Fifty strains of Rothia dentocariosa Georg and Brown were characterized morphologically, biochemically, and serologically. All strains had characteristics agreeing with previous morphological descriptions of this organism, although there was greater biochemical and serological strain variation than previously reported. Four biotypes were established on the basis of variability in reduction of nitrite, production of urease, hydrolysis of esculin, and formation of acid from lactose, mannitol, mannose, raffinose, rhamnose, salicin, and trehalose. Three serotypes and a group of fluorescent antibody-negative strains were identified on the basis of the fluorescent antibody technique. A relationship between the four biotypes and the three serotypes was established.The monospecific genus Rothia, with type species Rothia dentocariosa, was proposed by Georg and Brown (2) t o accommodate microorganisms previously designated as Actinomyces dentocariosus, Nocardia dentocariosus, and Nocardia salivae. Brown, Georg, and Waters (1) subsequently studied 50 isolates having the morphological and biochemical characteristics of Rothia. Hammond (3) showed that all of his strains of R . dentocariosa contained a soluble polysaccharide antigen (RPS), and the detection of this antigen by the fluorescent-antibody (FA) technique is useful in identifying this organism.Rothia is included in the family Actinomycetaceae because of its branching, filamentous morphology and its ability to septate into bacillary, diphtheroidal, or coccal cells, or a mixture of these; its colonial morphology, including spider microcolonies and mature colonies which may be heaped and rough or entirely smooth; and its cell wall composition. However, Rothia differs from the genera A ctinom y ces, A rachnia, Bifido bacterium, and Bacterionema in its aerobic tendencies, its production of catalase, its lack of growth stimulation by COZY and its production of lactose as the major end product from glucose fermentation.Among the organisms isolated from dental calculus in this laboratory were a number of filamentous, aerobic, gram-p ositive, catalasepositive strains resembling R o thia morphologically but possessing variant biochemical reactions and not reacting with antisera By comparing the morphological, biochemical, and serological characteristics of R othia with Rothia-like organisms, we hope t o clarify the uncertain status of the latter. MATERIALS AND METHODSBacterial strains. The sources and designations of the fifty strains used in this study are given in Table 1.All cultures were maintained by monthly transfer on trypiic soy agar (TSA) (Difco) slants. Prior to use, the cultures were transferred twice in tryptic soy broth (TSB) (Difco).Colonial morphology. TSB cultures were streaked onto two TSA plates and incubated aerobically and anaerobically at 37 C. The anaerobic plate was incubated in a Torbal jar containing N,:H,:CO, (80:20: 10). Microcolonies were observed after 18 and 24 h of incubation at a magnification of X l O O to X400. Mature colonies were observed a...

Bacillus subtilis, Neisseria subflava , and LYT coccus were found to undergo massive lysis after growth in media containing 0.01 to 10 mM NaF. When cells of these organisms were transferred from late-exponential-phase cultures to 0.02 M sodium phosphate buffer plus 0.1 M KCl, they underwent spontaneous autolysis. Cells grown in media with fluoride were more liable to autolysis, and walls isolated from them also showed enhanced autolytic sensitivity, even though added fluoride did not directly stimulate autolysins. Sporadic or partial lysis occurred in populations of Streptococcus sanguis and Streptococcus mutans BHT or LM-7 after growth in fluoridated media. Most bacteria that were tested did not undergo fluoride-induced lysis. However, cells of all test bacteria were found to have reduced amounts of peptidoglycan per unit of cell weight when grown in the presence of fluoride. Incorporation of labeled lysine or glucosamine into peptidoglycan (Park-Hancock residue) was stimulated, instead of inhibited, by fluoride. However, fluoride also stimulated the loss of radioactivity from Park-Hancock residues of cells that had previously incorporated labeled lysine or glucosamine. Thus, fluoride appeared to enhance peptidoglycan turnover, and this turnover reduced the peptidoglycan contents of all bacteria tested, but induced lysis in only those bacteria that normally have highly active autolytic systems.

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An extracellular polysaccharide identified as a levan has been isolated from Rothia dentocariosa, strain 477 serotype 2. The levan produced by strain 477 has been found to activate the complement cascade in the absence of specific antibodies. This activation was found to be cytotoxic for human gingival cells in tissue culture.

Pasteurella pneumotropica was isolated in essentially pure cultures from the bowels of hamsters with enteritis 7 days after parturition. Newly received hamsters showed presence of P. pneumotropica in their nasal cavities but not in their uteri, lungs, spleens, or bowels.