Katsuji Okuda

Prevalence of potential respiratory pathogens in the mouths of elderly patients and effects of professional oral care.

To evaluate the effectiveness of professional oral health care in reducing the risk of aspiration pneumonia, we examined the prevalence of potential respiratory pathogens in gargled samples from elderly persons. Samples were obtained from 54 elderly subjects over 65 years of age who required daily nursing care, from 21 healthy elderly subjects over 65 years old, and from 22 healthy young subjects under 30 as controls. The prevalence of possible pathogens was determined by culture and the polymerase chain reaction. The percentages detected in samples of Streptococcus pneumoniae, Staphylococcus species, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans from elderly patients requiring daily nursing care were 63.0, 37.0, 14.8, 5.6 and 66.7, respectively. The numbers of C. albicans cells recovered in samples from elderly subjects were significantly higher than those recovered from the healthy young group (P<0.001). Elderly patients needing daily care and receiving professional oral health care had lower prevalences and cell numbers of C. albicans than did the elderly patients without such oral care. This study showed that professional oral health care in elderly requiring daily nursing care reduced the cell numbers of potential respiratory pathogens.

Detection of Treponema denticola in Atherosclerotic Lesions

ABSTRACT We examined 26 atherosclerotic lesions and 14 nondiseased aorta specimens to detect the periodontopathogenic part of the bacterial 16S rRNA locus by PCR. Treponema denticola sequence of the 16S rRNA locus was found in 6 out of 26 DNA samples (23.1%) from the formalin-fixed, paraffin-embeded atherosclerotic lesions obtained during surgery but not in any of the 14 nondiseased aorta samples from deceased persons. Utilizing immunofluorescence microscopy, we observed aggregated antigenic particles reacting with rabbit antiserum againstT. denticola in thin sections of the PCR-positive samples, but we could not detect any reacting particles in the PCR-negative thin sections.

Involvement of Periodontopathic Anaerobes in Aspiration Pneumonia

Increasing evidence has linked the anaerobic bacteria forming periodontopathic biofilms with aspiration pneumonia in elderly persons. In experiments designed to eliminate the potent respiratory pathogens forming biofilms in the oral cavity, we have shown that the mechanical and chemical oral cleansing using povidone-iodine effectively reduced the detection rates and numbers of methicillin-sensitive Staphylococcus species, Streptococcus pneumoniae, and Haemophilus influenzae in patients scheduled to undergo oral surgery requiring endotracheal intubation. We confirmed the pathogenicity of periodontopathic anaerobic bacteria for aspiration pneumonia in an experimental mouse model. Based upon the finding of the coexistence of Porphyromonas gingivalis with Treponema denticola in chronic periodontitis lesions, we innoculated a mixed culture of P. gingivalis and T. denticola into the mouse trachea; the resulting infection induced inflammatory cytokine production and caused pneumonia. In another series of investigations, professional oral health care (POHC), mainly cleansing administered by dental hygienists once a week for 24 months to elderly persons requiring daily care, resulted in the reduction of the number of total anaerobes, Candida albicans, and Staphylococcus species and in the number of cases of fatal aspiration pneumonia. We also found that the POHC treatment of elderly persons for 6 months in the winter season reduced the salivary levels of protease, trypsin-like activity, and neuraminidase and also decreased the frequency of influenza cases.

Porphyromonas gulae sp. nov., an anaerobic, Gram-negative coccobacillus from the gingival sulcus of various animal hosts

A new species, Porphyromonas gulae sp. nov., is proposed to include strains isolated from the gingival sulcus of various animal hosts which are distinct from related strains of Porphyromonas gingivalis of human origin. This bacterium exhibits the following characteristics: black-pigmented colonies; asaccharolytic, obligate anaerobic growth; and Gram-negative, non-motile and non-spore-forming, rod-shaped cells. Colonies do not fluoresce under UV light. Vitamin K1 and haemin are required for growth. Cells haemagglutinate sheep erythrocytes. Major fatty acid end products are butyric acid, isovaleric acid, succinic acid and phenylacetic acid. Strains are catalase-positive and indole is produced. Alkaline phosphatase, trypsin-like and N-acetyl-beta-glucosaminidase activities are strong. A beta-galactosidase and a glutamylglutamic acid arylamidase are also present. The G+C content of the chromosomal DNA is 51 mol%. DNA-DNA homology data and 16S rRNA gene sequence analysis provide strong evidence that strains from the animal biotype of P. gingivalis represent a Porphyromonas species that is distinct from P. gingivalis. The type strain of P. gulae is Loup 1T (= ATCC 51700T = NCTC 13180T).

Prevalence of Cytolethal Distending Toxin Production in Periodontopathogenic Bacteria

ABSTRACT Cytolethal distending toxin (CDT) is a newly identified virulence factor produced by several pathogenic bacteria implicated in chronic infection. Seventy three strains of periodontopathogenic bacteria were examined for the production of CDT by a HeLa cell bioassay and for the presence of the cdt gene by PCR with degenerative oligonucleotide primers, which were designed based on various regions of the Escherichia coli and Campylobacter cdtB genes, which have been successfully used for the identification and cloning of cdtABC genes from Actinobacillus actinomycetemcomitans Y4 (M. Sugai et al., Infect. Immun. 66:5008-5019, 1998). CDT activity was found in culture supernatants of 40 of 45 tested A. actinomycetemcomintans strains, but the titer of the toxin varied considerably among these strains. PCR experiments indicated the presence of Y4-type cdt sequences in these strains, but the rest of A. actinomycetemcomitans were negative by PCR amplification and also by Southern blot analysis for the cdtABC gene. In the 40 CDT-positive strains, Southern hybridization with HindIII-digested genomic DNA revealed that there are at least 6 restriction fragment length polymorphism types. This suggests that the cdtABC flanking region is highly polymorphic, which may partly explain the variability of the CDT activity in the culture supernatants. The rest of tested strains of periodontopathogenic bacteria did not have detectable CDT production by the HeLa cell assay and for cdtB sequences by PCR analysis under our experimental conditions. These results strongly suggested that CDT is a unique toxin predominantly produced by A. actinomycetemcomitans among periodontopathogenic bacteria.

Arg-Gingipain A DNA Vaccine Induces Protective Immunity against Infection by Porphyromonas gingivalis in a Murine Model

ABSTRACT Arginine-specific cysteine proteinases (RgpA and RgpB) produced by the periodontal pathogen Porphyromonas gingivalis are suspected virulence factors and are involved in interrupting host defense mechanisms as well as in penetrating and destroying periodontal connective tissues. To induce a protective immune response againstP. gingivalis, we constructed an rgpA DNA vaccine. BALB/c mice were immunized intradermally by Gene Gun with plasmid DNA carrying rgpA. Antibody responses againstP. gingivalis were determined by an enzyme-linked immunosorbent assay. The rgpA DNA vaccine induced high levels of serum antibodies against P. gingivalis. Sera from the rgpA DNA vaccine-immunized mice diminished the proteolytic activity of RgpA and RgpB and inhibited the binding ofP. gingivalis to a type I collagen sponge. Moreover, the sera effectively reduced the hemagglutination of P. gingivalis, indicating that the hemagglutinin activity of the organism is associated with RgpA. We found with a murine abscess model that mice immunized with the rgpA DNA vaccine were resistant to an invasive P. gingivalis W50 challenge. These results suggest that the rgpA DNA vaccine induced specific antibodies against the enzyme and that this vaccine could confer protective immunity against P. gingivalis infection.

Helicobacter pylori May Have Only a Transient Presence in the Oral Cavity and on the Surface of Oral Cancer

We used the reverse transcription polymerase chain reaction (RT‐PCR) and culture methods to study the presence of Helicobacter pylori in the gastric and oral samples from a total of 116 gastritis and peptic ulcer patients, including 58 with oral cancer. Detection rates of H. pylori were 46.6% in stomach samples and 12.1 % in oral swab samples. All of the oral cancer surface swab samples were positive for H. pylori, as were their gastric samples suggesting that oral H. pylori derived from the stomach. The culture supernatants of Streptococcus mutans and Prevotella intermedia inhibited the growth of the H. pylori strain and caused the formation of the coccal form. In cases where H. pylori was detected in the oral cavity samples, including the oral cancer surface samples, it was believed that this species had colonized the stomach and were present in the oral cavity only as a transient organism.

Adherence of oral streptococci to an immobilized antimicrobial agent

An antimicrobial agent, 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride, was immobilized on silica. Interaction between the material (termed) OAIS) and various oral bacterial species were then studied. Seven species of Streptococcus and two Actinomyces were investigated for their ability to adhere to this biomaterial. Cell-surface hydrophobicity and zeta-potential were examined as well. Analysis of extracted hydrophobic proteins which adhered to OAIS revealed that the adherence of these micro-organisms was closely related to the hydrophobicity of their cell surfaces. The results of zeta-potential assays indicated that negative charge on the cell surface inhibited adherence to OAIS. Gel electrophoresis revealed that OAIS could absorb cell-surface hydrophobic proteins from all bacterial species tested. Preadsorption of hydrophobic components on the cell surface inhibited adherence of the Strep. mutans strain to OAIS in a dose-dependent manner. The results indicate that OAIS adsorption of these oral bacteria was dependent on the degree of hydrophobicity of their surfaces. A major component of this adherence was hydrophobic cell-surface proteins.

Inhibitory Effects of Funoran on the Adherence and Colonization of Mutans Streptococci

Funoran, a sulfated polysaccharide extracted from the seaweed Gloiopeltis furcata strongly inhibited the absorption of mutans streptococci to saliva-coated hydroxyapatite (S-HA), but enhanced that of Streptococcus sanguis ATCC 10556 and Streptococcus oralis ATCC 10557. Furthermore, funoran had a strong desorption activity against mutans streptococci preadsorbed to S-HA. In the presence of sucrose, the absorption of cells of Streptococcus sobrinus B13, Streptococcus mutans Ingbritt, and S. mutans MT8148R to S-HA was strongly inhibited by 0.01% funoran. The colonization of S. sobrinus 6715 inoculated on the molar teeth of experimental rats that were administered funoran was less frequent than that in a funoran-free group. The mean buccal and lingual, sulcal, and total caries scores of rat groups administered funoran were significantly lower than those of the funoran-free group.

Reduction of potential respiratory pathogens by oral hygienic treatment in patients undergoing endotracheal anesthesia.

AbstractPurpose. This study was conducted to evaluate the usefulness of mechanical and chemical prophylactic oral cleansing treatments for reducing potential respiratory pathogens existing in the oral cavity. Methods. Thirty-two patients scheduled to undergo oral and maxillofacial surgery that required endotracheal anesthesia were randomly allocated to one of the two groups, the oral cleansing group (n = 16) or the noncleansing group (n = 16). Culture and polymerase chain reaction (PCR) methods were used to detect and enumerate pathogens. Oral cleansing was carried out with an electric toothbrush capable of automatically supplying and aspirating povidone-iodine solution before surgery, followed by rinsing twice a day after surgery. Cephazolin (3 g·day−1) was given to all patients for 5 days after surgery. Results. The PCR detection rates of Streptococcus pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, and Porphyromonas gingivalis in gargle samples before treatment were 87.5%, 68.8%, 53.1%, and 40.6%, respectively. Oral cleansing reduced the detection rates and numbers of methicillin-sensitive Staphylococcus species, S. pneumoniae, and H. influenzae. In contrast, there was no significant reduction of methicillin-resistant Staphylococcus species, S. pneumoniae, H. influenzae, or P. aeruginosa in subjects who underwent systemic cephazolin administration without oral cleansing. Conclusion. The combination of mechanical and chemical oral cleansing resulted in a significant reduction of potential respiratory pathogens in the oral cavity.