RIBOTYPING SHOWS INTRAFAMILIAL SIMILARITY IN ACTINOBACILLUS-ACTINOMYCETEMCOMITANS ISOLATES

This study reports ribosomal RNA gene restriction patterns of 54 Actin obacillus actinomycetemcomitans isolates obtained from 9 families (12 children and 11 parents). The isolates represented serotypes a, b, c a nd d. The chromosomal DNA extracted from A. actinomycetemcomitans isol ates was digested with the restriction endonucleases EcoRI, BamHI, Hin dIII, ClaI and BglI. The DNA fragments were hybridized to the rrnB rib osomal RNA operon of the Escherichia coli chromosome. In 5 families, i solates belonging to the same family (mother and/or father and the chi ldren) had identical hybridization patterns when analyzed with all 5 e nzymes. In 3 families, each family member harbored only one ribotype o f A. actinomycetemcomitans, but at least one member harbored isolates that were of a different ribotype than the other members of the family . In one family, the mother harbored 2 ribotypes (and serotypes), one common with the daughter and one different. In conclusion, the study c onfirms the previous results that A. actinomycetemcomitans is transmit ted intrafamilially.