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REVIEW ARTICLE
NEONATAL CONJUNCTIVITIS – A REVIEW
ETIOLOGY
Ophthalmia neonatorum can be divided into aseptic and septic types.10 The aseptic type (chemical conjunctivitis) is generally secondary to the instillation of silver nitrate drops for ocular prophylaxis. Septic neonatal conjunctivitis is mainly caused by bacterial and viral infections. Chlamydia trachomatis and Neisseria gonorrhoea the two sexually transmitted agents are associated with systemic complications and severe visual loss if left untreated.19,20
Chlamydia trachomatis is the most common cause of ophthalmia neonatorum in the developed countries because of higher prevalence of Chlamydia as sexually transmitted disease. This is due to the fact that 60% to 80% of genital infections with Chlamydia in females are asymptomatic. Hence it is often labeled as “silent epidemic”.21 The Center for Disease Prevention and Control (CDC) estimates 3 million cases of chlamydial infections occur per year. It is more prevalent than gonococcal infection and approximately four to six times as common as herpes virus infection.22
Although gonococcus is the second commonest organism responsible for ophthalmia neonatorum, it is the most virulent infectious agent for neonatal conjunctivitis. It was previously the commonest cause of blindness within the first year of life, necessitating the use of prophylaxis at birth. Gonococcal ophthalmia neonatorum had been eradicated in the United States in the 1950’s. However, it has now resurfaced following the increasing incidence of adult gonococcal infections and the development of antimicrobial resistance.23
The other microbial causes of ophthalmia include Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Escherichia coli, Klebsiella sp and Pseudomonas aeruginosa.24,25
CLINICAL FEATURES
The genital serovars type D-K of Chlamydia trachomatis causes neonatal conjunctivitis. It has a later onset than gonococcal conjunctivitis. The incubation period is 5-14 days and the colonization of the eye after birth does not always result in infection. Almost 40% of the infected neonates develop watery conjunctivitis which becomes more copious and purulent later. Most of the cases are mild and self-limited, but occasionally may be severe with eyelid swelling, chemosis, papillary reaction, pseudo-membrane, peripheral pannus and corneal involvement. If left untreated, 10-20% of the cases will develop infantile pneumonia. Other extra ocular involvement of Chlamydia includes nasopharyngeal, rectal and vaginal colonization and other form of diseases such as infant pneumonia syndrome.26
Gonococcal conjunctivitis is more severe than chlamydialconjunctivitis. The incubation period is 2-5 days. However, it can occur earlier in cases of premature rupture of membranes. It is usually bilateral. The conjunctivitis is characterized by severe hyper-acute purulent discharge, eyelid edema and chemosis. Gonococci have the capacity to penetrate intact corneal epithelium, leading to corneal epithelial edema and corneal ulceration, which can progress to corneal perforation and endophthalmitis if unrecognized. Hence in all cases of neonatal conjunctivitis, the infant has to be screened for gonococcito prevent these serious consequences. Gonococcal infection of the newborn can also give rise to systemic complications like stomatitis, arthritis, rhinitis, septicemia and meningitis.27
Herpes simplex keratoconjunctivitis in an infant usually presents with generalized herpes infection. Vesicles around the eye and corneal involvement are also common.28 Chemical conjunctivitis usually occurs within 24 hours of instillation of silver nitrate solution and resolves spontaneously within a few days. It can present with lid swelling associated with redness of the eyes, rarely with lacrimal stenosis. Ophthalmia Neonatorum due to other microbial causes usually run a milder course without corneal and systemic involvement.
LABORATORY DIAGNOSIS
Ophthalmia neonatorum is essentially a clinical diagnosis made by observation of signs and symptoms. The clinical differentiation between various types of neonatal conjunctivitis can be difficult.29,30 Hence lab diagnosis is of paramount importance in establishing the correct diagnosis and initiating the best treatment. Conjunctival scrapings for Gram stain and Giemsa stain should be obtained from the palpebral conjunctiva of all the infants with neonatal conjunctivitis. The presence of intracellular gram negative diplococci (IGND) has a high sensitivity and specificity and predictive value.31 Blood agar, chocolate agar and/or Thayer-Martin media can be used to isolate Neisseria gonorrhoea and other bacteria.
Chlamydia trachomatis can be isolated by the presence of intracytoplasmic inclusion bodies in the Giemsa stain in 60-80% of all infants. Conjunctival swab, smeared on to a microscopic slide and stained with Chlamydia trachomatis specific fluorescent monoclonal antibody (direct immunofluorescence test) often shows the presence of an impressively large number of punctate, fluorescing chlamydial elementary bodies, resembling “star-spangled sky at night”.32 This antigen detection test is still considered the “gold standard” for the diagnosis of chlamydial infections.33 Polymerase chain reaction (PCR) analysis for diagnosing chlamydial conjunctivitis has an advantage of early diagnosis and higher specificity compared to McCoy cell culture.34 The other laboratory studies for diagnosing chlamydial infections include Micro immunofluorescence assay (MIF) for detection of Chlamydia trachomatis IgG and IgM antibodies and Elisa tests.
PROPHYLAXIS
Crédé introduced 2% silver nitrate as a prophylaxis treatment method for conjunctivitis in the newborns in Leipzig in 1881.35 The widespread use of silver nitrate prophylaxis was associated with a drastic decline in the incidence of gonococcal ophthalmia throughout Europe and the United States. However, silver nitrate is toxic and for many years has been recognised to be a common cause of chemical conjunctivitis.36 Currently, topical erythromycin and tetracycline are also used as alternatives for ocular prophylaxis.11 However, all these agents are considered effective only for gonococcal ophthalmia, and found to be ineffective as prophylactic treatment against chlamydial conjunctivitis.37 Bell et al38 found no significant difference in the efficacy of silver nitrate, topical erythromycin and no prophylaxis in preventing ophthalmia neonatorum. Instead of prophylaxis, the authors concluded that prenatal recognition and prompt treatment may prevent the development of the disease.
TREATMENT
Ophthalmia neonatorum is an ocular emergency so all infants with neonatal conjunctivitis should be admitted. Specific treatment modalities are available for different types of neonatal conjunctivitis and treatment should be based on clinical picture and laboratory diagnosis (Gram stain & Giemsa stain). It is important to treat the infants with systemic rather than topical drugs to prevent systemic dissemination of the organism. As the causative organism is sexually transmitted, it is vital to treat the mother and her sexual partner(s).
Current WHO guideline for the management of sexually transmitted infections recommends that all cases of ophthalmia neonatorum be treated for both N. gonorrhoea and C. trachomatis39). The co-infection rates are estimated to be around 2%.39
