Relationship between Antistreptolysin O Titer and Number of Colonies from Throat Swab Culture Plate in Group A Beta-hemolytic Streptococcal Carriers and Normal School Children

Cha, Sungho

Abstract

PURPOSE: To know the true carrier rate and the immunologic responses (antistreptolysin O :ASO) to beta-hemolytic streptococci which obtained from normal school children with or without carrying streptococci. And to study the clinical meaning of the number of organisms found in culture.
METHODS
One hundred ninty-eight first grade of elementary school children were included. I obtained throat swab culture from tonsil and tonsilar fossa with sterile cotton ball stick and plated on sheep blood agar dish, counted number of colonies of beta-hemolytic streptococci (BHS) after overnight incubation, examined ASO titer (Rantz-Randall method) simultaneously, and differentiated grouping of BHS with Streptex.
RESULTS
1) Of the 198 normal school children, 34 (17.2%) had cultured BHS. 16 (8.1%) were group A, 4 (2.0%) were group C, 2 (1.0%) were group G, and 12 (6.1%) were non-grouping BHS. 2) 14 (22.2%) out of 63 normal children without carrying BHS and 16 (47.1%) out of 34 with carrying BHS had come out above 250 units of ASO. 13 (59.1%) out of 22 group A,C,G streptococcal carriers had showed above 250 units of ASO. The true carrier rate of BHS were 18 (9.0%) out of 198 elementary school children. 3) When I had counted the number of colonies from 34 carrier of BHS, 1+ was 67.6% and 2+ was 17.6%. It was 85.2% of total children with carrier. 4) There were significant differences between the mean titer of logarithmic ASO obtained from group A BHS carrier and that of normal children without carrying BHS (P=0.001), and differences between that of group A and group B,C,G streptococci (P= 0.0005).
CONCLUSIONS
The ASO titer obtained from BHS carrier is higher than normal school children, which suggests the possibility of subclinical infection, the possibility of persistent habor of organism since past infection had contracted, and the possibility of replaced old organism in past infection with new organism. It should be performed follow-up study for identifying the persistence of immunologic response in accordance with or without culturing organism.