Antifungal Activity of Chitosan against Histoplasma capsulatum in Planktonic and Biofilm Forms: A Therapeutic Strategy in the Future?

Histoplasmosis is a respiratory disease caused by Histoplasma capsulatum, a dimorphic fungus, with high mortality and morbidity rates, especially in immunocompromised patients. Considering the small existing therapeutic arsenal, new treatment approaches are still required. Chitosan, a linear polysaccharide obtained from partial chitin deacetylation, has anti-inflammatory, antimicrobial, biocompatibility, biodegradability, and non-toxicity properties. Chitosan with different deacetylation degrees and molecular weights has been explored as a potential agent against fungal pathogens. In this study, the chitosan antifungal activity against H. capsulatum was evaluated using the broth microdilution assay, obtaining minimum inhibitory concentrations (MIC) ranging from 32 to 128 µg/mL in the filamentous phase and 8 to 64 µg/mL in the yeast phase. Chitosan combined with classical antifungal drugs showed a synergic effect, reducing chitosan's MICs by 32 times, demonstrating that there were no antagonistic interactions relating to any of the strains tested. A synergism between chitosan and amphotericin B or itraconazole was detected in the yeast-like form for all strains tested. For H. capsulatum biofilms, chitosan reduced biomass and metabolic activity by about 40% at 512 µg/mL. In conclusion, studying chitosan as a therapeutic strategy against Histoplasma capsulatum is promising, mainly considering its numerous possible applications, including its combination with other compounds.

Impact of a computer system as a triage tool in the management of pulmonary tuberculosis in a HIV reference center in Brazil.

BACKGROUND: The Neural Clinical Score for tuberculosis (NCS-TB) is a computer system developed to improve the triage of presumed pulmonary TB (pPTB). METHODS: A study was performed with cohorts of pPTB patients cared for at a reference hospital in Northeast Brazil. RESULTS: The NCS-TB sensitivity was 76.5% for TB diagnosis, which shortened the time from triage to smear microscopy results (3.3 to 2.5 days; p<0.001) and therapy initiation (6.7 to 4.1 days; p=0.045). CONCLUSIONS: Although the NCS-TB was not suitable as a screening tool, it was able to optimize laboratory diagnosis and shorten the time to treatment initiation.

Impact of a computer system as a triage tool in the management of pulmonary tuberculosis in a HIV reference center in Brazil

ABSTRACT Background: The Neural Clinical Score for tuberculosis (NCS-TB) is a computer system developed to improve the triage of presumed pulmonary TB (pPTB). Methods: A study was performed with cohorts of pPTB patients cared for at a reference hospital in Northeast Brazil. Results: The NCS-TB sensitivity was 76.5% for TB diagnosis, which shortened the time from triage to smear microscopy results (3.3 to 2.5 days; p<0.001) and therapy initiation (6.7 to 4.1 days; p=0.045). Conclusions: Although the NCS-TB was not suitable as a screening tool, it was able to optimize laboratory diagnosis and shorten the time to treatment initiation.

Synergistic effects of ketamine and azole derivatives on Candida spp. resistance to fluconazole.

The emergence of Candida spp. with resistance to antifungal molecules, mainly the azole class, is an increasing complication in hospitals around the globe. Aim: In the present research, we evaluated the synergistic effects of ketamine with two azole derivatives, itraconazole and fluconazole, on strains of Candida spp. to fluconazole. Materials & methods: The drug synergy was evaluated by quantifying the fractional inhibitory concentration index and by fluorescence microscopy and flow cytometry techniques. Results: Our achievements showed a synergistic effect between ketamine in addition to the two antifungal agents (fluconazole and itraconazole) against planktonic cells and biofilms of Candida spp. Conclusion: This combination promoted alteration of membrane integrity, generation of reactive oxygen species, damage to and DNA and externalization of phosphatidylserine.

Novel clinical and dual infection by Histoplasma capsulatum genotypes in HIV patients from Northeastern, Brazil.

Histoplasmosis is a worldwide-distributed deep mycosis that affects healthy and immunocompromised hosts. Severe and disseminated disease is especially common in HIV-infected patients. At least 11 phylogenetic species are recognized and the majority of diversity is found in Latin America. The northeastern region of Brazil has one of the highest HIV/AIDS prevalence in Latin America and Ceará State has one of the highest death rates due to histoplasmosis in the world, where the mortality rate varies between 33-42%. The phylogenetic distribution and population genetic structure of 51 clinical isolates from Northeast Brazil was studied. For that morphological characteristics, exoantigens profile, and fungal mating types were evaluated. The genotypes were deduced by a MSLT in order to define local population structure of this fungal pathogen. In addition, the relationships of H. capsulatum genotypes with clinically relevant phenotypes and clinical aspects were investigated. The results suggest two cryptic species, herein named population Northeast BR1 and population Northeast BR2. These populations are recombining, exhibit a high level of haplotype diversity, and contain different ratios of mating types MAT1-1 and MAT1-2. However, differences in phenotypes or clinical aspects were not observed within these new cryptic species. A HIV patient can be co-infected by two or more genotypes from Northeast BR1 and/or Northeast BR2, which may have significant impact on disease progression due to the impaired immune response. We hypothesize that co-infections could be the result of multiple exposure events and may indicate higher risk of disseminated histoplasmosis, especially in HIV infected patients.

Mixed infection by Histoplasma capsulatum isolates with different mating types in Brazilian AIDS-patients.

Mixed infection by Histoplasma capsulatum isolates with different mating types, in AIDS-patients are described in this study. Morphological, mating type-specific PCR assay and multilocus sequencing type analysis of H. capsulatum isolates recovered from two Brazilian AIDS-patients were performed. Five H. capsulatum isolates were recovered at different times from the two patients. Three isolates were obtained from bone marrow (day 1 - CE0411) and buffy coat cultures (day 1 - CE0311; day 2 - CE0511) of patient 1, and two isolates were isolated from buffy coat cultures (day 3 - CE2813; day 12 - CE2513) of patient 2. The mycelial colonies depicted different textures and pigmentation features. Dimorphic conversion to the yeast-phase in ML-Gema medium was achieved in all isolates. MAT1-1 idiomorph was identified in CE0311, CE0411 and CE2813 isolates; MAT1-2 idiomorph was found in CE0511 and CE2513 isolates. These H. capsulatum isolates were grouped within LAm A clade, highlighting that CE0311 and CE0411 isolates formed a subgroup supported by a high bootstrap value. The CE0511, CE2513, and CE2813 isolates clustered together with a Brazilian H151 isolate. This research reports mixed infections caused by H. capsulatum isolates with different mating types in Brazilian AIDS-patients for the first time in the literature.

RYP1 gene as a target for molecular diagnosis of histoplasmosis.

This study analyzed the RYP1 gene as a target for the molecular diagnosis of histoplasmosis. This assay detected fungal DNA in 13/13 blood samples from HIV/AIDS-patients with histoplasmosis. Therefore, the detection of RYP1 gene in whole blood sample is a quick and sensitive test to diagnose histoplasmosis.

Antiretroviral drugs saquinavir and ritonavir reduce inhibitory concentration values of itraconazole against Histoplasma capsulatum strains in vitro

Abstract Recent studies have shown that some drugs that are not routinely used to treat fungal infections have antifungal activity, such as protease inhibitor antiretroviral drugs. This study investigated the in vitro susceptibility of Histoplasma capsulatum var. capsulatum to saquinavir and ritonavir, and its combination with the antifungal itraconazole. The susceptibility assay was performed according to Clinical and Laboratory Standards Institute guidelines. All strains were inhibited by the protease inhibitor antiretroviral drugs. Saquinavir showed minimum inhibitory concentrations ranging from 0.125 to 1 μg mL−1 for both phases, and ritonavir presented minimum inhibitory concentrations ranging from 0.0312 to 4 μg mL−1and from 0.0625 to 1 μg mL−1 for filamentous and yeast phase, respectively. Concerning the antifungal itraconazole, the minimum inhibitory concentration values ranged from 0.0019 to 0.125 μg mL−1 and from 0.0039 to 0.0312 μg mL−1 for the filamentous and yeast phase, respectively. The combination of saquinavir or ritonavir with itraconazole was synergistic against H. capsulatum, with a significant reduction in the minimum inhibitory concentrations of both drugs against the strains (p < 0.05). These data show an important in vitro synergy between protease inhibitors and itraconazole against the fungus H. capsulatum.

Antiretroviral drugs saquinavir and ritonavir reduce inhibitory concentration values of itraconazole against Histoplasma capsulatum strains in vitro.

Recent studies have shown that some drugs that are not routinely used to treat fungal infections have antifungal activity, such as protease inhibitor antiretroviral drugs. This study investigated the in vitro susceptibility of Histoplasma capsulatum var. capsulatum to saquinavir and ritonavir, and its combination with the antifungal itraconazole. The susceptibility assay was performed according to Clinical and Laboratory Standards Institute guidelines. All strains were inhibited by the protease inhibitor antiretroviral drugs. Saquinavir showed minimum inhibitory concentrations ranging from 0.125 to 1µgmL(-1) for both phases, and ritonavir presented minimum inhibitory concentrations ranging from 0.0312 to 4µgmL(-1)and from 0.0625 to 1µgmL(-1) for filamentous and yeast phase, respectively. Concerning the antifungal itraconazole, the minimum inhibitory concentration values ranged from 0.0019 to 0.125µgmL(-1) and from 0.0039 to 0.0312µgmL(-1) for the filamentous and yeast phase, respectively. The combination of saquinavir or ritonavir with itraconazole was synergistic against H. capsulatum, with a significant reduction in the minimum inhibitory concentrations of both drugs against the strains (p<0.05). These data show an important in vitro synergy between protease inhibitors and itraconazole against the fungus H. capsulatum.

Disseminated histoplasmosis in HIV-infected patients: determinants of relapse and mortality in a north-eastern area of Brazil.

Many relapses and deaths resulting from disseminated histoplasmosis (DH) in acquired immunodeficiency syndrome (AIDS) patients have been observed in an endemic area in north-eastern Brazil. The objective of this study was to evaluate the risk factors associated with the clinical outcomes of DH/AIDS coinfection in patients from the state of Ceará, Brazil. A retrospective cohort of AIDS patients, after their hospital discharge due to first DH episode in the period 2002-2008, was followed until December 31, 2010, to investigate the factors associated with relapse and mortality. A total of 145 patients were evaluated in the study. Thirty patients (23.3%) relapsed and the overall mortality was 30.2%. The following variables were significantly (P < 0.05) associated with relapse and overall mortality (univariate analysis): non-adherence to highly active antiretroviral therapy (HAART), irregular use of an antifungal, non-recovery of the CD4+ count and having AIDS before DH; histoplasmosis relapse was also significantly associated with mortality. In the multivariate analysis, non-adherence to HAART was the independent risk factor that was associated with both relapse (Adj OR = 6.28) and overall mortality (Adj OR = 8.03); efavirenz usage was discovered to be significant only for the overall mortality rate (Adj OR = 4.50). Adherence to HAART was the most important variable that influenced the outcomes in this specific population.

Disseminated histoplasmosis and aids: relapse and late mortality in endemic area in North-Eastern Brazil.

The State of Ceará in north-eastern Brazil has one of the highest rates in the world of relapse and death due to disseminated histoplasmosis (DH) in acquired immunodeficiency syndrome (AIDS) patients. The objective of this study is to characterise the relapse and mortality of DH in AIDS cases residents in Ceará. We performed a retrospective analysis of the medical records of AIDS patients who had a first episode of DH from 2002 to 2008. We analysed the outcomes until December 31, 2010. A total of 145 patients participated in the study. The mean clinical follow-up duration was 3.38 years (SD = 2.2; 95% CI = 3.01-3.75). The majority of the subjects were male with a mean age of 35 years (SD = 2.2; 95% CI = 3.01-3.75) and were born in the capital of Ceará. DH was the first manifestation of AIDS in 59% of the patients. The relapse rate was 23.3%, with a disseminated presentation in 90% of these patients. The overall mortality during the study period was 30.2%. The majority of patients who relapsed or died had irregular treatment with antifungals or highly active antiretroviral therapy and did not have active clinical follow-up. High rates of recurrence and mortality were found in AIDS-associated DH in this area of the country.

Coccidioidomycosis in armadillo hunters from the state of Ceará, Brazil.

Coccidioidomycosis is a systemic mycosis with a variable clinical presentation. Misdiagnosis of coccidioidomycosis as bacterial pneumopathy leads to inappropriate prescription of antibiotics and delayed diagnosis. This report describes an outbreak among armadillo hunters in northeastern Brazil in which an initial diagnosis of bacterial pneumonia was later confirmed as coccidioidomycosis caused by Coccidioides posadasii. Thus, this mycosis should be considered as an alternative diagnosis in patients reporting symptoms of pneumonia, even if these symptoms are only presented for a short period, who are from areas considered endemic for this disease.

Coccidioidomycosis in armadillo hunters from the state of Ceará, Brazil

Coccidioidomycosis is a systemic mycosis with a variable clinical presentation. Misdiagnosis of coccidioidomycosis as bacterial pneumopathy leads to inappropriate prescription of antibiotics and delayed diagnosis. This report describes an outbreak among armadillo hunters in northeastern Brazil in which an initial diagnosis of bacterial pneumonia was later confirmed as coccidioidomycosis caused by Coccidioides posadasii. Thus, this mycosis should be considered as an alternative diagnosis in patients reporting symptoms of pneumonia, even if these symptoms are only presented for a short period, who are from areas considered endemic for this disease.

Synergistic effect of antituberculosis drugs and azoles in vitro against Histoplasma capsulatum var. capsulatum.

This study evaluated in vitro interactions of antituberculosis drugs and triazoles against Histoplasma capsulatum. Nine drug combinations, each including an antituberculosis drug (isoniazid, pyrazinamide, or ethambutol) plus a triazole (itraconazole, fluconazole, or voriconazole), were tested against both growth forms of H. capsulatum. Stronger synergistic interactions were seen in isoniazid or pyrazinamide plus triazoles for the mold form and ethambutol plus voriconazole for the yeast-like form. Further studies should evaluate these combinations in vivo.

In vitro effect of sulfamethoxazole-trimethoprim against Histoplasma capsulatum var. capsulatum.

This study evaluated the in vitro effect of sulfamethoxazole-trimethoprim against Histoplasma capsulatum var. capsulatum isolated from HIV-positive patients. The drugs were tested by microdilution testing in accordance with the CLSI guidelines. All of the strains were inhibited by sulfamethoxazole-trimethoprim, with MIC ranges of 0.039 (sulfamethoxazole)/0.0078 (trimethoprim) mg/ml to 0.625/0.125 mg/ml for mycelial forms and 0.0025/0.0005 to 0.02/0.004 mg/ml for yeast-like forms. However, in vivo studies are necessary to evaluate the significance of these results.