The major causes of neonatal conjunctivitis (in decreasing order) are
Viral infection (see also Overview of Conjunctivitis)
Infection is acquired from infected mothers during passage through the birth canal. Chlamydial ophthalmia (caused by Chlamydia trachomatis) is the most common bacterial cause; it accounts for up to 40% of conjunctivitis in neonates < 4 weeks of age. The prevalence of maternal chlamydial infection ranges from 2 to 20%. About 30 to 50% of neonates born to acutely infected women acquire infection, and 25 to 50% of those develop conjunctivitis (and 5 to 20% develop pneumonia). Other bacteria, including Streptococcus pneumoniae and nontypeable Haemophilus influenzae, account for another 30 to 50% of cases, whereas gonococcal ophthalmia (conjunctivitis due to Neisseria gonorrhoeae) accounts for < 1% of cases.
Chemical conjunctivitis is usually secondary to the instillation of topical therapy for ocular prophylaxis.
The major viral cause is herpes simplex virus types 1 and 2 (herpetic keratoconjunctivitis), but this virus causes < 1% of cases.
Because they overlap in both manifestation and onset, causes of neonatal conjunctivitis are difficult to distinguish clinically. Conjunctivae are injected, and discharge (watery or purulent) is present.
Chemical conjunctivitis secondary to topical prophylaxis usually appears within 6 to 8 hours after instillation and disappears spontaneously within 48 to 96 hours.
Chlamydial ophthalmia usually occurs 5 to 14 days after birth. It may range from mild conjunctivitis with minimal mucopurulent discharge to severe eyelid edema with copious drainage and pseudomembrane formation. Follicles are not present in the conjunctiva, as they are in older children and adults.
Gonococcal ophthalmia causes an acute purulent conjunctivitis that appears 2 to 5 days after birth or earlier with premature rupture of membranes. The neonate has severe eyelid edema followed by chemosis and a profuse purulent exudate that may be under pressure. If untreated, corneal ulcerations and blindness may occur.
Conjunctivitis caused by other bacteria has a variable onset, ranging from 4 days to several weeks after birth.
Herpetic keratoconjunctivitis can occur as an isolated infection or with disseminated or central nervous system infection. It can be mistaken for bacterial or chemical conjunctivitis, but the presence of dendritic keratitis is pathognomonic.
Conjunctival material is Gram stained, cultured for gonorrhea (eg, on modified Thayer-Martin medium) and other bacteria, and tested for chlamydia (eg, by culture, direct immunofluorescence, or enzyme-linked immunosorbent assay [samples must contain cells]). Conjunctival scrapings can also be examined with Giemsa stain; if blue intracytoplasmic inclusions are identified, chlamydial ophthalmia is confirmed. Nucleic acid amplification tests may provide equivalent or better sensitivity for the detection of chlamydia from conjunctival material compared to older methods.
Viral culture is done only if viral infection is suspected because of skin lesions or maternal infection.
Neonates with conjunctivitis and known maternal gonococcal infection or with gram-negative intracellular diplococci identified in conjunctival exudates should be treated with ceftriaxone or cefotaxime (see Table: Recommended Dosages of Selected Parenteral Antibiotics for Neonates) before results of confirmatory tests are available.
In chlamydial ophthalmia, systemic therapy is the treatment of choice, because at least half of affected neonates also have nasopharyngeal infection and some develop chlamydial pneumonia. Erythromycin ethylsuccinate 12.5 mg/kg orally every 6 hours for 2 weeks or azithromycin 20 mg/kg orally once a day for 3 days is recommended. Efficacy of this therapy is only 80%, so a 2nd treatment course may be needed. Because use of erythromycin in neonates is associated with the development of hypertrophic pyloric stenosis (HPS), all neonates treated with erythromycin should be monitored for symptoms and signs of HPS, and their parents should be counseled regarding the potential risks.
A neonate with gonococcal ophthalmia is hospitalized for evaluation of possible systemic gonococcal infection and given a single dose of ceftriaxone 25 to 50 mg/kg IM or IV to a maximum dose of 125 mg. Infants with hyperbilirubinemia or those receiving calcium-containing fluids should not receive ceftriaxone and may be given a single dose of cefotaxime 100 mg/kg IV or IM. Frequent saline irrigation of the eye prevents secretions from adhering. Topical antimicrobial ointments alone are ineffective and not needed when systemic therapy is provided.
Conjunctivitis due to other bacteria usually responds to topical ointments containing polymyxin plus bacitracin, erythromycin, or tetracycline.
Herpetic keratoconjunctivitis should be treated (with an ophthalmologist’s consultation) with systemic acyclovir 20 mg/kg every 8 hours for 14 to 21 days and topical 1% trifluridine ophthalmic drops or ointment, vidarabine 3% ointment, or 0.1% iododeoxyuridine every 2 to 3 hours, with a maximum of 9 doses/24 hours. Systemic therapy is important because dissemination to the central nervous system and other organs can occur.
Corticosteroid-containing ointments may seriously exacerbate eye infections due to C. trachomatis and herpes simplex virus and should be avoided.
Routine use of 1% silver nitrate drops, 0.5% erythromycin ointment, or 1% tetracycline ophthalmic ointment or drops instilled into each eye after delivery effectively prevents gonococcal ophthalmia. However, none of these agents prevents chlamydial ophthalmia; povidone iodine 2.5% drops may be effective against chlamydia and gonococci but is not available in the US. Silver nitrate and tetracycline ophthalmic ointments are also no longer available in the US.
Neonates of mothers with untreated gonorrhea should receive a single injection of ceftriaxone 25 to 50 mg/kg IM or IV, up to 125 mg (ceftriaxone should not be used in neonates with hyperbilirubinemia or those receiving calcium-containing fluids), and both mother and neonate should be screened for chlamydia infection, HIV, and syphilis.
C. trachomatis, S. pneumoniae, and nontypeable H. influenzae cause most bacterial conjunctivitis; N. gonorrhoeae is a rare cause.
Conjunctivae are injected, and discharge (watery or purulent) is present.
Test conjunctival material for pathogens (including gonorrhea and chlamydia) using culture, and sometimes nucleic acid amplification tests.
Give antibiotics active against the infecting organism; neonates with gonococcal infection should be hospitalized.
Give systemic therapy for chlamydial ophthalmia.
Chemical conjunctivitis can result from antimicrobial drops or silver nitrate given at birth to prevent bacterial conjunctivitis.