- Volume 27, Issue 1, 1988
Volume 27, Issue 1, 1988
- Articles
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Bactericidal activity of human serum against strains of Klebsiella from different sources
More LessSUMMARYOne hundred and eighty strains of Klebsiella were tested for sensitivity to pooled normal human serum, capsular type and faecal coliform reaction. Strains of K. pneumoniae isolated from clinical infections were more likely to be serum resistant thanthose from the gut flora or environmental sources. For K. oxytoca strains, there was no significant correlation between serum sensitivity and source of isolation. Of 60 strains of K. oxytoca tested, 19 (32%) were serum resistant, as were 27 (23%) of 120strains of K. pneumoniae. Strains of K. pneumoniae from human sources gavepositive reactions in the faecal coliform test more frequently than strains from environmental sources. There was no correlation between a positive faecal coliform reaction andresistance to the bactericidal effect of human serum. Strains of capsular type K21 were isolated more frequently from clinical infections and were more often serum resistant thanother strains. Serum resistance appears to be a virulence factor in strains of K. pneumoniae but does not account for the difference in pathogenicity between K. pneumoniae and K. oxytoca.
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Penicillin tolerance among oral streptococci
More LessSUMMARYPenicillin tolerance was elicited in 18 of 46 strains of viridans streptococci isolated from the mouths of 19 of 20 healthy subjects and in 31 of 54 consecutive blood-culture isolates of streptococci. Enterococci and Streptococcus sanguis were theorganisms most frequently tolerant but the property was also common among isolates of S. mutans, S. mitior and Lancefield Group G streptococci. Pneumococci and S. salivarius were rarely tolerant. When incubated with penicillin at 5 × MIC in batch or continuous cultures, both tolerant and sensitive strains of oral streptococci declined in number less rapidly than S. pyogenes. However, combinations of penicillin and gentamicin killed tolerant and sensitive oral streptococci.
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Experimental arthritis induced by atypical strains of Streptococcus pyogenes
More LessSummaryExperimental arthritis was induced in Sprague-Dawley rats by intraarticular injectionof whole-cell sonicates, heat-killed cells and cell-wall preparations of typical and atypical strains of Group-A streptococci (Streptococcus pyogenes). The non-haemolytic nitrosoguanidine-derived mutant and the naturally occurring Lowry strain induced a similar but less severe form of arthritis. Direct immunofluorescent staining demonstrated maximum fluorescence in the sections of articular joint taken 60 days after injection. The level of immune complexes increased for up to 90 days after injection of cell walls or whole-cell sonicates and correlated well with the development of the chronic stage of arthritis observed in haematoxylin and eosin and fluorescence staining of thin tissue sections.
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The urease enzymes of Campylobacter pylori and a related bacterium
More LessSUMMARYThe urease enzyme of Campylobacter pylori was studied and compared with that of a related spiral-shaped bacterium, St1, isolated from the rodent ileum. Both bacteria possessed constitutive urease enzymes with activities up to 20-70 times that of Proteusvulgaris. This activity was retained on SDS-polyacrylamide gels. Amajor catalytic subunit of mol. wt 300 000 was located for all (six) strains of C.pylori subjectedto SDS-PAGE whereas St1 had two active forms of mol. wts 140 000 and 150 000. Western-blot analysis indicated the presence of anti-urease antibodies in the sera of patients with C. pylori-associated gastritis. The response to C. pylori urease was not strain-specific but no cross-reactivity was detected between the C. pylori enzyme and that of St1. The very high urease activity of these bacteria is likely to be important in colonisation of the host. Possession of glutamate dehydrogenase activity by both organisms suggests that one role of the urease may be to assimilate the available urea nitrogen. Modification of the local environment to facilitate long-term colonisation is another possible function. Protection from acid is unlikely to be a primary role as the natural habitat of the organism St1 is the non-acid-secreting tissue of the small intestine.
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Isolation of a gastric campylobacter-like organism from the stomach of four Rhesus monkeys, and identification as Campylobacter pylori
More LessSummaryCampylobacter-like organisms, isolated from the gastric antrum of Rhesus monkeys, werecompared with Campylobacter jejuni and C. pylori. They were similar to C. pylori by light microscopy, in ultrastructural morphology, in enzymic, fatty-acid-methyl-ester, and protein-profile analysis, and in antigenic reactivity with rabbit antisera to C. jejuni and C. pylori and with C. pylori-specific monoclonal antibody. Because this natural infection of the Rhesus monkey is associated with chronic gastritis, resembling the disease in humans colonised with C. pylori, we recommend the animal as a model for the investigation of human gastritis.
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Size and homology of the genomes of leprosy-derived corynebacteria, Mycobacterium leprae, and other corynebacteria and mycobacteria
I. Antoine, M. Coene and C. CocitoSummaryThe genomes of Mycobacterium leprae and leprosy-derived corynebacteria (LDC), which have a similar base composition of guanine + cytosine 56 mol%, have been compared with those of reference bacteria of the CMN group (genera Corynebacterium, Mycobacterium, Nocardia). Genome sizes of three LDC strains were (1.2–2.5) × 106 base pairs. DNA from four of seven LDC strains examined had homology levels >60%. Two other strains had a homology of 40% when compared with the CMN strains and one strain was distinctly different. The DNA from all seven LDC strains gave 0.3–18% hybridisation with that of M. leprae, 5–16% with reference corynebacteria, 5–12% with M. bovis, and 2–8% with Nocardia caviae. The small size of the LDC genome and its unrelatedness to those of M. leprae and organisms of the CMN group shows the uniqueness of LDC.
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Reaction of monoclonal antibodies with species specific determinants in Leptospira interrogans outer envelope
B. H. Jost, B. Adler and S. FaineSummaryA set of 24 monoclonal antibodies (MABs) was produced against an outer envelope preparation from Leptospira interrogans serovar copenhageni. The MABs reacted in enzyme immunoassay with species-specific determinants of an antigen in the leptospiral outer envelope (OE) of pathogenic but not of saprophytic species of Leptospira. The MABs did not agglutinate whole leptospires, nor could they opsonise homologous leptospires for phagocytosis by mouse macrophages or protect new-born guinea-pigs against lethal infection. The MABs reacted by Western blotting with a 35 × 103-mol-wt band in OE separated on SDS-polyacrylamide gels, and also reacted with other bands to a lesser extent. The determinants to which the MABs were directed were localised in the leptospiral OE by immunogold labelling techniques.
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Isolation of colonial variants of Bacteroides gingivalis W50 with a reduced virulence
More LessSummaryThe spontaneous appearance of unusual colony forms was observed during prolonged growth of Bacteroides gingivalis W50 in a chemostat. Two variants were selected for further study which could be distinguished from the parent strain by the rate and intensity of pigmentation of their colonies. For example, after anaerobic incubation for 14 days, variant W50/BR1 produced brown colonies whereas those of the parent strain were black; in contrast, variant W50/BE1 did not show signs of pigmentation until incubation had continued for 21 days. In subsequent studies in the chemostat, variant W50/BE1 bred true even after prolonged growth whereas other colony forms appeared after incubation of variant W50/BR1 for 14 days. The relatedness of W50/BR1 and W50/BE1 to the parent strain was confirmed by comparisons of the whole-cell fatty-acid profiles, the patterns of pre-formed enzymes and by the metabolic end products after growth. However, the variants did differ from the parent strain in their virulence in a mouse pathogenicity model. The parent strain killed all mice given infective doses > 5 × 108 cfu whereas W50/BR1 wasmuch lessvirulent (2 out of 10 mice killed and higher infective doses needed for higher mortality rates) and W50/BE1 was avirulent at all infective doses tested.
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Preformed enzyme profiles of reference strains of grampositive anaerobic cocci
More LessSummaryThe preformed (constitutive) enzyme profiles of 30 type strains and reference strains of gram-positive anaerobic cocci were determined with two commercial systems, RapID ANA and a prototype system from API. Both systems identified Peptostreptococcus anaerobius, Ps. asaccharolyticus, Ps. indolicus, Ps. magnus and Ps. micros accurately, except for one strain of Ps. magnus misidentified as Ps. micros by the RapID ANA system. The indole-negative, butyrate-producing cocci (classified at present as Ps. prevotii and Ps.tetradius) produced several different, unique patterns with the prototype API system, but the results with RapID ANA were often misleading. Eight strains of Hare group cocci produced previously described profiles. Four strains of streptococci produced profiles easily distinguished from those of the gram-positive anaerobic cocci. We conclude that most gram-positive anaerobic cocci can be identified rapidly and reliably to the species level by their preformed enzyme profiles, providing that their underlying classification is sound. Problems were encountered with the butyrate-producing cocci, which appear to be a more heterogeneous group of organisms than is currently acknowledged; further taxonomic studies on these organisms are required.
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The role of diarrhoeagenic Escherichia coli in acute diarrhoeal diseases in Bandar-Abbas, Iran
More LessSummaryThe prevalence of different types of diarrhoea-producing Escherichia coli was measured in 273 patients attending 12 out-patient clinics in Bandar-Abbas, Stateof Hormozgan, Iran, during March 1984. Enteropathogenic E. coli (EPEC) belonging to 12 different serogroups, of which O128 and O126 were the most common, were found in almost 31% of the patients. Enterotoxigenic strains of E. coli (ETEC) were the next most frequent group (21.9%); among these, 36 (60%) strains produced heat-stable enterotoxin (ST), 14 (23.3%) strains produced both heat-labile enterotoxin (LT) and ST, and 10 (16.7%) strains produced LT only. The same pattern of toxigenicity was observed among the EPEC isolates. Ten of the 12 serogroups encountered in this study contained toxin producers, amongstwhich strains producing ST were dominant. Enteroinvasive E. coli (EIEC) strains were not isolated. These findings suggest that enterotoxin-producing E. coli may be an important cause of diarrhoea in this part of Iran.
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- Obituary Notice
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- Review Article
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- Announcement
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- Books Received
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