The agar dilution technique was used for determination of the antibiotic susceptibilities of 57 oral isolates and 2 nonoral isolates of Actinobacillus actinomycetemcomitans. Tetracycline, minocycline, and chloramphenicol inhibited more than 96% of the strains tested at a concentration of less than or equal to 2 micrograms/ml; 89% of the strains were inhibited by 2 micrograms of carbenicillin pe...

Actinobacillus actinomycetemcomitans from the human oral cavity was serologically characterized with rabbit antisera to the type strain NCTC 9710; a number of reference strains, including Y4, ATCC 29522, ATCC 29523, ATCC 29524, NCTC 9709; and our own isolates representative of each of 10 biotypes. Using immunoabsorbed antisera, we identified three distinct serotypes by immunodiffusion and indir...

Actinobacillus actinomycetemcomitans leukotoxin lysed human neutrophil cytoplasts. The reaction was associated with a rapid influx of extracellular calcium, a collapse in membrane potential, release of lactate dehydrogenase, and overt disintegration of the plasma membrane. These functional and structural alterations in the plasmalemma of neutrophil cytoplasts reinforce the hypothesis that A. ac...

A case of infective endocarditis in a 59-year-old female caused by Actinobacillus actinomycetemcomitans is reported. The organism was recovered from 9 blood cultures. Despite treatment with penicillin and gentamicin the illness led to destruction of the aortic valve.

A case of subacute bacterial endocarditis due to Actinobacillus actinomycetemcomitans followed dental extraction under penicillin cover. Isolation of the organism was only achieved by incubating blood cultures in a CO(2)-enriched atmosphere. The patient was successfully treated with streptomycin.

Three tetracyclines (tetracycline, doxycycline, and minocycline) were found to possess iron-chelating activity in a colorimetric siderophore assay. Determination of MICs indicated that the activity of doxycycline against the periodontopathogen Actinobacillus actinomycetemcomitans was only slightly influenced by the presence of an excess of iron that likely saturates the antibiotic. On the other...

The bacterium Actinobacillus actinomycetemcomitans has been implicated in the pathogenesis of juvenile periodontitis as the etiologic agent on the basis of several lines of circumstantial evidence. A matter of extensive debate is whether A. actinomycetemcomitans is an exogenous contagious pathogen or an opportunistic pathogen that resides in the normal oral microflora. Here we show evidence of ...

Bactericidal activity of human -defensin 3 (hBD-3) against Streptococcus mutans and Actinobacillus actinomycetemcomitans was inhibited in a dose-dependent manner by the presence of saliva and/or serum. Increasing the concentration of hBD-3 partially overcame this inhibition. A fast bactericidal effect was observed against both bacterial strains, suggesting a potential therapeutic use for hBD-3 ...

Purified Actinobacillus actinomycetemcomitans serotype b lipopolysaccharide (LPS) was found to be able to bind Fusobacterium nucleatum cells and to inhibit binding of F. nucleatum to A. actinomycetemcomitans serotype b. Sugar binding studies showed that the requirements for binding of A. actinomycetemcomitans serotype b LPS to the F. nucleatum lectin are the presence of a metal divalent ion, an...