- Volume 16, Issue 1, 1983
Volume 16, Issue 1, 1983
- Short Articles
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Isolation of species of Yersinia from patients with gastroenteritis in Nigeria
More LessSUMMARYFrom patients in Nigeria with acute gastroenteritis, strains of Yersinia were isolated from 14 (1.3%) of 1082 specimens of faeces examined specifically for yersiniae by direct plating and after cold enrichment. Clinical significance was ascribed to six isolates of Y. enterocolitica (serotypes 03, 05,27 and 09) but not to seven isolates of Y. intermedia or one isolate of Y. frederikseni.
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Use of Aspergillus fumigatus mycelial antigens in enzyme-linked immunosorbent assay and counter-immunoelectrophoresis
More LessSUMMARYAntigens obtained from the ruptured mycelium of Aspergillus fumigatus were separated on the basis of their attachment or non-attachment to Concanavalin A-linked Sepharose gel. They were analysed by double-diffusion and two-dimensional immunoelectrophoresis with rabbit antiserum and sera from patients with aspergillus-related disease. Their sensitivity was assessed in an enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G. Sera which gave very low or high extinction readings on ELISA gave, in general, comparable results on counter-immunoelectrophoresis; but weak electrophoretic reactions were not closely paralleled by ELISA results. The unfractionated extract and the fraction bound by Concanavalin A-Sepharose had similar ability to detect specific IgG in sera from patients with aspergillosis.
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- Articles
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The relationship between opacity factor and M protein in Streptococcus pyogenes
More LessSUMMARYLancefield acid extracts of Streptococcus pyogenes, type 22 (T12, M22, OF positive) gave good yields of M protein and little opacity factor (OF), but sodium dodecyl sulphate (SDS) extracts contained high titres of OF (> 20 000) and little M protein. Acid-extracted OF could be separated from M protein by Sepharose 4B chromatography, but some of the OF-positive fractions that did not precipitate with the absorbed homologous anti-M rabbit serum, were able to neutralise opsonic antibodies present in human serum. The isoelectric-focusing profiles of the two antigens showed partial similarity.
Some strains of the OF-positive serotypes, e.g., M-types 22 and 49, lost both M antigen and OF activity on serial transfer in Todd-Hewitt broth, but this was not seen in a representative of M-type 60, and no M-negative OF-negative variants could be detected after six subcultures. Among the OF-negative serotypes some, e.g., M-types 5 and 6, were completely stable, whereas others, e.g., M-types 12,55 and 57, lost their M antigens after serial subculture. One explanation is that the genes that code for M antigen are plasmid borne in some serotypes and, moreover, are carried on the same plasmid as the gene for OF in some OF-positive serotypes. However, analysis of cell lysates by agarose-gel electrophoresis failed to demonstrate the presence of plasmid DNA in any of the strains tested.
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The pathogenicity of Mycobacterium avium and related mycobacteria for experimental animals
More LessSUMMARYThe pathogenicity of 40 strains of Mycobacterium avium, M. paratuberculosis, M. intracellulare and M. lepraemurium was investigated in chickens, rabbits, guinea-pigs, mice and calves. Myco-bactin dependence and serological type were also determined. There was no evidence that mycobactin dependence was related to pathogenicity. Antigenic similarities were demonstrated between M. avium and M. paratuberculosis, and one isolate had the pathogenic characteristics of both species.
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Role of heat labile antigens of Shigella flexneri in hela cell invasion
More LessSUMMARYIn studies of the role of surface antigens of Shigella flexneri in HeLa cell invasion, three antisera were employed to block the invasion. Antisera against live (ALS) and boiled (ABS) S. flexneri blocked invasion very effectively. Reduction in the numbers of intracellular shigellae was always accompanied by reduction in the number adherent to the cells, indicating the importance of adhesion in the invasive process. Anti-live absorbed antiserum (ALAS) prepared by exhaustive absorption of ALS with boiled S. flexneri blocked adhesion and invasion at dilutions of 20 or 50; the efficiency of the absorption was indicated by absence of agglutinating and anti-lipopolysaccharide (LPS) antibodies. S. flexneri LPS did not block adhesion and invasion even at a concentration of 1.0 mg/ml. Hence it was concluded that heat-labile surface antigens are important in adhesion and invasion of HeLa cells by S. flexneri. Antiserum against heat stable antigen (ABS) probably blocks adhesion by steric hindrance.
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Occurrence of antibodies to teichoic acid in patients with diseases other than staphylococcal infection
SUMMARYTo determine the usefulness of the teichoic acid antibody (TAA) test in conditions where unspecific viral and bacterial antibodies are often encountered, we measured TAA by the gel-diffusion method in 475 patients without known staphylococcal disease; they included 213 patients with arthritis, 108 with liver diseases, 100 with gastro-intestinal disorders and 54 with acute pharyngitis. Positive controls were 104 patients with Staphylococcus aureus bacteraemia and 203 healthy adults were negative controls. Thirteen (6%) of the healthy adults had positive TAA titres (⩾4), and the highest titre was 8 in two people (1%). Positive titres were found in 38% of patients with S. aureus bacteraemia and high titres (⩾8) were seen in 24%. Among the patients with arthritis, positive TAA titres were found significantly more often than in healthy controls in patients with Yersinia arthritis (p < 0.01) and systemic lupus erythematosus (SLE; p < 0.02). In other patient groups, the percentage of positive TAA titres did not differ significantly from that in healthy adults. Eight (2%) of the 475 patients without known staphylococcal infection had TAA titres ⩾8 but these high, titres were not associated with any particular disease group. Only two of these eight patients had slightly raised antibody to staphylococcal α-haemolysin. We conclude that the TAA test cannot be used as a reliable indicator of septic staphylococcal disease in patients with Yersinia arthritis or SLE, but that in general, TAA titres ⩾8 point strongly to S. aureus infection even in patients with autoimmune or liver diseases.
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The isolation and immunochemical characterisation of a cell-wall carbohydrate and a membrane lipocarbohydrate antigen of group B streptococcus, type II
More LessSUMMARYTWO distinct carbohydrate antigens were isolated from the cell surface of group B streptococcus, type II. One antigen was extracted from SDS-purified cell walls by cold trichloroacetic acid and contained galactose, glucose, rhamnose, glucosamine and sialic acid in the approximate molar proportions 1.7:1.0:3.4:0.9:0.21 respectively. The serological activity of this polymer indicated that it is the group-specific antigen common to all group B streptococci. The second antigen was extracted by phenol from cell membranes and contained galactose, glucose, glucosamine, phosphorus and fatty acid in a molar ratio of 1.6:1.0:0.35:2.6:0.016 respectively. This antigen was shown to be specific for type II, group B streptococcus.
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Effect of glucose concentration in the growth medium upon neutral and acidic fermentation end-products of Clostridium bifermentans, Clostridium sporogenes and Peptostreptococcus anaerobius
More LessSUMMARYClostridium bifermentans, C. sporogenes and Peptostreptococcus anaerobius were grown in Fastidious Anaerobe Broth with glucose concentrations from 0–1.5% (w/v). Gas chromatographic (GLC) analysis of fermentation end-products revealed that a change in glucose concentration markedly affected fermentation patterns of each microorganism. Increased glucose concentration resulted in stimulation of ethanol production by all strains, and of butanol and butyric acid by C. sporogenes. With C. bifermentans, there was a parallel increase in ethanol and acetic acid production and decreased formation of propanol and propionic, iso-butyric and iso-valeric acids. Increased ethanol formation by P. anaerobius was accompanied by an increase in acetic acid and a decrease in butan-1-ol production. The greatest incremental change in GLC profiles occurred when glucose concentration was raised from zero to 0.1% (w/v). These data suggest that glucose concentration in a medium for GLC analysis must be rigorously controlled if reproducible results are to be obtained.
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The relative importance of the classical and alternative complement pathways in serum bactericidal activity against Escherichia coli
More LessSUMMARYThe relative importance of the classical and alternative complement pathways in serum bactericidal activity against Escherichia coli strains of the common urinary O-serogroups has been assessed with strains that differ widely in their sensitivity to normal human serum. With most promptly serum-sensitive strains, rapid killing occurred, mediated by the classical pathway and, when this pathway was eliminated, delayed killing by alternative-pathway activity occurred. However, one strain of serogroup O1 was affected by the classical pathway only and a strain of serogroup O9 was killed rapidly by the alternative pathway. Strains with delayed sensitivity to normal human serum were largely, and in some cases exclusively, affected by the classical pathway.
When added to heat-inactivated serum, some strains showed no significant growth whereas the viable numbers of other test strains increased more than 50-fold in 3 h. Whether this variation is due to differences in nutritional requirements or sensitivity to some non-complement-dependent bacteriostatic mechanism remains to be determined.
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Susceptibility of anaerobic bacteria to beta-lactam antibiotics and beta-lactamase production
More LessSUMMARYWe examined the susceptibility of various anaerobes to four beta-lactamase susceptible (ampicillin, amoxycillin, cyclacillin, and penicillin G) and two beta-lactamase resistant (moxalactam, and N-F-thienamycin) beta-lactam antibiotics and measured beta-lactamase production. Members of the Bacteroides groups were most resistant to the six antibiotics. N-F-thienamycin was the most effective antimicrobial agent against all the test strains, moxalactam the next most effective, and penicillin G the least. Beta-lactamase production was mainly confined to Bacteroides species. Cephalosporinase was the most common beta-lactamase produced; penicillinase was detected less often. About two thirds of the penicillin-resistant isolates produced cephalosporinase. N-F-thienamycin and moxalactam were the most active agents against those anaerobes that were resistant to many beta-lactam antibiotics.
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The identification of Gardnerella vaginalis
More LessSUMMARYA collection of 72 strains of catalase-negative gram-positive,-negative and -variable cocco-bacilli isolated from samples of vaginal discharge from women with non-specific vaginal infection was examined in an attempt to develop an identification system for Gardnerella vaginalis that could be used in a diagnostic laboratory. Carbohydrate fermentation tests were found to be poorly reproducible and of little differentiating value. Enzyme tests were found similarly unhelpful, as were many antibiotic-susceptibility and chemical-inhibition tests. However, seven tests—susceptibility to trimethoprim and two concentrations of metronidazole, growth in the presence of 2% (w/v) sodium chloride and on nutrient agar, lactic acid production from glucose and β-haemolysis on human-blood agar—were used successfully in this study to separate G. vaginalis from catalase-negative coryneforms and lactobacilli. Of these tests, susceptibility to trimethoprim and metronidazole together with β-haemolysis on human blood agar are the most likely to provide a rapid, accurate identification. A possible identification scheme is outlined.
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- The Fourth C. L. Oakley Lecture
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- Books Received
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