Biomedical subjects
Publications and source records attributed to Renato Panizzon.
Bacteremia due to Helicobacter canis has been reported in a patient with X-linked hypogammaglobulinemia. Here we report on the first human case of H. canis bacteremia in an immunocompetent host. Identification of the organism was made by genetic and phylogenetic analyses of the complete 16S rRNA sequence.
Fusarium spp. and other non-dermatophyte fungi are repeatedly isolated from abnormal nails. To investigate whether these fungi are the aetiological agents of infection or simply transient contaminants, a PCR/sequencing/RFLP assay was developed for direct and routine identification of the infecting fungi in onychomycosis. Fungal DNA was readily extracted using a commercial kit after dissolving nail fragments in a Na2S solution. Amplification of part of the 28S rDNA by PCR was performed with universal primers and the fungal species were identified by sequencing. The PCR/sequencing results were comparable with microbiological identification from the same nail sample. In addition to dermatophytes, Fusarium spp. and other less frequently isolated non-dermatophyte fungi were identified as single fungal agents in onychomycosis. Moreover, mixed infections were clearly demonstrated in 10% of cases by RFLP analysis of PCR products. Identification of infectious agents could be obtained in 2 days, whilst results from fungal cultures take 1-3 weeks. Rapid and reliable molecular identification of the infectious fungus expedites the choice of appropriate antifungal therapy, thereby improving the cure rate of onychomycosis.
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We have shown that dermatophyte species can be easily identified on the basis of a DNA sequence encoding a part of the large-subunit (LSU) rRNA (28S rRNA) by using the MicroSeq D2 LSU rRNA Fungal Sequencing Kit. Two taxa causing distinct dermatophytoses were clearly distinguished among isolates of the Trichophyton mentagrophytes species complex.
Proprietary systems for dermoscopy images analysis are available to improve the diagnosis and follow-up of the pigmented skin lesions. Their performance seems comparable with that of a human expert. Progress in computer-aided classification of melanocytic lesions depends notably on judicious choices of the algorithms dedicated to the extraction of signs from the dermoscopy images and of the method which combines these signs to classify the lesions. To allow the researcher's community to benefit from their large set of elementary algorithms already available for dermoscopy, we set up a system accessible through the Internet which: allows the engineers to register their algorithms while preserving their secrecy: their programs run on their own server; lets a user to define its own sequence of image analysis and to apply it to its images: the system automatically calls the appropriate remote programs; makes possible and stimulates the synergy of worldwide researchers in order to validate algorithms of images analysis best suited to achieve the correct diagnosis and to track the malignant melanoma; makes these techniques available to the greatest number of users through the Web and thus to support a mass screening; reduces the maintenance of the system to the minimum: it requires users only an Internet browser and engineers to follow a simple widespread standardised interface for distributed programs. Various problems should be addressed: the lack of standardisation of images acquisition: algorithms based on relative colours are best suited to this system; the copyrights on images and algorithms; charging the use of remote computer resources. This system allows for an international collaborative work in the fight against the malignant melanoma by offering a conceptual and technical platform of teledermoscopy. It is intended to support synergy between the engineers and the users implied in the diagnosis and teaching of dermoscopy.
BACKGROUND: The hazards due to sun exposure are well known. Many recent studies have emphasized the protection against the harmful effects of the sun by the use of sunscreens and, moreover, by staying in the shade and wearing long-sleeved shirts, hats and sunglasses. Switzerland has one of the highest rates of skin cancer induction in Europe and the incidence of melanoma in Switzerland is constantly increasing with an incidence of 10-12/100,000 inhabitants/year. Interestingly, some studies have evoked the possibility that sunscreen use can increase the risk of melanoma by increasing overall sun exposure. OBJECTIVE AND METHODS: In this context, the aim of our study was to estimate the amount of sun exposure of children, and their parents, living in Switzerland and to give a description of how they protect themselves against sun irradiation. Questionnaires were provided to pediatricians in every state (canton) in Switzerland and were given to families coming for consultation. RESULTS: A total of 328 forms including 1,285 individuals were returned from most of the cantons in Switzerland. The majority of the Swiss families had 2 children under 16 years of age with middle-aged parents (30-45 years) and a central European skin type (light skin of type II-III, brown or blue eyes, and brown to blond hair). An important sun exposure was noted even though the population seems to be conscious of the associated dangers. Sunscreens were the first-line defense against sun exposure with clothing and shielding oneself from the sun not being highly used. Moreover, sunscreens tended to be misused with most people applying them at the beach or swimming pool (instead of 15 min before exposure) and few applications throughout the day. CONCLUSIONS: Prevention should imperatively be emphasized for lower overall sun exposure as sunscreens are primarily used at the beach and not in routine daily exposure. In addition, it is agreed that prevention campaigns would be better directed towards children because up to 80% of detrimental sun exposure occurs during childhood.
BACKGROUND: The dermatophytes are important in the Swiss medical environment since 5-10% of consultations in dermatology concern mycotic infections. OBJECTIVE: To obtain information about the prevailing species of dermatophytes in the south-west of Switzerland and their pattern of infection. METHODS: An analysis was made of the dermatophytes isolated in the Department of Dermatology at the University Hospital of Lausanne and from samples collected in private practices of Switzerland during an 8-year period (1993-2000). The total number of samples sent for mycological analysis was 33,725. RESULTS: 4,193 cultures revealed a dermatophyte. Trichophyton rubrum was the most frequently isolated species accounting for 62.5% of the strains followed by T. mentagrophytes (24.5%) and Microsporum canis (5.0%). Less frequent isolates included Epidermophyton floccosum, M. langeroni, M. gypseum, T. soudanense, T. violaceum, T. verrucosum, T. gourvili and T. tonsurans. Analysis of the localisation of the isolated fungi confirms that the dermatophyte species have a predilection for certain body areas. CONCLUSIONS: The relative frequencies of isolation of the dermatophyte species partially depending of the record of the different tinea vary from one country to another. Our study reveals the importance of T. rubrum and the appreciable frequency of M. canis in the Swiss autochthonous population and the apparition of new species with immigrants.