MALDI-TOF-Based Dermatophyte Identification

International audienceMALDI-TOF MS has become increasingly popular for microorganism identification in the routine laboratory. Compared with conventional morphology- based techniques, MALDI-TOF is relatively inexpensive (per-unit identification), involves a rapid result turnaround time and yields more accurate results without the need for highly qualified staff. However, this technology has been technically difficult to implement for filamentous fungi identification. Identification of dermatophytes, a type of filamentous fungi, remains particularly challenging, partly due to the lack of clear species definition for some taxa or within some species complexes. Review of the ten studies published between 2008 and 2015 shows that the accuracy of MALDI-TOF MS-based identification varied between 13.5 and 100 % for dermatophytes. This variability was partly due to inconsistencies concerning critical steps of the routine clinical laboratory process. Use of both a complete formic acid-acetonitrile protein extraction step and a manufacturer library supplemented with homemade reference spectra is essential for an accurate species identification. This technique is conversely unaffected by variations in other routine clinical laboratory conditions such as culture medium type, incubation time and type of mass spectrometry instrument. Provided that a reference spectra library is adequate for dermatophyte identification, MALDI-TOF MS identification is more economical and offers an accuracy comparable to that of DNA sequencing. The technique also represents an advantageous alternative to the protracted and laborintensive dermatophyte identification via macroscopic and microscopic morphology in the routine clinical laboratory

Dual infection: What diptera has (have) bit her

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Visceral leishmaniasis in acute myeloid leukemia revealed on peripheral blood smear

International audienceKey Clinical Message Images of parasitic forms of Leishmania infantum are typical in the hands of a skilled expert but should be known by biologists of Hematology Department. In an endemic region, the diagnosis of visceral leishmaniasis (VL) must be considered because of its potential role in accelerating hematological malignancy

Epidemiology of human dermatophytoses in Africa

International audienceIn this critical literature review, we summarize the epidemiological trends of dermatophytoses reported in Africa. Our findings clearly emphasize the heavy burden of dermatophytosis in Africa. Tinea capitis is the primary clinical presentation of dermatophytosis in African children throughout the entire African continent. The disease affects more than 20% of school-age children in West Africa, while the prevalence ranges from 10% to more than 70% in other regions of Africa. In African adults, the presence of tinea corporis is the most frequent indicator of dermatophytosis. However, epidemiological studies have been primarily conducted on particular patient groups that are not representative of the general population. We examined dermatophyte species distribution patterns. We observed a predominance of anthropophilic dermatophytes, mainly T. violaceum, in the North and East of Africa and both T. soudanense and M. audouinii in the Western and Central regions of the continent. Interestingly, the zoophilic species, M. canis, has recently emerged in North and East Africa. Optimization of both mycology diagnosis capacities and epidemiological methodology would provide insight into the role that climate and other global aspects of the human environment play in dermatophyte epidemiology. We advocate that using a multisectoral and collaborative strategy would strengthen such future studies

Une dirofilariose inguinale simulant une hernie

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Performance of MALDI-TOF MS platforms for fungal identification

International audienceMatrix-assisted laser desorption/ionisation mass spectrometry (MALDI-TOF MS) is increasingly used by clinical microbiology laboratories to cope with the need for rapid, cost-effective and accurate identification of microorganisms. Several research teams have recently succeed in identifying moulds using MALDI-TOF MS, which was first adapted to bacteria, then to yeast identification. Since 2004, different commercial firms have released several ready-to-use MALDI-TOF MS platforms. This review describes the similarities and differences between the commercially available systems. In two parts, we first describe and compare the preprocessing and identification steps between the platforms and then compare the identification efficacy of yeast, moulds and dermatophytes species

Genetic and phenotypic characterization of commensal and clinical Candida albicans isolates reveals heterogeneous distribution of adherence and invasiveness properties

International audienceConsidering Candida albicans as a primarily clonal model of reproduction, distinct lineages of C. albicans could propagate independently, each clonal lineage having possibly variations in biological traits contributing to the pathogenicity of the fungus such as adherence or the yeast-hyphae transition. Indeed, adherence to epithelial cells is considered a virulence trait of C. albicans since contributing to the first contact of the fungus with the host’s epithelial layers. Moreover the ability of C. albicans to switch from the yeast to the hyphae form is an important determinant of C. albicans virulence since favoring invasion of the fungus into the host’s tissues. Using a Multi-Locus Microsatellite Typing (MLMT) approach, we previously addressedthe question of the pathogenicity of lineages of C. albicans with regard to their origin in three series of C. albicans isolates: 82 commensal isolates collected in healthy individuals, 46 invasive bloodstream isolates and 46 of nonbloodstream clinical isolates. In the current study, invasiveness (i.e. cytotoxicity effect) and adherence to epithelial cells of representative strains of the 3 series previously characterized at the genotypic level were investigated in the Caco-2 in vitro model of human intestinal barrier. Correlations between invasiveness, adherence, genotype and origin were then investigated. Principal component factor analysis failed to reveal specific correlation between genotypic and phenotypic characters for all of the strains studied. However, it was possible to group strains into three clusters based on their capabilities to adhere to and to invade intestinal cells. Interestingly, some clinical strains presented a decrease in their cytotoxic effect associated with a defect in their filamentation capability. To illustrate these observations, the clinical strain n°926 was further characterized in vitro with regard to its filamentation capabilities as compared to the reference strain C. albicans SC5314. Colony morphology on specific agar media reported a strong defect in its filamentation ability. This was confirmed by microscopic observations in specific liquid media. Despite similar adherence capability to epithelial cells, cytotoxicity of the strain n°926 was significantly lower than the reference strain C. albicans SC5314. These data suggest that (i) invasion of epithelial cells is mainly driven by the ability of C. albicans to switch from the yeast to the hyphal form and (ii) natural C. albicans strains could harbor atypical defect in their filamentation capabilities. Experiments are in progress in a mouse model of disseminated candidiasis originating from the gastro-intestinal tract to confirm the defect in filamentation capabilities of C. albicans natural strains observed in vitro

Fecal Excretion of Mycobacterium leprae , Burkina Faso

International audienceMycobacterium leprae was detected by optical microscopy, fluorescent in situ hybridization, and molecular detection in feces collected for the diagnosis of Entamoeba coli enteritis in a leprosy patient in Burkina Faso. This observation raises questions about the role of fecal excretion of M. leprae in the natural history and diagnosis of leprosy

Schistosoma haematobium infection with pulmonary involvement in a traveller returning from Congo: A case report and systematic review of literature on nodular pulmonary schistosomiasis

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Detection, fate and transport of the biohazardous agent Toxoplasma gondii in soil water systems: Influence of soil physicochemical properties, water chemistry and surfactant

A series of laboratory experiments were conducted to study the fate and transport of Toxoplasma gondii oocysts in soils as a function of soil physicochemical properties and soil water chemistry properties. Soil columns were homogeneously packed with loamy sand soils (Lewiston and Greenson series) and sandy loam soils (Sparta and Gilford series), and subject to hydrologic conditions characterized by the absence and presence of an anionic surfactant—Aerosol 22 in the artificial rainfall. Quantitative polymerase chain reaction (qPCR) was utilized for the detection and enumeration of oocysts in soil leachates to evaluate their breakthrough and in soil matrices to examine their spatial distribution. Differences in the rate and extent of transport of oocysts were observed as a function of physical and chemical parameters tested. The breakthrough of oocysts was observed for all the soils irrespective of the presence of surfactant. However, in the absence of surfactant, the predominant fate of oocysts in soils subject to simulated rainfall was their retention in the soil profile. The presence of surfactant induced a change in the fate of oocysts in these soils exposed to rainfall simulation as the predominant fate of oocysts was found to be in the soil leachates