Rapid identification of Actinobacillus actinomycetemcomitans based on analysis of 23S ribosomal RNA

Abstract

Actinobacillus actinomycetemcomitans is a key microorganism in the pathogenesis of several different forms of periodontal diseases. Identification of this bacterium from clinical specimens may often be complicated by the fact that the colony morphology on TSBV selective medium closely resembles that of Haemophilus aphrophilus and a key differentiating characteristic, catalase reaction, may be variable. Recent genetic studies have shown that the 23S ribosomal RNA molecule is split into two smaller forms in A. actinomycetemcomitans, but is intact in H. aphrophilus. Based on this finding, we describe a new, rapid method for identifying A. actinomycetemcomitans in which single colonies isolated from culture on TSBV agar in 5% CO2 in air are lysed, electrophoresed on 1.5% submarine agarose gels and visualized by staining with ethidium bromide. Using this assay, A. actinomycetemcomitans can be easily distinguished from morphologically similar colonies such as H. aphrophilus strains by differences in 23S rRNA within 2 h.

The distribution and transmission of Actinobacillus actinomycetemcomitans in families with localized juvenile periodontitis

“…Epidemiological studies of/), actinomycetemcomitans have suggested that the bacterium is primarily transmitted among family members in LJP families (Zambon etal. 1983, Okuda et al 1984, Preus & Olsen 1988, DiRienzo & Slots 1990, Alaluusua et al 1991. Preus et al 1993, Offenbacher et al 1985 and in families with general adult periodontitis (Petit e( al.…”

“…Subgingival bacterial plaque was obtained from all subjects by placing one paper point for 10 s into the mesial sulci/pockets of all teeth and if present, any additional sites with pockets of ^5 mm (Preus et al 1994). In edentulous patients sterile cotton swabs were gently brushed against the inner buccal mucosa and dorsum of the tongue.…”

Prevalence and distribution of bacteriophage φAa DNA in strains of Actinobacillus actinomycetemcomitans

“…All 42 test strains had been identified by colony morphology and catalase test on a selective medium. The preliminary identification was verified by fermentation of selected sugars as well as rapid rRNA assay [18], and the serotype of each strain determined by indirect immunofluorescence using serotype-specific antisera [19]. All 1 strains were grown at 37°C for 48 h in 100 ml of strength Brain Heart Infusion (BHI) broth containing 5 mg/1 hemin, 1 g/l sodium bicarbonate and 10 gg/ml vitamin K1, in an atmosphere of 5% CO 2 in air.…”

“…All 1 strains were grown at 37°C for 48 h in 100 ml of strength Brain Heart Infusion (BHI) broth containing 5 mg/1 hemin, 1 g/l sodium bicarbonate and 10 gg/ml vitamin K1, in an atmosphere of 5% CO 2 in air. The cells were pelleted and checked for purity [18], and chromosomal DNA was extracted from each of the A. actinomycetemcomitans strains as described previously Growth and purification of bacteriophage 4a Aa Bacteriophage d~Aa was grown in its indicator strain A. actinomycetemcomitans 29524, and purified using a modification of the procedure pre- were identified by comparing the electrophoretic pattern of the restriction fragments with that obtained from HindlII digestion of purified cbAa DNA. The phage 4)Aa HindlII fragment F was isolated from the agarose gel by electroelution and used in preparing the phage-specific probe.…”

Complete Genome Sequence of Aggregatibacter actinomycetemcomitans Strain IDH781

“…Despite the lack of a complete genomic sequence, IDH781, a rough strain, is commonly used as a model for pathogenesis and basic bacteriology studies (3–11). Rough strains of A. actinomycetemcomitans display the classic star-shaped colony morphology observed in clinical isolates from LAP patients, so they are more appropriate for the study of A. actinomycetemcomitans biology than those displaying a smooth colony phenotype (12, 13). …”