Tjm. Vansteenbergen et al., COMPARISON OF 6 TYPING METHODS FOR ACTINOBACILLUS-ACTINOMYCETEMCOMITANS, Journal of clinical microbiology, 32(11), 1994, pp. 2769-2774
Actinobacillus actinomycetemcomitans is an important pathogen in the e
tiology of severe periodontitis. For epidemiological studies on the pr
evalence of certain pathogenic clones and transmission of this bacteri
um, adequate typing methods are necessary. The purpose of this study w
as to compare six different typing methods for A. actinomycetemcomitan
s. Five reference strains and 27 fresh clinical isolates from periodon
titis patients were used. Serotyping showed 12 serotype a strains, 13
type b strains, 6 type c strains, and 1 nontypeable strain. Biotyping
on the basis of the fermentation of mannose, mannitol, and xylose resu
lted in six biotypes. Antibiogram typing was evaluated by measuring th
e inhibition zones of seven antibiotics in agar diffusion tests. With
this method eight main types which could be further differentiated int
o 15 subtypes were found. Sodium dodecyl sulfate-polyacrylamide gel el
ectrophoresis patterns of outer membrane proteins were similar among a
ll isolates tested. Restriction endonuclease analysis (REA) of whole c
hromosomal DNA resulted in five main types. These five main types were
further differentiated into 24 subtypes on the basis of DNA fragment
differences in the high-molecular-weight region. Hybridization of DNA
fragments, with ribosomal DNA (ribotyping) resulted in 22 to 24 differ
ent types, depending on the restriction endonuclease used. Ribotype pa
tterns were easy to interpret and provided an univocal distinction bet
ween different strains compared with REA results. When applied to epid
emiologically related isolates, all methods were able to discriminate
two clonal types among five isolates from five children from one famil
y. We conclude that serotyping, biotyping, and outer membrane patterns
were reproducible but had a low discriminatory potential. REA and rib
otyping were reproducible and gave the highest number of distinct type
s. When the DNA typing methods were compared, all strains tested could
be distinguished. These findings confirm the heterogeneity found with
in the species A. actinomycetemcomitans.