Neonatal conjunctivitis due to uncommon pathogen Streptococcus mitis/oralis: a case report

Neonatal conjunctivitis (NC), historically attributed to Neisseria gonorrhoeae, is now known to be caused by various pathogens, including Staphylococcus, Streptococcus, and Chlamydia trachomatis. Although viridans group streptococci are generally regarded as commensal organisms, they may cause opportunistic conjunctival infections. Here, we present a case of NC caused by Streptococcus mitis/oralis, a member of the Mitis group of viridans group streptococci. A 15-day-old female neonate presented with bilateral severe eyelid edema and moderate hemopurulent discharge that precluded anterior segment evaluation. Symptoms began at nine days of age with serous discharge, which gradually worsened. The severe presentation initially raised concern for orbital cellulitis. Upon hospital admission, a conjunctival swab was obtained, and treatment was initiated with topical moxifloxacin and fusidic acid, along with empirical intravenous penicillin and gentamicin. Eyelid edema and discharge improved significantly within 24-48 h. Culture results confirmed Streptococcus mitis/oralis, which was sensitive to the administered antibiotics. Complete clinical recovery was subsequently achieved without complications. This case highlights the diagnostic challenge of differentiating severe NC from orbital cellulitis and underscores the potential of S. mitis/oralis to cause significant ocular morbidity in neonates. The prompt and dramatic response to antibacterial treatment prevented long-term complications, and this case supports the hypothesis of postnatal transmission from the neonate's own nasopharyngeal flora or that of the caregiver rather than exclusive acquisition from the birth canal.