152 research outputs found
Contribution des tests platelia et de la PCR au diagnostic d'infection fongique invasive chez le patient neutropénique
No full textLILLE2-BU Santé-Recherche (593502101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
Diagnostic biologique des candidoses
No full textCandidiasis is the most common fungal infection in humans. Conventional techniques are usually sufficient for the diagnosis of superficial candidiasis. For deep-seated or systemic candidiasis, blood cultures still represent the “gold standard”, although their sensitivity can be overtaken. In recent decades, numerous alternative tests have been developed to overcome this lack of sensitivity. These techniques allow the detection of antibodies, antigens, metabolites or nucleic acids.
In most cases, serological results have to be interpretated according to the immune status of patients. Detection of antibodies alone is often poorly contributive to the diagnosis, except when this is associated with the detection of circulating antigens. Thus, the detection of circulating mannans is useful in the diagnosis of infections caused by the most frequent Candida species; the sensitivity of this test increases with the repetition of samplings and the joint detection of anti-mannan antibodies. Besides, detection of β(1.3)-D glucans, alone or in association with the detection of mannans, may be useful for early diagnosis of deep-seated candidiasis.
Molecular biology helps us to diagnose deep-seated candidiasis without referring to the patient\u27s immune status. With the newly commercialized kits, molecular detection of Candida should expand in laboratories. In the same way, proteomic analysis by MALDI-TOF allows to substantially shorten the time for identification of isolated yeasts.
Modern methods of molecular typing, which are based on the analysis of genome variability, replaced phenotypic techniques. Although insufficiently standardized, they represent a powerful tool to better understand the epidemiology of Candida infections
Conventional Methods for the Diagnosis of Dermatophytosis
No full textDermatophytes are keratinolytic fungi responsible for a large variety of diseases that can affect glabrous skin, nails and hair. In many cases, the diagnosis is not clinically obvious, and mycological analysis is required. This includes both direct microscopic examination and cultures. First of all, clinical specimens have to be sampled according to localization and characteristics of the lesions. Direct microscopic examination is usually performed using clearing reagents (KOH or Amman’s chloral-lactophenol), but its sensitivity may be greatly enhanced by the use of stains or fluorochromes such as Congo red or Calcofluor white. Histological analysis is an efficient method, but it is constraining for the patients and, as direct examination, it does not allow precise identification of the pathogen. Cultures are therefore needed, and specific culture media may be used to overcome the growth of rapidly growing contaminating moulds which may hamper the recovery of dermatophytes. Identification at the species level which may be useful to initiate an appropriate treatment or for setting prophylactic measures, relies on macroscopic and microscopic morphology. Subcultures on culture media which stimulate conidiation and, for some species, the production of pigments, are often necessary. Additionally, in case of atypical isolates, some biochemical or physiological tests may be performed such as the search for urease activity or the in vitro hair perforation test. However, their contribution to species identification is rather limited, and progress is still needed for the development of biochemical or immunological tests allowing an accurate identification at the species level, pending for the availability of molecular biology-based kits
Les dermatophytes : les difficultés du diagnostic mycologique
No full textRésuméLes dermatophytes sont des champignons filamenteux responsables de lésions variées de la peau et des phanères, dont le diagnostic n’est pas toujours évident cliniquement. Devant une lésion évoquant une dermatophytie, un examen mycologique s’impose donc le plus souvent. Cependant, bien que cette recherche soit d’usage courant dans les laboratoires d’analyses médicales, la mise en évidence d’une étiologie fongique n’est pas assurée pour autant. En effet, pour obtenir un résultat fiable, le biologiste doit surmonter plusieurs niveaux d’obstacles : 1. la réalisation du prélèvement selon le type de lésion, 2. l’examen direct des différents produits biologiques, ainsi que leur mise en culture, 3. l’identification des champignons isolés, 4. l’interprétation des résultats. Les difficultés susceptibles d’être rencontrées au cours des différentes étapes du diagnostic des dermatophyties reposent essentiellement sur l’absence de standardisation des prélèvements et des techniques mycologiques, ainsi que sur le manque de commercialisation de certains réactifs et milieux de culture. Les auteurs se proposent de passer en revue les principaux pièges à éviter
Les onychomycoses à moisissures
No full textOnychomycoses represent about 30% of superficial mycosis that are encountered in Dermatology consults. Fungi such as dermatophytes, which are mainly found on the feet nails, cause nearly 50% of these onychopathies. Yeasts are predominantly present on hands, whereas non-dermatophytic moulds are very seldom involved in both foot and hand nails infections. According to literature, these moulds are responsible for 2 to 17% of onychomycoses. Nevertheless, we have to differentiate between onychomycoses due to pseudodermatophytes such as Neoscytalidium (ex-Scytalidium) and Onychocola canadensis, which present a high affinity for keratin, and onychomycoses due to filamentous fungi such as Aspergillus, Fusarium, Scopulariopsis, Acremonium… These saprophytic moulds are indeed most of the time considered as colonizers rather than real pathogens agents. Mycology and histopathology laboratories play an important role. They allow to identify the species that is involved in nail infection, but also to confirm parasitism by the fungus in the infected nails. Indeed, before attributing any pathogenic role to non-dermatophytic moulds, it is essential to precisely evaluate their pathogenicity through samples and accurate mycological and/or histological analysis. The treatment of onychomycoses due to non-dermatophytic moulds is difficult, as there is today no consensus. The choice of an antifungal agent will first depend on the species that is involved in the infection, but also on the severity of nail lesions and on the patient himself. In most cases, the onychomycosis will be cured with chemical or mechanical removing of the infected tissues, followed by a local antifungal treatment. In some cases, a systemic therapy will be discussed
Erratum to: Reappraisal of Conventional Diagnosis for Dermatophytes
No full textInternational audienc
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