J. L Finquelievich

Itraconazole and flucytosine+itraconazole combination in the treatment of experimental cryptococcosis in hamsters.

Summary. The efficacy of two different daily doses of itraconazole (ITRA) and the combination of flucytosine (5‐FC) with ITRA in the treatment of an experimental model of cryptococcosis in hamsters was studied. Five groups of 20 animals each were inoculated by the intracardiac route with 105 cells of Cryptococcus neoformans. Treatment started 3 days after the infection, and was administered by gavage for 30 days. ITRA was applied at a daily dose of 25 mg kg‐1 or 50 mg kg‐1 and the combination of 5‐FC and ITRA was given at 75 mg kg‐1 day‐1 or 50 mg kg‐1 day‐1 respectively. One group of 20 hamsters received the vehicle and was used as a control group. Treatment evaluation was based on the following parameters: number of surviving animals 60 days after the infection; presence of encapsulated yeasts on microscopic examination of wet preparations of brain, lungs, liver, spleen and kidneys at necropsy; and brain qualitative (massive seeding) and quantitative cultures (determination of colony forming units, CFU). ITRA 50 (50 mg kg day‐1) was the most effective treatment according to the studied parameters; 70% of brain cultures became negative and 95% of the treated hamsters survived to the end of the study period. ITRA efficacy was dose dependent. The combination of ITRA with 5‐FC was less effective than administering the drugs separately; the reason for this finding is not known. The results obtained in this study should encourage the use of high doses of ITRA in cases of disseminated cryptococcosis in humans.

Brote de histoplasmosis en la provincia de Neuquén, Patagonia argentina

BACKGROUND In Argentina, there are no reports of autochthonous cases of histoplasmosis in the southern regions of the country. AIM To report a histoplasmosis outbreak in Zapala town, Province of Neuquén, Patagonia Argentina. METHODS We evaluated the clinical and epidemiological characteristics of 5 patients involved in the outbreak. Environmental studies were conducted to determine the source of infection. The genetic profile of Histoplasma capsulatum strains isolated from the index case (IC) were compared with clinical isolates from Argentinean patients not related to the outbreak, using RAPD-PCR with primers 1281-1283. RESULTS The patients were residents of Zapala, and had not visited other geographical areas before. All patients had an influenza-like syndrome, and X-ray revealed disseminated micronodular images throughout the lung parenchyma. The IC needed specific antifungal therapy; the remaining 4 patients had mild symptoms, and did not require therapy. All of them had a good clinical outcome. Strains of H. capsulatum isolated from blood culture and lung biopsy of the IC showed a genetic profile different from other strains analyzed. The presence of the fungus in the environment was demonstrated by the detection of anti-Histoplasma antibodies in BALB/c mice inoculated with soil obtained in a culvert where workers had dug up earth after a landslide. CONCLUSIONS This outbreak suggests the histoplasmosis endemic area is under the 38° S parallel. Patients from Neuquén, Patagonia Argentina, with compatible symptoms of histoplasmosis should be tested, regardless of their travel or exposure history.

Determination of the therapeutic activity of caspofungin compared with the amphotericin B in an animal experimental model of histoplasmosis in hamster (Mesocrisetus auratus)

BACKGROUND Treatment with amphotericin B is highly effective in histoplasmosis. Caspofungin has shown good activity against Candida and Aspergillus spp. In vitro studies have demonstrated that Histoplasma capsulatum is inhibited by caspofungin. OBJECTIVES The purpose of this study was to evaluate the effectiveness of caspofungin in the treatment of histoplasmosis in an animal experimental model. METHODS Three strains of Histoplasma capsulatum var. capsulatum were used. Treatment started one week post-inoculation and the animals were randomly assigned to six groups: amphotericin B 6mg/Kg/d, caspofungin 2mg/Kg/d, 4mg/Kg/d, 8mg/Kg/d and the other two groups received saline solution and dextrose solution. Blood samples for culture were obtained once a week, from day 7 to 35 post-inoculation. One week after the end of the treatment the animals were sacrificed and spleen cultures were performed. RESULTS Blood cultures were negative in all the hamsters which received amphotericin B (100%, P<0.001); those treated with caspofungin and the control animals presented 30 and 32% of positive cultures respectively (P=0.59). Spleen cultures were negative in the animals treated with amphotericin B, while the percentage of positive spleen cultures in the caspofungin groups varied from 25 to 100%, and in the control groups from 35 to 94.8% (P=0.07). The statistical analysis of the undiluted cultures showed the use of amphotericin B as the only independent predictor of negative culture (P<0.001). CONCLUSIONS The efficacy of amphotericin B is well known for the treatment of histoplasmosis, though we could not demonstrate that caspofungin is better than control.

Fungemia and interstitial lung compromise caused by Malassezia sympodialis in a pediatric patient

A case of fungemia with interstitial lung compromise caused by Malassezia sympodialis is reported in an obese pediatric patient on long-term treatment with inhaled corticosteroids for asthma. The patient was hospitalized due to a post-surgical complication of appendicitis. The patient was treated with amphotericin B for 3 weeks, with good clinical evolution and subsequent negative cultures.

Estudio de la variabilidad genética entre aislamientos clínicos de Candida albicans formadores de biopelículas

Resumen Las biopeliculas estan constituidas por microcolonias incluidas dentro de una matriz polimerica y representan una forma de crecimiento microbiano. Candida albicans puede colonizar las superficies de cateteres, protesis y epitelios formando biopeliculas que son resistentes a las drogas antifungicas. El objetivo de este trabajo fue la caracterizacion genotipica de aislamientos clinicos de C. albicans formadores de biopeliculas usando la tecnica RAPD (Random Amplified Polymorphic DNA) . Fueron estudiados 25 aislamientos clinicos de C. albicans de fauces, sangre, piel, unas, materia fecal, biopsia de esofago, y flujo vaginal de pacientes con candidiasis. Cada cepa fue previamente analizada en su capacidad de crecer y adherirse a la superficie de poliestireno, y la cuantificacion de la biopelicula formada fue realizada mediante el ensayo de reduccion de XTT 2,3-bis (2-metoxi-4 nitro-5 sulfofenil) -2 H tetrazolio-5 carboxanilida.. Los coeficientes de similitud generados por RAPD variaron entre el 49 y el 91% con los cuatro iniciadores usados, revelando un alto nivel de variabilidad genetica. El dendrograma agrupo los aislamientos en cuatro grupos, incluyendo todos ellos cepas con muy diferente capacidad para formar biopeliculas. Aislamientos con genotipos similares mostraron diferente capacidad de formacion de biopeliculas. Las cepas fueron agrupadas independientemente del origen de la muestra. Nuestros resultados sugieren que en poblaciones naturales de C. albicans no existe correlacion entre la capacidad de formar biopeliculas y el genotipo determinado por PCR-RAPD.

Experimental coccidioidomycosis in hamsters. Disease kinetics and death curve in relation to infective dose

A study of experimental coccidioidomycosis in hamsters (Mesocricetus auratus) is presented. Two experiments were conducted on 75 animals inoculated intracardially with the mycelial form of Coccidioides immitis. The first research (experiment I) studied the kinetics of experimental disease in 15 hamsters inoculated with 300 C. immitis arthroconidia. The parameters studied were: (a) presence of macroscopic lesions in the brain, lungs, liver, spleen and kidneys; (b) microscopic identification of spherules in wet mount preparations of these specimens; (c) samples from all organs cultured at 37 °C on Sabouraud glucose agar; (d) blood cultures drawn every 24 h during the first week and subsequently every 48 h and (e) histopathological studies of all organs. The second experiment (experiment II) determined the relationship between the inoculum size and death curve in six groups of 10 animals each, which had received doses of 10, 50, 100, 150, 200 and 300 arthroconidia, respectively. On day 14 post‐inoculation, all the animals underwent skin tests and 1 ml of blood was obtained by cardiac puncture to detect antibodies. Disseminated disease with persistent fungaemia developed in all the studied animals. Coccidioides immitis was recovered from all organs, with the lungs being the first to present disease. Death occurred in all groups, regardless of the dose of arthroconidia and 83.3% died between day 22 and day 28 post‐infection. The use of this model is proposed for the biological standardization of antigens, the study of prophylactic measures and the ‘‘in vivo’’ evaluation of new antifungal treatments.