Does This Patient With Acute Infectious Conjunctivitis Have a Bacterial Infection?The Rational Clinical Examination Systematic Review

Question  Which clinical findings differentiate patients with viral conjunctivitis from those with bacterial conjunctivitis?

Findings  In this systemic review, the relative prevalence of bacterial conjunctivitis was higher than viral conjunctivitis in children, and the prevalence of viral conjunctivitis was higher than bacterial conjunctivitis in adults, but the underlying prevalence data were limited. Clinical findings associated with a higher likelihood of viral conjunctivitis included pharyngitis, preauricular lymphadenopathy, and contact with an individual with red eye; clinical findings associated with a higher likelihood of bacterial conjunctivitis included mucopurulent discharge and otitis media.

Meaning  Among patients presenting with ocular redness and discharge suggestive of infectious conjunctivitis, certain clinical findings may suggest viral vs bacterial conjunctivitis, although no single symptom or sign differentiated the 2 conditions with high certainty.

Importance  Acute infectious conjunctivitis is characterized by ocular redness and discharge, and is a common clinical entity. Evidence-based tools to aid the clinical diagnosis of viral vs bacterial conjunctivitis are lacking and may contribute to overprescribing of topical antibiotics.

Objective  To determine the relative prevalence of viral vs bacterial conjunctivitis in adults and children, and to determine which symptoms or signs are suggestive of a viral vs bacterial etiology.

Data Sources  A MEDLINE search (January 1946-March 2022) yielded 1891 articles. Included articles were rated using a quality score based on a modified Rational Clinical Examination grading system. Methodological quality levels 1 through 4 required a microbiological reference standard for diagnosis, whereas quality level 5 (the lowest quality) used a clinical reference standard for diagnosis.

Study Selection  Consecutive series of patients presenting with acute infectious conjunctivitis and case series of viral or bacterial conjunctivitis alone. Thirty-two studies were included in a meta-analysis to determine prevalence and diagnostic accuracy measures; 27 used a microbiological reference standard for diagnosis and 5 used a clinical reference standard for diagnosis.

Results  In studies involving children (5 studies; 881 patients; mean age, 4.7 years [age range, 1 month-18 years]), the prevalence of bacterial conjunctivitis was higher than viral conjunctivitis (71% vs 16%, respectively, P = .01). In the only study of adults (n = 207 patients; mean age, 25.7 years), the prevalence of viral conjunctivitis was higher than bacterial conjunctivitis (78% vs 16%, respectively, P < .001). For the primary analysis of level 1 (n = 6) and level 2 (n = 5) studies (1725 patients total), the clinical findings that best distinguished a viral etiology for conjunctivitis from a bacterial etiology included pharyngitis (sensitivity range, 0.55-0.58; specificity range, 0.89-0.94; positive likelihood ratio [LR] range, 5.4-9.9), preauricular lymphadenopathy (sensitivity range, 0.17-0.31; specificity range, 0.93-0.94; positive LR range, 2.5-5.6), and contact with another person with red eye (sensitivity, 0.18 [95% CI, 0.14-0.22]; specificity, 0.93 [95% CI, 0.90-0.95]; positive LR, 2.5 [95% CI, 1.6-3.7]). Mucopurulent ocular discharge (sensitivity, 0.76 [95% CI, 0.60-0.87); specificity, 0.66 [95% CI, 0.58-0.73]; positive LR, 2.1 [95% CI, 1.7-2.6]) and otitis media (sensitivity, 0.24 [95% CI, 0.20-0.29]; specificity, 0.91 [95% CI, 0.85-0.94]; positive LR, 2.5 [95% CI, 1.5-4.4]) were associated with the presence of bacterial conjunctivitis.

Conclusions and Relevance  In this review, bacterial conjunctivitis was more common than viral conjunctivitis in children and viral conjunctivitis was more common than bacterial conjunctivitis in adults, although the prevalence estimates were based on limited evidence. Symptoms and signs associated with a higher likelihood of viral conjunctivitis in adults and children included concomitant pharyngitis, an enlarged preauricular node, and contact with another person with red eye, and signs associated with a higher likelihood of bacterial conjunctivitis included the presence of mucopurulent discharge and otitis media, but no single symptom or sign differentiated the 2 conditions with high certainty.