title: Streptococcal pharyngitis: diagnosis by gram stain.
abstract: Group A beta-hemolytic streptococci were isolated from 49 (10.4%) of 472 patients with pharyngitis. Throat culture results, interpreted by five observers of varying experience, showed the mean sensitivity, specificity, and predictive value of a positive Gram-stained smear of pharyngeal secretions as 73%, 96%, and 71%. Assignment to a high-risk group by clinical algorithm gave sensitivity, specificity, and predictive value of only 45%, 83%, and 23%. The Gram-stained smear is the most accurate method of early diagnosis of streptococcal pharyngitis.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001431:Bacteriological Techniques; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D008875:Middle Aged; D010612:Pharyngitis / Q000175:diagnosis* / Q000382:microbiology; D013194:Staining and Labeling / Q000379:methods; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D013291:Streptococcus / Q000302:isolation & purification; D013297:Streptococcus pyogenes / Q000302:isolation & purification