Wednesday, January 7, 2015

A 9-day-old baby presents to the emergency department with purulent conjunctivitis.

A 9-day-old baby presents to the emergency department with purulent conjunctivitis. Topical erythromycin  prophylaxis was given in the nursery. The most likely cause of this neonate’s conjunctivitis is:

a. Syphilis.
b. Neisseria gonorrhoeae.
c. Group B Streptococcus.
d. Herpes simplex virus.
e. Chlamydia trachomatis.

The answer is e. Neonatal conjunctivitis (ophthalmia neonatorum) occurs within the first month of life. Previously, the most common cause was chemical irritation from application of silver nitrate eyedrops as antimicrobial prophylaxis at birth, which is usually seen 1–2 days after birth. Presently, most hospitals use erythromycin ointment as the standard prophylaxis and as a result, the incidence of chemical conjunctivitis has gone down. However, erythromycin ointment does not prevent all gonococcal and other bacterial ocular infections and is not effective against C. trachomatis. Although N. gonorrhoeae is no longer a major cause of neonatal conjunctivitis in the United States, it should be presumed in infants who have purulent conjunctivitis until proven otherwise. Corneal perforation is a known complication. You should do a Gram stain of the eye discharge looking  for Gram–negative diplococci, as well as gonococcal and chlamydial cultures or nucleic acid amplication (PCR)
tests. Gonococcal conjunctivitis is commonly seen between 3 and 5 days after birth. By the end of first week of life and throughout the first month of life, C. trachomatis becomes the most frequent cause of conjunctivitis. Other important but less common bacterial causes are Haemophilus influenzae and Streptococcus pneumoniae.


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