title: Streptococcal pharyngitis. Comparison of latex agglutination and throat culture.
abstract: Despite its imperfections, the throat culture remains the "gold standard" against which all rapid streptococcal antigen detection tests are compared. Using triple throat swabs, the accuracy of a rapid latex agglutination (LA) test and back up throat culture was determined and compared with a simultaneously obtained additional throat culture in children with suspected streptococcal pharyngitis. Although there was a 95 percent concordancy between throat cultures, the sensitivity of the throat culture was only 87 percent. Despite the LA test's lower sensitivity (78 percent), in this clinical population with a relatively low prevalence of positive throat cultures (19 percent), the predictive value of a negative LA test was only slightly lower than that of the throat culture (94-95 percent vs. 97 percent). Backup throat cultures are commonly recommended for patients with initially negative LA test results, but 10 percent of the patients with group A beta-hemolytic streptococci-positive throat cultures would have been undetected using this approach.
mesh_terms: D000293:Adolescent; D001431:Bacteriological Techniques; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007841:Latex Fixation Tests; D010612:Pharyngitis / Q000175:diagnosis* / Q000382:microbiology; D010614:Pharynx / Q000382:microbiology*; D011237:Predictive Value of Tests; D013290:Streptococcal Infections / Q000175:diagnosis*; D013297:Streptococcus pyogenes / Q000302:isolation & purification