Minoru Murase

Evaluation of immunochromatography method for rapid detection of Shigatoxin

The Shigatoxin detection kit based on the immunochromatography system is commercially available. To obtain the identification result rapidly, we devised the improved method (ICG-Imp) replaced to an original method (ICG). Modification provided that Shigatoxins extracted directly from the strains grown on TSI medium without centrifugation. ICG-Imp was compared with ICG, RPLA and PCR. Comparing with RPLA, the sensitivity, specificity, and concordance rate of Shigatoxin 1 showed 77.5, 100 and 90.5%, respectively on ICG, 93.8, 100 and 97.4%, respectively on ICG-Imp, and 100, 99.1 and 99.5%, respectively on PCR. On the other hand, the patterns of Shigatoxin 2 showed 95.3, 100 and 96.3%, respectively on ICG, 100, 100, and 100%, respectively on ICG-Imp, and 100, 100 and 100%, respectively on PCR. The time required from TSI medium to the final result are 24 h, 30-60 min, 48 h, and 6 h, respectively by ICG, ICG-Imp, RPLA, and PCR. It seems that the ICG-Imp is recommended for the identification by means of the accuracy and rapidness.

[T-serotype distribution of group A hemolytic streptococci in a rapidly expanding residential area in Sanda City, Hyogo Prefecture, with reference to an outbreak of serotype T-28 in autumn, 1988].

In the fall of 1988, an outbreak of streptococcal infections was observed at 2 pediatric clinics in Sanda City, Hyogo prefecture. The 2 clinics were independent of each other; one (clinic A) was located in the down town area, in the older part of the city, where there is little population turn over, while the other (clinic B) was in a newly developed-fast growing residential district. The strains and the distribution of T-serotypes isolated at each location are as follows: clinic A; 58 strains (34.5% serotype T-4, 31.0% serotype T-12, 10.3% serotype T-1, and 23.3% serotype T-28), clinic B; 43 strains (48.8% serotype T-28, 23.3% serotype T-12, 11.6% serotype T-4 and 7.0% serotype T-1). According to the data from Kobe City infectious disease surveillance center, there were a total of 102 group A hemolytic streptococci strains isolated in 1988, the T-serotypes distribution of which was as follows: 47.0% serotype T-4, 15.7% serotype the T-12, 10.8% serotype T-1 and 9.8% serotype T-28. Serotype T-4 was dominant here, as it was in location A of Sanda City. The epidemic proportion of serotype T-28 found at location B is considered to be due to the fact that location B has very little social interaction with location A and other areas. No difference was observed among the different serotypes on the drug susceptibility test: all strains showed a sensitivity to ampicillin and penicillin G, but were resistant to tetracycline and chloramphenicol.