Background: The oral cavity is a reservoir for colonization and infection of systemic organs by pathogenic bacteria. It is understood that aging, tooth eruption, hormonal changes, active disease, oral hygiene, and other factors have an influence on biofilm formation and bacterial accumulation in the oral cavity. Objective: To understand the influence of systemic health care on microfloral changes, we conducted epidemiological studies of nursing home residents in an attempt to elucidate the relationship between underlying systemic diseases and the isolation frequency of oral opportunistic pathogens. Methods: The prevalence of bacteria and fungi causing pneumonia in association with oral biofilm bacteria were determined using detection culture plates. The influences of gender, age, denture-wearing status, number of teeth, and bedridden status in the patients residing in nursing homes were then analyzed. Results: The isolation frequency rates of Candida albicans, Pseudomonadaceae, Staphylococcus spp., and some strains of Enterobacteriaceae in plaque samples, as well as C. albicans and Xanthomonas maltophilia in samples from the pharynx, were significantly higher in those requiring systemic care (mean age 83.9 years) than in those who did not require such care (mean 71.0 years). In particular, the frequencies of Pseudomonas spp., C. albicans, and Serratia marcescens in plaque were significantly higher in those who were bedridden. Furthermore, the isolation of Pseudomonas spp. and Klebsiella pneumoniae, and/or C. albicans in plaque was significantly associated with heart disease. Conclusion: The coexistence of Pseudomonas spp. and C. albicans in elderly with 10–19 teeth is a potential indicator of high risk for pneumonia and heart disease. Therefore, attention to oral hygiene and professional care for removing the indicators may diminish the occurrence of systemic disease in the elderly requiring systemic care.

Based on the findings of this study and other numerous reports, cigarette smoking leads to deterioration of periodontal conditions in Japanese adults.

The effect of human plasma and saliva on co-aggregation between Bacteroides gingivalis and Streptococcus mitis was studied by means of a turbidimetric assay. The co-aggregation activity was obtained from the maximum slope of the absorbance vs. time curve. Its dependence on pH, temperature, and ionic strength was examined, and the number of Bacteroides cells in relation to the number of Streptococcus cells resulting in optimal co-aggregation was established. Co-aggregation inhibition experiments showed that the co-aggregation activity was inhibited by l-arginine and l-lysine, although the activity was unaffected by the sugars tested. Human plasma and saliva were able to inhibit the co-aggregation in a dose-dependent reaction. Plasma exhibited the most potent inhibitory activity in these fluids. Fibrinogen was the most potent inhibitor of the plasma-derived proteins tested. These data suggest the possibility that the oral fluids may modulate the attachment of B. gingivalis to Gram-positive bacteria in periodontal pockets.

Exohemagglutinin was found in the culture medium of Bacteroides gingivalis 381. Exohemagglutinin was purified 3,150-fold from culture fluid by ultracentrifugation followed by gel filtration on Sepharose CL-4B and by affinity chromatography on argmine-agarose. Examination of the final preparation of exohemagglutinin by biochemical analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the isolated

This study describes the effect of transferrin as an iron source on the growth of Porphyromonas (formally Bacteroides) gingivalis. Bacterial growth was monitored spectrophotometrically. All strains of P. gingivalis tested grew well in medium containing transferrin. The growth of P. gingivalis depended not only on the concentration of transferrin, but also on the iron saturation level of the protein. However, growth was not stimulated with either the ferrous or ferric iron salts tested. The addition of dipyridyl to the medium containing transferrin suppressed the growth of P. gingivalis, which also did not show species-specificity for human transferrin. Transferrin-binding activity was found in P. gingivalis by solid-phase assay with peroxidase-conjugated human transferrin. These results suggest that P. gingivalis may be capable of utilizing transferrin as an iron source for growth in vivo.