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The Physician's Ability to Clinically Differentiate Between Bacterial and Viral Conjunctivitis is Poor Unless Additional Physical Findings of Otitis Media or Pharyngitis are Present


  • In children with conjunctivitis, are there clinical exam findings that allow us to distinguish between bacterial and viral conjunctivitis?

Clinical Bottom Lines

  1. Conjunctivitis is common in the pediatric population.
  2. Most common etiology: Haemophilus influenza, Adenovirus, and Strep pneumoniae.
  3. No study has been done specifically to analyze our ability as physicians to clinically distinguish bacterial vs. viral conjunctivitis.
  4. 'Gold Standard' diagnosis for etiology of infectious conjunctivitis - conjunctivae culture.
  5. Physical exam findings of concurrent otitis media increases the likelihood of conjunctivitis having bacterial (haemophilus influenzae) etiology (+ LR 2.78). However the relationship is not as strong as concurrent pharyngitis and adenovirus as cause (+ LR 9.9).1

Summary of Key Evidence

  1. In this prospective study two hundred one patients were involved.1 Ninety percent were enrolled from a private pediatric office. Ten percent were enrolled from a walk-in clinic in the same geographical area. Ninety-nine patients were clinically diagnosed with conjunctivitis based on conjunctival inflammation and 102 did not have conjunctival inflammation and were used as controls for the study. Patient with a history suggesting allergy, foreign body, trauma to the eye, or recently received antibiotics were excluded from the study.
  2. All patients had the inferior palpebral conjunctiva swabbed with two cotton swabs. Bacterial testing required minimum 2-3 days for culture results. Viral testing required 14 days for culture results.
  3. Three pathogens were isolated more frequently from patients clinically diagnosed with conjunctivitis. H. influenzae was obtained from 42% of those clinically diagnosed with conjunctivitis compared to zero obtained from the control group (p < 0.0001). S. pneumoniae was obtained from 12% of those clinically diagnosed with conjunctivitis compared to <3% obtained from the control group (p<0.03). Adenovirus was obtained from 20% of those clinically diagnosed with conjunctivitis compared to zero from the control group (p<0.0001). There was no statistical difference between patients and controls in regards to the following organisms that were obtained by culture: S. epidermidis, S. Aureus, alpha-hemolytic strep, Micrococcus sp., Corynebacterium sp, Moraxella.
  4. The results indicate that clinicians may best be able to distinguish between bacterial and viral conjunctivitis if concurrent otitis media or pharyngitis are present. With concurrent otitis media, the most likely etiology is H. influenza. With concurrent pharyngitis, the most likely etiology is adenovirus.
    Exam Findings
    (+) Likelihood Ratio
    (-) Likelihood Ratio
    Bilateral Disease
    Ocular Purulence
    Concurrent Otitis Media
    Concurrent Pharyngitis

Additional Comments

  • In a later paper by the same authors, at day 3-5 of treatment with antibiotics vs. no treatment, there was a statistically significant degree of clinical cure in those receiving antibiotic treatment.2 At 8-10 days of treatment there was no statistically significant degree of cure. Antibiotic used in this later study was polymyxin-bacitracin.
  • Cost of bacterial cultures as well as the time required to obtain results makes this method of determining etiology of conjunctivitis in the common pediatric population relatively unrealistic, especially in light of the low cost of antibiotics, relative few and rarely serious outcomes of treatment, and pressure from school and daycare facilities.


  1. Gigliotti F, Williams WT, Hayden FG, Hendley JO, Etiology of acute conjunctivitis in children. J Pediatrics. 1981; 98: 531-536.
  2. Gigliotti F, Hendley JO, Morgan J, Michaels R, Dickens M, Lohr, J. Efficacy of topical antibiotic therapy in acute conjunctivitis in children. J Pediatrics. 1984; 104: 623-6.
  3. Gigliotti F. Management of the child with conjunctivitis. Pediatric Infectious Disease Journal. 1994; 13(12) 1161-2.
  4. Reed DB. Viral and bacterial conjunctivitis. Prevention of disastrous results. Postgraduate Medicine. 1989; 86(4): 103-4, 107-9, 113-14.
  5. Rietveld RP, vanWeert HC, terReit G, Bendels PJ. Diagnostic impact of signs and symptoms in acute infectious conjunctivitis: systematic literature search. BMJ. 2003; 327(7418): 789.
  6. Stock EL. External eye disease. Postgraduate Medicine. 1985; 78(8): 102-4, 107, 110-11.
  7. Weiss, A. Acute conjunctivitis in childhood. Current Problems in Pediatrics. 1994; 24(1): 4-11.

CAT Author: Melissa L. McNier, MD

CAT Appraisers: John Frohna, MD

Date appraised: February 18, 2004

Last updated April 26, 2004
Department of Pediatrics and Communicable Diseases
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