Levels of erythromycin in tear fluid and serum in infants with conjunctivitis

Area of Science:

• Ophthalmology
• Neonatal Medicine
• Pharmacology

Background:

• Purulent conjunctivitis is a common neonatal infection.
• Chlamydia trachomatis is a frequent causative agent of neonatal conjunctivitis.
• Erythromycin is a standard treatment, but its penetration into tear fluid requires investigation.

Purpose of the Study:

• To evaluate the efficacy of oral erythromycin ethylsuccinate in treating neonatal purulent conjunctivitis.
• To measure erythromycin concentrations in both serum and tear fluid of newborns receiving oral therapy.
• To compare tear fluid erythromycin levels with serum levels and the minimum inhibitory concentration (MIC) for Chlamydia trachomatis.

Main Methods:

• A cohort of 38 newborns with purulent conjunctivitis received oral erythromycin ethylsuccinate (25 mg/kg every 12 hours for 14 days).
• Serum and tear fluid samples were collected 1 and 12 hours after drug administration, 3-4 days into therapy.
• Erythromycin levels were quantified and compared between serum and tears, and against the in vitro MIC for Chlamydia trachomatis.

Main Results:

• Erythromycin concentrations in tear fluid were significantly higher than in serum at both 1 and 12 hours post-administration.
• Both serum and tear fluid erythromycin levels exceeded the MIC for Chlamydia trachomatis.
• The treatment regimen demonstrated effective drug penetration into the ocular tissues.

Conclusions:

• Oral erythromycin ethylsuccinate achieves therapeutic concentrations in the tear fluid of newborns treated for purulent conjunctivitis.
• The drug levels achieved support the use of oral erythromycin for treating Chlamydia trachomatis-related neonatal conjunctivitis.
• This study validates the effectiveness of systemic erythromycin in targeting ocular infections.