Neonatal chlamydia infection is caused by Chlamydia trachomatis (CT), a microorganism from the Chlamydiaceae family that requires living cells for survival and replication. Among its four species, CT is the primary pathogen associated with neonatal infections. This disease is predominantly transmitted through sexual contact and is one of the most common sexually transmitted infections (STIs) in developed countries. In neonates, CT infection is typically acquired during delivery via exposure to the birth canal. Infants born via cesarean section have a low risk of infection, with cases often attributed to an ascending infection caused by premature rupture of membranes.
Clinical Manifestations
The most common presentations of neonatal CT infection include conjunctivitis and pneumonia; less common manifestations include otitis media, nasopharyngitis, and vaginitis in female infants.
Chlamydial Conjunctivitis
CT is the most frequent cause of conjunctivitis in the neonatal period. Approximately one-third of infants exposed to the pathogen develop the infection. The incubation period ranges from 5 to 14 days, occasionally extending to 19 days. Infants with premature rupture of membranes may exhibit conjunctivitis earlier. The condition initially presents as serous discharge, which quickly becomes purulent. Marked eyelid swelling, conjunctival hyperemia, and thickening can occur. Neonates lack lymphatic tissue, so typical follicular hyperplasia seen in trachoma is absent, though pseudomembrane formation may be observed. Lesions primarily affect the inferior fornix and lower eyelid conjunctiva. CT rarely involves the cornea. If left untreated, hyperemia gradually resolves, discharge diminishes, and recovery occurs over several weeks. Corneal pannus may appear but blindness is rare.
Chlamydial Pneumonia
Pneumonia typically results from conjunctival or nasopharyngeal colonization with CT that ascends to the lower respiratory tract. Onset is generally between 2 to 4 weeks of age. Early symptoms resemble an upper respiratory infection and often involve no fever or mild low-grade fever. Severe cases may present with paroxysmal coughing, tachypnea, or apnea, accompanied by crackles on lung auscultation. Without treatment, the illness may persist for weeks or months. Chest X-rays often reveal findings more severe than clinical symptoms, including hyperinflation of both lungs, bilateral diffuse interstitial and alveolar infiltrates, peribronchial inflammation, and scattered focal atelectasis. Radiographic changes can persist for weeks to months. Peripheral white blood cell counts are usually normal, but eosinophilia may be observed.
Diagnosis
Diagnosis is based on characteristic symptoms of conjunctivitis and pneumonia, supplemented by chest X-rays and laboratory investigations. The following methods are used to confirm the diagnosis:
- Giemsa or iodine staining of cytoplasmic inclusion bodies in conjunctival scrapings from the inferior fornix or lower eyelid.
- Isolation of CT through tissue culture of scrapings, deep tracheal secretions, or nasopharyngeal aspirates, which increases the likelihood of a positive result.
- Detection of CT antigens via direct fluorescent antibody (DFA) assays or enzyme immunoassays (EIA), which are highly sensitive and specific and useful for the rapid diagnosis of CT conjunctivitis.
- Detection of specific IgM antibodies via immunofluorescence with a titer ≥1:16. Since specific IgG antibodies can cross the placenta, a repeated measurement showing a fourfold or greater increase in IgG titers is needed for diagnostic confirmation.
Treatment
The treatment of neonatal chlamydial conjunctivitis and pneumonia typically involves erythromycin as the first-line therapy. The dosage is 20–50 mg/kg per day, divided into 3–4 oral doses, over a 14-day course. Azithromycin is also effective and is characterized by good absorption, intracellular penetration, and minimal side effects. The recommended dose is 10 mg/kg once daily for three consecutive days.
For chlamydial conjunctivitis, topical treatments such as 0.1% rifampicin eye drops or 10% sodium sulfacetamide eye drops, administered four times daily, can be used. Topical 0.5% erythromycin ointment, applied for two weeks, is also an option. However, these treatments do not eliminate nasopharyngeal colonization of CT, which means the risk of developing CT conjunctivitis or pneumonia remains.