Ophthalmic Specimen Collection
Jennifer A. Dunbar
A. Introduction
Neonatal conjunctivitis is considered an ocular emergency (1, 2). Conjunctivitis may be the presenting sign of coexisting life-threatening systemic infection. Signs include diffuse conjunctival injection with mucoid, purulent, or watery ophthalmic discharge, and eyelid edema and erythema. Both bacterial and viral pathogens cause corneal ulceration and opacity, which may lead to blindness. Neisseria gonorrhea, Klebsiella species, or Pseudomonas species may rapidly perforate the globe (3).
B. Indications
1. To obtain specimen for testing to determine the cause of conjunctivitis (Table 26.1)
a. The most common cause of neonatal conjunctivitis is chemical conjunctivitis, which presents in the first 24 hours of life as a reaction to prophylaxis and usually resolves within 48 hours.
b. Infectious neonatal conjunctivitis may be bacterial or viral, and it is often associated with exposure in the birth canal or through spontaneous rupture of membranes. The classic causes include Chlamydia, Streptococcus spp., Staphylococcus spp., Escherichia coli, Haemophilus spp., N. gonorrhea, and herpes simplex (4).
c. In addition to the classic causes of neonatal conjunctivitis above, methicillin-resistant Staphylococcus aureus, group B Streptococcus, and N. meningitides have been described in neonates (5, 6, 7).
d. Hospital-acquired conjunctivitis affects 6% to 18% of infants in neonatal intensive care units (NICUs) and may occur in epidemics (8, 9, 10, 11).
(1) The eye may be contaminated by respiratory secretions, or gastrointestinal flora, with coagulase-negative Staphylococcus, S. aureus, and Klebsiella sp. reported as the most common pathogens (6, 12).
(2) Hospitalized premature babies experience increased risk for infectious conjunctivitis due to gram-negative organisms, such as Klebsiella, E. coli, Serratia, and Haemophilus influenzae. This risk increases in neonates <1,500 g and 29 weeks’ gestational age (13).
C. Relative Contraindications
1. Corneal epithelial defect
a. If fluorescein staining of the cornea reveals an epithelial staining defect, then corneal ulceration or infectious keratitis may be present. This requires referral to an ophthalmologist.
D. Special Considerations for Ophthalmic Specimen Management
1. Conjunctival scrapings are the specimen of choice because many pathogens are intraepithelial (1).
2. The ocular specimen size is small; requiring special care for specimen handling.
3. Direct placement of the conjunctival scrapings on slides for staining and direct plating onto culture medium at the bedside will maximize the yield.
4. Communication with laboratory personnel regarding specimen handling improves culture results (16).
TABLE 26.1 Analysis of Conjunctival Scrapings | |||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||||||||||||||||||||||||||||||||||||||
E. Materials
1. Equipment for staining the cornea to rule out epithelial defect
a. Fluorescein dye or strips
b. Wood lamp or other blue light source
2. Equipment for obtaining specimen
a. Choose topical anesthetic:
(1) 0.5% preservative-free tetracaine in unit-dose containers (Alcon Laboratories, Fort Worth, Texas).
(2) 0.5% proparacaine hydrochloride ophthalmic solution (Akorn, Inc., Lake Forest, Illinois, USA).
(3) Historically some physicians chose to perform the procedure without anesthetic because topical ophthalmic anesthetics, both containing preservatives and preservative-free may inhibit bacterial growth in culture. However, this is quite painful for the infant. Some anesthetics minimally inhibit bacterial growth (17, 18).
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
