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Volume 31,
Issue 3,
1990
Volume 31, Issue 3, 1990
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Hydrolytic enzyme production by Clostridium difficile and its relationship to toxin production and virulence in the hamster model
More LessSummaryThirty isolates of Clostridium difficile expressing different degrees of toxigenicity and virulence in an animal model were assayed for the production of chondroitin-4-sulphatase, hyaluronidase, heparinase, collagenase and protease. All strains demonstrated some hydrolytic enzyme activity. There was no direct correlation between toxigenic status, or virulence, and hydrolytic enzyme production. However, all five strains known to be highly virulent in the hamster model had hyaluronidase, chondroitin-4-sulphatase and collagenase activity whereas only three of five toxigenic but poorly virulent strains had these activities, the collagenase activity being weak in all three cases. The only two proteolytic strains are also highly virulent. The potential tissue damaging properties of these hydrolytic enzymes may help to explain the differences in virulence of C. difficile strains seen in the Syrian hamster model of antibiotic-associated colitis, and may contribute to the spectrum of disease seen in man. It is also possible that chondroitin-4-sulphatase, hyaluronidase and collagenase activity may release essential nutrients, promoting establishment of C. difficile in the gut.
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The production and characterisation of rabbit antiserum and murine monoclonal antibodies to Haemophilus ducreyi
More LessSummaryRabbit antiserum and murine monoclonal antibodies were raised against a strain of Haemophilus ducreyi. The antiserum gave high immunofluorescence titres and strong dot blot reactions with all H. ducreyi strains tested and the only cross reaction was with Bordetella pertussis. Three monoclonal antibodies, all of isotype IgG2a, also gave high immunofluorescence titres with H. ducreyi but did not cross react with any other species tested. Immunoblotting showed the monoclonal antibodies to react with a single polypeptide band of mol. wt 29 000 in the outer-membrane fraction of H. ducreyi. These antibodies have potential for use as diagnostic reagents and for investigating the pathogenicity of H. ducreyi.
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Porphyrin ring source can alter the outer membrane protein profile of non-typable Haemophilus influenzae
More LessSummaryPorphyrin ring source appears to alter the outer membrane protein (OMP) profile of some, but not all, non-typable (NT) Haemophilus influenzae strains isolated from sputum. When haemin was replaced with protoporphyrin IX, 41% of strains examined produced increased amounts of a polypeptide of 84 Kda and new OMPs of either 120 or 150 Kda. Immunoblotting with paired patient's sera revealed that antibodies reactive with these proteins were present, demonstrating OMP antigenicity and expression in vivo and indicating that these isolates of NT H. influenzae may display an altered OMP phenotype when growing in the human lung.
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Differences in susceptibility of inbred and outbred infant mice to enterotoxigenic Escherichia coli of bovine, porcine and human origin
More LessSummaryInfant mice from outbred Swiss OF1 and from inbred DBA/2, C57BL/6, BALB/cBy and CBA strains were screened for usefulness in the diarrhoea model with enterotoxigenic Escherichia coli (ETEC) strains of bovine, porcine and human origin. Mouse strains were either weakly susceptible or not susceptible to ETEC strains of porcine or human originbearing antigen K88, 987P, CFA/I or CFA/II. In contrast, some mouse strains were highly susceptible to bovine and porcine ETEC strains bearing K99 or F41 or both antigens. Swiss OF1 and CBA infant mice were highly susceptible to one bovineETEC strain bearing antigen K99, whereas DBA/2, BALB/cBy and C57BL/6 mice exhibited nearly complete resistance to the same ETEC strain. Except DBA/2, all mouse strains were highly susceptible to bovine and porcine ETEC strains bearing antigen F41 alone or in combination with antigen K99. Challenge ETEC strains colonised intestines of all infant mice, but theyreached very high levels soon after inoculation in the diarrhoeic ones only.
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Virulence factors of bacteraemic Escherichia coli with particular reference to production of cytotoxic necrotising factor (CNF) by P-fimbriate strains
More LessSummaryThirty-seven strains of Escherichia coli isolated from bacteraemia and 40 faecal strains isolated from healthy individuals were O serogrouped and investigated for the production of colicins, haemolysin (Hly), cytotoxic necrotising factor (CNF), lethal activity for mice, the expression of P fimbriae, mannose-resistant (MRHA) and mannose-sensitive (MSHA) haemagglutination, and relative cell surface hydrophobicity. Virulence factors significantly associated with bacteraemic strains were: serogroups O2, O4, O6, O7, O8 and O75 (54% versus 10%, p<0.001), production of Hly (32% versus 8%, p<0.02) and CNF (38% versus 10%, p<0.01), expression of P fimbriae (27% versus 5%, p<0.02), MRHA types III, IVa and IVb (51% versus 8%, p<0.001), and possession of a moderate cell surface hydrophobic charge (35% versus 13%, p<0.05). Virulence factors were strongly associated with strains expressing defined MRHA types. Thus, all strains belonging to MRHA types III and IVa were toxigenic, whereas only 11% of strains belonging to MRHA types IVb, V or VI were toxigenic (p<0.001). Virulence factors were concentrated in strains belonging to O serogroups usually found in E. coli that cause extra-intestinal infections, especially in strains of O4 and O6 groups. The most interesting result of this study was that all 12 P-fimbriate strains expressed the MRHA type IVa and 11 of them synthesised CNF.
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Comparison of host responses induced by Salmonella typhimurium infection in genetically resistant and susceptible mice
More LessSummaryA/J and BALB/c mice differ genetically in their resistance to the facultative intracellular bacterium Salmonella typhimurium. We compared the responses of these strains of mice to a virulent S. typhimurium infection. BALB/c mice mobilised more peritoneal exudate cells in response to the infection than did A/J mice 30 h after infection, but the increase in bacterial counts in the livers and spleens of BALB/c mice was 10-fold higher than in A/J mice. The response to Concanavalin A (Con A) of spleen cells from BALB/c mice was depressed, and both L3T4+ and Lyt-2+ T cell subpopulations were decreased following the infection, whereas the response to Con A of A/J mice was increased and the T cell subpopulations were not altered significantly. These results suggest that A/J mice respond more actively to S. typhimurium infection than do BALB/c mice, and this may be related to the natural resistance of mice.
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Serotyping and subtyping of Neisseria meningitidis isolates by co-agglutination, dot-blotting and ELISA
More LessSummaryTyping of meningococci with a panel of serotype and subtype specific monoclonal antibodies (MAbs) was compared in co-agglutination, dot-blotting and ELISA tests. Twenty reference strains, 50 case isolates and 133 throat isolates from healthy carriers were studied. The typing results with dot-blotting and ELISA were identical, whereas co-agglutination gave different results for three case and 24 carrier strains. The distribution of serotypes and subtypes among the strains is reported. The combination of the subtypes P1.1 and P1.15 in a serotype 15 patient strain was observed. With one case strain and 15 carrier strains, neither serotype nor subtype could be determined. Non-typable and non-subtypable isolates were further characterised by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Co-agglutination is useful for typing small numbers of strains with a few MAbs, but less suitable for large-scale typing than the other two methods. Dot-blotting needs less expensive equipment, smaller volumes of antibodies and fewer manipulations than ELISA.
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- Articles
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Porphyrin ring source can alter the outer membrane protein profile of non-typable Haemophilus influenzae
More LessSummaryPorphyrin ring source appears to alter the outer membrane protein (OMP) profile of some, but not all, non-typable (NT) Haemophilus influenzae strains isolated from sputum. When haemin was replaced with protoporphyrin IX, 41% of strains examined produced increased amounts of a polypeptide of 84 Kda and new OMPs of either 120 or 150 Kda. Immunoblotting with paired patient's sera revealed that antibodies reactive with these proteins were present, demonstrating OMP antigenicity and expression in vivo and indicating that these isolates of NT H. influenzae may display an altered OMP phenotype when growing in the human lung.
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-
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Hydrolytic enzyme production by Clostridium difficile and its relationship to toxin production and virulence in the hamster model
More LessSummaryThirty isolates of Clostridium difficile expressing different degrees of toxigenicity and virulence in an animal model were assayed for the production of chondroitin-4-sulphatase, hyaluronidase, heparinase, collagenase and protease. All strains demonstrated some hydrolytic enzyme activity. There was no direct correlation between toxigenic status, or virulence, and hydrolytic enzyme production. However, all five strains known to be highly virulent in the hamster model had hyaluronidase, chondroitin-4-sulphatase and collagenase activity whereas only three of five toxigenic but poorly virulent strains had these activities, the collagenase activity being weak in all three cases. The only two proteolytic strains are also highly virulent. The potential tissue damaging properties of these hydrolytic enzymes may help to explain the differences in virulence of C. difficile strains seen in the Syrian hamster model of antibiotic-associated colitis, and may contribute to the spectrum of disease seen in man. It is also possible that chondroitin-4-sulphatase, hyaluronidase and collagenase activity may release essential nutrients, promoting establishment of C. difficile in the gut.
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Virulence factors of bacteraemic Escherichia coli with particular reference to production of cytotoxic necrotising factor (CNF) by P-fimbriate strains
More LessSummaryThirty-seven strains of Escherichia coli isolated from bacteraemia and 40 faecal strains isolated from healthy individuals were O serogrouped and investigated for the production of colicins, haemolysin (Hly), cytotoxic necrotising factor (CNF), lethal activity for mice, the expression of P fimbriae, mannose-resistant (MRHA) and mannose-sensitive (MSHA) haemagglutination, and relative cell surface hydrophobicity. Virulence factors significantly associated with bacteraemic strains were: serogroups O2, O4, O6, O7, O8 and O75 (54% versus 10%, p≪0.001), production of Hly (32% versus 8%, p≪0.02) and CNF (38% versus 10%, p≪0.01), expression of P fimbriae (27% versus 5%, p≪0.02), MRHA types III, IVa and IVb (51% versus 8%, p≪0.001), and possession of a moderate cell surface hydrophobic charge (35% versus 13%, p≪0.05). Virulence factors were strongly associated with strains expressing defined MRHA types. Thus, all strains belonging to MRHA types III and IVa were toxigenic, whereas only 11% of strains belonging to MRHA types IVb, V or VI were toxigenic (p≪0.001). Virulence factors were concentrated in strains belonging to O serogroups usually found in E. coli that cause extra-intestinal infections, especially in strains of O4 and O6 groups. The most interesting result of this study was that all 12 P-fimbriate strains expressed the MRHA type IVa and 11 of them synthesised CNF.
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Differences in susceptibility of inbred and outbred infant mice to enterotoxigenic Escherichia coli of bovine, porcine and human origin
More LessSummaryInfant mice from outbred Swiss OF1 and from inbred DBA/2, C57BL/6, BALB/cBy and CBA strains were screened for usefulness in the diarrhoea model with enterotoxigenic Escherichia coli (ETEC) strains of bovine, porcine and human origin. Mouse strains were either weakly susceptible or not susceptible to ETEC strains of porcine or human origin bearing antigen K88, 987P, CFA/I or CFA/II. In contrast, some mouse strains were highly susceptible to bovine and porcine ETEC strains bearing K99 or F41 or both antigens. Swiss OF1 and CBA infant mice were highly susceptible to one bovine ETEC strain bearing antigen K99, whereas DBA/2, BALB/cBy and C57BL/6 mice exhibited nearly complete resistance to the same ETEC strain. Except DBA/2, all mouse strains were highly susceptible to bovine and porcine ETEC strains bearing antigen F41 alone or in combination with antigen K99. Challenge ETEC strains colonised intestines of all infant mice, but they reached very high levels soon after inoculation in the diarrhoeic ones only.
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Comparison of host responses induced by Salmonella typhimurium infection in genetically resistant and susceptible mice
More LessSummaryA/J and BALB/c mice differ genetically in their resistance to the facultative intracellular bacterium Salmonella typhimurium. We compared the responses of these strains of mice to a virulent S. typhimurium infection. BALB/c mice mobilised more peritoneal exudate cells in response to the infection than did A/J mice 30 h after infection, but the increase in bacterial counts in the livers and spleens of BALB/c mice was 10-fold higher than in A/J mice. The response to Concanavalin A (Con A) of spleen cells from BALB/c mice was depressed, and both L3T4+ and Lyt-2+ T cell subpopulations were decreased following the infection, whereas the response to Con A of A/J mice was increased and the T cell subpopulations were not altered significantly. These results suggest that A/J mice respond more actively to S. typhimurium infection than do BALB/c mice, and this may be related to the natural resistance of mice.
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Serotyping and subtyping of Neisseria meningitidis isolates by co-agglutination, dot-blotting and ELISA
More LessSummaryTyping of meningococci with a panel of serotype and subtype specific monoclonal antibodies (MAbs) was compared in co-agglutination, dot-blotting and ELISA tests. Twenty reference strains, 50 case isolates and 133 throat isolates from healthy carriers were studied. The typing results with dot-blotting and ELISA were identical, whereas co-agglutination gave different results for three case and 24 carrier strains. The distribution of serotypes and subtypes among the strains is reported. The combination of the subtypes P1.1 and P1.15 in a serotype 15 patient strain was observed. With one case strain and 15 carrier strains, neither serotype nor subtype could be determined. Non-typable and non-subtypable isolates were further characterised by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Co-agglutination is useful for typing small numbers of strains with a few MAbs, but less suitable for large-scale typing than the other two methods. Dot-blotting needs less expensive equipment, smaller volumes of antibodies and fewer manipulations than ELISA.
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Long-term viability of stored mycoplasmas and ureaplasmas
More LessSummaryAll of five lyophilised cultures of Mycoplasma orale kept for 23 years at room temperature were still viable, as were all but one of 12 lyophilised cultures of six Mycoplasma spp. that had been stored for 18–22 years at 4°C. Similarly, 11 of 13 lyophilised ureaplasma cultures were viable after 8–22 years at 4°C; the titre of organisms in the viable cultures had diminished no more than 100-fold, Seven broth cultures of five different Mycoplasma spp. all proved viable 5-13 years after being frozen and stored at — 70°C, although there was up to 104-fold reduction in the titre of organisms in some cultures. Furthermore, 18 (82%) of 22 different Mycoplasmaspp., originally lyophilised and then reconstituted and stored at — 70°C, were viable after 16 years. Viable organisms were found, with little or no reduction in titre, in all of seven broth cultures of Ureaplasma urealyticum, comprising six serotypes, after storage for 6-10 years at — 70°C, but five of 18 broth cultures of other human and animal ureaplasmas stored likewise were not viable after 13-14 years and in a further seven of them the titre of viable organisms had diminished ≥ 104-fold.
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Identification and cloning of the Type IIIa plasmidencoded dihydrofolate reductase gene from trimethoprim-resistant gram-negative bacteria isolated in Britain
More LessSummaryA clinical strain of Escherichia coli isolated in Nottinghamshire in 1980 was shown to harbour the type IIIa trimethoprim-resistant dihydrofolate reductase gene, previously identified on only one occasion, in New Zealand in 1979. The gene was identified by hybridisation with an 855-bp type III gene probe and its classification as a type IIIa dihydrofolate reductase was confirmed by detailed biochemical analysis of the enzyme product. The dihydrofolate reductase was identical in size and isoelectric point with the original type IIIa enzyme and shared similar inhibitory and kinetic profiles. The trimethoprim resistance gene was subsequently cloned and the type IIIa dihydrofolate reductase gene was localised to a 700-bp EcoRI-PstI fragment. This smaller fragment may prove to be a more specific DNA probe for the future identification of type IIIa dihydrofolate reductase genes.
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The production and characterisation of rabbit antiserum and murine monoclonal antibodies to Haemophilus ducreyi
More LessSummaryRabbit antiserum and murine monoclonal antibodies were raised against a strain of Haemophilus ducreyi. The antiserum gave high immunofluorescence titres and strong dot blot reactions with all H. ducreyi strains tested and the only cross reaction was with Bordetella pertussis. Three monoclonal antibodies, all of isotype IgG2a, also gave high immunofluorescence titres with H. ducreyi but did not cross react with any other species tested. Immunoblotting showed the monoclonal antibodies to react with a single polypeptide band of mol. wt 29 000 in the outer-membrane fraction of H. ducreyi. These antibodies have potential for use as diagnostic reagents and for investigating the pathogenicity of H. ducreyi.
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Volumes and issues
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Volume 74 (2025)
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Volume 72 (2023 - 2024)
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Volume 71 (2022)
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