topical or oral erythromycin? - phthyriuspubis

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in neonatal eye infection
gonorrheal conjunctivitis
chlamydial conjuctivitis

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I think topical

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Neonatal conjunctivitis is purulent ocular drainage due to a chemical irritant or a pathogenic organism. Topical prevention is routine. Diagnosis is clinical and confirmed by laboratory testing. Treatment is with organism-specific antimicrobials.

Etiology

The major causes are, in decreasing order, chemical inflammation, bacterial infection, and viral infection (see also Conjunctival and Scleral Disorders: Conjunctivitis). Chemical conjunctivitis is generally secondary to the instillation of silver nitrate drops for ocular prophylaxis. Bacterial infection is acquired from infected mothers during passage through the birth canal. Chlamydial ophthalmia (caused by Chlamydia trachomatis) is the most common bacterial cause, occurring in 2 to 4% of births; it accounts for about 30 to 50% of conjunctivitis in neonates < 4 wk of age. The prevalence of maternal chlamydial infection ranges from 2 to 20%. About 30 to 50% of neonates born to acutely infected women develop conjunctivitis (and 5 to 20% develop pneumonia). Other bacteria, including Streptococcus pneumoniae and nontypeable Haemophilus influenzae, account for another 15% of cases. The incidence of gonorrheal ophthalmia (conjunctivitis due to Neisseria gonorrhoeae) in the US is 2 to 3/10,000 births. Isolation of bacteria other than H. influenzae, S. pneumoniae, and N. gonorrhoeae, including Staphylococcus aureus, usually represents colonization rather than infection. The major viral cause is herpes simplex virus (HSV) types 1 and 2 (herpetic keratoconjunctivitis).

Symptoms and Signs

Because they overlap in both presentation 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 silver nitrate usually appears within 6 to 8 h after instillation and disappears spontaneously within 48 to 96 h.

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.

Gonorrheal ophthalmia produces 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.

Herpetic keratoconjunctivitis can occur as an isolated infection or with disseminated or CNS infection. It can be mistaken for bacterial or chemical conjunctivitis, but the presence of dendritic keratitis is pathognomonic.

Diagnosis

Conjunctival material is Gram stained, cultured for gonorrhea (eg, on modified Thayer-Martin medium), and tested for chlamydia (eg, by direct immunofluorescence, enzyme-linked immunosorbent assay, nucleic acid amplification techniques”samples must contain cells). Conjunctival scrapings can also be examined with Giemsa stain; if blue intracytoplasmic inclusions are identified, chlamydial ophthalmia is confirmed. Viral culture is obtained only if viral infection is suspected by skin lesions or maternal infection.

Treatment

Neonates with conjunctivitis and maternal gonococcal infection or with gram-negative intracellular diplococci identified in conjunctival exudates should be treated with ceftriaxoneSome Trade Names
ROCEPHIN
Drug Information
before results of confirmatory tests.

In chlamydial ophthalmia, systemic therapy is the treatment of choice, because at least 1⁄2 of affected neonates also have nasopharyngeal infection and some develop chlamydial pneumonia. Erythromycin ethylsuccinate 12.5 mg/kg po q 6 h for 2 wk is recommended. Efficacy of this therapy is only 80%, so a 2nd treatment course may be needed.

A neonate with gonorrheal ophthalmia is hospitalized to observe for possible systemic gonococcal infection and given a single dose of ceftriaxoneSome Trade Names
ROCEPHIN
Drug Information
25 to 50 mg/kg IM to a maximum dose of 125 mg (some clinicians use 100 mg/kg). Frequent saline irrigation of the eye prevents secretions from adhering. Topical antimicrobial ointments alone are ineffective.

Conjunctivitis due to other bacteria usually responds to topical ointments containing polymyxin plus bacitracin, erythromycin, or tetracyclineSome Trade Names
ACHROMYCIN V
TETRACYN
TETREX
Drug Information
.

Herpetic keratoconjunctivitis should be treated (with an ophthalmologist's consultation) with systemic acyclovirSome Trade Names
ZOVIRAX
Drug Information
20 mg/kg q 8 h for 14 to 21 days and topical 1% trifluridine ophthalmic drops or ointment, vidarabine 3% ointment, or 0.1% iododeoxyuridine q 2 to 3 h, with a maximum of 9 doses/24 h. Systemic therapy is important, because dissemination to the CNS and other organs can occur.

Corticosteroid-containing ointments may seriously exacerbate eye infections due to C. trachomatis and HSV and should be avoided.

Prevention

Routine use of 1% silver nitrate drops, 0.5% erythromycin, or 1% tetracyclineSome Trade Names
ACHROMYCIN V
TETRACYN
TETREX
Drug Information
ophthalmic ointments or drops instilled into each eye after delivery effectively prevents gonorrheal ophthalmia. However, none of these agents prevents chlamydial ophthalmia; povidone iodine 2.5% drops may be effective against chlamydia and is effective against gonococci but is not available in the US.

Neonates of mothers with untreated gonorrhea should receive a single injection of ceftriaxoneSome Trade Names
ROCEPHIN
Drug Information
50 mg/kg IM or IV, up to 125 mg, and both mother and neonate should be screened for chlamydia infection.