Biomedical subjects

S Katzwinkel-Wladarsch

Publications and source records attributed to S Katzwinkel-Wladarsch.

5 recordsLinked to original sources

PubMed1998

Strain differentiation in microsporidia.

Microsporidia are obligate intracellular, spore-forming protozoa and are regarded as newly emerging pathogens . Enterocytozoon spp. as well as Encephalitozoon spp. are recognized as major aetiological agents in chronic diarrhoea of immnunocompromised patients. The detection and differentiation of strains within microsporidial species is a prerequisite for the elucidation of their hitherto unknown reservoirs and their mode of transmission . In Enterocytozoon bieneusi, the most prevalent human-pathogenic microsporidium, 6 different genotypes of the internal transcribed spacer (ITS) of the rRNA gene are known so far, with 12 polymorphic sites . This pathogen has infrequently been detected in 2 animal hosts only, pigs and rhesus macaques, and only the genotype of the latter has also been found in a human patient, too. Encephalitozoon cuniculi has a wider confirmed spectrum of animal hosts, but only one polymorphic site is known in the ITS, differing in 3 different numbers of a tetranucleotide repeat. Therefore, further genomic targets may have to be characterized, too. Few data are available on strain differentiation in Encephalitozoon intestinalis and E. hellem.

Animals↗

PubMed1997

Comparison of polymerase chain reaction with light microscopy for detection of microsporidia in clinical specimens.

The detection of microsporidial DNA by the polymerase chain reaction (PCR) has been suggested as an alternative or supplement to conventional microscopic methods. However, the relative merits of these techniques remain uncertain. In the present study, clinical specimens of different origin (stool, urine, sputum, nasal discharge, and cerebrospinal fluid) containing four different microsporidial species were blinded after microscopic examination and analyzed by PCR and subsequent restriction fragment length polymorphism (RFLP) to determine the respective species. Thirty-four specimens from 31 patients were evaluated, 16 of which were positive and 18 negative by microscopic examination; PCR detection of microsporidia produced identical results in 82% (28/34) of these specimens. Four samples were microscopically negative, PCR-positive, and two were microscopically positive, PCR-negative. Species determination by RFLP analysis of the amplified product was accurate for all isolates containing Enterocytozoon bieneusi, Encephalitozoon intestinalis, Encephalitozoon hellem, and Encephalitozoon cuniculi compared with microscopic identification of the genus Enterocytozoon or molecular analysis of Encephalitozoon species after in vitro culture. Therefore, PCR-RFLP is useful for the rapid detection and differentiation of microsporidian spores in clinical specimens.

Animals↗

PubMed1997

Evidence for the existence of genetically distinct strains of Enterocytozoon bieneusi.

Enterocytozoon bieneusi is the most frequently found microsporidium in human infections. In all, 3 distinct genotypes were detected in 12 stool samples from 8 patients with acquired immunodeficiency syndrome (AIDS). A total of 9 polymorphic sites were found in the 243-bp-long internal transcribed spacer (ITS) of the rDNA gene, whereas none was found in 241 bp of adjacent rRNA coding regions. The genotype was stable in samples taken during 11 weeks of infection from one of the patients. The existence of and the ability to discriminate among strains of E. bieneusi are important prerequisites for elucidation of the hitherto unknown reservoirs of this pathogen and the mode of its transmission and may explain its pathogenicity.

AIDS-Related Opportunistic Infections↗

PubMed1996

Direct amplification and species determination of microsporidian DNA from stool specimens.

Microsporidia are recognized as a major aetiological agent in chronic diarrhoea of immunocompromised patients. Their detection by light microscopy is hampered by the small size of the spores. A simple and rapid DNA extraction method has been developed for the detection of microsporidian DNA by PCR directly from stool specimens. It can be performed at room temperature in a 1.5-ml microcentrifuge tube format in less than 1 hour. The subsequent nested polymerase chain reaction permits the detection of 3-100 spores in a 0.1-g stool sample. The amplification products can be verified and the species Enterocytozoon bieneusi, Encephalitozoon cuniculi and Encephalitozoon (Septata) intestinalis distinguished by a simple restriction endonuclease digest.

Animals↗

PubMed1994

Direct amplification and differentiation of pathogenic and nonpathogenic Entamoeba histolytica DNA from stool specimens.

Discrimination of pathogenic and nonpathogenic Entamoeba histolytica is of great clinical importance. A simple and rapid DNA extraction method that can be used directly with stool specimens was developed without the need for prior cultivation of the parasites. The entire protocol can be performed at room temperature in a 1.5-ml microcentrifuge tube format. There is no DNA precipitation step. The subsequent nested polymerase chain reaction consists of an initial E. histolytica-specific amplification, followed by two separate amplifications using two primer pairs specific for pathogenic and nonpathogenic E. histolytica, respectively. Amplification products can be verified by restriction endonuclease digests. There is no need for hybridizations or the use of radionucleotides. One trophozoite per milligram of stool sample could be detected and differentiated in a 0.1-g specimen.

Animals↗