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Results for “pathogen identification”

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PubMed1993

Clinical and laboratory findings in chronic conjunctivitis in cats: 91 cases (1983-1991).

Clinical findings and laboratory test results from 91 cats with chronic conjunctivitis were studied to determine the causes of the disease and the sensitivity of diagnostic procedures used, and to identify correlations between results of various diagnostic procedures and clinical or signalment variations. Mean age of affected cats was 2.9 +/- 2.7 years (+/- SD), with a range from 1 month to 11 years. Conjunctivitis was more likely to be bilateral (56 cats) than unilateral (35 cats). In cats tested for FeLV or feline immunodeficiency virus infection, 15 and 8.5%, respectively, of the results were positive, compared with 4 and 2.6% for the general hospital population. Culturing or immunofluorescent assay (IFA) for feline herpesvirus 1 (FHV-1) and Chlamydia psittaci IFA resulted in identification of pathogens (positive test results) in 19% (FHV-1) and 18% (C psittaci) of tested cats. For FHV-1, culturing was more sensitive than was IFA, yielding positive results in 19 vs 8.8% of cases. In only 1 cat were FHV-1 and chlamydiae recovered. The probability of positive test results for FHV-1 or chlamydiae was unrelated to concurrent corneal disease, unilateral vs bilateral involvement, or age. Cause of conjunctivitis could not be definitively determined in the remaining 35 cases tested for both agents. Bacterial species considered to be potentially pathogenic were isolated from conjunctival sac specimens in only 1 of 38 attempts. Cytologic changes considered compatible with chlamydial or FHV-1 infection (intracytoplasmic inclusions or multinucleated epithelial cells, respectively) were found in 8 and 5 cases, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

A strain of urease negative Cryptococcus neoformans isolated from the environment in China.

This is the first report of a strain of urease negative Cryptococcus neoformans isolated from the environment in China. The colonies of this isolate showed brown pigmentation on cornmeal agar with 300 micrograms/ml caffeic acid, but failed to hydrolyze urea. Microbiological identification and pathogenicity tests in mice confirmed this as a strain of C. neoformans. A similar strain had reportedly been isolated from an AIDS patient.

Animals↗
PubMed1993

Basic mycology underscoring medically important fungi.

This article details the basic mycologic features of yeast and mold-like fungi causing infections in humans. Concordant with the mycologic attributes delineating species identification, the pathogenic potential of mycotic agents is discussed with particular reference to intrinsic fungal virulence factors (e.g., exoenzymes) and host factors (e.g., neutrophil function, underlying disease) predisposing to colonization and infection.

Fungi↗
PubMed1993

[Diagnosis in urinary tract infections].

For a rational diagnostic work-up of urinary tract infections (UTI), a detailed history and a standardised examination of smear material, prostatic fluid and urine are essential. Examination of the urine is simple, with test strips, microscopic examination of the sediment and determination of the bacterial count by the dipstick procedure having proved their worth in practice. Isolation and identification of pathogens and the preparation of an antibiogram require special knowledge of microbiological techniques. Accurate evaluation of the urine and its constituents requires a knowledge of how the urine has been collected; we recommend spontaneously passed urine in men and young children, and catheter urine in women. Acute complicated and chronic recurrent UTIs require radiological studies and sonography. Occasionally, nuclear-medical investigations and angiography or CT may be necessary for detailed classification. In cases of obstruction of the lower UT or neurogenic problems with urinary bladder, urodynamic investigation and endoscopy must be performed. This stepwise diagnostic evaluation allows both optimal classification of the UTI and a saving in costs.

Bacterial Infections↗
PubMedDate not supplied

The amyloid peptide and its precursor in Alzheimer's disease.

Alzheimer's disease, the most frequent cause of dementia, is characterized by the formation in the brain of neurofibrillary tangles and senile plaques. Neurofibrillary tangles are composed of bundles of paired helical filaments containing the microtubule-associated protein tau. In autopsy-derived brain samples from patients with Alzheimer's disease, tau is hyperphosphorylated and constitutes a promising disease marker. Senile plaques contain a small amyloid peptide derived from the amyloid precursor protein. Mutations of the amyloid precursor protein gene have been identified in rare cases of familial Alzheimer's disease, suggesting a causal role for amyloid peptide deposition in the disease. However, Alzheimer's disease has been demonstrated to be characterized by an important genetic heterogeneity. The identification of pathogenic DNA mutations, different from those of the amyloid precursor protein gene, will reveal whether the corresponding genes are involved in either an increased production of the amyloid peptide or a decrease of its removal, or in the fibrillogenic properties of the peptide, which seem to be related to its toxicity. Several mammalian cells are able to produce the amyloid peptide from its precursor. Understanding the cellular mechanisms that determine how cleavages occur in cells could help to identify new strategies for modulating amyloid peptide production. In attempts to produce animal models of Alzheimer's disease, investigators have used transgenic strategies. To date, these efforts have not been very successful. However, the expression in transgenic mice of both mutated amyloid peptide precursor and amyloid associated proteins should prove useful for examining the importance of putative etiological factors, and for testing novel therapies including anti-amyloidogenic strategies.

Aged↗
PubMed1996

[Comparative profitability of hepatic biopsy and microbiological tests in patients with HIV infection].

OBJECTIVES: Diagnostic liver biopsy is proposed in HIV-positive patients who present unexplained fever. This invasive procedure is truly useful if it allows establishing a difficult diagnosis or improves survival rate. We conducted a retrospective study to determine the diagnostic and prognostic power of liver biopsy in HIV-positive patients with fever. METHODS: One hundred thirty-eight liver biopsies were performed in 129 patients. Utility was defined as demonstration of the pathogen or identification of a tumoral process. RESULTS: The liver biopsy met the utility criteria in 27 cases showing mycobacterial infections (n = 22) and herpes hepatitis, type 1 herpes simplex virus, cytomegalovirus and cryptococcosis infections (n = 1 each). These last 4 diagnoses were also possible with other tests. Comparing non-contributive liver biopsies (n = 111) with those demonstrating hepatic mycobacterial infection (n = 22) showed that the two groups were not different in terms of demographic data. Splenomegalia was more frequent in the non-contributive group (68% vs 37%, p = 0.007) as was superficial lymph node enlargement (45% vs 12%, p < 10(-3)). Laboratory tests were not discriminating. Mycobacterial infection was diagnosed in 22 patients in the non-contributive group. Bacteriological samples were positive for mycobacterium in 20 of the 22 patients in the contributive group. The mean delay to the first positive test for mycobacterium was 15 +/- 8 days compared with 30 +/- 10 days for liver tissue cultures. Mean survival after liver biopsy was 10 months: patients with a positive Ziehl-Neelson stain on the liver biopsy did not have a longer survival (9.7 +/- 7.6 vs 10.2 +/- 10.4 months). CONCLUSION: In most cases, liver biopsy in HIV-positive patients with fever provides a diagnosis which can be obtained with non-invasive techniques without improving prognosis.

AIDS-Related Opportunistic Infections↗
PubMed1994

Identification and analyses of periodontal pathogens in Taiwan by microbiological tests.

The purpose of this study was to use microbiological tests for diagnosis of periodontal diseases in Taiwan. Anaerobic culture, direct microscopy, indirect immunofluorescence (IF), and biochemical tests were used to examine 336 samples for the specific microorganisms in subgingival plaque. The results indicated that gram-negative species and motile bacteria were less frequently detected, and in lower proportion, in samples from healthy sites. The bacteria found frequently in healthy group were the coccal forms. However, Bacteroides forsythus detected by IF showed a close association with periodontal inflammation. Porphyromonas gingivalis was found with about 53% frequency in the periodontitis group; in more than half the samples the proportion was above 5%. Actinobacillus actinomycetemcomitans was recovered with 48% frequency of periodontitis group. Other cultivable species including Campylobacter rectus, Capnocytophaga species, Centipeda periodontii, Eikenella corrodens, Fusobacterium nucleatum, Prevotella intermedia, Selenomonas species, and the Spirochetes were detected in a significantly higher proportion in periodontitis group. The results strongly support the use of microbiological tests as adjuncts to diagnosis, and for assessment of the importance of microbiota in periodontal disease.

Adult↗
PubMedDate not supplied

[Bacteriological and clinical aspects of corynebacterium].

The microbiologists use the term corynebacteria to describe aerobically growing, asporogenous, irregularly sharped gram-positive rods. They comprise strictly aerobic bacteria isolated from environment as well as preferentially anaerobic bacteria found in clinical specimens. A large part of these bacteria is considered as commensal of skin and mucous membranes. This group of organisms has recently been subjected to considerable taxonomic revisions, which have resulted in the proposal of several new species, many of them representing previous Centers for Diseases Control coryneform groups. Moreover, recent investigations demonstrated the existence of a pathogenic role for some of them. These bacteria comprise well-known pathogens such as C. diphtheriae responsible for diphtheria, Actinomyces spp. responsible for actinomycosis and Arcanobacterium haemolyticum recovered from pharyngitis, but other corynebacteria were related to particular infections. For example, the lipophilic and antibiotics multiresistant species Corynebacterium urealyticum and C. jeikeium were found to be responsible for urinary tract infections and septicemias, respectively. The recently described species Turicella otitidis was found to be implicated in otitis media and C. seminale were recovered from genital specimens of male patients. Implantation of material devices, use of broad-spectrum antibiotics led to an increase of sepsis due to the species C. jeikeium and C. amycolatum. Many of the new Actinomyces species grow well under aerobic conditions and are often implicated in various abscesses. Moreover an increase of immunocompromised patients led to the development of infections due to the aerobic actinomycete Rhodococcus equi. The association of some corynebacteria with particular diseases should prompt the microbiologist to identify these bacteria when they are encountered in a pathogenic situation. Identification of the major part of corynebacteria isolated from clinical specimens can now be achieved by using recent schemes.

Anaerobiosis↗
PubMed1998

[Diseases associated with organic dusts].

Organic dust is ubiquitous and is a mixture of both allergens and several pro-inflammatory agents. Exposure to organic dust elicits a very complex immune response leading to pulmonary and systemic symptoms, in some occupational settings as well as in domestic environment. In this later setting, identification of pathogenic components from the organic dust could improve our understanding of pathogenesis of asthma as well as chronic obstructive pulmonary diseases.

Allergens↗
PubMed1999

Oligogalacturonide-mediated induction of a gene involved in jasmonic acid synthesis in response to the cell-wall-degrading enzymes of the plant pathogen Erwinia carotovora.

Identification of Arabidopsis thaliana genes responsive to plant cell-wall-degrading enzymes of Erwinia carotovora subsp. carotovora led to the isolation of a cDNA clone with high sequence homology to the gene for allene oxide synthase, an enzyme involved in the biosynthesis of jasmonates. Expression of the corresponding gene was induced by the extracellular enzymes from this pathogen as well as by treatment with methyl jasmonate and short oligogalacturonides (OGAs). This suggests that OGAs are involved in the induction of the jasmonate pathway during plant defense response to E. carotovora subsp. carotovora attack.

Amino Acid Sequence↗
PubMed2001

Development of Saccharomyces cerevisiae as a model pathogen. A system for the genetic identification of gene products required for survival in the mammalian host environment.

Saccharomyces cerevisiae, a close relative of the pathogenic Candida species, is an emerging opportunistic pathogen. An isogenic series of S. cerevisiae strains, derived from a human clinical isolate, were used to examine the role of evolutionarily conserved pathways in fungal survival in a mouse host. As is the case for the corresponding Candida albicans and Cryptococcus neoformans mutants, S. cerevisiae purine and pyrimidine auxotrophs were severely deficient in survival, consistent with there being evolutionary conservation of survival traits. Resistance to the antifungal drug 5-fluorocytosine was not deleterious and appeared to be slightly advantageous in vivo. Of mutants in three amino acid biosynthetic pathways, only leu2 mutants were severely deficient in vivo. Unlike the glyoxylate cycle, respiration was very important for survival; however, the mitochondrial genome made a respiration-independent contribution to survival. Mutants deficient in pseudohyphal formation were tested in vivo; flo11Delta mutants were phenotypically neutral while flo8Delta, tec1Delta, and flo8Delta tec1Delta mutants were slightly deficient. Because of its ease of genetic manipulation and the immense S. cerevisiae database, which includes the best annotated eukaryotic genome sequence, S. cerevisiae is a superb model system for the identification of gene products important for fungal survival in the mammalian host environment.

Amino Acids↗
PubMed2004

The O-antigen gene cluster of Shigella boydii O11 and functional identification of its wzy gene.

Shigella strains are human pathogens and their identification is usually based on their O-antigens. The O-antigen gene cluster of Shigella boydii O11 was sequenced. All the expected genes for the synthesis of the O-antigen were identified on the basis of homology and genes for the biosynthesis of dTDP-l-Rhamnose, genes encoding sugar transferases, as well as genes encoding O unit flippase (wzx) and O-antigen polymerase (wzy). The identity of the putative wzy gene was confirmed by showing that a wzy deficient mutant strain of S. boydii O11 produced a semi-rough LPS phenotype. The predicted wzx gene has an opposite transcription direction to that of all of the other genes in the S. boydii O11 O-antigen gene cluster. This unusual feature for the wzx gene has only previously been reported in S. boydii O6. Further comparison revealed an evolutionary relationship between O6 and O11 O-antigen gene clusters. Adjacent-gene PCR showed that Escherichia coli O105 and S. boydii O11, which share the identical O-antigen, also have the same genes and organization for their respective O-antigen gene clusters. Three genes specific for the S. boydii O11 and E. coli O105 gene clusters were identified.

Bacterial Proteins↗
PubMed2001

Missense and splice site mutations in tau associated with FTDP-17: multiple pathogenic mechanisms.

Recent identification of mutations in the gene encoding the microtubule-associated protein tau in the inherited frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) has demonstrated that tau dysfunction can lead to neurodegeneration. At least nine missense mutations and one deletion mutation (DeltaK280) have been identified in exons 9 through 13 that encode the microtubule-binding domains of tau. In addition, five mutations have been found close to the 5' splice site of exon 10. The FTDP-17 missense and splice site mutations have multiple effects on the biology and function of tau. It is likely that these varied pathogenic mechanisms explain the wide range of clinical and neuropathologic features observed in the FTDP-17 tauopathies.

Exons↗
PubMed2002

Quantitative multiprobe PCR assay for simultaneous detection and identification to species level of bacterial pathogens.

We describe a novel adaptation of the TaqMan PCR assay which potentially allows for highly sensitive detection of any eubacterial species with simultaneous species identification. Our system relies on a unique multiprobe design in which a single set of highly conserved sequences encoded by the 16S rRNA gene serves as the primer pair and is used in combination with both an internal highly conserved sequence, the universal probe, and an internal variable region, the species-specific probe. A pre-PCR ultrafiltration step effectively decontaminates or removes background DNA. The TaqMan system described reliabAly detected 14 common bacterial species with a detection limit of 50 fg. Further, highly sensitive and specific pathogen detection was demonstrated with a prototype species-specific probe designed to detect Staphylococcus aureus. This assay has broad potential in the clinical arena for rapid and specific diagnosis of infectious diseases.

Bacteria↗
PubMed1999

Novel detection techniques for human pathogens that contaminate poultry.

Poultry products are presumed to be a major contributor to human foodborne illness due to their high frequency of contamination with pathogens Salmonella spp. and Campylobacter spp. This has stimulated the development of more sensitive and rapid methods for identifying pathogens present in poultry. These new methods include immunomagnetic separation of pathogen, PCR amplification of pathogen-specific sequences, pathogen-specific DNA and RNA probes, and identification of pathogen-specific ions by mass spectrometry.

Animals↗
PubMedDate not supplied

Proteomics and bioinformatics strategies to design countermeasures against infectious threat agents.

The potential devastation resulting from an intentional outbreak caused by biological warfare agents such as Brucella abortus and Bacillus anthracis underscores the need for next generation vaccines. Proteomics, genomics, and systems biology approaches coupled with the bacterial ghost (BG) vaccine delivery strategy offer an ideal approach for developing safer, cost-effective, and efficacious vaccines for human use in a relatively rapid time frame. Critical to any subunit vaccine development strategy is the identification of a pathogen's proteins with the greatest potential of eliciting a protective immune response. These proteins are collectively referred to as the pathogen's immunome. Proteomics provides high-resolution identification of these immunogenic proteins using standard proteomic technologies, Western blots probed with antisera from infected patients, and the pathogen's sequenced and annotated genome. Selected immunoreactive proteins can be then cloned and expressed in nonpathogenic Gram-negative bacteria. Subsequently, a temperature shift or chemical induction process is initiated to induce expression of the PhiX174 E-lysis gene, whose protein product forms an E tunnel between the inner and outer membrane of the bacteria, expelling all intracellular contents. The BG vaccine system is a proven strategy developed for many different pathogens and tested in a complete array of animal models. The BG vaccine system also has great potential for producing multiagent vaccines for protection to multiple species in a single formulation.

Bacillus anthracis↗
PubMed2004

Hereditary non-polyposis colorectal cancer: identification of mutation carriers and assessing pathogenicity of mutations.

Hereditary non-polyposis colorectal cancer (HNPCC), also referred to as Lynch syndrome, is an autosomal dominantly inherited disorder that is characterized by susceptibility to colorectal cancer and extracolonic malignancies, in particular endometrial cancer. HNPCC is caused by pathogenic mutations in the mismatch repair (MMR) genes, which play an important role in maintaining genomic stability during DNA replication. Identification of MMR gene mutation carriers is important as this enables them to enrol in surveillance programmes, thus reducing their risk of cancer and increasing survival. Clinical criteria as well as non-clinical criteria have been formulated to select patients for mutation analysis. In this paper we review the approaches used to select patients for mutation analysis. Mutation analysis in the MMR genes may yield mutations of which the pathogenic nature is unclear. Criteria to determine the pathogenicity of such variants are discussed, as well as differences in design of functional assays to assess pathogenicity.

Base Pair Mismatch↗
PubMed2005

Rapid detection of food-borne pathogens by using molecular techniques.

Traditional methods of identification of food-borne pathogens, which cause disease in humans, are time-consuming and laborious, so there is a need for the development of innovative methods for the rapid identification of food-borne pathogens. Recent advances in molecular cloning and recombinant DNA techniques have revolutionized the detection of pathogens in foods. In this study the development of a PCR-based technique for the rapid identification of the food-borne pathogens Salmonella and Escherichia coli was undertaken. Suitable primers were designed based on specific gene fimA of Salmonella and gene afa of pathogenic E. coli for amplification. Agarose gel electrophoresis and subsequent staining with ethidium bromide were used for the identification of PCR products. The size of the amplified product was 120 bp as shown by comparison with marker DNA. These studies have established that fimA and afa primers were specific for detecting Salmonella and pathogenic E. coli, respectively, in the environmental samples. Thus a rapid, sensitive and reliable technique for the detection of Salmonella and pathogenic E. coli was developed.

Adhesins, Escherichia coli↗