No abstract

Spirochetes are thought to remain motile in environments (such as intercellular spaces) that immobilize extracellularly flagellated eubacteria. This attribute suggests that the viscosity of the milieu is of importance to locomotion. We sought to determine the interdependence of oral spirochete locomotion with media viscosity. Video time-lapse microscopy using darkfield optics was used. The motility of the spirochetes in media of different viscosities (various concentrations of Noble agar) was measured. Treponema denticola exhibited the fastest speed (18.7 +/- 4.4 microns/min) at a viscosity of 30 mPa.s. The highest speeds for Treponema vincentii and Treponema socranskii were 41.9 +/- 14.9 and 33.4 +/- 13.2 microns/min, respectively, at 88 mPa.s. These data show that optimal migration of spirochetes is viscosity-dependent. The results support the hypothesis that such viscosity-dependent locomotion could be a virulence factor that enables oral spirochetes to initiate and sustain periodontal disease.

Colony-forming units or cells in suspension of oral anaerobic spirochetes (Treponema denticola, Treponema vincentii and Treponema socranskii) bind hemin and Congo red. Hemin or Congo red binds to a hydrophobic polypeptide receptor that is located in the outer membrane of the bacterial cells and it has a relative molecular mass of 47 kDa. These oral spirochetes also lyse sheep erythrocytes to produce beta-hemolytic zones around colony-forming units. The oral spirochetes may acquire iron for growth when they lyse erythrocytes and bind heme from which they may sequester and transport iron into the cells.

Spirochetes are markedly prevalent in periodontal disease but are not included as predominant cultivable organisms because of the inability to quantify them by viable count. A successful method was developed for enumerating viable oral spirochetes as colony-forming units (CFU) in an agarose-based medium. Treponema denticola, Treponema vincentii and Treponema socranskii in log-phase growth in new oral spirochete (NOS) broth were used for evaluation of the method. Critical components of the method include enzyme-free low temperature-gelling (37 degrees C) agarose in NOS medium in small tissue-culture flasks into which the spirochetes were seeded and diluted. The flasks were anaerobically incubated in a glove-box. Reliable, consistent and reproducible viable counts of pure spirochete cultures were obtained. The injurious effects of spirochete temperature-sensitivity were averted by using molten agarose at 37 degrees C. Distinctive colony morphologies of spirochete species could be compared from pure cultures. Addition of rifampin into the medium showed no decrease in spirochete CFU count. The method as described allows for selection of mutants and detection of biochemical activity and is potentially useful for enumeration of spirochetes from periodontal pockets as members of the predominant cultivable flora.

Human immunodeficiency virus (hiv)‐associated gingivitis (HIV‐G) and HIVassociated periodontitis (HIV‐P) are two intraoral lesions manifested by patients with HIV infection. Periodontal indices were measured for 87 subjects in 5 study groups: HIV‐seropositive patients with healthy periodontium (HIV‐H), with HIV‐G, or with HIVP; and non‐HIV‐infected subjects with healthy periodontium (H) or with adult chronic periodontitis (P). The quantitative clinical parameters were compared and statistically significant intergroup differences were noted. The mean scores on PI and PD do not discriminate between HIV‐seropositive and non‐HIV‐infected seronegative cohorts, but a significant difference in the GI between HIV‐H and H was noted. When categories of PD and AL are examined, some differences become apparent. Generally, the PD and AL of HIV‐P are not as great as those of P. PI correlates well with GI (r = 0.86) in P, but does not (r = 0.33) in HIV‐P. In addition, the occurrence of selected putative periodontopathic bacteria (Porpfiyromonas gingivalis, spirochetes, and motile eubacteria) in these lesions was determined by brightfield (after staining), darkfield and immunofluorescent microscopy. No difference in microbiological profile in the bacterial groups monitored was found between P and HIV‐P. Spirochetes were found to be more abundant than P. gingivalis in the lesions of P and HIV‐P. In marked contrast, P. gingivalis was found to be in highest numbers in samples from the gingival crevice of H as determined by indirect immunofluorescence. J Periodontol 1991; 62:576–585.