Chlamydia trachomatis is the most common, curable bacterial sexually transmitted disease in the UK affecting 3 - 6% of sexually active women in Scotland. Infection is often asymptomatic, and pregnant mothers are not routinely screened. Overall transmission rate at delivery is around 25%, ranging from 67% for vaginal delivery to less than 10% for infants born by caesarean section. Apparently successful treatment of the mother during pregnancy does not preclude neonatal infection.
When a mother is known to be infected with chlamydia, management of the infant should be expectant. In a symptomatic infant it would be reasonable to commence empiric treatment pending the result of eye swabs or NP secretions.
Presentation
Chlamydial eye infection often presents unilaterally and becomes a bilateral conjunctivitis. This may initially be serosanguineous but later becomes mucoid or mucopurulent in appearance. It is commonly associated with eyelid swelling and marked conjunctival injection (Figure 2). Onset is usually around day 5-14 but may be as late as 60 days. 10-20% of infected neonates develop pneumonia and infants may have feeding difficulties at initial presentation as a consequence of this.

Figure Two: Infants with chlamydial eye infection
Investigation
Chlamydia is detected in conjunctival cells by NAAT. Cells should be obtained by firmly swabbing the everted lower eye lid using a virology swab which is then placed in VPSS transport medium. Samples should be sent to the virology laboratory at Glasgow Royal Infirmary. The laboratory will routinely test eye swabs for chlamydia, herpes simplex, adenovirus and varicella and results will generally be available in 48 hours.
Treatment
Systemic therapy is always required. Although topical therapy may be clinically effective for treatment of the eye infection, it does not eradicate nasopharyngeal carriage or prevent subsequent pneumonia. Systemic treatment is effective with eradication in 80-100% of cases.
First line: Oral erythromycin 12.5 mg/kg/dose, four times daily, 14 days
Second line treatment, oral azithromycin, 20mg/kg, once daily, for 3 days, may be considered if there are any substantive concerns regarding compliance.
There are limited data available on the use of other macrolides. Erythromycin has been associated with development of pyloric stenosis if used in infants under 6 weeks of age but is still the recommended treatment of choice. Parents should be advised of this risk and infants monitored closely following treatment.
Remember maternal screening and treatment will be required.
Complications
Symptoms may resolve spontaneously but infection in untreated or inadequately treated cases can persist for up to a year and may result in corneal scarring. Other systemic complications include pneumonitis, rhinitis and otitis.
Pneumonia
Chlamydial pneumonia presents as an afebrile respiratory illness with paroxysmal cough and wheeze. Symptoms can be very similar to viral bronchiolitis or whooping cough but infection may be atypical in preterm infants. Onset is usually between 2-12 weeks post delivery: antecedent conjunctivitis is not a prerequisite.
Investigations
Laboratory markers may show a marked eosinophilia and the CRP can remain normal.
Chest x-ray: hyperinflated with pulmonary infiltrates
NP or ET secretions should be collected in chlamydia transport medium. All NPAs sent in babies less than 1 month are routinely tested for chlamydia if all other virology is negative. Samples collected late in the day should be refrigerated overnight before being sent to the laboratory first thing in the morning. (NB. In the PRM, samples may be sent at any time via the pod system)
Treatment
Untreated the infection is self-limiting but it can last for several weeks even in term infants. Treatment shortens the duration of the illness. More severe disease can occur in premature infants and those with BPD. An association with reactive airway disease over 1st year of life is reported.
Erythromycin 12.5mg/kg/dose, four times daily, 14 days
Oral or I.V.
Failure rate is 20% and a second or third course of treatment may be required.