Haemophili and related bacteria in the human oral cavity

A selective medium for Actinobacillus actinomycetemcomitans and the incidence of the organism in juvenile periodontitis

A selective medium, malachite green bacitracin agar, was developed for the isolation of Actinobacillus actinomycetemcomitans from subgingival plaque of periodontally diseased patients. The medium consisted of Trypticase soy agar 40 gm/liter, bacitracin 128 micrograms/ml, malachite green 8 micrograms/ml and 5% defibrinated sheep blood. The medium, when incubated in an atmosphere of air plus 10% CO2 for 5 days, permitted greater than 80% recovery of pure cultures of A. actinomycetemcomitans when compared with a nonselective medium. The most frequent contaminant in plaque samples from different clinical conditions was Haemophilus aphrophilus. Decomposition of H2O2 was useful in differentiating these two species. Clinical studies employing the malachite green bacitracin medium revealed a significant association between the presence of the organism, A. actinomycetemcomitans and juvenile periodontitis.

Saliva-induced aggregation of micro-organisms from skin, tooth surfaces, oral mucosa, and rectum

A total of 57 bacterial strains were isolated from tooth surfaces, oral mucosa, skin of the upper lip, and rectum of 3 persons. Identification of the strains indicated that each type of surface had a characteristic microflora. Aggregation of bacterial suspensions, induced by salivary agglutinins, was measured spectrophotometrically as the decrease in optical density (OD) by time. The aggregation curves for the oral strains followed a sigmoid pattern. The aggregation rates varied between individuals and strains. Most fecal strains showed an aggregation pattern which differed from that of the oral strains and was characterized by only a small, initial decrease in OD. The few strains, mainly Propionibacterium strains, collected from the skin of the upper lip did not aggregate. It appears from the data that several mechanisms are involved in the retention of bacteria to surfaces.

Morphology and ultrastructure of oral strains of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus

Selected human oral and nonoral strains of the genera Actinobacillus and Haemophilus were examined by transmission and scanning electron microscopy. The strains examined were morphologically identical to recognized Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, and Haemophilus paraphrophilus. By transmission electron microscopy, the cells were typically gram negative in morphology, with several strains possessing some extracellular ruthenium red-staining polymeric material. Numerous vesicular structures, morphologically identical to lipopolysaccharide vesicles, were seen to originate from and be continuous with the surface of the outer membrane. Large numbers of these vesicles were also found in the external environment. Scanning electron microscopic observations revealed that both actinobacilli and haemophili possessed surface projections and an amorphous surface material which connected and covered adjacent cells.

Actinobacillus actinomycetemcomitans in human periodontal disease: a cross-sectional microbiological investigation

Actinobacillus actinomycetemcomitans is a facultative gram-negative bacterium which has been associated with severe oral and nonoral infections. This study examined its occurrence in the oral cavities of 10 normal juveniles, 11 normal adults, 10 juvenile periodontitis patients, and 12 adult periodontitis patients. Four deep periodontal pockets and two normal periodontal sites were sampled in the diseased patients, and six normal periodontal sites were sampled in the healthy individuals. In all subjects samples were obtained from the cheek, tongue, and saliva. Samples from a total of 172 normal periodontal sites, 83 deep periodontal pockets, 42 cheek mucosae, 42 tongue dorsa, and 42 salivas were examined. Isolation was performed by using a medium for selective isolation of A. actinomycetemcomitans (Trypticase soy agar [BBL Microbiology Systems] supplemented with 10% serum and 75 mug of bacitracin per ml). The carrier rates were 20% for normal juveniles, 36% for normal adults, 50% for adult periodontitis patients, and 90% for juvenile periodontitis patients. A. actinomycetemcomitans was on average recovered in about fivefold-higher numbers from infected deep periodontal pockets than from infected normal subgingival areas. Samples of periodontal pockets generally contained 100-fold-more cells of A. actinomycetemcomitans than did samples of the cheek, tongue, and saliva. A. actinomycetemcomitans is commonly isolated from patients with juvenile periodontitis, often isolated from patients with adult periodontitis, and occasionally isolated from normal juveniles and adults. Its primary oral ecological niche appears to be dental plaque and periodontal pockets.

Cellular fatty acid composition of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus

Strains of Actinobacillus actinomycetemcomitans isolated from deep pockets of patients with juvenile periodontitis were analyzed for their content of cellular fatty acids. Oral Haemophilus strains, morphologically and biochemically similar to Haemophilus aphrophilus, were also examined for their content of cellular fatty acids. The extractable lipids of the actinobacilli represented approximately 10% of the cell dry weight, with the bound lipids representing 2 to 5%. The major fatty acids consisted of myristic (C14:0) and palmitic (C16:0) acids and a C16:1 acid, possibly palmitoleic acid, accounting for 21, 35, and 31% of the total extractable fatty acids, respectively. Haemophilus strains had a similar cellular fatty acid content.

Rapid biochemical characterization of Haemophilus species by using the micro-ID

Biotyping of Haemophilus influenzae into five type and H. parainfluenzae into three types based on indole production, ornithine decarboxylase, and urease has been reported (M. Kilian, Acta Pathol. Microbiol. Scand. Sect. B 82:835--842, 1976). A commercially available test system designed for the 4-h identification of Enterobacteriaceae. Micro-ID, proved efficacious for the rapid biotyping of these two Haemophilus species. The nitrate reductase, indole production, ornithine decarboxylase, urease, and o-nitrophenyl-beta-D-galactopyranoside hydrolysis tests in Micro-ID correlated over 99% with conventional methodology. By utilizing the indole and o-nitrophenyl-beta-D-galactopyranoside tests it was possible, with 261 of 272 (96.1%) isolates, to distinguish H. influenzae from H. parainfluenzae. Cerebrospinal fluid isolates were over 90% H. influenzae biotype I, and conjunctival isolates were approximately 70% biotype II. Type b H. influenzae were predominantly biotypes I and II; these type b isolates were also overwhelmingly indole producers. Although over 90% of biotypes I and II have been reported to produce beta-lactamase, this was not confirmed by the small number of beta-lactamase producers encountered here. The 4-h Micro-ID should prove a useful mechanism, amenable to the routine clinical laboratory, for the further exploration of the association of Haemophilus with the site of isolation, antigenicity, and antibiotic resistance.

A study of the bacteria associated with advancing periodontitis in man

Samples of apical plaque were taken by means of an anaerobic gas-flushed syringe from 21 sites in eight patients. The samples were anaerobically dispersed, diluted and plated and incubated in an atmosphere of 80% N2, 10% H2 and 10% CO2 for 7-21 days. All colonies on plates containing 20-50 isolates were picked, repeatedly restreaked, characterized and identified where possible by a probabilistic computer identification program. The sites were divided into four groups on the basis of clinical features. The significance of differences between bacterial populations in the groups was determined by the Kruskal Wallis and Mann-Whitney U tests, while the Spearman rank correlation coefficient was used to determine the rank correlation of clinical features of diseases and microbial species. The subgingival microbiota in advanced destructive sites was predominated by Gram-negative rods. The microbiota of two young adult patients with generalized extensive bone loss, extensive clinical inflammation and suppuration was dominated by Bacteroides asaccharolyticus and an organism with characteristics consistent with Actinobacillus actinomycetemcomitans. The predominant cultivable microbiota in two patients with extensive bone loss but minimal clinical inflammation was predominated by Bacteroides melaninogenicus ss intermedius and Eikenella corrodens in one patient and E. corrodens and a slow growing fusiform-shaped Bacteroides in a second patient. A third group of four patients demonstrated moderate levels of clinical inflammation and evidence of continued bone loss in the last year. Predominant organisms in this group were more heterogeneous and included B. asaccharolyticus, Fusobacterium nucleatum, the "fusiform" Bacteroides and anaerobic vibrios. Sites with minimal disease in the patients revealed higher proportions of Gram-positive organisms including Rothia dentocariosa, Actinomyces naeslundii and Actinomyces viscosus. A positive rank correlation could be detected between clinical inflammation including suppuration and B. asaccharolyticus and a negative rank correlation between inflammation and E. corrodens.

Initial colonization of teeth in monkeys as related to diet

The initial phases of plaque development on nonretentive tooth surfaces were studied bacteriologically in Macaca irus monkeys fed by stomach tube and provided with various oral supplements. Except for the oral implantation of Streptococcus mutans in some of the animals, the oral flora was not changed prior to the studies. Dental plaque was allowed to develop on initially cleaned tooth surfaces for 3 to 5 h. Plaque samples were collected and cultured on a number of selective and nonselective agar media, and several hundred isolates from each sample were isolated and identified. The numerically predominant organisms in initial plaque were S. mutans, Streptococcus sanguis, and Actinomyces viscosus. Additional organisms regularly found, but usually in smaller numbers, were Streptococcus mitior and a group of fastidious gram-negative rods including Haemophilus species, Eikenella corrodens, and Actinobacillus actinomycetem-comitans. The colonization of S. mutans was dependent on sucrose and occurred at the expense of S. sanguis. In these experiments S. mutans accounted for 25 to 65% of the primary plaque formers. All other species encountered colonized the teeth irrespective of the diet. It is postulated that the early sucrose-dependent establishment of S. mutans directly on the enamel pellicle plays a key role in the development of a cariogenic plaque.