DIFFERENTIATION OF CLINICAL ISOLATES OF ACTINOBACILLUS-ACTINOMYCETEMCOMITANS USING AN INSERTION-SEQUENCE, ISAA1

We previously identified an IS200-like sequence (ISAa1) in the genome of Actinobacillus actinomycetemcomitans FDC Y4. One or more hybridizin g bands to the ISAa1 probe were detected in each of several reference strains, representing three of the serotypes (a through c) of A. actin omycetemcomitans. In this study, we examined whether a restriction fra gment-length polymorphism (RFLP) with ISAa1 as a probe could different iate clinical isolates. One or more hybridizing bands mere detected in each of the 27 strains examined, which could be divided into seven gr oups according to restriction fragment-length polymorphism pattern. Se veral strains were observed with identical restriction fragment-length polymorphism types but with different serotypes. Conversely, strains were also observed with differing restriction fragment-length polymorp hism types and identical serotypes.