Defect in small millipore filters disclosed by new technique for isolating oral treponemes

A Spirochaete is suggested as the causative agent of Akoya oyster disease by metagenomic analysis

Mass mortality that is acompanied by reddish browning of the soft tissues has been occurring in cultured pearl oyster, Pinctada fucata martensii. The disease is called Akoya oyster disease (AOD). Although spreading pattern of the disease and transmission experiments suggest that the disease is infectious, the causative agent has not yet been identified. We used shotgun and 16S rRNA-based metagenomic analysis to identify genes that are present specifically in affected oysters. The genes found only in diseased oysters were mostly bacterial origin, suggesting that the causative agent was a bacterial pathogen. This hypothesis was supported by the inhibition of AOD development in naïve oysters injected with the hemolymph of diseased animals followed immediately with penicillin bath-administration. Further analyses of the hemolymph and mantle specifically and universally detected genes of bacteria that belong to phylum Spirochaetes in diseased pearl oysters but not in healthy oysters. By in situ hybridization or immunostaining, a Brachyspira-like bacterium was observed in the smears of hemolymph from affected oysters, but not from healthy oysters. Phylogenetic analysis using 16S rRNA sequences showed that the presumptive causative bacterium was outside of but most closely related to family Brachyspiraceae. We propose ‘Candidatus Maribrachyspira akoyae’ gen. nov, sp nov., for this bacterium.

BIOCHEMICAL CHARACTERISTICS OF VIBRIO SPUTORUM AND RELATIONSHIP TO VIBRIO BUBULUS AND VIBRIO FETUS

Loesche, Walter J. (Forsyth Dental Center and Harvard School of Dental Medicine, Boston, Mass.), Ronald J. Gibbons, and Sigmund S. Socransky. Biochemical characteristics of Vibrio sputorum and relationship to Vibrio bubulus and Vibrio fetus. J. Bacteriol. 89:1109-1116. 1965.-Twenty-seven strains of Vibrio sputorum were isolated from human gingival debris. All strains reduced nitrate beyond nitrite, and all produced H(2)S. None produced catalase, indole, or acetylmethylcarbinol. Carbohydrates were not fermented, and acid end products or volatile neutral products could not be detected. Motility was observed infrequently, although 14-hr cultures usually had a few cells which displayed darting motility. Shadowed electron microscopic preparations demonstrated that most cells in a given culture were nonflagellated, although some cells with a single terminal or subterminal flagellum were always observed. V. sputorum was demonstrated not to be a strict anaerobe as previously described, but rather a microaerophile. Addition of nitrate to culture media markedly enhanced growth. V. sputorum was found to be closely related to the animal microaerophilic vibrios, V. bubulus and V. fetus. V. sputorum differed from V. fetus by being capable of anaerobic growth, producing H(2)S, and failing to produce catalase or to grow in 10% O(2). Antigens of V. sputorum cross-reacted in low titer with antisera to V. fetus serotypes I, II, III, and V. V. sputorum differed from V. bubulus by being inhibited by 3.5% NaCl and by qualitative differences in growth in the presence of 1% glycine and 10% O(2). These differences do not appear sufficient to recognize two distinct species, and it is proposed that both species be recognized as V. sputorum, which has priority. Strains unable to grow in 3.5% NaCl would be considered V. sputorum var. sputorum, whereas strains capable of growth in 3.5% NaCl would be V. sputorum var. bubulum.

Detection frequencies and the colony-forming unit recovery of oral treponemes by different cultivation methods

Selected media were compared for primary isolation and detection of oral treponemes from clinical samples. Forty-eight subgingival plaque samples from 45 patients suffering from periodontitis were anaerobically cultivated for 2 weeks at 37 degrees C. Of the 9 media studied, Medium 10 (M10), which was supplemented with 10% rabbit serum and incubated using the plate-in-bottle method, supported the highest colony-forming units of the anaerobes. The treponemal colonies were detected at least on one medium from 83% of the subgingival plaque samples. The new oral spirochete medium in an anaerobic chamber supported the highest detection frequency of the oral treponemes (64% of samples); however, M10 in the plate-in-bottle was found to produce the highest colony-forming unit recovery of the oral treponemes (median 3.6% of the total colony-forming units). This study suggests that M10 in the plate-in-bottle and new oral spirochete medium in the anaerobic chamber are essential in cultivating oral treponemes.

Improved detection of oral spirochetes with an anaerobic culture method

A method for routine culturing of oral spirochetes was studied in periodontitis patients and subjects with healthy gingivae. Subgingival plaque bacteria, including oral spirochetes were cultured anaerobically using the steel wool jar method, the glove-box procedure and the plate-in-bottle method. They were also observed directly with a phase-contrast microscope. The number of colonies of recovered spirochetes was significantly higher with the plate-in-bottle method when Medium 10 (M10) or M10 supplemented with 10% rumen fluid was used. In almost all cases, spirochetes were detected with this culture method. The ratios of spirochetes from patient samples, cultured by the plate-in-bottle method, and of other microorganisms, cultured in Eggerth-Gagnon (EG) medium by the steel wool jar method, were almost identical of those observed by phase-contrast microscopy. These results indicate that it can be just as possible to culture certain oral spirochetes as other anaerobic bacteria.

The role of spirochetes in periodontal disease

The spirochetal accumulation in subgingival plaque appears to be a function of the clinical severity of periodontal disease. It is not known how many different spirochetal species colonize the plaque, but based upon size alone, there are small, intermediate-sized, and large spirochetes. Four species of small spirochetes are cultivable, and of these, T. denticola has been shown to possess proteolytic and keratinolytic enzymes as well as factors or mechanisms which suppress lymphocyte blastogenesis and inhibit fibroblast and polymorphonuclear leukocyte (PMNL) function. All of these attributes could contribute to periodontal tissue insult. Yet independent of these potential virulence mechanisms, the overgrowth of spirochetes can be clinically useful if simply interpreted as indicating the result of tissue damage. In this case, the spirochetes would be indicators of disease and could be easily monitored by microscopic examination of plaque, or possibly by the measurement of benzoyl-DL-arginine-2-naphthylamide (BANA) hydrolytic activity in the plaque.

Inhibition of superoxide production in human polymorphonuclear leukocytes by oral treponemal factors

The inhibition of superoxide (O2-) production by human peripheral blood polymorphonuclear leukocytes (PMNs) in the presence of oral treponemes, their cellular components, and their culture supernatants was investigated. Superoxide production was inhibited 56% by a 25-microgram/ml phenol extract of a human clinical isolate. Inhibition by culture supernatants of both the clinical isolate and a reference strain was related to the bacterial phase of growth and viability, though inhibition also persisted in the decline phase. Inhibition of superoxide production was not evident when either opsonized or nonopsonized whole spirochetes were reacted with PMNs. The suppressive activity depended, therefore, on the treponemes either being disrupted or growing and releasing the inhibitory factor into the culture medium. These results suggest that oral treponemes possess factors which interfere with the activity of PMNs and thereby alter the inflammatory process in the diseased periodontal pocket.

Common antigens of Treponema denticola: chemical, physical, and serological characterization

A sodium deoxycholate-ethanol extractable antigen (DES-Ag) was obtained from four serotypes of Treponema denticola and characterized by chemical, physical, and serological procedures. The cross-reactivity of these antigens was demonstrated by indirect microhemagglutination, immunodiffusion, and immunoelectrophoresis with hyperimmune rabbit antiserum against each of the T. denticola serotypes. Antiserum against two nonoral treponemes, T. phagedenis biotype Reieter and T. pallidum Nichols strain, did not cross-react with the DES-Ag of T. denticola. Chemical analysis of the DES-Ag indicated that proteins (84%) and hexoses (12%) accounted for 96% of the total dry weight of the antigen. Trace amounts of N-acetylglucosamine (0.6%) were also detected. Fatty acids, including palmitic, oleic, and stearic, were identified by gas-liquid chromatography. Polyacrylamide gel electrophoresis of the DES-Ag of each serotype revealed the presence of two bands. The molecular weights of the bands were estimated to be 58,000 and 31,000 by comparing the electrophoretic mobility of the DES-Ag to that of five protein standards of known molecular weights. Although only a single precipitin line was observed by immunodiffusion when each antigen was reacted against its homologous antiserum, two precipitin lines were evident by immunoelectrophoresis. Antiserum against the DES-Ag of T. denticola was shown to agglutinate whole cells of the homologous serotype. Adsorption of this anti-DES-Ag serum with whole cells of T. denticola resulted in the elimination of precipitating antibodies to the DES-Ag by immunodiffusion. It is concluded that the DES-Ag is a component of the outer sheath of T. denticola.

Morphological and biochemical differentiation of three types of small oral spirochetes

THIRTY STRAINS OF HUMAN ORAL ANAEROBIC SPIROCHETES WERE ISOLATED IN THREE DIFFERENT MEDIA: veal heart infusion-ascitic fluid, Spirolate-Brain Heart Infusion-rabbit serum, and supplemented PPLO broth. The morphological and biochemical characteristics of the isolates permitted their differentiation into three distinct species: Treponema denticola, T. macrodentium, and T. oralis (proposed new species). These species could be differentiated as follows. Organisms of the T. denticola type had a "2-4-2" axial fibril relationship as determined by electron microscopy, required serum for growth, did not utilize glucose or lactate, and produced indole, ammonia, acetate, and lactate as end products. T. macrodentium had a "1-2-1" axial fibril relationship, did not require serum, utilized glucose but not lactate, did not produce indole or ammonia, and produced formate, acetate, lactate, and succinate as acid end products. T. oralis had a "1-2-1" axial fibril relationship, required serum for growth, utilized lactate but not glucose, produced indole but not ammonia, and produced propionate and acetate as acid end products.