeruginosa resistance to moxifloxacin increased from 19% to 52% in southern India) 1
• Erythromycin, while effective for some gram-positive infections and commonly used in neonatal prophylaxis, has limited activity against gram-negative organisms like coliforms 4, 3
• Fortified antibiotics should be prepared by a compounding pharmacy that is a member of the Pharmacy Compounding Accreditation Board and designated by the FDA as a 503A and/or 503B facility 1
• Risk factors for fluoroquinolone resistance include recent fluoroquinolone use, hospitalization, advanced age, and recent ocular surgery 2

Monitoring and Follow-up

• Severe cases (deep stromal involvement or infiltrates larger than 2 mm with extensive suppuration) require daily follow-up initially 1
• Consider culture and sensitivity testing if the infection does not respond to initial therapy 5
• Topical corticosteroid therapy may be considered after initial control of infection to reduce inflammation and subsequent corneal scarring 1