Here’s another USMLE® Step 2 CK Question of the Day! Today’s case involves a 3-day-old male infant with a purulent discharge from the eyes and associated edema of the upper and lower eyelids. Can you figure it out?
A 3-day-old male infant is brought to the pediatric emergency department for evaluation of purulent discharge from both eyes for the past day. The patient was born at 40 weeks gestation via vaginal delivery at home. He has been breastfed exclusively. Vitals are within normal limits. Physical examination demonstrates bilateral conjunctival injection, purulent discharge from the eyes, and associated edema of the upper and lower eyelids. Which of the following medications is used to prevent this patient’s clinical condition?
A. Ophthalmic erythromycin
B. Intravenous acyclovir
C. Intravenous ganciclovir
D. Intravenous ceftriaxone
E. Ophthalmic levofloxacin
F. Oral erythromycin
The correct answer to today’s USMLE® Step 2 CK Question is…
A. Ophthalmic erythromycin
Before we get to the Main Explanation, let’s see why the answer wasn’t B, C, D, or E. Skip to the bottom if you want to see the correct answer right away!
Incorrect answer explanations
Today’s incorrect answers are…
B. Intravenous acyclovir
Incorrect: Intravenous acyclovir is an effective treatment for neonatal herpes simplex infection, which instead presents with excessive watery discharge from the eyes, eye pain, and conjunctival erythema. If untreated, patients can develop irreversible vision impairment or blindness.
C. Intravenous ganciclovir
Incorrect: Ganciclovir is an effective treatment for patients with cytomegalovirus (CMV)-induced retinitis. This neonates patient’s presentation, however, is more consistent with bacterial conjunctivitis.
D. Intravenous ceftriaxone
Incorrect: Intravenous ceftriaxone is an appropriate treatment for gonococcal conjunctivitis, but it would not have prevented the condition even if given initially at the time of delivery.
E. Ophthalmic levofloxacin
Incorrect: Ophthalmic levofloxacin is useful in patients presenting with bacterial conjunctivitis caused by Staphylococcus aureus or Haemophilus influenzae. It is not useful against N. gonorrhoeae, nor is it used prophylactically in the prevention of gonococcal conjunctivitis.
F. Oral erythromycin
Incorrect: Oral erythromycin is the preferred treatment for neonatal C. trachomatis infections, including both conjunctivitis and pneumonia. C. trachomatis typically presents 5-14 days after birth with mucopurulent discharge, as opposed to this neonate’s discharge, which is purulent. Additionally, oral erythromycin is not used for prophylaxis of gonococcal conjunctivitis.
Main Explanation
This neonate, recently born at home, is presenting with purulent eye discharge and bilateral eyelid swelling, consistent with gonococcal conjunctivitis. Ophthalmic erythromycin is routinely applied at birth to prevent the development of this condition.
Neonates are at higher risk of conjunctivitis due to decreased tear production, lack of IgA in tears, poor native immune function, and absence of lymphoid tissue in conjunctiva. Neonatal conjunctivitis, also called ophthalmia neonatorum, typically presents during the first four weeks of life and is usually acquired from the mother (as the patient passes through the birth canal) or following the application of chemical agents.
The age of the neonate is an important clue in determining the etiology of neonatal conjunctivitis:
- First 24 hrs of life: Chemical causes from prophylactic medications, such as silver nitrate drops (now rarely used because of the increased risk of chemical conjunctivitis) or erythromycin drops for gonococcal conjunctivitis
- 24 – 48 hrs of life: Bacterial causes are most likely (Neisseria gonorrhoeae is the most common cause in the time range, Staphylococcus aureus).
- 5 – 14 days of life: Chlamydia trachomatis
- 6 – 14 days of life: Herpes keratoconjunctivitis
Major Takeaway
Neonatal conjunctivitis can be differentiated based on the timeline of symptom onset; if neonates develop conjunctivitis within the first 5 days of birth, it is likely gonococcal conjunctivitis, whereas if it occurs within the first 5 to 14 days of life, it is likely Chlamydial conjunctivitis. Gonococcal conjunctivitis is preventable with the routine application of ophthalmic erythromycin at the time of birth.
References
Makker K, Nassar GN, Kaufman EJ. Neonatal Conjunctivitis. [Updated 2020 Jul 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441840/
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