Kari Ranta

Facultative gram-negative enteric rods in persistent periapical infections.

A bacteriological investigation has been made in two cases of persistent periapical infections. Neither of the two infections responded to root canal therapy including penicillin or penicillin and erythromycin. Samples were taken aseptically for bacteriological examination through and root canals. Chloroform-washed, sterile paper points were used for sampling. Cultivation was performed immediately at chairside on Kanamycin-Vancomycin laked blood agar (KVLB) and blood agar supplemented with menadione, cysteine and glucose for anaerobic incubation and chocolate agar for aerobic incubation. Enterobacter cloacae was only isolate in case 1; Klebsiella pneumoniae and enterococci were found in case 2. Obligately anaerobic bacteria were not found. The treatment was successful after antibiotic therapy based on susceptibility testing of the isolates. The route of infection by facultative enteric rods is discussed.

Mitsuokella dentalis sp. nov. from Dental Root Canals

On the basis of phenetic and chemotaxonomic criteria a new nonmotile anaerobic gram-negative rod-shaped bacterium from dental root canals is described. The new species has characteristics in common with species of the genus Bacteroides, but there are also many differences. According to a detailed biochemical analysis the new species is closer to the genus Mitsuokella than to Bacteroides. We propose a new species, Mitsuokella dentalis. The type strain of M. dentalis is strain DSM 3688.

Bacteriology of Odontogenic Apical Periodontitis and Effect of Penicillin Treatment

The microbiology and treatment of apical periodontitis was studied in 62 patients, followed-up for 1 year. The clinical treatment and the radiological technique were standardized. One third of the patients received no systemic antibiotics, one third received phenoxymethylpenicillin for 1 week, and one third for 3 months. On the average, 0-2 facultatively anaerobic and 4-6 anaerobic bacteria were isolated from periapical infections. The genera Bacteroides and Fusobacterium in addition to anaerobic gram-positive cocci were found most frequently. Minimum inhibitory concentrations of benzylpenicillin against 269 strains were tested. 12 strains were resistant at the concentration 2.4 micrograms/ml, including 4 strains of Fusobacterium sp. All patients were free of symptoms 1 month after the admission. Only 1 patient failed to show any progress in radiological healing. No differences between the groups in relation to penicillin therapy were found.

Biochemical and Structural Characterization of an Unusual Group of Gram-negative, Anaerobic Rods from Human Periapical Osteitis

The biochemical and chemotaxonomic properties of three previously undescribed strains from human dental root canal infections are presented. The strains were obligately anaerobic Gram-negative rods with fimbriae and a thick capsule-like structure. Carbohydrates were not fermented and agglutination tests were negative. The presence of alpha-galactosidase, alpha- and beta-glucosidase, beta-N-acetylglucosaminidase and beta-galactosidase was confirmed. The strains produced acetic and succinic acids as metabolic end products. They contained a peptidoglycan structure based upon meso-diaminopimelic acid (Al gamma) and lacked respiratory quinones. The cellular fatty acids were mainly straight-chain saturated and methyl-branched molecules. High interstrain DNA homology was observed and the DNA base compositions were between 56 and 59 mol % G + C. These three strains appear to comprise the nucleus of a new genus of anaerobic, Gram-negative rods from odontogenic infections.

Ultrastructure of Bacteroides capillus, B. buccae, B. pentosaceus, B. oris, B. oralis, B. veroralis, and Pentose Sugar-Fermenting Bacteroides sp. from Humans with Periapical Osteitis: Occurrence of External Proteinaceous Cell Wall Layer

We describe the comparative ultrastructures of bile-sensitive Bacteroides species which were isolated from oral cavities and ferment xylose and arabinose. Reference strains Bacteroides buccae ATCC 33574T(T = type strain), Bacteroides capillus ATCC 33690Tand ATCC 33691, and Bacteroides pentosaceus NP333Tand WPH61 and Bacteroides sp. strains ES42 and ES57 all had an extra surface layer (S-layer) outside the outer membrane. No S-layer was detected in Bacteroides oris ATCC 33573Tand ATCC 27518, Bacteroides oralis, Bacteroides veroralis, or Bacteroides sp. strains ES2759 and ES2834. The deoxyribonucleic acid guanine-plus-cytosine contents and both the malate dehydrogenase and glutamate dehydrogenase mobilities of the strains with an S-layer were identical. We suggest that the oral pentose-fermenting Bacteroides isolates with an S-layer may belong to the same species.

Demineralization of Dentin with EDTA in Organic Solvent: Immunofluorescence of Collagen in Osteogenesis Imperfecta and Normal Teeth

The immunofluorescence of dentin collagen(s) after demineralization with ethanolic trimethylammonium ethylenediaminetetra-acetic acid (EtOH-TMA-EDTA) was studied using normal deciduous teeth, and deciduous and permanent teeth from three patients with Osteogenesis imperfecta (OI). Sections of the demineralized teeth were immunostained with anti type I, III and IV collagen sera. Preservation of the antigenicity of the collagens after treatment with EtOH-TMA-EDTA was confirmed by staining of the soft tissue controls. Anti type I collagen sera stained the normal dentin matrix peritubularly only. In OI, a homogeneous fluorescence of the mantle dentin and the dentin zone surrounding the abnormal canal-like structures was observed. With anti type III collagen serum, the normal dentin matrix failed to stain. In OI, the staining pattern was a narrow halo surrounding the canal-like structures. Alteration in the collagen or the noncollagenous components of the dentin matrix may explain the staining reactions of the various collagens in OI.

Dental students' knowledge of AIDS and HIV infection in Helsinki, Finland, and in Dar es Salaam, Tanzania

The purpose of this investigation was to study the knowledge about HIV infection and AIDS among dental students in Helsinki, Finland, and in Dar es Salaam, Tanzania. All respondents knew that HIV is not transmitted via hand-shaking, drinking water, or breathing air. More than half of the students in both countries did not know that HIV can be transmitted via breast-feeding. A higher proportion of students in Dar es Salaam than in Helsinki believed that all HIV-positive persons will get AIDS. Tanzanians recognized the early symptoms of HIV infection better than the Finnish students. Many students in both countries did not mention bisexual men as belonging to the high-risk group. Most of the dental students in Dar es Salaam but only one in five in Helsinki believed that dentists belong to the at-risk group.