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M Altwegg

Publications and source records attributed to M Altwegg.

At least 37 records · Page 2Linked to original sources
PubMed2001

Recurrent soft tissue abscesses caused by Legionella cincinnatiensis.

Recurrent soft tissue abscesses of the jaw, wrist, and arm developed in a 73-year-old housewife with nephrotic syndrome and immunoglobulin A(kappa) gammopathy of unknown etiology. Conventional cultures remained negative, despite visible gram-negative rods on microscopy. Broad-spectrum PCR revealed Legionella cincinnatiensis, which was confirmed by isolation of the organism on special Legionella medium. Infections due to Legionella species outside the lungs are rare. L. cincinnatiensis has been implicated in only four cases of clinical infection; these involved the lungs in three patients and the central nervous system in one patient. We conclude that broad-spectrum PCR can be a valuable tool for the evaluation of culture-negative infections with a high probability of bacterial origin and that Legionella might be an underdiagnosed cause of pyogenic soft tissue infection.

Abscess↗
PubMed2001

Quantitative detection of Streptococcus pneumoniae in nasopharyngeal secretions by real-time PCR.

Streptococcus pneumoniae is an important cause of community-acquired pneumonia. However, in this setting the diagnostic sensitivity of blood cultures is below 30%. Since during such infections changes in the amounts of S. pneumoniae may also occur in the upper respiratory tract, quantification of these bacteria in nasopharnygeal secretions (NPSs) may offer a suitable diagnostic approach. Real-time PCR offers a sensitive, efficient, and routinely reproducible approach to quantification. Using primers and a fluorescent probe specific for the pneumolysin gene, we were able to detect DNA from serial dilutions of S. pneumoniae cells in which the quantities of DNA ranged from the amounts extracted from 1 to 10(6) cells. No difference was noted when the same DNA was mixed with DNA extracted from NPSs shown to be deficient of S. pneumoniae following culture, suggesting that this bacterium can be detected and accurately quantitated in clinical samples. DNAs from Haemophilus influenzae, Moraxella catarrhalis, or alpha-hemolytic streptococci other than S. pneumoniae were not amplified or were only weakly amplified when there were > or =10(6) cells per reaction mixture. When the assay was applied to NPSs from patients with respiratory tract infections, the assay performed with a sensitivity of 100% and a specificity of up to 96% compared to the culture results. The numbers of S. pneumoniae organisms detected by real-time PCR correlated with the numbers detected by semiquantitative cultures. A real-time PCR that targeted the pneumolysin gene provided a sensitive and reliable means for routine rapid detection and quantification of S. pneumoniae present in NPSs. This assay may serve as a tool to study changes in the amounts of S. pneumoniae during lower respiratory tract infections.

Bacterial Proteins↗
PubMed2000

[Whipple's disease with normal intestinal histology: rarity or reality?].

Whipple's disease has been diagnosed more frequently in recent years as a consequence of better awareness and of improved diagnostic tools. The number of case reports of Whipple's disease without gastrointestinal symptoms and without histological lesions of the intestinal mucosa is increasing. Therefore, the traditional perception of this disease as well as the methods for its diagnosis need to be revised. We report on 2 patients with Whipple's disease who had systemic inflammatory reactions but neither gastrointestinal symptoms nor an abnormal duodenal histology. Whipple's disease was diagnosed on the basis of extraintestinal tissue histology (lymph node, vertebral body) and by polymerase chain reaction, and was treated successfully with antibiotics. Recommendations for diagnostic procedure in Whipple's disease with both typical and atypical clinical presentation are discussed.

Anti-Bacterial Agents↗
PubMed2000

Intestinal infection due to enteroaggregative Escherichia coli among human immunodeficiency virus-infected persons.

To investigate the pathogenic role of enteroaggregative Escherichia coli (EAggEC) among human immunodeficiency virus-infected persons, 111 outpatients with and 68 without diarrhea were evaluated. Examination of stool samples included the HeLa cell adherence assay and an EAggEC polymerase chain reaction (PCR) assay using primers complementary for the plasmid locus CVD432. The pCVD432 genotype, adherence phenotype, and patient characteristics were correlated with occurrence of diarrhea by multivariate analyses. EAggEC PCR and adherence assays were positive in 7 (6%) and 24 (22%) patients with diarrhea and in 1 (1%) and 21 (31%) asymptomatic control patients, respectively. Clinical manifestations associated with EAggEC PCR-positive isolates were nonspecific; EAggEC infections were independent of CD4 lymphocyte counts. Of the pCVD432 genotype, 5 (71%) of 7 were resistant to cotrimoxazole and ampicillin, and 1 strain was resistant to ciprofloxacin. Overall, pCVD432 PCR-positive E. coli was the most prevalent intestinal organism associated with diarrhea. The adherence assay results did not correlate with diarrhea.

Adult↗
PubMed2000

[The value of bronchoalveolar lavage in the clarifying of HIV-associated lung diseases].

BACKGROUND AND OBJECTIVE: Examination of sputum is the first diagnostic step in the evaluation of HIV-infected patients with pulmonary complications. We were interested in the indications and the diagnostic value of subsequent bronchoscopy and bronchoalveolar lavage (BAL) and especially the importance of so-called atypical bacteria. PATIENTS AND METHODS: We analysed 59 consecutive BALs performed in HIV positive patients with pulmonary symptoms (48 men, 11 women, age 22-70 years, 36 in stage C). Culture for Legionella pneumophila and PCR analysis for Mycoplasma pneumoniae and Chlamydia pneumoniae were done in all cases. RESULTS: In 50 patients (85%) there was a clear indication for performing a BAL because either an infectious agent could no be detected on sputum examination (n = 36), or the patient's sputum production was insufficient (n = 14). In 30 (60%) of these cases bronchoscopy and BAL were able to establish a diagnosis. The most frequent agent was Pneumocystis carinii (n = 12). In contrast, BAL was able to establish coinfection in patients with positive sputum samples in one case only. So-called atypical bacteria were not found. CONCLUSION: In patients with a clear indication, especially a non-diagnostic sputum examination, BAL plays an important role in the work-up of HIV-associated pulmonary disease. The search for so-called atypical bacteria yields unsatisfactory results.

AIDS-Related Opportunistic Infections↗
PubMed2000

Automated ribotyping and pulsed-field gel electrophoresis reveal a cluster of group A streptococci in intravenous drug abusers.

BACKGROUND: In 1998, an unexpected increase of group A streptococci (GAS) in blood cultures was observed at our institution. MATERIALS AND METHODS: To determine whether they were from unrelated sporadic cases or attributable to a common source, all isolates were analyzed by pulsed-field gel electrophoresis (PFGE) and by automated ribotyping. RESULTS: Two clusters were found. All isolates, except one, of cluster 2 had been isolated from intravenous drug abusers. CONCLUSION: All patients were hospitalized either in different hospitals or at different times in the same hospitals indicating that the putative common source is to be found in the drug community rather than in a particular hospital.

Adult↗
PubMed2000

Rapid detection of Mycoplasma pneumoniae in clinical samples by real-time PCR.

M. pneumoniae is a common causative agent of community-acquired pneumonia in children. The diagnosis of such infections is usually based on serology using complement fixation or, more recently, enzyme-immuno assays. PCR has been shown to be a promising alternative. We have evaluated a real-time PCR assay targeting the P1 adhesion protein gene and compared it to a conventional semi-nested PCR assay with the 16S rDNA as target. Comparison of 147 specimens from 48 patients showed an overall agreement of 97.4%. Real-time PCR proved to be of equal value on clinical specimens as conventional PCR regarding sensitivity and specificity, but is clearly advantageous regarding speed, handling and number of samples that can be analyzed per run.

Adolescent↗
PubMed2000

Genotypic characterization of Salmonella typhi by amplified fragment length polymorphism fingerprinting provides increased discrimination as compared to pulsed-field gel electrophoresis and ribotyping.

Amplified fragment length polymorphism (AFLP) is a recently developed, PCR-based high resolution fingerprinting method that is able to generate complex banding patterns which can be used to delineate intraspecific genetic relationships among bacteria. In the present study, AFLP was evaluated for its usefulness in the molecular typing of Salmonella typhi in comparison to ribotyping and pulsed-field gel electrophoresis (PFGE). Six S. typhi isolates from diverse geographic areas (Malaysia, Indonesia, India, Chile, Papua New Guinea and Switzerland) gave unique, heterogeneous profiles when typed by AFLP, a result which was consistent with ribotyping and PFGE analysis. In a further study of selected S. typhi isolates from Papua New Guinea which caused fatal and non-fatal disease previously shown to be clonally related by PFGE, AFLP discriminated between these isolates but did not indicate a linkage between genotype with virulence. We conclude that AFLP (discriminatory index=0.88) has a higher discriminatory power for strain differentiation among S. typhi than ribotyping (DI=0.63) and PFGE (DI=0.74).

DNA Fingerprinting↗
PubMed2000

Development and evaluation of a broad-range PCR-ELISA assay with Borrelia burgdorferi and Streptococcus pneumoniae as model organisms for reactive arthritis and bacterial meningitis.

We have developed an assay based on a 16S rDNA broad-range amplification system followed by species-specific detection with a commercially available PCR-ELISA kit. B. burgdorferi and S. pneumoniae were used as model systems for arthritis and meningitis, respectively. The sensitivity of the B. burgdorferi assay was comparable to that of a species-specific PCR, whereas for S. pneumoniae the detection limit was one to three organisms as determined by plate counts. To specifically differentiate two species, two discontinuously located nucleotide differences in the region complementary to the capture probe are required during the detection step with the PCR-ELISA kit. A preliminary clinical evaluation was performed with eight specimens (joint and cerebrospinal fluids) previously shown to contain B. burgdorferi DNA. Except for one sample which was positive by the broad-range PCR-ELISA system only, the results were in agreement with those obtained by B. burgdorferi species-specific PCR. None of the 23 control samples were positive by either method. Thus, broad-range amplification in combination with the PCR-ELISA kit promises to be a sensitive and specific format for the detection of agents causing reactive arthritis, meningitis or other diseases associated with a limited number of different bacteria.

Arthritis, Reactive↗
PubMed2000

Catalase-negative Actinomyces neuii subsp. neuii isolated from an infected mammary prosthesis.

In this case report a catalase-negative strain of Actinomyces neuii subsp. neuii is described as the possible causative agent of an infected mammary prosthesis. DNA hybridization studies and 16S rRNA analysis confirmed that the strain belongs to the species Actinomyces neuii subsp. neuii. Since this strain is the first A. neuii subsp. neuii strain reported to be catalase negative, the catalase reaction should no longer be considered a key reaction for the diagnosis of this species but must be interpreted in conjunction with other characteristics.

Actinomyces↗
PubMed2000

Analysis of the actinobacterial insertion in domain III of the 23S rRNA gene of uncultured variants of the bacterium associated with Whipple's disease using broad-range and 'Tropheryma whippelii'-specific PCR.

Heterogeneity in the 16S-23S rDNA spacer of uncultured 'Tropheryma whippelii' has previously been reported. In this study, the hypervariable insertion in the 23S rDNA domain III characteristic for actinobacteria was analysed. The finding of a unique sequence virtually identical among the subtypes supports the classification of 'T. whippelii' among the actinobacteria and the concept of three subtypes rather than three subspecies, and provides an alternative target for diagnostic assays.

Actinobacteria↗
PubMed2000

Evaluation of a specific nested PCR targeting domain III of the 23S rRNA gene of "Tropheryma whippelii" and proposal of a classification system for its molecular variants.

"Tropheryma whippelii"-associated infections are usually confirmed histopathologically by using light microscopy. PCR assays targeting the 16S rRNA gene (16S rDNA) of "T. whippelii" are increasingly being applied for this purpose. Compared to microscopic analysis, PCR seems to be more sensitive, as indicated by the fact that several cases of Whipple's disease with negative histopathological findings but positive PCR results have been reported. Considering the lack of pathognomonic clinical features for this disease and the fact that "T. whippelii" DNA has repeatedly been found in patients without clinical Whipple's disease, such PCR results should be confirmed by additional tests. We have, therefore, evaluated a "T. whippelii"-specific nested PCR targeting domain III of the 23S rDNA with 41 clinical specimens known to contain "T. whippelii" 16S rDNA. All of these specimens were also positive for "T. whippelii" 23S rDNA. The specificity of the test was shown by sequencing of the amplicons and by the absence of amplicons in 38 negative controls. We consider this PCR test to be a suitable tool for confirming the presence of "T. whippelii" DNA in specimens with inconclusive histopathological findings. The information derived from sequencing of the partial "T. whippelii" 23S rDNA was then combined with our recent data of the 16S-23S rDNA spacer region of this organism. Overall, four different rDNA types are recognized in our proposed classification system for molecular variants of "T. whippelii." This preliminary scheme may provide a basis for further epidemiological and clinical studies with "T. whippelii" and associated diseases.

Actinobacteria↗
PubMed2000

Cloning and sequencing of a part of the heat shock protein 65 gene (hsp65) of "Tropheryma whippelii" and its use for detection of "T. whippelii" in clinical specimens by PCR.

Using broad-spectrum primers, we have amplified, cloned, and sequenced a 620-bp fragment of the "Tropheryma whippelii" heat shock protein 65 gene (hsp65) from the heart valve of a patient with Whipple's endocarditis. The deduced amino acid sequence shows high similarity to those from actinobacteria, confirming that "T. whippelii" is indeed a member of this phylum. Based on the nucleotide sequence, we have developed a "T. whippelii"-specific seminested PCR. Seventeen patients shown to be positive by 16S ribosomal DNA (rDNA) PCR and/or internal transcribed spacer (ITS) PCR were also positive by hsp65 PCR. All 33 control specimens from patients without Whipple's disease and negative for "T. whippelii" by both seminested 16S rDNA and ITS PCR remained negative. All amplicons digested with XhoI revealed an identical restriction pattern. Eight of the 17 hsp65 amplicons representing all three previously described ITS types were sequenced. Three of the amplicons showed slight differences, but none of the mutations detected affected the amino acid sequence of the corresponding protein. We conclude that the hsp65 gene is a suitable target for the specific detection of "T. whippelii." Its product represents a putative antigen for a future serodiagnostic assay.

Actinobacteria↗
PubMed1999

Whipple endocarditis without overt gastrointestinal disease: report of four cases.

BACKGROUND: Cardiac manifestations of Whipple disease are rarely diagnosed before death. OBJECTIVE: To describe four patients with endocarditis caused by Tropheryma whippelii who did not have overt gastrointestinal disease. DESIGN: Case series. SETTING: Five hospitals in eastern Switzerland. PATIENTS: Three men and one woman undergoing replacement of insufficient heart valves. MEASUREMENTS: Histologic characteristics of heart valves and intestinal biopsy; broad-range and specific polymerase chain reaction for T. whippelii. RESULTS: Tropheryma whippelii was found in the heart valves (three aortic valves and one mitral valve) of four patients with culture-negative endocarditis necessitating valve replacement. All patients had arthralgia for different lengths of time. Only one patient had mild gastrointestinal symptoms. Histologic characteristics of intestinal mucosa were normal in all patients, and polymerase chain reaction on intestinal biopsy was positive for T. whippelii in only one patient, who did not have diarrhea. In all patients, arthralgia resolved promptly after institution of antibiotic therapy. Disease did not recur in any patient after prolonged antibiotic therapy with cotrimoxazole. CONCLUSION: In patients with culture-negative endocarditis, the absence of clinical, microscopic, or microbiological evidence of gastrointestinal disease did not rule out T. whippelii.

Actinobacteria↗
PubMed1999

Enteric infections and diarrhea in human immunodeficiency virus-infected persons: prospective community-based cohort study. Swiss HIV Cohort Study.

BACKGROUND: Persons infected with human immunodeficiency virus (HIV) are at increased risk for diarrhea and enteric infections. We studied (1) the epidemiology of enteric pathogens associated with diarrhea, (2) the diagnostic yield of stool examination and endoscopic evaluation, (3) risks to develop diarrhea, and (4) the impact of diarrhea on patients' survival. METHODS: A total of 1933 participants in the Swiss HIV Cohort Study were prospectively followed up for a median of 25.5 months. A total of 560 diarrheal episodes were evaluated by standardized stool examination. Endoscopic evaluation was performed in 25% of patients with chronic diarrhea. RESULTS: The incidence of diarrhea was 14.2 per 100 person-years (95% confidence interval, 13.0-15.4). Among patients with CD4 cell counts below 0.05 x 10(9)/L, the probability to develop diarrhea within 1, 2, and 3 years was 48.5%, 74.3%, and 95.6%, respectively. The risk to develop diarrhea was increased among patients with severe immunodeficiency, homosexual men, and patients taking antiretroviral therapy. Pneumocystis carinii chemoprophylaxis did not reduce the risk of diarrhea. Diarrhea was an independent negative predictor of survival. Enteric pathogens were detected in 16.5% of 212 acute diarrheal episodes and in 46% of 348 chronic diarrheal episodes. The sensitivity of histological and stool examination was similar except for the diagnosis of intestinal cytomegalovirus infection and leishmaniasis, which required invasive evaluation. CONCLUSIONS: Intestinal infections were diagnosed in less than 50% of chronic diarrheal episodes. The prevalence of enteric pathogens tended to decrease during the observation period, possibly because of improved antiretroviral therapy. Endoscopic evaluation did not improve the diagnostic yield compared with stool examination except for the diagnosis of cytomegalovirus enteritis and leishmaniasis.

AIDS-Related Opportunistic Infections↗