Search results for "Chain reaction"
showing 10 items of 1862 documents
Infection with cagA -Positive and cagA -Negative Types of Helicobacter pylori Among Children and Adolescents with Gastrointestinal Symptoms in Latvia
2003
In order to determine the prevalence of concomitant cagA-positive and cagA-negative Helicobacter pylori genotypes in individual subjects, a group of 56 symptomatic patients (aged 8-18 years) was studied. Among 31 patients culture-positive for Helicobacter pylori, only cagA-positive colonies were isolated from 18 patients, both cagA-positive and cagA-negative genotypes were isolated from 4 patients, and in 9 patients all of the individual colonies isolated were cagA-negative, but in seven of them a pool of colonies was positive for cagA. Thus, the presence of both cagA-positive and cagA-negative genotypes in the same individual was identified in 11 of the 31 culture-positive patients tested,…
Borrelia miyamotoi is widespread in Ixodes ricinus ticks in southern Norway.
2015
From April to October 2007, host-seeking Ixodes ricinus ticks were collected from four locations in southern Norway; Farsund, Mandal, Sogne and Tromoy, respectively. Larvae (n=210), nymphs (n=1130) and adults (n=449) were investigated for infection with Borrelia miyamotoi by real-time polymerase chain reaction (PCR) amplification of part of the 16S rRNA gene. Results were verified by direct sequencing of the PCR amplicon generated from the rrs (16S)-rrl (23S) intergenetic spacer. B. miyamotoi was detected at all sites and throughout the period of questing activity, with infection prevalence (≤1.26%) similar to what has been seen in other European countries. Detection of the relapsing fever …
PCR testing for Treponema pallidum in paraffin-embedded skin biopsy specimens: test design and impact on the diagnosis of syphilis
2007
Background: Syphilis, a chronic infection caused by Treponema pallidum (T. pallidum), is a disease which is increasing in incidence, and thus more and more becoming a differential diagnosis in routine pathology. Aim: Since histological changes are not specific, we sought to develop a polymerase chain reaction (PCR)-based molecular assay for the detection of T. pallidum in formalin-fixed, paraffin-embedded tissues, and evaluate its diagnostic power, especially in comparison with other ancillary methods, i.e. immunohistochemistry and Dieterle staining. Methods: 36 skin biopsies with the clinical and /or serological diagnosis of syphilis were evaluated by morphology, immunohistochemistry and s…
The incidence of influenza-associated hospitalizations in children in Germany
2002
Since new vaccines and anti-viral drugs for influenza have become available, collation of actual and country-specific epidemiological data is essential. Since respiratory syncytial virus (RSV) is a well known paediatric airway pathogen and some epidemiological data exist already, a comparison between influenza and RSV seems warranted. From July 1996 to June 2001 the naso-pharyngeal aspirates (NPA) of children from birth to 16 years of age, admitted to one of the two paediatric hospitals in Kiel, Germany, were investigated by a nine-valent multiplex reverse transcriptase PCR assay. NPA were investigated in 60·8% of 3469 children admitted with an acute respiratory tract infection. Community-a…
pilF polymorphism-based PCR to distinguish Vibrio vulnificus strains potentially dangerous to public health
2010
ABSTRACT Vibrio vulnificus is a heterogeneous species that comprises strains virulent and avirulent for humans and fish, and it is grouped into three biotypes. In this report, we describe a PCR-based methodology that allows both the species identification and discrimination of those isolates that could be considered dangerous to public health. Discrimination is based on the amplification of a variable region located within the gene pilF , which seems to be associated with potential human pathogenicity, regardless of the biotype of the strain.
Cloning and characterization of the genes encoding the malolactic enzyme and the malate permease of Leuconostoc oenos
1996
Using degenerated primers from conserved regions of the protein sequences of malic enzymes, we amplified a 324-bp DNA fragment by PCR from Leuconostoc oenos and used this fragment as a probe for screening a Leuconostoc oenos genomic bank. Of the 2,990 clones in the genomic bank examined, 7 with overlapping fragments were isolated by performing colony hybridization experiments. Sequencing 3,453 bp from overlapping fragments revealed two open reading frames that were 1,623 and 942 nucleotides long and were followed by a putative terminator structure. The first deduced protein (molecular weight, 59,118) is very similar (level of similarity, 66%) to the malolactic enzyme of Lactococcus lactis; …
dltA overexpression: A strain-independent keystone of daptomycin resistance in methicillin-resistant Staphylococcus aureus
2013
The mechanisms leading to reduced susceptibility to daptomycin (DAP) are multifactorial and have not been fully elucidated. We analysed, by sequencing and expression studies, the role of the major molecular targets (cell-envelope charge genes, dltA, mprF, cls2; cell-wall turnover and autolysis genes, sceD, atl) involved in the emergence of DAP resistance in three series of isogenic clinical methicillin-resistant Staphylococcus aureus (MRSA) in which DAP resistance emerged after a heterogeneous glycopeptide-intermediate S. aureus (hGISA) step under teicoplanin and DAP therapy. All of the isolates had different genotypes and were delta-haemolysin negative, reflecting a strain proclivity to ac…
Quantification of a novel group of nitrate-reducing bacteria in the environment by real-time PCR
2004
Abstract Nitrate reduction is performed by phylogenetically diverse bacteria. Analysis of narG (alpha subunit of the membrane bound nitrate reductase) trees constructed using environmental sequences revealed a new cluster that is not related to narG gene from known nitrate-reducing bacteria. In this study, primers targeting this as yet uncultivated nitrate-reducing group were designed and used to develop a real-time SYBR® Green PCR assay. The assay was tested with clones from distinct nitrate-reducing groups and applied to various environmental samples. narG copy number was high ranging between 5.08×108 and 1.12×1011 copies per gram of dry weight of environmental sample. Environmental real-…
Identification of a clone of Escherichia coli O103:H2 as a potential agent of hemolytic-uremic syndrome in France
1993
In a French multicenter study, six verocytotoxin-producing Escherichia coli strains were isolated from the stools of 6 of 69 children suffering from hemolytic-uremic syndrome. All strains belonged to serotype O103:H2, a serotype commonly associated with diarrhea in weaned rabbits in France. To determine whether the strains from humans and rabbits were genetically related, they were compared by analyzing their esterase electropherotypes and the restriction fragment length polymorphisms of the ribosomal DNA regions. A common clonal origin of these pathogenic strains was suggested by their identical esterase electropherotypes and their identical ribotypes, in addition to their identical seroty…
Comparison of two PCR methods for detection of Leptospira interrogans in formalin-fixed and paraffin-embedded tissues
2012
In this study we compared two polymerase chain reaction (PCR) methods using either 16S ribosomal RNA (rRNA) or 23S rRNA gene primers for the detection of different Leptospira interrogans serovars. The performance of these two methods was assessed using DNA extracted from bovine tissues previously inoculated with several bacterial suspensions. PCR was performed on the same tissues before and after the formalin-fixed, paraffin-embedding procedure (FFPE tissues). The 23S rDNA PCR detected all fresh and FFPE positive tissues while the 16S rDNA-based protocol detected primarily the positive fresh tissues. Both methods are specific for pathogenic L. interrogans. The 23S-based PCR method successfu…