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M Altwegg

Publications and source records attributed to M Altwegg.

At least 55 records · Page 3Linked to original sources
PubMed1999

Diagnosis of Cardiobacterium hominis endocarditis by broad-range PCR from arterio-embolic tissue.

A case of culture-negative endocarditis is reported, in which the diagnosis of Cardiobacterium hominis endocarditis was made from arterio-embolic tissue removed by percutaneous transluminal embolectomy by broadrange polymerase chain reaction amplification of the 16 rRNA gene, followed by single-strand sequencing. The use of this technique to identify etiologic agents from arterio-embolic material has not been reported so far. A serologic assay employing complement fixation against a crude antigen of Cardiobacterium hominis confirmed the diagnosis of endocarditis caused by this unusual fastidious etiologic agent.

Adult↗
PubMed1999

Duke criteria-negative endocarditis caused by Bartonella quintana.

Bartonella spp. were recently recognized as causative agents of culture-negative endocarditis. Molecular techniques, such as broad-range PCR, are now available to detect fastidious or slow-growing microorganisms, or those which cannot be cultured. Such microorganisms may be responsible for culture-negative endocarditis. Alcoholism and homelessness are known risk factors for Bartonella quintana endocarditis, even in patients without previous valvular disease. We report a case of B. quintana endocarditis diagnosed by PCR amplification on the excised heart valve, in a young non-alcoholic and immunocompetent patient with few clinical signs of infection who did not fulfill the Duke criteria.

Adult↗
PubMed1999

Influence of residual uracil-DNA glycosylase activity on the electrophoretic migration of dUTP-containing PCR products.

In diagnostic amplification protocols contamination by previously amplified nucleic acids is considered the major source of false positive results. Substituting dUTP for dTTP in the PCR and initial treatment with uracil-DNA glycosylase (UNG) virtually eliminates these carryover contaminations. Subsequent procedures to visualize the amplicons or to optimize sensitivity and specificity of the test are not always fully compatible with UNG-treated PCR products. Here we describe the more pronounced influence of residual UNG activity on the migration of PCR amplification products in polyacrylamide as compared to agarose gels.

DNA Glycosylases↗
PubMed1999

Detection of three different types of 'Tropheryma whippelii' directly from clinical specimens by sequencing, single-strand conformation polymorphism (SSCP) analysis and type-specific PCR of their 16S-23S ribosomal intergenic spacer region.

The 16S-23S rDNA intergenic spacer region of organisms identical with or closely related to 'Tropheryma whippelii', the uncultivated causative agent of Whipple's disease, was analysed directly from 38 clinical specimens of 28 patients using a specific nested PCR followed by direct sequencing. As compared to the reference sequence in public databases, two novel 'T. whippelii' spacer types were recognized. In the absence of DNA-DNA hybridization data it is uncertain whether the three types found represent subtypes of a single species or three different but closely related species. Methods were developed to detect all three variants by single-strand conformation polymorphism analysis and by type-specific PCR assays, thus allowing the screening of large numbers of specimens. Further studies may provide a clue to the possible associations between the type of infecting strain and the various clinical presentations of Whipple's disease.

Actinobacteria↗
PubMed1999

Homogeneity of 16S-23S ribosomal intergenic spacer regions of Tropheryma whippelii in Swiss patients with Whipple's disease.

The current genetic strategies used to identify Tropheryma whippelii, the putative agent of Whipple's disease, are based on PCR-mediated amplification of a part of its 16S rRNA gene (16S rDNA). Because there is very little intraspecies variation in these molecules, they are not suitable as targets for epidemiologic investigations. However, the intergenic spacer region between the 16S and 23S rDNAs is usually much more variable and has repeatedly been used for epidemiologic purposes. We have therefore amplified the spacer region of T. whippelii directly from clinical specimens from nine independent Swiss patients with Whipple's disease by PCR with primers complementary to the 3' and 5' ends of the 16S and 23S rDNAs, respectively. The amplicons were directly sequenced and the sequences were compared to the T. whippelii reference sequence in GenBank/EMBL (accession no. X99636). Complete sequence homogeneity was found between the samples from our nine patients; the spacer sequence was also identical to the reference sequence. However, the sequences corresponding to the 3' and 5' ends of the 16S and the 23S rDNAs of T. whippelii, respectively, differed from the respective sequences in GenBank/EMBL. The same sequence found in our patients was then found in a sample from the German patient from which the published sequence had been derived. We conclude that the 16S-23S rDNA spacer region seems to be very conserved in T. whippelii and that the respective reference entry in public databases should be revised.

Actinobacteria↗
PubMed1999

Detection of Bartonella henselae DNA by two different PCR assays and determination of the genotypes of strains involved in histologically defined cat scratch disease.

Cat scratch disease (CSD) is a common cause of subacute regional lymphadenopathy, not only in children but also in adults. Serological and molecular studies demonstrated that Bartonella henselae is the etiologic agent in most cases of CSD. Amplification of B. henselae DNA in affected tissue and detection of antibodies to B. henselae are the two mainstays in the laboratory diagnosis of CSD. We designed a retrospective study and investigated formalin-fixed, paraffin-embedded lymph nodes from 60 patients (25 female, 35 male) with histologically suspected CSD by PCR amplification. The sensitivities of two different PCR assays were compared. The first primer pair amplified a 296-bp fragment of the 16S rRNA gene in 36 of the 60 samples, corresponding to a sensitivity of 60%. The second primer pair amplified a 414-bp fragment of the htrA gene in 26 of the 60 lymph nodes, corresponding to a sensitivity of 43.3%. Bartonella DNA could be detected in a total of 39 (65%) of the 60 lymph nodes investigated. However, histopathologic findings are typical but not specific for CSD and cannot be considered as a "gold standard" for diagnosis of CSD. The sensitivity of the PCR assays increased from 65 to 87% if two criteria (histology and serology) were used in combination for diagnosis of CSD. Two genotypes (I and II) of B. henselae are described as being involved in CSD. Genotype I was found in 23 (59%) and genotype II was found in 9 (23%) of the 39 PCR-positive lymph nodes. Seven (18%) lymph nodes were negative in both type-specific PCR assays. Thirty (50%) of our 60 patients were younger than 20 years old (15 were younger than 10 years), 20 (33%) were between 21 and 40 years old, and 10 (17%) patients were between 41 and 84 years old. Our data suggest that detection of Bartonella DNA in patients' samples might confirm the histologically suspected diagnosis of CSD.

Adolescent↗
PubMed1999

Septicemia caused by dysgonic fermenter 3 in a severely immunocompromised patient and isolation of the same microorganism from a stool specimen.

Dysgonic fermenter 3 (DF-3)-associated bacteremia occurred in a febrile patient with acute myelocytic leukemia during aplasia. Another DF-3 isolate, identical by ribotyping, was grown 10 weeks later from stool collected in the absence of diarrhea. This is the first case in which DF-3 was isolated from blood and stool specimens from the same patient.

Bacteremia↗
PubMed1999

Relapsing Whipple's disease presenting with hypopituitarism.

A 44-year-old man with a history of Whipple's disease 8 years ago presented with recurrent grand mal seizures and signs of hypopituitarism on physical examination. Magnetic resonance imaging of the brain revealed a hypothalamic lesion of 1 cm diameter in the region of the rostral infundibulum. Hypopituitarism was confirmed by low levels of serum cortisol, free testosterone and free thyroxine without an elevated TSH. Whipple encephalitis with hypothalamic involvement was suggested and verified by positive polymerase chain reaction (PCR) for Tropheryma whippelii in the cerebrospinal fluid. PCR for T. whippelii has become an important diagnostic tool for establishing the diagnosis of Whipple's disease especially in patients with unusual presentations and if the diagnosis cannot be confirmed histologically. Whipple's disease should be included in the differential diagnosis in hypopituitarism caused by infectious disease.

Actinobacteria↗
PubMed1998

An outbreak of nontoxigenic Corynebacterium diphtheriae infection: single bacterial clone causing invasive infection among Swiss drug users.

From 1990 to 1996, a total of 65 patients from whom Corynebacterium diphtheriae had been isolated were reported to the Swiss Federal Office of Public Health. A retrospective review of medical and microbiological records as well as results of ribotyping of available isolates was performed. Twenty-seven patients had acquired their infection without evidence of use of illicit drugs, mostly as a skin infection imported from subtropical areas (20 patients); 38 isolations were associated with intravenous drug use (IVDU) (skin, 15; respiratory tract, 10; blood, 13). Endocarditis was documented in nine patients with bloodstream infection, four of whom died. There were two additional deaths due to overwhelming sepsis. The same ribotype of nontoxigenic C. diphtheriae was found in 31 of the 32 examined isolates associated with IVDU. All non-IVDU isolates had different ribotypes. Among Swiss drug users, a single clone of nontoxigenic C. diphtheriae was found over a period of several years with a high potential to cause severe invasive infection.

Bacteremia↗
PubMed1997

[Molecular biology detection and antibiotic sensitivities of Shigella spp. and entero-invasive Escherichia coli (EIEC) in patients returning from the tropics].

1579 stool samples from patients with travel-associated diarrhea were examined by conventional culture methods to detect Shigella spp. (48 positive samples or 3.2%) and by PCR to detect shigellae and enteroinvasive Escherichia coli (EIEC) (87 positive samplers or 5.8%). The numerical relation of shigellae to EIEC in PCR-positive samples was about 60 to 40%. However, the lack of discrimination between shigellae and EIEC is not important for the physician because the choice of antibiotics remains the same.

Diarrhea↗
PubMed1997

Deactivation of macrophages with interleukin-4 is the key to the isolation of Tropheryma whippelii.

Whipple's disease is a systemic illness caused by a specific agent. Despite recognition of bacteria in lesions, efforts to isolate the causative agent remained futile. A novel strategy was devised to culture Whipple bacilli in deactivated mononuclear phagocytes. Infected tissue was inoculated into human phagocytes deactivated with interleukin (IL)-4, IL-10, and dexamethasone. Within 8-10 days, diastase-resistant periodic acid-Schiff-positive inclusions appeared, corresponding to intact and degenerating bacteria shown to be Tropheryma whippelii by electron microscopy and molecular analyses. T. whippelii was passaged several times in deactivated monocytes and a monoblastic cell line. Time-kinetics growth studies and comparative polymerase chain reaction analysis documented multiplication of T. whippelii in deactivated macrophages. Complementary studies showed that IL-4 rendered phagocytes permissive for T. whippelii, a strong indication that host factors contribute to the pathogenesis of Whipple's disease. The propagation of T. whippelii will permit microbiologic, immunologic, seroepidemiologic, and therapeutic studies of this pathogen.

Actinobacteria↗
PubMed1997

Inclusion of Aeromonas DNA hybridization group 11 in Aeromonas encheleia and extended descriptions of the species Aeromonas eucrenophila and A. encheleia.

The recently reported chemotaxonomic and genotypic description of two well-separated subgroups (I and II) in Aeromonas eucrenophila and their affiliation to Aeromonas encheleia and the unnamed Aeromonas DNA hybridization group (HG) 11 (G. Huys, M. Altwegg, M.-L. Hänninen, M. Vancanneyt, L. Vauterin, R. Coopman, U. Torck, J. Lüthy-Hottenstein, P. Janssen, and K. Kersters, Syst. Appl. Microbiol. 19:616-623, 1996) has questioned the original species descriptions of A. eucrenophila and A. encheleia. In order to elucidate the unclear taxonomic status of these taxa in the genus Aeromonas, we have further investigated a collection of 14 reference strains and 14 related isolates encompassing the taxa A. eucrenophila subgroups I and II, A. encheleia, and HG11 by DNA-DNA hybridization (on 17 of the 28 strains) and phenotypic characterization (on all 28 strains). Genotypically, the investigated strains could be grouped into two DNA hybridization groups that exhibited between-group homologies ranging from 42 to 52%. The members of DNA homology group I (DNA binding, 76 to 100%) were strains of A. eucrenophila subgroup I, including the type strain LMG 3774, and two A. eucrenophila-like isolates, leading to the conclusion that these strains should be considered true representatives of the species A. eucrenophila. The strains of A. eucrenophila subgroup II, HG11, and A. encheleia, on the other hand, were closely joined in DNA homology group II (DNA binding, 74 to 105%) together with two presumptive A. encheleia isolates. The fact that strain LMG 16330T of A. encheleia was the only type strain residing in DNA homology group II implies that HG11 and A. eucrenophila subgroup II should be classified in the species A. encheleia. Except for the somewhat aberrant phenotypic positions of HG11 strains LMG 13075 and LMG 13076, the establishment of DNA homology groups I and II was supported by the delineation of phena 1 and 2 (level of correlation, 90%), respectively, as revealed by numerical analysis of 136 phenotypic test results. These data indicate that A. eucrenophila and A. encheleia are phenotypically highly related but can be easily separated by testing the production of acid from D-cellobiose and lactose and the assimilation of D-cellobiose. Extended descriptions of both species are given.

Aeromonas↗
PubMed1997

Aeromonas popoffii sp. nov., a mesophilic bacterium isolated from drinking water production plants and reservoirs.

We examined the taxonomic position of seven Aeromonas isolates, recovered from Flemish and Scottish drinking water production plants and reservoirs, which were previously recognized by numerical analysis of genomic AFLP fingerprints as members of an unknown Aeromonas taxon that most closely resembled the species Aeromonas bestiarum (DNA hybridization group [HG] 2). The new phenotypic and DNA-DNA hybridization data obtained in this study show that the A. bestiarum-like strains constitute a separate Aeromonas species, for which the name Aeromonas popoffii sp. nov. is being proposed. The new species exhibited an internal DNA relatedness ranging from 79 to 100% and was 22 to 63% related to the type or reference strains of other Aeromonas spp. The highest DNA binding values were determined with A. bestiarum (51 to 63%), followed by Aeromonas hydrophila sensu stricto (HG1; 50 to 60%) and Aeromonas salmonicida (HG3; 39 to 55%). Although fingerprints generated by ribotyping and cellular fatty acid analysis often were highly similar, minor differences between the respective fingerprints were of significance for the differentiation of A. popoffii from its closest taxonomic neighbors, HG1, HG2, and HG3. Phenotypically, all seven strains of A. popoffii were positive for acid and gas production from D-glucose and glycerol, growth in KCN broth, arginine dihydrolase, DNase, Voges-Proskauer reaction, and resistance to vibriostatic agent O/129 and ampicillin but displayed negative reactions for production of urease, tryptophan deaminase, ornithine decarboxylase, and lysine decarboxylase (LDC). None of the strains displayed strong hemolytic activity. The lack of D-sucrose fermentation and LDC production and the ability to utilize DL-lactate as the sole energy and carbon source were useful characteristics for the biochemical separation of A. popoffii from A. bestiarum. Other Aeromonas spp. could be differentiated phenotypically from the new species by at least two features. The chromosomal G+C content of A. popoffii ranges from 57.7 to 59.6 mol%. Strain LMG 17541 is proposed as the type strain.

Aeromonas↗
PubMed1997

Molecular diagnosis of bacterial endocarditis by broad-range PCR amplification and direct sequencing.

Broad-range PCR amplification of part of the 16S rRNA gene followed by single-strand sequencing was applied to samples of 18 resected heart valves from patients with infective endocarditis. The PCR results were compared with those of cultures of valves and with those of previous blood cultures. For two patients there was agreement with the cultures of the valves; for nine patients there was agreement with the previous blood cultures, which were positive, while the cultures of the valves were negative; a Streptococcus sp. and Tropheryma whippelii each were found in one patient with negative cultures (valve and blood); for two patients the cultures of the valves as well as the PCR results were negative but the blood cultures were positive; for one patient amplification was inhibited; and for two patients the PCR results were positive but the amplicons could not be sequenced. It is concluded that broad-range PCR is a promising tool for patients with culture-negative endocarditis and allows the detection of rare, noncultivable organisms.

Actinobacteria↗
PubMed1997

Lethal maternal sepsis caused by Campylobacter jejuni: pathogen preserved in placenta and identified by molecular methods.

Campylobacter jejuni is one of the most common organisms in the etiology of febrile diarrhea. Bacteremia is reported to be rare. In pregnant women, however, C. jejuni (previous name, Vibrio fetus) can cause fetal death. We report the case of a pregnant woman with enterocolitis and sepsis that caused the death of the fetus and, 11 days later, the death of the mother. C. jejuni was detected by culture techniques at the time of the first symptoms but not during the subsequent course of disease. Bacteria were detected by silver staining and electron microscopic examination in the placenta, but for identification, we used molecular methods. From formalin-fixed, paraffin-embedded placental tissues, a part of the bacterial 16S rRNA was amplified by broad-range polymerase chain reaction, which resulted in a 461-nucleotide sequence. Direct sequencing and comparison to reference sequences revealed C. jejuni as the causative agent for the sepsis and deaths. With this approach, the adverse outcome could be related etiologically to the same infectious agent identified at the onset of the disease. From this and other recent reports, we conclude that C. jejuni must be considered an important pathogen in pregnancy.

Adult↗
PubMed1996

Spondylodiscitis caused by Tropheryma whippelii.

We describe the first case of spondylodiscitis caused by Tropheryma whippelii in which this so far unculturable organism was shown to be present at the site of infection in a patient without significant gastrointestinal symptoms. The methods used included broad-range PCR amplification with universal primers complementary to constant sequences of the gene coding for 16S rRNA, direct sequencing of the amplified fragment, and comparison of the sequence determined with those deposited in sequence databases. In addition to demonstrating the presence of this organism in the affected vertebral body, we found in our patient that the specific PCR is more sensitive than histology for detecting Whipple's bacilli in bowel biopsy specimens. Because histology of small bowel biopsies from the duodenum were-in contrast to PCR from the same site-not diagnostic for Whipple's disease in our patient, we recommend PCR whenever Whipple's disease has to be excluded.

Actinobacteria↗