C. Iovannitti

Phenotypic and genotypic characterization of Aspergillus lentulus and Aspergillus fumigatus isolates in a patient with probable invasive aspergillosis.

Characteristic morphological and phylogenetic analyses demonstrated the presence of Aspergillus fumigatus and Aspergillus lentulus as the aetiological agents in a case of probable invasive aspergillosis (IA). This is believed to be the first report of an A. lentulus strain isolated from a patient with probable IA in Argentina.

Phenotypic and genotypic identification of Candida dubliniensis from subgingival sites in immunocompetent subjects in Argentina.

INTRODUCTION It is generally recognized that Candida dubliniensis is commonly found in immunocompromised patients, such as those with advanced human immunodeficiency virus infection, at sites of periodontal disease. Since there are no data available for Argentina, the aim of this study was to determine the prevalence of and to identify C. dubliniensis in periodontal pockets from immunocompetent subjects living in Buenos Aires, Argentina, through a comparison of phenotypic and molecular assays. METHODS Yeasts recovered from subgingival plaque samples were studied for 180 immunocompetent non-smoking patients with periodontal disease. Yeasts were identified by conventional mycological methods and by specific polymerase chain reaction (PCR) assay. Fluconazole and voriconazole susceptibility studies were performed in keeping with the Clinical and Laboratory Standards Institute. RESULTS Among 76 yeasts isolated, C. dubliniensis comprised 10.5% (n = 8; 95% confidence interval 4.7-19.7), which corresponded to 4.4% of patients studied (8/180). C. albicans was the most frequently isolated species of yeast. A great majority of C. dubliniensis isolates was susceptible with only one isolate resistant to both antifungals. CONCLUSION Micromorphology on Staib agar was the phenotypic method that was most concordant with PCR and it was useful for selecting presumptive C. dubliniensis. This is the first report to use PCR to identify C. dubliniensis in subgingival fluid from immunocompetent individuals with periodontal disease in Argentina. On the basis of the findings presented here, we confirm that C. dubliniensis can colonize periodontal pockets of immunocompetent patients with periodontal disease.

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.

Chronic meningoencephalitis due to Histoplasma capsulatum. Usefulness of serodiagnostic procedures in diagnosis

Abstract This study presents details of four male patients with meningoencephalitis of chronic evolution, probably due to Histoplasma capsulatum . The diagnoses were mainly made by immunodiffusion test (ID), counterimmunoelectrophoresis test (CIF) and complement fixation test (CFT) with specific antigens. In case 1, the diagnosis of histoplasmosis was established through the isolation of H. capsulatum from a cutaneous biopsy and in the other three patients, through the results of serological tests. The neurological changes were those typical of chronic meningitis of basal predominance, with non-purulent cerebrospinal fluid (CSF) and signs of hydrocephaly in three patients. Two patients had other organ involvement which was clinically consistent with histoplasmosis (nose, oral mucosa, lungs, adrenal glands). The four patients were treated with amphotericin B and received fluconazole, itraconazole, cotrimoxazole (TMS) and ketoconazole, in most cases as secondary prophylaxis. Three of the patients presented episodes of valvular obstruction which complicated their clinical courses.

Comparative study of four antifungal drugs in an experimental model of murine cryptococcosis

AbstractsA comparative study among amphotericin B, 5-fluorocytosine, itraconazole and fluconazole in the treatment of experimental cryptococcosis in mice, was carried out.Seventy male Balb C mice were inoculated intraperitoneally with 107 cells of Cryptococcus neoformans var. neoformans. They were divided in 7 groups of 10 animals each one: 1) treated with fluconazole by gavage at a daily dose of 16 mg/kg; 2) treated with itraconazole by gavage at a daily dose of 16 mg/kg; 3) treated with 5-fluorocytosine by gavage at a daily dose of 300 mg/kg; 4) treated with amphotericin B intraperitoneally at a dose of 6 mg/kg every other day; 5) control animals receiving polietilenglicol 200 by gavage; 6) control animals receiving distilled water by gavage and 7) control animals receiving sterile distilled water by intraperitoneal route. All the treatments started 5 days after the challenge inoculation and they were given for 2 weeks.The following parameters were taken into account: survival time, macroscopic aspect of the organ after the complete autopsy, microscopic investigation of yeasts in brain, lungs, spleen and liver, histopathology studies of these organs, the colony forming units per gram and massive seeding of brain and lungs.The survival index of the different groups was the most efficient method to measure the antifungal compounds activity. Amphotericin B increased significantly the animals survival and modified the histopathologic response in the studied organs. The colony forming units and the massive seeding in brain and lung showed that this antifungal agent is unable of producing the biological cure of this experimental model.The remaining drugs assayed did not promote important modifications in the histopathologic picture as well as in the tissues cultures. However, the three drugs increased the animals survival. In this aspect, fluconazole proved to be slightly superior.

Treatment of disseminated histoplasmosis in hamsters.

A comparative study between itraconazole, ketoconazole and amphotericin B in the treatment of experimental histoplasmosis in hamsters was carried out.Seventy five animals were inoculated intracardiacally with the yeast-phase of Histoplasma capsulatum. They were divided in 5 groups: 1) treated with itraconazole by gavage (g) at a daily dose of 16 mg/kg; 2) treated with ketoconazole by (g) at a daily dose of 80 mg/kg; 3) treated with amphotericin B intraperitoneally (i.p.) at 6 mg/kg every other day; 4) control animals receiving distilled water i.p. and 5) control animals receiving P.E.G. 200 by (g). All the treatments were started one week after the challenge inoculation and they were given for 21 days. The results were evaluated by autopsy of all the animals one week after the end of the treatments. The following determinations were taken into account: microscopic examinations of spleen, liver and lungs and cultures of the spleen with determination of colony forming units/g.All the antifungal drugs used in this study were able to cause negative microscopic examinations of the liver, spleen and lungs; but only amphotericin B produced culture negative results. Itraconazole and ketoconazole presented 66% and 86% of positive cultures respectively, nevertheless the C.F.U. were lower than those obtained in control groups.In these experimental conditions amphotericin B seems to be more active than the azolic compounds and itraconazole is slightly superior to ketoconazole at a lower dose.

In Vitro Activities of Amphotericin B, Terbinafine, and Azole Drugs against Clinical and Environmental Isolates of Aspergillus terreus Sensu Stricto

ABSTRACT The antifungal susceptibilities of 40 clinical and environmental isolates of A. terreus sensu stricto to amphotericin B, terbinafine, itraconazole, and voriconazole were determined in accordance with CLSI document M38-A2. All isolates had itraconazole and voriconazole MICs lower than epidemiologic cutoff values, and 5% of the isolates had amphotericin B MICs higher than epidemiologic cutoff values. Terbinafine showed the lowest MICs. No significant differences were found when MICs of clinical and environmental isolates were compared.

Genetic diversity of Histoplasma capsulatum strains isolated from Argentina based on nucleotide sequence variations in the internal transcribed spacer regions of rDNA.

The internal transcribed spacer (ITS) regions of rDNA genes of 49 Histoplasma capsulatum (48 from clinical samples and one from soil) isolates were examined. Nucleotide sequence heterogeneity within this region was useful for phylogenetic classification of H. capsulatum and species identification. Thus, in 45 of 49 isolates we observed higher percentages of identity in the nucleotide sequences of ITS regions when the isolates studied herein were compared with those reported in our country in the South America B clade. Phylogenetic analyses of rDNA sequences corresponding to the 537 bp of the ITS region obtained from H. capsulatum isolates assigned South America type B clade (45 isolates), North America type 1 and Asia clade (2 isolates each one). H. capsulatum strains isolated from soil and from patients living in Argentina (45 of 49) clustered together with the H. capsulatum isolates of the South America B clade. The high level of genetic similarity among our isolates suggests that almost one genetic population is present in the microenvironment. Isolates described as H. capsulatum var. capsulatum or var. farciminosum (2 isolates) did not form a monophyletic group and were found in the Asia clade. Subsequent studies are needed to properly identify these isolates.