- Volume 10, Issue 2, 1977
Volume 10, Issue 2, 1977
- Short Articles
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Effects of Biliary Diversion on Intestinal Microflora in the Rat
More LessSUMMARYCertain bile acids inhibit the growth in vitro of organisms commonly found in the intestine and, in particular, anaerobic bacteria. As the importance of this effect in vivo has not been demonstrated, we investigated changes in intestinal flora in the rat after diversion of bile to the urinary bladder.
Five days after operation there was an increase in numbers of Proteus sp. in the stomach, mid-jejunum and caecum and of coliform bacilli in the stomach and mid-jejunum. Lacto-bacilli were increased in the stomach. There was no change in numbers of anaerobic organisms. Similar changes in bacterial flora followed 5 days of pair feeding in control rats. Our results do not suggest a specific antibacterial effect of bile salts in the rat in vivo. The changes found are probably related to semi-starvation, because the food intake of the rats after operation was about half that of control rats having an unrestricted diet.
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The Effect of Treponema Pallidum on Mouse Survival
More LessSUMMARYIntraperitoneal infection with Treponema pallidum did not shorten the lives of inbred CBA mice. One hundred and fifty infected mice survived to a mean age of 41.24 months and 60 uninfected mice to a mean age of 41.38 months.
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Delayed Culture of Group-A Streptococci: An Evaluation Of Variables in Methods of Examining Throat Swabs
More LessSUMMARYWe studied the effects on the frequency of isolation of group-A streptococci from throat swabs of school children of three variables: (1) plating the cultures within 4 h of collecting the swabs or after storage for 4 days at room temperature; (2) using a plain or a serum-coated cotton swab; and (3) including silica gel in the swab tube or omitting this. Under the conditions of our experiment, only delayed plating of the swab gave a statistically significant advantage. When the delayed-isolation technique was used, neither the swab type nor the presence or absence of silica gel significantly influenced the result. The least advantageous combination of variables was: plating within 4 h, a plain swab, and the absence of silica gel.
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The Activity of Polymyxins Against Escherichia Coli in An in-Vitro Model of the Urinary Bladder
More LessSUMMARYThe activities against a strain of Escherichia coli of polymyxin B, colistin (polymyxin E) and their sulphomethyl derivatives sulphomyxin and colistin sulphomethate have been examined in an in-vitro model of the urinary bladder under conditions similar to those that may operate in the therapeutic situation. In the dynamic conditions of the model, poly-myxins exhibited a reduced activity against E. coli in comparison with activity against exponentially growing cultures in a static system. Nevertheless, long-term suppression of bacterial growth was achieved with levels of polymyxin B and colistin that can be attained during therapy, whereas sulphomethylpolymyxins had little effect on bacterial growth even on prolonged exposure.
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Continuous-Culture Studies of Interactions Among Human Skin-Commensal Bacteria
P. D. Marsh and S. SelwynSUMMARYChemostat studies were made of an antibiotic-producing Staphylococcus epidermidis strain (S6+), a similar, but antibiotic non-producing S. epidermidis strain (S6−), and a sensitive indicator strain of Micrococcus sp. (M7). Pure and mixed continuous cultures were investigated at low population levels (in 0.1% peptone water) and at higher levels (in 0.5% peptone water). Strain S6+ antagonised the growth of strain M7 when its colony count was maintained above 107.0 per ml, while strain S6− remained unaffected.
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- Articles
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Determination of Antibacterial Antibodies in Serum by Immunoradiometric Assays
More LessSUMMARYWhen used to determine immunopurified antibacterial globulins in saline-phosphate buffer, the detection sensitivities of direct competitive and indirect immunoradiometric assays were respectively 25 and 2 ng. Normal human and rabbit sera interfered in both types of assay, markedly decreasing sensitivity and precision. Various pre-treatments of sera and modifications of reaction conditions substantially decreased interference in the competitive assay without affecting the activity of added antibody, but they had only marginal effects in the indirect assay. When serum samples taken from rabbits after vaccination with the Live Vaccine strain of Francisella tularensis were tested with the two assays and agglutination tests, newly synthesised circulating antibody was usually detected earlier by the competitive assay than by the other methods.
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Studies on Antagonism Between Human Skin Bacteria
P. D. Marsh and S. SelwynSUMMARYAntagonism by an antibiotic-producing Staphylococcus epidermidis strain (S6+) against other bacteria was studied semi-quantitatively on solid media and quantitatively in liquid batch culture. Parallel experiments were performed with a similar but non-antibiotic producing strain (S6−). On solid media strain S6+ in the logarithmic growth phase unilaterally inhibited members of all gram-positive species tested, whereas S6− had no effect. In liquid media, more complex interactions were observed, including mutual and reversed antagonisms. The relevance of these findings to the ecology of human skin is discussed.
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Properties Of Strains of Staphylococcus Aureus in the 94, 96 Complex
More LessSUMMARYStrains of Staphylococcus aureus that are lysed by typing phages 94 or 96, or by both phages, are usually resistant to lysis by other basic-set typing phages. They are, however, sensitive to several experimental phages and show a number of different lytic patterns when tested against these phages. These differences in susceptibility are due, in part, to immunity imposed by temperate phages carried by the different strains. Resistance to lysis by other basic-set phages was not due to prophage immunity, but to at least one restriction and modification system in such strains. Restrictionless mutants were isolated from one strain in several experiments. These showed an increased sensitivity to many basic-set phages. However, all of these mutants retained the ability to modify the phages to the characteristic “94, 96” specificity.
Strains in the 94, 96 complex showed a remarkable homogeneity in biological traits. The majority were non-pigmented, and produced lipase, fibrinolysin, α and δ haemolysins and enterotoxin B. This homogeneity may well be a reflexion of the restriction and modification systems in these strains, that prevent the acquisition of genetic material from strains outside the complex. A new lytic group V is proposed for members of the 94, 96 complex.
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Immunogenicity and Characteristics of M Protein Released by Phage-Associated Lysin from Group-A Streptococci Types 1 And 23
More LessSUMMARYA phage-associated lysin (PAL) was used to release M protein from group-A streptococci of types 1 and 23. Much of the lysin-released-M protein (LYSIN-M) of both types was of high molecular weight, since LYSIN-M appeared just after the void volume on Sephadex G-200 gel-filtration. Some of the LYSIN-M of both types was found to be firmly attached to group-A carbohydrate. Type-1 LYSIN-M was partially purified by ammonium-sulphate precipitation followed by absorption and elution from an immunoabsorbent column containing antibody for group-A carbohydrate. Type-23 LYSIN-M was partially purified by precipitation at its isoelectric point, pH 4-9. Rabbits immunised in the footpads with either type-1 or type-23 LYSIN-M responded by producing both precipitins and bactericidal (opsonising) antibodies. Some of the antisera were absorbed and rendered specific for homologous acid extracts. The LYSIN-M preparations of both types 1 and 23 were originally contaminated with heat-labile antigen(s). Antibodies to these heat-labile antigen(s), which cross-react from type to type, were found in the type-specific antisera distributed by the Center for Disease Control. The specificity of Lancefield typing antisera depends on their being tested with extracts of streptococci prepared at pH 2 and 100°C for 10 min. Although LYSIN-M is more difficult to prepare and purify than acid-heat released M protein, it might prove useful for studying the nature of native streptococcal M protein.
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The Culture of Clinical Specimens for Anaerobic Bacteria: A Comparison Of Three Regimens
More LessSUMMARYThree procedures for the anaerobic culture of clinical specimens are compared: (i) a conventional bench routine, (ii) a system whereby primary anaerobic plates were incubated for 48 h before examination, and (iii) an anaerobic chamber.
It was shown that the anaerobic chamber was of no advantage over bench regimens when primary anaerobic plates were incubated for 48 h before being examined.
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Picornaviruses: Rapid Differentiation and Identification by Immune Electronmicroscopy and Immunodiffusion
More LessSUMMARYImmune electronmicroscopy (IEM) was used to identify human picorna-viruses rapidly and to differentiate enteroviruses from rhinoviruses. Human sera, diluted 10- to 50-fold beyond the neutralisation endpoints for homologous virus, readily agglutinated C-type antigens of seven human picornaviruses. Human sera did not react by IEM with a control animal picornavirus. By IEM after acid treatment, differentiation of a human enterovirus from a human rhinovirus was possible. There was an excellent correlation between the results of IEM and immunodiffusion (ID) tests for the presence of antibody to human picornavirus group antigens. By ID, only one of 21 human sera reacted with one of six animal picornaviruses. Immune electronmicroscopy appears to be a sensitive and simple technique for the detection of picornavirus C-type antigens, and may be useful for identifying viruses belonging to groups comprising many serotypes and sharing a common group antigen.
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A Sequential Bacteriological and Serological Investigation of Rhesus Monkeys Immunised Against Dental Caries with Streptococcus Mutans
More LessSUMMARYIn a serial investigation of the effects of immunisation with S. mutans in rhesus monkeys maintained on a “human” type of cariogenic diet, the numbers of S. mutans in cervical plaque, crevicular-fluid washings, fissures of teeth, and in saliva were lower in immunised animals than in sham-immunised controls. Immunisation also caused a delay in initial colonisation and a slowing of the rate of colonisation with S. mutans. These bacteriological changes were associated with a reduction in the smooth-surface-caries score. No relationship was found between the presence of S. sanguis and caries, but there was an inverse relationship between the proportions of S. mutans and S. sanguis isolated. Increased titres of complement-fixing, haemagglutinating and precipitating antibodies to S. mutans were found in the sera of immunised but not of control monkeys. A significant increase in salivary haemagglutinating antibodies was not detected. The results suggest that immunisation with S. mutans causes an increase in serum antibodies and a reduction in the number of S. mutans in the oral flora, and that these are associated with a reduction in dental caries.
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A Protein Factor Associated With Serum Resistance in Escherichia Coli
More LessSUMMARYImmunogel-diffusion studies showed that 60°C LiCl extracts of the smooth serum-resistant mutant Escherichia coli strain 17 contained greater amounts of a protein antigen than did extracts of the parent strain LP729. An extract of strain 17 was fractionated on Sepharose 4B and the protein antigen was found as the only detectable antigen in a number of fractions; sodium dodecyl sulphate-polyacrylamide gel electrophoresis indicated that these fractions contained one major polypeptide band with a molecular weight of 46 000 daltons. We suggest that this protein antigen may be partly responsible for the serum resistance of strain 17 though its presence in other serum-sensitive strains suggests that additional factors are essential for full serum resistance.
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The Effect of the Nitroimidazole Drug Dimetridazole on Microaerophilic Campylobacters
More LessSUMMARYDimetridazole, a nitroimidazole drug reported to act only on obligately anaerobic micro-organisms, is widely used for the prevention and treatment of swine dysentery. Forty-four strains of the microaerophilic bacterium Campylobacter coli isolated from either healthy or diseased pigs, and a strain of Campylobacter fetus, were all sensitive to dimetridazole. The sensitivities (minimal inhibitory concentration < 10 µg per ml) were similar to those of anaerobic bacteria. Dimetridazole inhibited growth of campylobacters in a shaken culture in air, but did not inhibit uptake of oxygen. Inhibition of growth appeared to result from an inhibition of nucleic-acid synthesis and does not seem to depend upon interference with electron transport in the catabolism of pyruvate.
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- Proceedings Of The Pathological Society Of Great Britain And Ireland
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- Books Received
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