Four Clinical Factors Linked to Low Risk for Bacterial Conjunctivitis

From Medscape Medical News
Laurie Barclay, MD

March 4, 2010 — A combination of 4 clinical factors may predict low risk for bacterial conjunctivitis and thereby reduce routine antibiotic drug administration, according to the results of a prospective observational cohort study reported in the March 3 issue of the Archives of Pediatrics & Adolescent Medicine.

"Bacterial resistance to antibiotic drugs is an ever-increasing problem, and there is a nationwide effort to find conditions for which antibiotic drug use can be restricted," write James A. Meltzer, MD, from Jacobi Medical Center and Albert Einstein College of Medicine in Bronx, New York, and colleagues.
"No guidelines exist to help clinicians differentiate bacterial from nonbacterial conjunctivitis with confidence. The objective of this study was to identify a population of children at low risk for bacterial conjunctivitis on the basis of history and physical examination findings."

At an urban pediatric emergency department, the investigators enrolled 368 children aged 6 months to 17 years with conjunctival erythema, eye discharge, or both.

Children with eye trauma, noxious chemical exposure, contact lens use, or antibiotic drug use in the previous 5 days were excluded. Median patient age was 3 years (interquartile range, 1 - 5 years); 52.7% were boys.

Clinicians collected a conjunctival swab for bacterial culture and completed a checklist of signs and symptoms.
Approximately one third (35.3%) of patients had negative results on conjunctival cultures.

The investigators developed a prediction model for a negative bacterial culture result using the χ2 test, Mann-Whitney test, and logistic regression.

The clinical factors found to be independently associated with a negative conjunctival culture result were
age 6 years or older,
presentation to the emergency department in April through November,
no or watery discharge,
and absence of a glued eye in the morning.

Culture result was negative in 92.3% of patients when all 4 factors were present (95% confidence interval [CI], 66.1% - 98.2%) and in 76.4% of patients when 3 of 4 factors were present (95% CI, 63.6% - 85.6%).

"The combination of 4 clinical factors may enable clinicians to identify children at low risk for bacterial conjunctivitis and may reduce routine antibiotic drug administration," the study authors write.
"Age 6 years and older, absence of a glued eye in the morning, no or watery discharge, and presentation in April through November were the variables found to be most associated with having a negative bacterial culture."

Limitations of this study include possible variations across time in technique of specimen collection, seasonal variation in causes of conjunctivitis in the northeastern United States, and failure to specify the exact duration of symptoms required to define acute conjunctivitis.

"The medical community is concerned about the excessive use of antibiotic drugs and the rapidly growing rate of bacterial resistance," the study authors conclude. "If these findings are validated in other populations, we may be able to limit routine antibiotic drug administration for children with acute conjunctivitis."

The study authors have disclosed no relevant financial relationships.

Arch Pediatr Adolesc Med. 2010;164:263-267. Abstract