- Volume 19, Issue 1, 1985
Volume 19, Issue 1, 1985
- Short Article
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The Effect of Homogenising Tissues either Before or After Storage on the Isolation of Chlamydia Trachomatis
More LessSummaryTo determine whether freezing before homogenisation or the reverse procedure was the best way of achieving maximal recovery of chlamydiae from solid tissues, specimens from mice infected experimentally with Chlamydia trachomatis were used. For 10 of 12 mice, three-fold to over fifty-fold more chlamydiae were isolated from portions of spleens which were homogenised before freezing in liquid nitrogen than from those which were homogenised after being stored frozen. The value of homogenising small strips of infected genital tissue before freezing was less apparent. Nevertheless, if this was undertaken, the number of chlamydiae recovered from the tissues of four of 10 mice was three-fold to seven-fold more than if the tissues were homogenised after freezing.
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- Article
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Specificity of Antibodies for T Sites and F Sites of Streptolysin O
More LessSummaryAntistreptolysin antibody (ASO) inhibits haemolysis of erythrocytes coated with streptolysin O (SLO), but antistreptolysin activity may also be due to the presence in sera of peptide fragments of altered β lipoproteins. SLO-mediated haemolysis results from activity of a molecular site (the t site) distinct from that at which the SLO becomes attached to the cell (the f site), and both sites might be expected to function antigenically. Absorption studies with SLO-coated latex particles, and with SLO-coated erythrocytes in the cold, provide evidence for the existence of both classes of antibody. Results also suggest explanations for the frequent observation of false-negative and false-positive latex tests.
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Polyacrylamide Gel Electrophoresis (Page) of Whole-Cell Proteins of Cutaneous Propionibacterium Species
More LessSummaryPolyacrylamide gel electrophoresis (PAGE) was applied to the study of whole-cell proteins of cutaneous propionibacteria in an attempt to characterise possible protein patterns that may be typical for strains isolated from acne skin. Isolates were obtained from the faces of 33 individuals aged 7–16 years. Some of these subjects had apparently normal healthy skin, whereas others had acne vulgaris of varying severity. Twenty-five facial isolates of Propionibacterium acnes and eight of P. granulosum were studied. A further seven axillary strains of P. avidum were included for purely taxonomic interest. No particular protein pattern was characteristic of an isolate from acne skin; in fact the P. acnes strains from all sources appeared to be identical.
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Effect of Repeated High Dose Prophylaxis with Amoxycillin on the Resident Oral Flora of Adult Volunteers
More LessSummaryHealthy adult volunteers received either single or repeated 3-g doses of amoxycillin by mouth at weekly intervals on three occasions. The salivary flora of each volunteer was monitored before, during and up to 11 weeks after the final dose of antibiotic. Viable counts of anaerobic bacteria, streptococci and streptococci resistant to amoxycillin 2 mg/L and 40 mg/L were determined in samples of saliva. All 20 volunteers harboured low numbers of streptococci resistant to amoxycillin 2 mg/L (mean count = 6·57 × 103 cfu/ml of saliva) before administration of the antibiotic; much lower carriage rates (45%) were observed for bacteria resistant to amoxycillin 40 mg/L (mean count = 116 cfu/ml of saliva). Each dose of amoxycillin had a rapid but transient effect on the numbers of salivary bacteria. A placebo lacking the antibiotic had no effect. A single 3-g dose of amoxycillin had little or no effect on the numbers of resistant streptococci and, therefore, it was concluded that in patients at risk of infective endocarditis a second prophylactic dose would not be invalidated. The numbers of resistant streptococci increased significantly after the second and third doses of amoxycillin, and persisted for 4–7 weeks. Consequently, in at-risk patients requiring repeated dental procedures liable to produce bacteraemia, either alternative antibiotic regimens should be used each time or intervals of at least 4 weeks should be left between treatment sessions.
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Electronmicroscopy of the Surface of Pasteurella Haemolytica
More LessSummaryThe surfaces of Pasteurella haemolytica, biotype A, serotypes 1, 2, 6, 7 and 9 and of P. haemolytica, biotype T serotypes 3, 4, 10 and 15 were examined by transmission electronmicroscopy with ruthenium red staining and polycationic ferritin labelling, by scanning electronmicroscopy, and by light microscopy. Electronmicroscopy showed that the surface of strains of P. haemolytica biotype A was covered by irregular protrusions which were probably capsular material. The surface and general morphology of P. haemolytica biotype T were distinct from those of biotype A.
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Fimbrial and Non-Fimbrial Haemagglutinins in Enterobacter Aerogenes
More LessSummaryTen strains of Enterobacter aerogenes were examined for their ability to produce haemagglutinins and fimbriae. Nine strains formed a mannose-sensitive (MS) haemagglutinin associated with thin (4 nm) non-channelled fimbriae. These thin fimbriae of E. aerogenes were antigenically different from the thin fimbriae of other fimbriate strains of Enterobacter and Klebsiella and probably represent a new kind of fimbria not previously described in Enterobacteriaceae. Eight of these same nine strains also formed a non-fimbrial mannose-resistant, proteus-like (MR/P) haemagglutinin. The formation of thin fimbriae associated with MS haemagglutinin and of non-fimbrial MR/P haemagglutinin are properties not associated with other strains of Enterobacter and Klebsiella.
E. aerogenes strain NCIB11460 was unusual among the strains examined in this series in that it alone produced mannose-resistant, Klebsiella-like (MR/K) haemagglutinin and type-3 fimbriae which, as judged by immunoelectronmicroscopy, were antigenically like those of type-3 fimbriate Klebsiella strains. The identifying characters of this exceptional strain of E. aerogenes are discussed in detail.
All ten strains also produced thick fimbriae which by immunoelectronmiscroscopy behaved like the type-1 fimbriae of Klebsiella strains. However, correlation between their presence and the production of MS haemagglutinin in E. aerogenes was not established. The findings are discussed in the light of the present difficult taxonomic status of E. aerogenes within the tribe Klebsielleae.
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PSE-4 Beta Lactamase: A Serotype-Specific Enzyme in Pseudomonas Aeruginosa
More LessSummaryPSE-4 enzyme is the most common plasmidic β lactamase in Pseudomonas aeruginosa but its production is invariably non-transferable by conjugation. Of 20 PSE-4+ isolates from 10 separate sources, 16 were serotype 0:16 and two belonged to the related 0:2(b) serotype. One of the two remaining organisms was not O-typable and the other was agglutinated by several unrelated antisera. Examination of additional 0:16 strains confirmed the unusual frequency of PSE-4 enzyme in this serotype. None of the PSE-4+ strains was able to transfer carbenicillin resistance in mating experiments and none contained extrachromoso-mal DNA. Two explanations of the relationship between enzyme production and O antigenicity are proposed. PSE-4 production may be transmissible, perhaps by transduction, between strains of 0:16 or related serotypes, or PSE-4+ P. aeruginosa may represent a disseminated subtype. A third hypothesis, that the PSE-4 coding element carried serotype determinants, was discounted. PSE-4+ and PSE-4- P. aeruginosa strains of 0:16 and related serotypes were found to represent a definite cluster by their phage-susceptibility pattern and pyocin type (type 1). The only characters linked to PSE-4 production were resistance to spectinomycin, streptomycin and sulphonamide and the genes responsible for these characters seemed to occur on the PSE-4 coding element.
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Uropathogenic Properties of Proteus Mirabilis and Proteus Vulgaris
More LessSummaryA group of faecal isolates of Proteus vulgaris and P. mirabilis was studied for the presence of possible virulence factors such as growth rates in urine and broth, haemolysin production, hydrophobicity, sensitivity to the bactericidal activity of human serum and cell invasiveness. Differences were found in haemolysin production, cell invasiveness and experimental virulence in a mouse model. These differences might explain why P. mirabilis is much more common in human urinary-tract infections than P. vulgaris.
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Contribution of the traT Gene to Serum Resistance Among Clinical Isolates of Enterobacteriaceae
More LessSummaryAntimicrobial resistance plasmids containing the traT gene confer resistance to serum bactericidal activity upon some laboratory strains of Escherichia coli. We have examined the DNA of Enterobacteriaceae from human extraintestinal infections to determine the frequency of traT-like genes. DNA sequences homologous with traT were found among 58% of Escherichieae but among none of the Klebsielleae or Proteeae tested and were found as frequently among serum-sensitive E. coli as among serum-resistant strains. Sequences related to traT were always associated with large plasmids. The potential contribution of traT-containing plasmids to serum resistance of clinical isolates is discussed.
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Polymorphism of a Mycobacterial Antigen Participating in Cell-Mediated Immunity
More LessSummaryThe cross-reactivity of crude sonic extracts of six species of mycobacteria was studied by skin tests in mice and guinea pigs immunised with live Mycobacterium tuberculosis strain H37Rv, and in patients with pulmonary tuberculosis. All slowly growing mycobacteria elicited a strong delayed hypersensitivity response, M. vaccae a moderate response and M. phlei a poor or no response. A specific target antigen for cell-mediated immunity, known to be present in M. tuberculosis, was also present in all the mycobacteria studied. This shared antigen was shown, by immunoprecipitation tests, to be identical in all the slowly growing species but only a partial reaction of identity was obtained with M. phlei. It is concluded that the antigen shared by the slowly growing mycobacteria is immunodominant in cell-mediated immunity.
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Susceptibility of Mycobacterium Leprae to the Bactericidal Activity of Mouse Peritoneal Macrophages and to Hydrogen Peroxide
More LessSummaryMacrophages from athymic nude mice were infected in vitro with Mycobacterium leprae to study the intracellular fate of this organism. Using the proportional bactericidal test, we have shown that the viability of M. leprae declines rapidly within these macrophages, although results of clearance experiments demonstrate that live and killed organisms are cleared at comparable rates. We have also shown that M. leprae is susceptible to the bactericidal effects of hydrogen peroxide and we suggest that hydrogen peroxide generated by macrophages is responsible for the killing of intracellular M. leprae.
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Degradation of Human Immunoglobulins G and M and Complement Factors C3 and C5 by Black-Pigmented Bacteroides
More LessSummaryStrains of Bacteroides, Capnocytophaga and Fusobacterium were examined by immunological methods for their ability to degrade the human serum proteins IgG, IgM, C3 and C5. The proteolytic activity of the strains was measured in terms of the breakdown of serum into trichloroacetic acid-soluble material. Only black-pigmented Bacteroides strains showed proteolytic activity. Strains of B. gingivalis degraded IgG, IgM, C3 and C5, strains of B. intermedius IgG and C3, strains of B. endodontalis C3 and IgG and a strain of B. loeschei degraded only IgG. These findings are discussed in relation to the pathogenicity of the black-pigmented Bacteroides.
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Evaluation of Stabilised Cells in the Indirect Haemagglutination Test for Echinococcosis
More LessSummaryWe have evaluated the use of sheep red-blood cells stabilised in various ways in indirect haemagglutination tests on the sera of 21 surgically confirmed cases of echinococcosis, and on control sera. Tests with Double-Aldehyde-Stabilised cells—treated sequentially with pyruvic aldehyde, tannic acid and glutaraldehyde—were more sensitive than tests with the cells treated only with formaldehyde, glutaraldehyde or pyruvic aldehyde, and subsequently tanned.
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An Assay of Bordetella Pertussis Adhesion to Tissue-Culture Cells
More LessSummaryThe ability of Bordetella pertussis to bind to cell surfaces was determined with a simple, accurate, reproducible assay measuring the adhesion of radiolabelled bacteria to monolayers of HeLa cells. The rate of adhesion was approximately linear with time for at least 1 h. Viable and radioactivity counts of bound bacteria correlated well. Bacteria grown in the avirulent C-mode were markedly less adhesive than virulent X-mode cells. Reductions in the level of attachment after treatment of bacteria with preparations of specific immunoglobulin suggest that adhesion of B. pertussis depends upon specific mechanisms involving filamentous haemagglutinin and the agglutinogens.
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Elastase Activity of Coccidioides Immitis
More LessSummaryTwenty-two strains of Coccidioides immitis were tested for the ability to hydrolyse elastin. Screening assays with Czapek’s or Tryptic Soy Agar supplemented with 0·5% elastin demonstrated that 21 strains (95%) were elastolytic. In broth cultures, elastase activity was induced by incorporation of insoluble elastin into the medium and induction was suppressed by supplementation with yeast extract. C. immitis appears to be unique amongst dimorphic fungal pathogens in its digestion of elastin.
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Phagocytosis by Human Leukocytes, Phagosomal pH and Degradation of Seven Species of Bacteria Measured by Flow Cytometry
More LessSummaryPhagocytosis by human leukocytes, phagosomal pH and degradation of seven species of bacteria were studied by a flow cytometric method. The percentage of phagocytosing leukocytes was similar for all bacterial strains examined, but Salmonella typhi and Neisseria meningitidis were more slowly phagocytosed than other bacteria. The phagosomal pH surrounding the different bacterial species 15 min after the start of phagocytosis were: Streptococcus pneumoniae 4·4; N. meningitidis 4·9; Str. pyogenes 5·1; Staphylococcus aureus 5·2; Escherichia coli 5·3; S. typhi 5·4; and Klebsiella pneumoniae 5·7. For longer incubation periods, the phagosomal pH remained nearly constant. Staph. aureus, E. coli and S. typhi were the most readily degraded of the species tested. The proteins of all bacteria were degraded more rapidly than their DNA as determined by measurements of the loss of fluorescein-isothiocyanate-fluorescence and ethidium bromide-fluorescence, respectively. The rate of degradation varied from one bacterial species to another. The degradation of proteins and DNA was maximal for bacteria residing in a phagosomal environment estimated to be between pH 5·2 and 5·4.
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- Obituary Notice
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- Books Received
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Volumes and issues
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Volume 73 (2024)
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