[Pneumocystis: epidemiology and molecular approaches]. / Pneumocystis : épidémiologie et approches moléculaires.

Pneumocystosis is a common opportunistic infection in immunocompromised patients, especially in AIDS patients. The diagnosis of this pneumonia has presented several difficulties due to the low sensitivity of conventional staining methods and the absence of culture system for Pneumocystis. The molecular biology techniques, especially the PCR, have improved the detection of DNA of this fungus in invasive and noninvasive samples, and in the environment which highlighted human transmission and the existence of environmental source of Pneumocystis. In addition, various molecular biology techniques were used for typing of Pneumocystis strains, especially P. jirovecii, which is characterized by a significant genetic biodiversity. Finally, the widespread use of cotrimoxazole for the treatment and prophylaxis of pneumocystosis has raised questions about possible resistance to sulfa drugs in P. jirovecii.

A comparison of capillary electrophoresis and direct sequencing in upstream conserved sequence region analysis of Pneumocystis jirovecii strains.

The major surface glycoprotein (MSG) of Pneumocystis jirovecii is the most abundant surface protein and appears to play a critical role in the pathogenesis of pneumocystosis. The expressed MSG gene is located immediately downstream of a region called the upstream conserved sequence (UCS). The UCS contains a region of tandem repeats that vary in number and sequence. In the present study, we have used capillary electrophoresis and direct sequencing to detect the variability in the repeat units of UCS. By direct sequencing the PCR products from samples of 13 patients, we have identified three types of repeat units which consisted of 10 nt and three different patterns in the UCS region with three and four repeats: 1, 2, 3 (84.6 %); 1, 2, 3, 3 (8.2 %); and a new genotype 2, 2, 3, 3 (8.2 %). The same samples were analysed by capillary electrophoresis. Three samples (23 %) contained a mixture of two or three different patterns of UCS repeats. In conclusion, quantifying the number of repeat units in the UCS by capillary electrophoresis provides a potential new method for the rapid typing of P. jirovecii and the detection of mixed infection.

First environmental isolations of Cryptococcus neoformans and Cryptococcus gattii in Tunisia and review of published studies on environmental isolations in Africa.

Cryptococcus neoformans and Cryptococcus gattii are pathogenic yeasts that cause cryptococcosis. These fungi were commonly associated with pigeon droppings and plant materials. The habitat of these pathogens has not been yet studied in Tunisia, although the ecology of these yeasts must be elucidated in order to establish surveillance programs and to prevent infections. The aim of this survey was to recover C. neoformans and C. gattii environmental isolates from pigeon droppings and plant materials in different areas of Sfax region, Tunisia. Nine hundred and fifty samples from leaves, wood, flowers, fruits and soil around trunk bases of 40 almond (Prunus dulcis) and 60 eucalyptus trees were collected as well as 250 pigeon droppings samples from different sites: buildings (n = 150), houses (n = 50) and zoo (n = 50). The identification of Cryptococcus neoformans complex was confirmed using the ID32C auxanogram panel (BioMérieux, Marcy l'Etoile, France); species were determined by multiplex PCR using the CN70 and CN49 primers, and mating type was determined by PCR. C. neoformans was recovered from 26 specimens of pigeon droppings (10.4%). This yeast was obtained more frequently from dry droppings (9.2%) than from moist droppings (1.2%). The mating type was determined. All the 31 environmental strains of C. neoformans and C. gattii were MATα. Out of 700 samples tested from 100 trees, only 5 isolates of Cryptococcus neoformans species complex were recovered (0.6%), two isolates of C. gattii and one isolate of C. neoformans were recovered from the wood of E. camaldulensis trees, and only two isolates of C. gattii were recovered from the wood of almond trees (Prunus dulcis Mill. var. zaaf and var. achek). These two Tunisian almond tree varieties were recorded for the first time in Africa as hosts for C. gattii. These results add new information to the ecology and epidemiology of C. neoformans species complex in Tunisia.

[Contribution of Western blotting to the diagnosis of hydatidosis]. / Apport de la technique Western blot dans le diagnostic de l'hydatidose.

The aim of this study is to evaluate the contribution of the immunoWesternblot for the diagnosis and the post surgical follow-up of the hydatidosis. 71 sera from patients with hydatidosis confirmed by surgery were studied. All had a negative hydatic serology by screening tests (enzyme-linked immunosorbent assay, hemagglutination, electrosyneresis). 12 patients with sera in pre and post operative were monitored for 2 years. The Echinococcus Western blot IgG permitted to rectify the diagnosis of hydatidosis in 67.6 %. The rate of positivity was 100 % for the multivesicular liver cysts, 60 % for the young cysts and 50 % for the calcified cysts. Western blot permitted to rectify the diagnosis of lung cysts in 62.5 % of cases and in 50 % of cranial-spinal localizations. Analysis of Western Blot evolution in the 12 patients followed in pre and post-surgical revealed the disappearance of the bands 16, 18 and 26-28kDa in 8 month in the 8 patients with complete exeresis. This study proved the value added of Western blot compared to the other traditional techniques for the immunodiagnostic and the post-surgical monitoring of hydatidosis.