A spark-resistant bulk-micromegas chamber for high-rate applications

We report on the design and performance of a spark-resistant bulk-micromegas chamber. The principle of this design lends itself to the construction of large-area muon chambers for the upgrade of the detectors at the Large Hadron Collider at CERN for luminosities in excess of 10**34/cm2/s or other high-rate applications.Comment: 12 pages, 13 figure

Association between clinical presentation, biogroups and virulence attributes of Yersinia enterocolitica strains in human diarrhoeal disease

Traditionally the enteric pathogen Yersinia enterocolitica has been differentiated into biogroups. Despite being considered as non-pathogenic, biogroup 1A isolates have constituted a sizeable fraction of strains from patients with gastroenteritis in many reports. To establish a potential clinical significance for biogroup 1A isolates of Y. enterocolitica, clinical disease in patients with gastroenteritis excreting such isolates was compared with symptoms among patients found infected with pathogenic biogroups. Clinical data and isolates of 66 patients from whom Y. enterocolitica had been isolated by direct plating were available for study. There was an association between patient age below 3 years and infection with ‘pathogenic' Y. enterocolitica. The severity of gastroenteritis and other symptoms, however, did not depend on the biogroup, or the presence of the virulence plasmid in the yersinia strain isolated from the patients. Strains belonging to biogroup 1A of Y. enterocolitica showed two clusters of ribotypes, one of which encompassed most isolates recovered from humans, the other being associated with environmental isolates. This might indicate the existence of human-adapted and potentially pathogenic strains among biogroup 1A of Y. enterocolitic

Association between clinical presentation, biogroups and virulence attributes of Yersinia enterocolitica strains in human diarrhoeal disease

Traditionally the enteric pathogen Yersinia enterocolitica has been differentiated into biogroups. Despite being considered as non-pathogenic, biogroup 1A isolates have constituted a sizeable fraction of strains from patients with gastroenteritis in many reports. To establish a potential clinical significance for biogroup 1A isolates of Y. enterocolitica, clinical disease in patients with gastroenteritis excreting such isolates was compared with symptoms among patients found infected with pathogenic biogroups. Clinical data and isolates of 66 patients from whom Y. enterocolitica had been isolated by direct plating were available for study. There was an association between patient age below 3 years and infection with ‘pathogenic’ Y. enterocolitica. The severity of gastroenteritis and other symptoms, however, did not depend on the biogroup, or the presence of the virulence plasmid in the yersinia strain isolated from the patients. Strains belonging to biogroup 1A of Y. enterocolitica showed two clusters of ribotypes, one of which encompassed most isolates recovered from humans, the other being associated with environmental isolates. This might indicate the existence of human-adapted and potentially pathogenic strains among biogroup 1A of Y. enterocolitica

Discrimination of Helicobacter pullorum and Campylobacter lari by analysis of whole cell fatty acid extracts

Helicobacter pullorum and Campylobacter lari are rarely isolated from humans with acute enteritis. Hitherto the two species could only be identified by genotypic techniques. Gas liquid chromatography of whole cell fatty acid extracts is described as the first phenotypic method for discrimination of the two species. Cholesteryl glucoside, a characteristic feature of the genus Helicobacter, but seldom found in other bacteria, could not be detected in Helicobacter pullorum. Therefore, rapid determination of this glycolipid may serve as a discrimination marker for Helicobacter pullorum from most other Helicobacter species

Discrimination of Helicobacter pullorum and Campylobacter lari by analysis of whole cell fatty acid extracts

Helicobacter pullorum and Campylobacter lari are rarely isolated from humans with acute enteritis. Hitherto the two species could only be identified by genotypic techniques. Gas liquid chromatography of whole cell fatty acid extracts is described as the first phenotypic method for discrimination of the two species. Cholesteryl glucoside, a characteristic feature of the genus Helicobacter, but seldom found in other bacteria, could not be detected in Helicobacter pullorum. Therefore, rapid determination of this glycolipid may serve as a discrimination marker for Helicobacter pullorum from most other Helicobacter specie

Genetic relationships among strains of Salmonella enteritidis in a national epidemic in Switzerland

A collection of Salmonella enteritidis strains isolated in Switzerland (1965-90) was characterized. The phage type and plasmid profile of isolates were compared with the copy number and insertion loci of the DNA insertion element IS200. Three clonal lines of S. enteritidis were identified by IS200 profile; the various phage types were subtypes reproducibly associated with one of these lines. All human and poultry isolates contained a 38 Mda plasmid which hybridized with a mouse virulence-associated gene probe. In S. enteritidis, the IS200 profile is a race-specific molecular marker of the chromosome, and may be particularly applicable for studying the epidemiology of less common serovar

Restriction fragment length polymorphisms among the flagellar genes of the Lior heat-labile serogroup reference strains and field strains of Campylobacter jejuni and C. coli

Several typing systems have been described for Campylobacter jejuni and C. coli, to assess the complex epidemiology of these important enteric pathogens. In the present study two typing methods, slide agglutination according to the Lior scheme, and the demonstration of restriction-fragment length polymorphisms (RFLP) of flagellar genes, have been used in parallel on a set of 194 strains. This set comprised 118 sero-reference strains of C. jejuni and C. coli of the Lior scheme, as well as 76 clinical isolates. All isolates were serotyped and subjected to PCR for amplification of flagellar genes, and the PCR product was restricted with Alu I. Flagellar genes could be amplified in 152 strains. Among 85 seroreference strains, 74 different RFLP patterns were observed, and among 67 clinical isolates, there were 36 patterns. There was only limited correlation between flagellar RFLP and the Lior serogroup, and the variability of patterns in serogroups HL2 and HL4 were as marked as the variability between serogroups. Flagellar gene RFLP patterns are shown to be stable, highly discriminatory epidemiologic marker