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Results for “pathogenicity classification”

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At least 127 records · Page 7Linked to original sources
PubMed1997

Identification of pathogenic yeasts of the imperfect genus Candida by polymerase chain reaction fingerprinting.

With the increase in the number of immunocompromised hosts, the number of fungal pathogens has increased markedly. Identification and classification, especially of yeast species and strains, is often difficult when based solely on phenotypic characteristics. Since it became clear that different fungal pathogens require specific treatment strategies, there is a need for simple, rapid and reliable methods to identify fungal isolates. Polymerase chain reaction (PCR) fingerprinting was successfully applied here to identify yeast isolates. Microsatellite [(GTG)5; (GACA)4] and minisatellite [(5'GAGGGTGGCGGTTCT 3'), derived from the core-sequence of the phage M13] specific primers were used as single primers in the PCR to amplify hypervariable interrepeat DNA sequences from over 200 European, American and Australian clinical isolates within the genus Candida. Each species, represented by its type strain, could be identified by a specific multilocus pattern, allowing for the assignment of all the isolates to the appropriate species. Intra-species variation in the multilocus profiles was about 20% compared to inter-species variation, which was up to 80%. Anamorph-teleomorph pairs could be identified by highly homologous PCR fingerprint patterns. PCR fingerprinting was more discriminatory when compared with routinely used biochemical tests (Vitek YBC and API ID 32C). PCR fingerprinting has proven to be a powerful tool for the identification of medically important yeasts. It is rapid, sensitive, reliable, highly reproducible, stable in vitro and in vivo, and applicable to large scale experiments. Potential applications include: yeast taxonomy, epidemiology, environmental surveys, and improvement of the diagnosis of mycotic diseases.

Australia↗
PubMedDate not supplied

[A proposed classification of swollen legs].

The subject of enlarged legs is vast and complex. Up to now there has been no organic classification of the clinical picture involved. The basic problem is that of the criterion on which to base the classification. Literature on this subject has opted for the pathogenic criterion because it seems to facilitate the formulation of a classification which is of use to the doctor. One possibility would be to divide the syndrome into vascular and non-vascular swollen legs. The first group could in turn be separated into macro-circulating and micro-circulatory. The micro-circulatory forms can be primitive or secondary. Amongst the secondary micro-circulatory forms, two other groups can be singled out: secondary forms with local cause and secondary forms caused by organic pathology. However, there are clinical forms which are on the periphery of these different groups and these forms are subject to discussion regarding nosographic localization.

Edema↗
PubMed1990

The detection of genetic variation in Leptospira interrogans serogroup ICTEROHAEMORRHAGIAE by ribosomal RNA gene restriction fragment patterns.

Deoxyribonucleic acid from Leptospira interrogans serogroup ICTEROHAEMORRHAGIAE reference strains together with clinical and animal isolates were cleaved with EcoRI, electrophoresed and transferred to nylon membranes. An Escherichia coli MRE 600, 16S + 23S ribosomal RNA template was used in the synthesis of a single strand biotin-labelled cDNA probe using a reverse transcriptase. Ribosomal RNA cistrons present in the DNA fragments of strains were located using the cDNA probe. Between 4 and 7 well defined ribosomal RNA restriction bands were detected for the leptospires studied that varied in size from 12.1 to 0.57 kb. The hybridisation patterns were distinctive and unique for the reference strains that allowed for their characterisation. Similar patterns were observed for I. budapest M 20, I. "icterohaemorrhagiae" Ictero I and the type strain, I. icterohaemorrhagiae RGA. Clinical isolates and a isolate from a rat were compared with reference strain DNA patterns and identified as being similar to I. copenhageni M 20, I. "icterohaemorrhagiae" Ictero I and I. icterohaemorrhagiae RGA. These results indicate that ribosomal DNA fingerprinting may be useful in the classification and molecular epidemiology of pathogenic leptospires.

DNA Probes↗
PubMedDate not supplied

Nasal fossa malformations and paramedian facial cleft: new perspectives.

Choanal atresia may be associated with other cranio-facial malformations, including various degrees of nasal fossa malformation, and may be a part of paramedian facial clefts (as described by Tessier et al. [1977]). We identified five such cases with combined clinical elements corresponding to Tessier's paramedian facial cleft, including eyelid coloboma, mild to severe choanal and nasal fossa anomalies, ethmoidal hypoplasia and anterior skull base malformation, sometimes with proboscis lateralis and half-nose hypoplasia. These observations incited us, first, to elaborate a conception which accounts for the likely embryological mechanisms involved; second, to propose a new classification based on anatomical and pathogenic embryological considerations; and last, to propose the use of transpalatal approach to restore choanal permeability, since endonasal laser therapy is particularly dangerous in such cases.

Child, Preschool↗
PubMed2000

The neuropathology of multiple sclerosis.

This article reviews the pathology of multiple sclerosis in an attempt to allow the reader to better understand the pathogenesis of the lesions. The elements comprising the lesions are discussed in light of their pathogenic implications. Current ideas of classification are discussed, and wherever possible, correlations with clinical and imaging studies are drawn.

Animals↗
PubMed1978

[Effectiveness of antibiotics in bovine staphylococcal and streptococcal mastitis].

The present knowledge of the efficiency of antibiotics against bovine mastitis has been reviewed. Criteria for the choice of papers are given, together with tabulated results of treatments with one antibiotic or two. Results are discussed in relation to the time of treatment and the pathogenic agent involved, and a classification of the antibiotics into three groups is proposed: recommended; not advised; not sufficiently studied.

Animals↗
PubMed1977

[Bioptic investigations of the nervous system (author's transl)].

Bioptic investigation of nervous tissue can be made by taking tissue samples of nerves, skin, muscle, rectum, dental pulp and brain. The choice of site for the biopsy depends on the results of previous clinical neurological, neurophysiological and biochemical investigations. Indications are: unexplained peripheral neuropathies, progressive degenerative diseases of the central nervous system and enzymopathies which are principally manifest in the nervous system (neurometabolic diseases). The result of a nerve tissue biopsy usually only leads to classification in a disease group (pathogenic unit) which only becomes diagnostically relevant in conjunction with the clinical data. In biopsies of the brain a virological examination should always be performed in addition to the morphological (light and electron microscopic) and biochemical investigation.

Adult↗
PubMed1995

[Persistent diarrhea in HIV infected patients: role of Enterocytozoon bieneusi].

OBJECTIVES: To determine the epidemiologic, clinical and aetiologic features of chronic diarrhoea in patients with human immunodeficiency virus (HIV) infection. METHODS: Between January 1992 and April 1993, all HIV positive patients with chronic diarrhoea were enrolled in a prospective study. There were 46 patients in the study group including 33 (22 homosexuals) in stage C according to the 1993 Centers for Disease Control classification. RESULTS: Thirty-four pathogenic agents were isolated in 26 of the patients (57%). Enterocytozoon bieneusi was the most frequently found pathogen (11 patients, 24%) followed by Cryptosporidium sp (8 patients). Enterocytozoon bieneusi was found in association with other pathogens in 7 patients. All patients with microsporidiosis were in stage C (p = 0.04) and had a longer duration of diarrhoea (19.6 vs 9.8 weeks, p = 0.03), greater weight loss (9.6 vs 2.1 kg, p = 0.0003) and a lower Karnofsky index (48% vs 67%, p = 0.01). Prophylaxy with dapsone or pyrimethamine during the 3 months prior to inclusion had been more frequent (p = 0.04 and p = 0.05 respectively) in patients without microsporidiosis. CONCLUSION: Microsporidiosis should be suspected as a probable cause of chronic diarrhoea in HIV positive patients with a CD4 count < 100/mm3. Multiple infections may be a factor leading to treatment failure. Microsporidiosis seems to be linked to homosexual intercourse.

AIDS-Related Opportunistic Infections↗
PubMed1996

Randomly amplified polymorphic DNA polymerase chain reaction assay for molecular epidemiologic investigation of Pasteurella pneumotropica in laboratory rodent colonies.

After an episode of clinical Pasteurella pneumotropica infection was diagnosed in a C57BL/6N mouse, a randomly amplified polymorphic DNA polymerase chain reaction assay (RAPD-PCR) was developed and used to genetically characterize and differentiate 52 field isolates and laboratory reference strains of P. pneumotropica and related bacteria. A survey of rodents in the facility recovered 36 isolates of P. pneumotropica from 30 mice, six isolates from hamsters, and three isolates from rats during the follow-up investigation. Antibiograms and routine bacteriologic evaluations for morphologic and biochemical characteristics on selective media did not substantively aid in the differentiation of these isolates, but the RAPD-PCR revealed four strains of P. pneumotropica in the colony, two of which were confined to rats and hamsters. The RAPD-PCR unambiguously differentiated Heyl and Jawetz biotypes of P. pneumotropica recovered from mice, identified two additional genetic groups for rat and hamster isolates, and clearly distinguished P. pneumotropica from related bacteria. Most field isolates were genetically consistent with the Jawetz biotype of P. pneumotropica. The RAPD-PCR is a fast, sensitive, and efficient method for identifying genetic differences between strains of the P. pneumotropica complex and can contribute substantially in addressing the epidemiology, pathogenesis, and taxonomic classification of this common opportunistic pathogen.

Animals↗
PubMed1996

[Malformations of the nasal fossa and paramedian facial clefts. New perspectives].

Since choanal atresia may be associated with other cranio-facial malformations, including various degrees of nasal fossa malformation, and be a part of paramedian facial clefts, (as described by Tessier), they can be integrated into the larger group of neurocristopathies. We identified four such cases with combined clinical elements corresponding to Tessier's paramedian facial cleft, including eyelid coloboma, mild to severe choanal and nasal fossa anomalies, ethmoidal hypoplasia and anterior skull base malformation, sometimes with proboscis lateralis. These various malformations are due to abnormality of the olfactive placode and the adjacent mesenchyme. These discoveries incited us to elaborate a conception first of all on the pertinent embryology involved, second, to propose a new classification based on anatomical and pathogenic embryological considerations. And finally, since endonasal laser therapy is particularly dangerous in such cases, to propose the use of transpalatal approach to restore choanal permeability. Pediatric ENT surgeons should pay special attention to any small stigmatism of facial cleft when dealing with children affected by choanal atresia.

Abnormalities, Multiple↗
PubMedDate not supplied

[Tympanosclerosis. I: proposed anatomical-surgical classification].

Tyrnpanosclerosis continues to be a clinically and pathogenically controversial topic. The options for dealing with it range from a conservative approach using hearing aids to surgery. With a view to justifying our therapeutic criteria, 29 cases of tympanosclerosis, out of a total of 200 surgical operations for otorrhea, were reviewed. An anatormical-surgical classification was established for use in approaching specific therapy for each particular case.

Cerebrospinal Fluid Otorrhea↗
PubMed1991

Differentiation of pathogenic from nonpathogenic Entamoeba histolytica by restriction fragment analysis of a single gene amplified in vitro.

We previously reported the identification of homologous cDNA clones derived from a pathogenic isolate and a nonpathogenic isolate of Entamoeba histolytica, which had been designated cEh-P1 and cEh-NP1, respectively. Sequence analysis of both clones had revealed 10% nucleic acid substitutions, which were dispersed over the entire sequence. This genetic difference had been found to be conserved between all four pathogenic and all five nonpathogenic laboratory strains of E. histolytica tested. On the basis of nucleic acid substitutions, we have now developed a sensitive assay to distinguish pathogenic from nonpathogenic forms of E. histolytica by using fresh clinical isolates. Comparing the sequence of cEh-P1 and cEh-NP1, we identified a 482-bp segment that contained identical 5' and 3' ends but differed in internal cleavage sites for restriction endonucleases. By using oligonucleotide primers corresponding to the 5' and 3' ends of this segment, the corresponding gene was amplified by the polymerase chain reaction. Endonuclease digestion of the amplified DNA yielded restriction fragments that are characteristic for pathogenic and nonpathogenic forms. This assay allows the detection and classification of fewer than 10 amoebae within a few hours. The differentiation of 48 isolates into pathogenic and nonpathogenic strains by using this method corresponded to the clinical status of the infected individuals and to the classification obtained by isoenzyme determination. The results further support the concept that pathogenic and nonpathogenic strains of E. histolytica constitute distinct subspecies.

Animals↗
PubMed1983

Interstrain mitochondrial DNA polymorphism detected in Acanthamoeba by restriction endonuclease analysis.

The genus Acanthamoeba includes pathogenic and nonpathogenic strains of amebas with unclear taxonomic and evolutionary relationships. To explore these relationships further, we have examined mitochondrial DNA fragment patterns obtained for 15 Acanthamoeba strains by use of five restriction endonucleases. The mitochondrial DNA molecules were circular, averaging 41.6 +/- 1.5 kilobase pairs. Fragments resulting from endonuclease digestion of the DNA were separated by agarose gel electrophoresis. Ten distinct families of electrophoretic patterns (digestion phenotypes) were observed. Seven phenotypes were found for seven strains considered nonpathogenic or of unknown pathogenicity. Three phenotypes were associated with pathogenic strains. One of these phenotypes included a single pathogenic strain, a second included one pathogen and one strain of unknown pathogenicity, and the third included five pathogenic strains. The latter five were of widespread geographic origin and previously were assigned to two different species. The results suggest that extensive nucleotide sequence diversity occurs among strains from a single species of Acanthamoeba, but that subgroups of strains with similar sequences also occur. Thus, restriction enzyme analysis can identify clusters of strains and may be a useful approach to classification in the genus. Improvements in classification should help clarify relationships among pathogenic and non-pathogenic strains.

Amoeba↗
PubMed2000

Discrimination of the notifiable pathogen Gyrodactylus salaris from G. thymalli (Monogenea) using statistical classifiers applied to morphometric data.

The identification and discrimination of 2 closely related and morphologically similar species of Gyrodactylus, G. salaris and G. thymalli, were assessed using the statistical classification methodologies Linear Discriminant Analysis (LDA) and k-Nearest Neighbours (KNN). These statistical methods were applied to morphometric measurements made on the gyrodactylid attachment hooks. The mean estimated classification percentages of correctly identifying each species were 98.1% (LDA) and 97.9% (KNN) for G. salaris and 99.9% (LDA) and 73.2% (KNN) for G. thymalli. The analysis was expanded to include another 2 closely related species and the new classification efficiencies were 94.6% (LDA) and 98.% (KNN) for G. salaris; 98.2% (LDA) and 72.6% (KNN) for G. thymalli; 86.7% (LDA) and 91.8% (KNN) for G. derjavini; and 76.5% (LDA) and 77.7% (KNN) for G. truttae. The higher correct classification scores of G. salaris and G. thymalli by the LDA classifier in the 2-species analysis over the 4-species analysis suggested the development of a 2-stage classifier. The mean estimated correct classification scores were 99.97% (LDA) and 99.99% (KNN) for the G. salaris-G. thymalli pairing and 99.4% (LDA) and 99.92% (KNN) for the G. derjavini-G. truttae pairing. Assessment of the 2-stage classifier using only marginal hook data was very good with classification efficiencies of 100% (LDA) and 99.6% (KNN) for the G. salaris G. thymalli pairing and 97.2% (LDA) and 99.2% (KNN) for the G. derjavini-G. truttae pairing. Paired species were then discriminated individually in the second stage of the classifier using data from the full set of hooks. These analyses demonstrate that using the methods of LDA and KNN statistical classification, the discrimination of closely related and pathogenic species of Gyrodactylus may be achieved using data derived from light microscope studies.

Animals↗
PubMed2026

TaxTriage: an open-source metagenomic sequencing data analysis pipeline enabling putative pathogen detection.

MOTIVATION: TaxTriage is a comprehensive pathogen identification workflow designed for both short- and long-read untargeted DNA and RNA sequencing data. Combining read classification, mapping, and de novo assembly approaches, putative pathogens are identified through comparisons to curated pathogens and abundance expectations from healthy cohort data. Flexible installation options are enabled using Nextflow&#x2122; (NF), including cloud deployment via NF Tower (Seqera Platform) and local installation on a variety of systems, including standalone installations without external internet access. Final analysis summaries are compiled into an Organism Discovery Report, which lists likely pathogens and supporting data, including a custom confidence score. RESULTS: Evaluation of published in silico, clinical, and outbreak datasets identified performance comparable to alternative cloud-based processing pipelines for expected pathogen and co-infection detection with similar sensitivity and increased specificity. To support both public health and veterinary diagnostics communities, customization options have been incorporated to enable improved performance for host species of interest. AVAILABILITY AND IMPLEMENTATION: Source code for TaxTriage is freely available at https://github.com/jhuapl-bio/taxtriage. TaxTriage v2.1.1 has been archived on Zenodo at https://zenodo.org/records/17081354 to permit reproducible analysis as described in this manuscript.

Software↗
PubMed1994

[Entamoeba histolytica (Schaudinn 1903) and Entamoeba dispar (E. Brumpt 1925) are 2 different species].

On the basis of epidemiologic and clinical data in humans, and of experimental studies in kittens, E. Brumpt in 1925 showed that Entamoeba histolytica producing quadrinucleate cysts was a complex of 2 species. He differentiated a pathogenic and invasive form, from a non pathogenic and non invasive one that he called Entamoeba dispar. His explanation gained little support until recently, when Sargeaunt reported a study of isoenzyme typing and allow then the classification of amoebae resembling E. histolytica in pathogenic and non pathogenic species. Monoclonal antibodies and PCR have recently been used and have shown to react specifically with the two forms of amoebae. Genetic evidence has also demonstrated that the pathogenic and non pathogenic amoebae represent different species.

Animals↗