Evaluation of a new latex agglutination test for detection of streptolysin O antibodies.
Acute- and convalescent-phase serum specimens were collected from 50 patients with group A streptococcal pharyngitis. The anti-streptolysin O (ASO) titer for each serum specimen was determined by using both the standard neutralization assay and the latex agglutination (LA) test (Rheumagen ASO; Biokit Inc., New Britain, Conn.). When the ASO titers derived by the two methods were compared, the correlation coefficient was 0.93. When the ability of the LA test to demonstrate a significant ASO titer rise (greater than or equal to 2 dilutions) was compared with that of the standard neutralization assay, the LA test had a sensitivity of 91%, a specificity of 86%, a positive predictive value of 83%, and a negative predictive value of 92%. Triplicate LA test determinations were performed on a subset of 31 serum specimens, and for 29 (94%), the repeated ASO titers were all within 1 dilution of each other; the width of the 95% confidence interval for the triplicate measurements of each serum specimen was +/- 32.8 IU. We found the Rheumagen ASO to be a simple, rapid LA procedure for measuring ASO titers that produces results that are highly reproducible, show little lot-to-lot variability, and are comparable to the ASO titers obtained with the standard neutralization assay.
Gerber
M A
MA
Department of Pediatrics, University of Connecticut Health Center, Farmington 06032.
Caparas
L S
LS
Randolph
M F
MF
D000293:Adolescent; D000328:Adult; D000989:Antistreptolysin / Q000032:analysis*; D001426:Bacterial Proteins; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007841:Latex Fixation Tests; D009500:Neutralization Tests; D010612:Pharyngitis / Q000175:diagnosis*; D011237:Predictive Value of Tests; D013290:Streptococcal Infections / Q000175:diagnosis*; D013297:Streptococcus pyogenes; D013301:Streptolysins / Q000276:immunology*
D001426:Bacterial Proteins; D013301:Streptolysins; C025964:streptolysin O; D000989:Antistreptolysin