Bacteriological characteristics of Histophilus ovis and its relationship to similar bacteria

Seventeen strains of Histophilus ovis were obtained from a variety of pathological conditions and geographical areas and were examined to determine the bacteriological characteristics of the organism. All were Gram-negative pleomorphic rods which only grew under micro-aerophilic conditions in media enriched with blood, serum or meat particles. All strains were catalase negative, indole positive and nitrate positive while most produced acid from glucose, fructose, galactose, mannose, xylose, mannitol and sorbitol. Eight strains were examined serologically and compared with two strains of Actinobacillus seminis. In agglutination and precipitation tests, all strains of H ovis appeared antigenically identical and showed antigenic relationships to A seminis. Results of complement fixation tests confirmed the close, if not identical, antigenic relationship of H ovis and A seminis. It is suggested that H ovis and A seminis are biochemical variants of the same organism.

Serology of oral Actinobacillus actinomycetemcomitans and serotype distribution in human periodontal disease

Actinobacillus actinomycetemcomitans from the human oral cavity was serologically characterized with rabbit antisera to the type strain NCTC 9710; a number of reference strains, including Y4, ATCC 29522, ATCC 29523, ATCC 29524, NCTC 9709; and our own isolates representative of each of 10 biotypes. Using immunoabsorbed antisera, we identified three distinct serotypes by immunodiffusion and indirect immunofluorescence. Serotype a was represented by ATCC 29523 and SUNYaB 75; serotype b was represented by ATCC 29522 and Y4; and serotype c was represented by NCTC 9710 and SUNYaB 67. Indirect immunofluorescence revealed no reaction between the three A. actinomycetemcomitans serotype-specific antisera and 62 strains representing 23 major oral bacterial species. Distinct from the serotype antigens were at least one A. actinomycetemcomitans species common antigen and an antigen shared with other Actinobacillus species, Haemophilus aphrophilus, and Haemophilus paraphrophilus. All serotype a A. actinomycetemcomitans strains failed to ferment xylose, whereas all serotype b organisms fermented xylose. Serotype c included xylose-positive as well as xylose-negative strains. A total of 301 isolates of A. actinomycetemcomitans from the oral cavity of 74 subjects were serologically categorized by indirect immunofluorescence with serotype-specific rabbit antisera. Each patient harbored only one serotype of A. actinomycetemcomitans. Fourteen healthy subjects, five diabetics, and seventeen adult periodontitis patients exhibited serotypes a and b in approximately equal frequency, whereas serotype c was found less frequently. In contrast, in 29 localized juvenile periodontitis patients, the incidence of serotype b was approximately two times higher than that of serotypes a or c, suggesting a particularly high periodontopathic potential of A. actinomycetemcomitans serotype b strains. In subjects infected with A. actinomycetemcomitans, serum antibodies were detected to the serotype antigens, indicating that these antigens may play a role in the pathogenesis of periodontal disease.

The periodontal microflora of juvenile diabetics. Culture, immunofluorescence, and serum antibody studies

These studies demonstrate a unique constellation of organisms populating the subgingival area in periodontitis lesions of patients with juvenile or insulin-dependent diabetes mellitus (IDDM). The cultivable microflora was predominated by Capnocytophaga and anaerobic vibrios in the patients studied. In some patients, Actinobacillus actinomycetemcomitans were also found. This distinguishes the subgingival flora of IDDM patients suffering from periodontitis from that of patients with localized juvenile periodontitis (LJP), and that of adult periodontitis patients. In LJP most patients harbor both A actinomycetemcomitans and Capnocytophaga subgingivally; and in periodontitis lesions from nondiabetic adults, black-pigmented Bacteroides such as B gingivalis or B melaninogenicus subspecies intermedius are often found. Antibiotic susceptibility patterns suggest that penicillin or tetracycline or its analogs such as minocycline may be effective against the predominant cultivable microflora in periodontal lesions of IDDM patients; however, individual patients may harbor flora with significant resistance to these antibiotics.

The reaction of ovine neutrophils to Histophilus ovis in relation to genital infection of rams

Histophilus ovis was shown to be phagocytized by neutrophils when the organisms enter the lumen of the reproductive tract of the ram. The phagocytosis and destruction of H. ovis by neutrophils was demonstrated in vitro by the viable count method and by electron microscopy. It was shown that immunoglobulins and complement had no influence on the phagocytosis and destruction of H. ovis. Phagocytosis and killing of H. ovis was accomplished equally well by neutrophils from immunized and non-immunized rams. Immunized rams showed a massive infiltration of neutrophils into the walls, epithelium and lumen of their ampullae when dead H. ovis were introduced into their lumen.

Morphological, biochemical, antigenic, and cytochemical relationships among Haemophilus somnus, Haemophilus agni, Haemophilus haemoglobinophilus, Histophilus ovis, and Actinobacillus seminis

Morphology, biochemical reactions, pigmentation, antigens, and cell envelope proteins were examined in 12 strains of Haemophilus somnus, Haemophilus agni, Histophilus ovis, and Actinobacillus seminis. All of the strains except A. seminis are related and are considered as a single Haemophilus-Histophilus (HH) group. In immunodiffusion tests, HH group bacteria had at least two antigens common to all members of the group, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that they have similar cell envelope protein profiles. A quantitatively variable yellow pigment with absorption maxima of 430 to 435 nm was present in strains of H. somnus and H. agni. The HH group did not produce catalase and grew only in air containing 10% CO2. Of 10 HH group bacteria, 9 required thiamine monophosphate for growth. A. seminis was distinguished from the HH group by its lack of yellow pigment, production of catalase, growth in air, lack of a thiamine monophosphate requirement, and different cell envelope protein profile. In gel immunodiffusion tests, A. seminis antigens produced two lines of partial identity with the HH group when antiserum against H. somnus was used. Reference strains of Haemophilus influenzae, Actinobacillus lignieresii, and Haemophilus haemoglobinophilus were compared with the test strains. In immunodiffusion tests, a single antigen was found to be common to H. haemoglobinophilus, A. seminis, and the HH group. No similarities between any of the test strains and H. influenzae or A. lignieresii were noted. The close relationship of H. somnus, H. agni, and Histophilus ovis suggests that these unofficially named bacteria may belong to a single taxon.

Studies of leukotoxin from Actinobacillus actinomycetemcomitans using the promyelocytic HL-60 cell line

The promyelocytic HL-60 cell line was examined for susceptibility to leukotoxin from Actinobacillus actinomycetemcomitans. Strains of A. actinomycetemcomitans which caused lysis of human peripheral blood polymorphonuclear leukocytes also lysed HL-60 cells as determined by release of intracellular lactate dehydrogenase. The killing of HL-60 cells by A. actinomycetemcomitans was dose dependent and temperature dependent, reached maximal levels after 45 min of incubation, and was inhibited by rabbit antisera to A. actinomycetemcomitans. Of 100 oral isolates of A. actinomycetemcomitans from 55 subjects, 16% from 11 healthy subjects, 43% from 13 adult periodontitis patients, 75% from 4 insulin-dependent diabetics, 66% from 2 generalized juvenile periodontitis patients, and 55% from 25 localized juvenile periodontitis patients produced leukotoxin. The same subject could harbor both leukotoxin-producing and -nonproducing isolates. The significantly higher proportion of leukotoxin-producing isolates in the disease groups compared with the healthy group is consistent with the hypothesis that leukotoxin from A. actinomycetemcomitans is an important virulence factor in the pathogenesis of certain forms of periodontal disease.

Regulatory effect of monocytes on T cell proliferative responses to oral microbial antigens

Mononuclear cell preparations isolated by Ficoll-Hypaque centrifugation from human peripheral blood were found to vary considerably in the number of monocytes they contained (mean, 20.3%; range, 13 to 33%). The regulatory role of monocytes in T cell proliferative responses to sonic extracts of a panel of oral microorganisms was therefore investigated. T cells were fractionated by anti-immunoglobulin chromatography and depleted of monocytes by treatment with a monoclonal anti-human Ia-like (DR locus antigen) antibody and complement. Purified populations of monocytes were obtained by extensive adherence procedures. The resultant cell populations were greater than 95% pure, as judged by indirect immunofluorescence on a fluorescence-activated cell sorter. Monocyte-depleted T cells failed to respond by proliferation to the nonoral antigen tetanus toxoid, as well as to any oral microorganism, but retained responsiveness to phytohemagglutinin. Readdition of monocytes in final concentrations of from 5 to 15% resulted in the restoration of maximal T cell proliferation. Monocytes in greater numbers suppressed T cell responses to all sonic extracts tested.

Bacteriology of severe periodontitis in young adult humans

A total of 78 bacteriological samples were taken from the supragingival tooth surface after superficial cleaning with toothpicks or from the periodontal sulci of 42 affected sites in 21 adolescents or young adults with severe generalized periodontitis. Of 190 bacterial species, subspecies, or serotypes detected among 2,723 isolates, 11 species exceeded 1% of the subgingival flora and were most closely associated with the diseased sulci. Eleven others were also sufficiently frequent to be suspect agents of tissue destruction. Many of these species are known pathogens of other body sites. In addition, 10 species of Treponema were isolated. One of these and the "large treponeme" were also more closely associated with severe periodontitis than they were with healthy sites or gingivitis. There were highly significant differences between the composition of the flora of the affected sulci and the flora of (i) the adjacent supragingival tooth surface, (ii) the gingival crevice of periodontally healthy people, and (iii) sites with a gingival index score of 0 or 2 in experimental gingivitis studies. The floras of different individuals were also significantly different. There was no statistically detectable effect of sampling per se upon the composition of the flora of subsequent samples from the same sites. The composition of the supragingival flora of the patients with severe generalized periodontitis that had serum antibody to Actinobacillus actinomycetemcomitans was significantly different from the supragingival flora of patients without this serum antibody. However, there was no statistically significant difference in the composition of their subgingival floras.

Study of agglutinins to Brucella abortus, B canis and Actinobacillus equuli in horses

Horses at a veterinary teaching hospital and a slaughterhouse were surveyed for antibodies to Brucella abortus, B canis and Actinobacillus equuli. Four of the 141 hospitalised horses and none of the 73 slaughtered horses had titres of 1:100 or greater to B abortus. Six horses of both populations reacted to the card test. One was culture positive. A card test using B canis antigen was positive in 38 per cent of the sera from hospitalised horses and all of the slaughtered horses. Twenty (27.4 per cent) of the latter group had high tires in a tube agglutination test. High titres could not be reduced by 2-mercaptoethanol serum treatment. The titres appeared to be associated with advanced age but not to sex. Adsorption of sera with B canis did not affect titres to A equuli but the reverse was true.

Relationship between attachment loss and precipitating serum antibody to Actinobacillus actinomycetemcomitans in adolescents and young adults having severe periodontal destruction

The purpose of this study was to determine if adolescents and young adults with severe periodontal disease had precipitating serum antibody reactive with Actinobacillus actinomycetemcomitans, and, if so, to correlate presence or absence of the precipitin with clinical patterns of periodontal destruction. Double diffusion in gel was used to detect precipitins. Test and known positive standard sera were run in different wells against a common well containing a minute of sonicates from two strains of A. actinomycetemcomitans (Y4 and N27). Periodontal loss of attachment was measured with a probe on four surfaces per tooth; missing and unerupted teeth were noted with the aid of radiographs. Precipitating antibody was seen in 77% of sera from 22 subjects with localized juvenile periodontitis, 40% of 35 young subjects with more generalized severe disease, and 2% of 44 periodontally healthy individuals. About 80% of the positive reactions were with strain Y4. Within the diseased groups, there were significantly fewer involved teeth in subjects with precipitating antibody (Ab+) than among those in whose sera precipitins were not seen (Ab-). Comparisons of the distribution and severity of involved teeth between Ab+ and Ab- subjects were consistent with an hypothesis that high levels of antibody specific for A. actinomycetemcomitans have a protective effect against periodontal destruction.

Human immune responses to oral micro-organisms. I. Association of localized juvenile periodontitis (LJP) with serum antibody responses to Actinobacillus actinomycetemcomitans

The association between periodontal disease in humans and serum and salivary antibody to Actinobacillus actinomycetemcomitans strain Y4 was determined. An Elisa was used to examine anti-Y4 antibody of the IgM, IgG, IgA and IgE isotypes in serum from 127 individuals and IgA in parotid saliva. Patients diagnosed as having localized juvenile periodontitis (n = 37) had significantly higher levels and frequency of serum IgG antibodies to Y4 than all other groups. Serum and salivary IgA and serum IgE antibody levels were significantly increased in patients with both localized and generalized types of juvenile periodontitis (n = 48) when compared to all other patient groups. Specificity studies suggested that the antigenic determinants that were differentiating the group responses were unique to the Y4 organism. These results indicate that serum antibodies to Y4 may reflect an infectious process with this micro-organism and that these responses may provide some diagnostic value in delineating different types of periodontal diseases.

Polyclonal B-cell activation induced by extracts of Gram-negative bacteria isolated from periodontally diseased sites

The objective of this research was to determine whether gram-negative bacteria frequently isolated from periodontally diseased sites contained polyclonal B-cell activators. Polyclonal B-cell activation, which results in nonspecific activation of multiple B-cell clones was analyzed by a hemolysis-in-gel assay designed to detect a broad range of antibody specificities. Extracts from numerous bacterial strains, including Bacteroides gingivalis, Bacteroides melaninogenicus subsp. melaninogenicus, B. melaninogenicus subsp. intermedius, Fusobacterium nucleatum, Selenomonas sputigena, Capnocytophaga ochracea, and Actinobacillus actinomycetemcomitans, were tested. Extracts of the above organisms were found to stimulate polyclonal antibody responses in cultures of normal human peripheral blood lymphocytes, although the magnitude of stimulation varied among the extracts. Optimal antibody-forming cell responses were found at stimulator doses between 5 and 1,000 micrograms/ml. We conclude that the resident gram-negative subgingival flora associated with periodontal lesions possesses potent polyclonal B-cell activators. These activators may contribute to disease pathogenesis by inducing B lymphocytes to produce antibody, osteolytic factors, or both and possibly other mediators of inflammation.

Serum neutralizing activity against Actinobacillus actinomycetemcomitans leukotoxin in juvenile periodontitis

A relatively high incidence of infection by Actinobacillus actionomycetemcomitans can be shown in subgingival plaque samples obtained from patients with juvenile periodontitis. These organisms possess a potent leukotoxin(s) which rapidly destroys isolated human polymorphonuclear leukocytes (PMNs) and monocytes. If such leukotoxins operate in vivo, they could deprive the gingival crevice area of an essential antibacterial defense mechanism. We have found that sera from juvenile periodontitis patients consistently (greater than 90%) contain antibodies which neutralize Actinobacillus actinomycetemcomitans leukotoxin(s). On the other hand, sera from normal individuals or patients with other types of periodontal disease usually amplified rather than inhibited the leukotoxic reaction. Many patients with juvenile periodontitis have demonstrable defects in PMN or monocyte chemotaxis and this may place them at risk to gingival infection by Actinobacillus actinomycetemcomitans. The immune response against these organisms could be a crucial determinant in the course of juvenile periodontitis. While this disease is relatively rare, it does cause immeasurable emotional, physical and economic hardship for patients and their families. The identification of Actinobacillus actinomycetemcomitans as a potential pathogen in this disorder may eventually lead to specific forms of therapy to prevent and eliminate infection by this organism in these patients.

Comparative antibody titers to Actinobacillus actinomycetemcomitans in juvenile periodontitis, chronic periodontitis and periodontally healthy subjects

Circulating antibody levels to four strains of Actinobacillus actinomycetemcomitans (Aa) were determined by means of an indirect immunofluorescent technique in three groups of 21 subjects each, including one with juvenile periodontitis (JP), one with chronic periodontitis (CP) and one free of periodontal disease (N). Mean levels of antibody to Aa were significantly elevated in the JP group as compared to the CP and N groups with respect to strains Y4, 29522 and 29524, but not strain 29523. Since strains Y4, 29522 and 29524 contain a leukotoxin that is missing from strain 29523, the results suggest that the leukotoxin could account for the difference in the immune response among the three groups of subjects. Varying the end-point considered to represent positive fluorescence did not significantly affect the results, although discrimination among the three groups appeared to be somewhat better at lower intensities of fluorescence. Because of wide variations in antibody titers recorded in individual subjects, elevated levels of antibody to certain strains of Aa may not be useful as a primary diagnostic test for JP, but may be of value in confirming an otherwise uncertain clinical diagnosis.

Diagnosing ovine epididymitis by immunofluorescence

Antisera against Actinobacillus seminis, Brucella ovis and Corynebacterium pseudotuberculosis were prepared in adult female goats. Specific immunofluorescence was observed in cultural smears of A seminis, B ovis and C pseudotuberculosis by the direct technique and in smears of A seminis also by the indirect technique. Individual organisms could be recognised. Specific fluorescence of A seminis was readily detected in semen. The results indicate that immunofluorescence may offer an effective method for rapidly and accurately diagnosing bacterial epididymitis in sheep, especially before epididymal lesions are palpable.

Serologic study of Pasteurella aerogenes sp n

The antigenic attributes of Pasteurella aerogenes sp n were serologically compared with species of the genera Actinobacillus and Pasteurella. Examination included the tube-agglutination and double-immunodiffusion techniques. The results indicated the possibility of serologically different strains of P aerogenes. Antisera prepared from strains of P aerogenes also reacted well with antigens prepared from Yersinia pseudotuberculosis (P pseudotuberculosis) and P pneumotropica.

Serological comparison between Histophilus ovis, Actinobacillus seminis and Brucella ovis

The serological relationships between 4 strains of Histophilus ovis, the neotype strain of Actinobacillus seminis and Brucella ovis were examined using a cross-absorption complement-fixation technique. It was found that the 4 strains of H. ovis were serologically homologous and that an incomplete relationship existed between these organisms and A. seminis. Anteriserums prepared against one strain of H. ovis and the strain of A. seminis gave a weak, apparently non-specific cross-reaction with Br. ovis antigen. The practical significance of these results is discussed.

Hydrolysis of urea in the gastrointestinal tract of "monoxenic" rats: effect of immunization with strains of ureolytic bacteria

Axenic rats, in whose feces urea is ordinarily excreted, were inoculated with ureolytic strains of Lactobacillus or Actinobacillus originally derived from the microflora of "holoxenic" rats. In these "monoxenic" animals, harboring one or another of the bacterial strains, fecal urea was hydrolyzed, with a more rapid onset of ureolysis in the case of Actinobacillus as compared with Lactobacillus. In vitro, a parallel difference between the two strains with regard to the onset of ureolysis was observed, hydrolysis beginning at the onset of growth in the case of Actinobacillus and only at the end of the exponential growth phase in the case of Lactobacillus. Extracellular urease activity was demonstrated in cultures of Lactobacillus, whereas none was found extracellularly with Actinobacillus. The pH optimum for the Lactobacillus urease in vitro was found to be 3.0, whereas the corresponding value for Actinobacillus was 6.0. In the two types of monoxenic rats, urea was consistently present in the small intestine and virtually absent from cecum and colon. Hydrolysis of urea in stomach was almost complete in rats bearing Lactobacillus but much less so in animals monoxenic with Actinobacillus, despite essentially equal numbers of organisms in that location. When rats carrying a monoflora of ureolytic Lactobacillus were immunized with either whole cells or soluble extract of the same organism, urea appeared in cecum and feces, indicating suppression of ureolytic activity. Immunization with an extract of nonureolytic Lactobacillus failed to produce such a result. Similar immunization techniques applied to animals monoassociated with ureolytic Actinobacillus did not alter ureolysis, and no appreciable quantity of urea appeared in feces. These studies demonstrate that it is indeed possible to inhibit the ureolytic activity of some bacteria in vivo by immunological means, but that the urease system of other organisms may not be as amenable to such manipulation.

Haemophilus somnus complex: antigenicity and specificity of fractions of Haemophilus somnus

Five Haemophilus somnus type 8025 preparations (whole cell, sonicate, crude polysaccharide, purified polysaccharide, and protein) were produced for studies of their antigenicity in rabbits. Bacterial agglutination and passive hemagglutination tests were used to assess the level of antibody produced in rabbits inoculated with the different antigenic preparations. Cross-reactions were seen between the antiserums against the H sumnus 8025 antigens and a variety of related and unrelated bovine pathogens. The strongest cross-reaction occurred between antiserums against H somnus 8025 whole cell and crude polysaccharide antigens and Haemophilus agni and Actinobacillus lignieresii cell suspensions.

Serological studies on Actinobacillus actinomycetem-comitans

One hundred strains of Actinobacillus actinomycetem-comitans were examined serologically by determining their agglutination reactions with six absorbed antisera. Twenty-four reaction patterns were found, and the results were reproducible. The agglutinating antigens were heat-stable. Precipitation reactions were also studied by means of the Ouchterlony agar-gel diffusion technique with Fuller and acetone extracts. The agglutination test was considered preferable for epidemiological and ecological investigations on A. actinomycetem-comitans.