28 research outputs found
Rapid detection and simultaneous molecular profile characterization of Acanthamoeba infections
Diagnosis of Acanthamoeba by microscopic examination, culture, and polymerase chain reactions (PCRs) has several limitations (sensitivity, specificity, lack of detection of several strains, cost of testing for discrimination among strains). We developed a new high-resolution melting real-time PCR (HRM) to detect and characterize Acanthamoeba infections. HRM performances were evaluated with strains from the American Type Culture Collection (ATCC) and with 20 corneal scrapings. The DNA extracted from specimens were amplified, detected, and characterized in 1 run using 2 original primers diluted in a solution containing an intercalating dye. Detection and molecular characterization of Acanthamoeba infections could be achieved in less than 2.5 h with a dramatic reduction in cost of reactants (postamplification procedures and radioactive or fluorescent-labeled molecular probes were unnecessary). HRM detection limits were 0.1 cyst/μL or less (including genotypes T5 and T11), and its sensitivity and specificity were higher than other molecular tests. For the tested strains from the ATCC, the HRM drafted 4 different profiles: Type I (genotypes T2 and T4), Type II (T5 and T7), Type III (T8), and Type IV (T1, T3, T6, T9, T11, T12, and T13)
Panton-Valentine leukocidin positive sequence type 80 methicillin-resistant Staphylococcus aureus carrying a staphylococcal cassette chromosome mec type IVc is dominant in neonates and children in an Algiers hospital
Methicillin-resistant Staphylococcus aureus (MRSA) is a major antimicrobial
drug-resistant pathogen causing serious infections. It was first detected in
healthcare settings, but in recent years it has also become disseminated in the
community. Children and young adults are most susceptible to infection by
community-acquired (CA) MRSA strains. In this study 25 MRSA isolates implicated
in infections of neonates and children admitted to an Algiers hospital during an
18 month period were characterized by molecular methods including staphylococcal
cassette chromosome (SCC) mec typing, PCR amplification of pvl genes, pulsed
field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Fifteen
out of 25 isolates were from hospital-acquired infections. Twenty-four isolates
carried SCCmec type IVc and belonged to the sequence type (ST) 80, one isolate
carried SCCmec type II and was ST 39. Twenty-two out of 24 ST80-MRSA-IVc isolates carried pvl genes. Our results suggest that the Panton-Valentine leukocidin positive ST80- MRSA-IVc is the dominant MRSA clone causing disease in neonates and children in Algiers
A Novel Mechanism Is Involved in Cationic Lipid-Mediated Functional siRNA Delivery
A key challenge for therapeutic application of RNA interference is to efficiently deliver synthetic small interfering RNAs (siRNAs) into target cells that will lead to the knockdown of the target transcript (functional siRNA delivery). To facilitate rational development of nonviral carriers, we have investigated by imaging, pharmacological and genetic approaches the mechanisms by which a cationic lipid carrier mediates siRNA delivery into mammalian cells. We show that 95% of siRNA lipoplexes enter the cells through endocytosis and persist in endolysosomes for a prolonged period of time. However, inhibition of clathrin-, caveolin-, or lipid-raft-mediated endocytosis or macropinocytosis fails to inhibit the knockdown of the target transcript. In contrast, depletion of cholesterol from the plasma membrane has little effect on the cellular uptake of siRNA lipoplexes, but it abolishes the target transcript knockdown. Furthermore, functional siRNA delivery occurs within a few hours and is gradually inhibited by lowering temperatures. These results demonstrate that although endocytosis is responsible for the majority of cellular uptake of siRNA lipoplexes, a minor pathway, probably mediated by fusion between siRNA lipoplexes and the plasma membrane, is responsible for the functional siRNA delivery. Our findings suggest possible directions for improving functional siRNA delivery by cationic lipids.National Institutes of Health (U.S.) (NIH Grant AI56267)National Institutes of Health (U.S.) (NIH Grant CA112967)National Institutes of Health (U.S.) (NIH Grant CA119349)Natural Sciences and Engineering Research Council of Canada (NSERC) (Post-doctoral fellowship
New Strategy for Rapid Diagnosis and Characterization of Fungal Infections: The Example of Corneal Scrapings
PURPOSE: The prognosis of people infected with Fungi especially immunocompromised depends on rapid and accurate diagnosis to capitalize on time administration of specific treatments. However, cultures produce false negative results and nucleic-acid amplification techniques require complex post-amplification procedures to differentiate relevant fungal types. The objective of this work was to develop a new diagnostic strategy based on real-time polymerase-chain reaction high-resolution melting analysis (PCR-HRM) that a) detects yeasts and filamentous Fungi, b) differentiates yeasts from filamentous Fungi, and c) discriminates among relevant species of yeasts. METHODS: PCR-HRM detection limits and specificity were assessed with a) isolated strains; b) human blood samples experimentally infected with Fungi; c) blood experimentally infected with other infectious agents; d) corneal scrapings from patients with suspected fungal keratitis (culture positive and negative) and e) scrapings from patients with suspected bacterial, viral or Acanthamoeba infections. The DNAs were extracted and mixed with primers diluted in the MeltDoctor® HRM Master Mix in 2 tubes, the first for yeasts, containing the forward primer CandUn (5'CATGCCTGTTTGAGCGTC) and the reverse primer FungUn (5'TCCTCCGCTT ATTGATATGCT) and the second for filamentous Fungi, containing the forward primer FilamUn (5'TGCCTGTCCGAGCGTCAT) and FungUn. Molecular probes were not necessary. The yields of DNA extraction and the PCR inhibitors were systematically monitored. RESULTS: PCR-HRM detected 0.1 Colony Forming Units (CFU)/µl of yeasts and filamentous Fungi, differentiated filamentous Fungi from yeasts and discriminated among relevant species of yeasts. PCR-HRM performances were higher than haemoculture and sensitivity and specificity was 100% for culture positive samples, detecting and characterizing Fungi in 7 out 10 culture negative suspected fungal keratitis. CONCLUSIONS: PCR-HRM appears as a new, sensitive, specific and inexpensive test that detects Fungi and differentiates filamentous Fungi from yeasts. It allows direct fungal detection from clinical samples and experimentally infected blood in less than 2.30 h after DNA extraction
Green Tea Epigallocatechin-3-Gallate Suppresses Autoimmune Arthritis Through Indoleamine-2,3-Dioxygenase Expressing Dendritic Cells and the Nuclear Factor, Erythroid 2-Like 2 Antioxidant Pathway
Long‐Term Results of Cultured Limbal Stem Cell Versus Limbal Tissue Transplantation in Stage III Limbal Deficiency
Synthesis of an Artificial Cornea Allowing In Vitro Colonization of the Host Cells
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