Trichophyton tonsurans strains from Brazil: phenotypic heterogeneity, genetic homology, and detection of virulence genes

The objective of this study was to establish the phenotypical and molecular patterns of clinical isolates of Trichophyton tonsurans circulating in the state of Ceará, northeastern Brazil. For this purpose, 25 T. tonsurans strains isolated from independent cases of tinea capitis in children were phenotypically evaluated regarding their macro- and micro-morphological characteristics, vitamin requirements, urease production, and antifungal susceptibility. The molecular characterization was carried out with random amplified polymorphic DNA molecular markers and M13 fingerprinting. The presence of the genes CarbM14, Sub2, CER, URE, ASP, PBL, and LAC, which encode enzymes related to fungal virulence, was also evaluated. Finally, melanin production was assessed through specific staining. The data obtained demonstrated that these T. tonsurans strains have considerable phenotypical variation, although they showed a low degree of genetic polymorphism according to the markers used. The genes CarbM14, Sub2, CER, and URE were detected in all the analyzed strains. The gene LAC was also identified in all the strains, and melanin synthesis was phenotypically confirmed. The strains were susceptible to antifungals, especially itraconazole (GM = 0.06 μg/mL) and ketoconazole (GM = 0.24 μg/mL). Therefore, T. tonsurans strains can present great phenotypical heterogeneity, even in genetically similar isolates. Moreover, the presence of the LAC gene indicates the possible participation of melanin in the pathogenesis of these dermatophytes.

Antifungal susceptibility of emerging opportunistic yeasts and yeast-like fungi from Rhea americana

Opportunistic yeasts and yeast-like fungi have been recognized as important pathogens in high-risk patients. This study aimed to evaluate the presence of these microorganisms in the microbiota of captive rheas and to investigate the antifungal susceptibility of the isolated strains. Isolates representing Magnusiomyces capitatus (Geotrichum capitatum, n = 11), Trichosporon mucoides (n = 11), Trichosporon asteroides (n = 5), Rhodotorula mucilaginosa (n = 4), Trichosporon asahii (n = 3), Trichosporon cutaneum (n = 3), and Trichosporon ovoides (n = 3) were obtained from the oropharynx, cloaca, and feces of 58 animals. Most of the isolates were susceptible to antifungals in vitro; however, resistance against fluconazole (n = 1) and itraconazole (n = 2) was detected among T. mucoides. This study indicates that healthy rheas can be reservoirs of opportunistic pathogens. Primary resistance to azoles in T. mucoides obtained from these animals demonstrates the potential risk to humans.

Species of Candida as a component of the nasal microbiota of healthy horses

Respiratory infections are a common problem among equines and occur with variable rates of morbidity and mortality. Although some fungal species are considered primary agents of respiratory tract infections in several mammals, their relevance in respiratory diseases of equines is frequently neglected. In the present study, we performed an active search for Candida spp. in the nasal cavity of horses. The presence of Candida spp. was investigated through the use of nasal swabs that were streaked on culture media. These yeasts were identified through physiological testing and their in vitro antifungal susceptibility were also characterized. The analysis of the material from the nasal cavity of 97 randomly chosen horses resulted in the isolation of Candida spp. from 35 animals (36.08%), out of which 18 (32.14%) were C. famata, 14 (25%) C. parapsilosis, 12 (21.42%) Meyerozyma guilliermondii (C. guilliermondii), 11 (19.64%) C. tropicalis and 1 (1.78%) Wickerhamomyces anomalus (C. pelliculosa). The minimum inhibitory concentration (MIC) values ranged from 0.03125-1 μg/ml for amphotericin B; and from 0.03125-> 16 μg/ml and 0.125 to > 64 μg/ml for itraconazole and fluconazole, respectively. Resistance to fluconazole and itraconazole was observed among C. tropicalis (n = 3) and C. guilliermondii (n = 1). The data show a predominance of non-C. albicans Candida species in the nasal microbiota of healthy equines, including antifungal resistant isolates, reiterating the importance of monitoring fungal pathogens in these animals.

Detection of Candida species resistant to azoles in the microbiota of rheas (Rhea americana): possible implications for human and animal health

There is growing interest in breeding rheas (Rhea americana) in Brazil. However, there are no data on the yeast microbiota of the gastrointestinal tract of this avian species, and the phenotypic characteristics of these yeasts are not known. Therefore, the aim of this work was to isolate Candida species from the digestive tract of rheas and to evaluate the in vitro antifungal susceptibility and secretion of phospholipases of the recovered isolates. For this purpose, 58 rheas from breeding operations in the cities of Fortaleza and Mossoró, north-eastern Brazil, were used. Samples were gathered from the oropharynx and cloaca of the animals using sterile swabs. Stool samples were collected from their pens by scraping with a scalpel blade. For the primary isolation, the material was seeded onto 2 % Sabouraud dextrose agar supplemented with chloramphenicol (0.5 g l(-1)). The isolates were identified based on morphological and biochemical features. After identification, all the strains were submitted to antifungal susceptibility testing for amphotericin B, itraconazole and fluconazole. The phospholipase activity of the Candida species isolates was also tested by culturing on egg yolk agar. Candida species were isolated from at least one anatomical site in 36/58 birds (14/17 juveniles and 22/41 adults) and in 6/10 faecal samples. Mostly, only a single species was isolated from each collection site (36/56 positive sites), with up to three species being observed only in four cases (4/56). A total of 77 isolates were obtained, belonging to the species Candida parapsilosis sensu lato (19), Candida albicans (18), Candida tropicalis (13), Candida guilliermondii (12), Candida krusei (10) and Candida famata (5). C. albicans was more prevalent in the oropharynx of the juvenile rheas when compared with adult ones (P<0.001). All tested isolates were susceptible to amphotericin B, but 16 isolates were simultaneously resistant to the two azole derivatives (11/18 C. albicans, 1/10 C. krusei, 2/19 C. parapsilosis sensu lato and 2/13 C. tropicalis). C. albicans presented a particularly high resistance rate to fluconazole (15/18) and itraconazole (13/18). Finally, 23/77 strains secreted phospholipases. In summary, healthy rheas carry potentially pathogenic Candida species in their gastrointestinal tract, including azole-resistant strains that secrete phospholipases, and are prone to disseminating them in the environment. Thus, breeding and handling these animals may have some implications for human and animal health.

Ciprofloxacin shows synergism with classical antifungals against Histoplasma capsulatum var. capsulatum and Coccidioides posadasii

This study evaluated the in vitro interaction between ciprofloxacin (CIP) and classical antifungals against Histoplasma capsulatum var. capsulatum in mycelial (n = 16) and yeast-like forms (n = 9) and Coccidioides posadasii in mycelial form (n = 16). This research was conducted through broth microdilution and macrodilution, according to Clinical Laboratory Standards Institute. Inocula were prepared to obtain from 0.5 × 10(3) to 2.5 × 10(4)  cfu ml(-1) for H. capsulatum and from 10(3) to 5 × 10(3)  cfu ml(-1) for C. posadasii. Initially, minimum inhibitory concentration (MIC) for each drug alone was determined. Then, these MICs were used as the highest concentration for each drug during combination assays. The procedures were performed in duplicate. For all combination assays, MICs were defined as the lowest concentration capable of inhibiting 80% of visible fungal growth, when compared to the drug-free control. Drug interaction was evaluated by paired sample t-Student test. The obtained data showed a significant MIC reduction for most tested combinations of CIP with antifungals, except for that of CIP and voriconazole against yeast-like H. capsulatum. This study brings potential alternatives for the treatment of histoplasmosis and coccidioidomycosis, raising the possibility of using CIP as an adjuvant antifungal therapy, providing perspectives to delineate in vivo studies.

Genetic diversity of Coccidioides posadasii from Brazil

Studies of the genetic variation within populations of Coccidioides posadasii are scarce, especially for those recovered from South America. Understanding the distribution of genotypes among populations is important for epidemiological surveillance. This study evaluated the genetic diversity of 18 Brazilian strains of C. posadasii through the sequencing of the 18-28S region of nuclear rDNA, as well as through RAPD and M13-PCR fingerprinting techniques. The sequences obtained were compared to Coccidioides spp. previously deposited in GenBank. The MEGA5 program was used to perform phylogenetic analyses. Within the C. posadasii clade, a single cluster was observed, containing seven isolates from Ceará, which presented a single nucleotide polymorphism. These isolates were from the same geographical area. The strains of C. posadasii showed a lower rate of genetic diversity in the ITS1 and ITS2 regions. The results of M13 and RAPD-PCR fingerprinting indicated a similar electrophoretic profile. No differences between clinical and environmental isolates were detected. This was the first study assessing the genetic variability of a larger number of C. posadasii isolates from Brazil.

Coccidioides posadasii infection in bats, Brazil

To analyze the eco-epidemiologic aspects of Histoplasma capsulatum in Brazil, we tested 83 bats for this fungus. Although H. capsulatum was not isolated, Coccidioides posadasii was recovered from Carollia perspicillata bat lungs. Immunologic studies detected coccidioidal antibodies and antigens in Glossophaga soricina and Desmodus rotundus bats.

Viral protease inhibitors affect the production of virulence factors in Cryptococcus neoformans

The effects of the protease inhibitors saquinavir, darunavir, ritonavir, and indinavir on growth inhibition, protease and phospholipase activities, as well as capsule thickness of Cryptococcus neoformans were investigated. Viral protease inhibitors did not reduce fungal growth when tested in concentrations ranging from 0.001 to 1.000 mg/L. A tendency toward increasing phospholipase activity was observed with the highest tested drug concentration in a strain-specific pattern. However, these drugs reduced protease activity as well as capsule production. Our results confirm a previous finding that antiretroviral drugs affect the production of important virulence factors of C. neoformans.

Central nervous system involvement in dengue: a study in fatal cases from a dengue endemic area

OBJECTIVE

This study aimed to determine the frequency of CNS infection by dengue virus (DENV) in individuals with fatal outcomes.

METHODS

Samples of 150 individuals suspect of an infection disease and with fatal outcomes were investigated for evidence of the presence of DENV. The sampling was made up of 150 CSF, 120 tissue samples, and 109 blood specimens. The tests used were viral isolation, reverse transcriptase PCR, immunohistochemistry, nonstructural 1 antigen, and immunoglobulin M detection.

RESULTS

Out of 150 studied patients, 84 were dengue positive. Evidence of the presence of DENV was found in 41 CSF, showing the following neurologic diagnosis: 46.3% encephalitis, 34.1% meningoencephalitis, and 19.5% meningitis, giving a frequency of 48.8% of the 84 dengue-positive cases. The major clinical manifestations observed on these individuals were fever, headache, mental irritability, breathless, vomiting, muscle pain, tiredness, abdominal pain, somnolence, restlessness, dizziness, cough, seizure, coma, and neck stiffness.

CONCLUSION

Clinical manifestations and laboratory-positive results in CSF that may indicate the presence of DENV led to consider the invasion of CNS by DENV in these fatal cases studied, and showed that neurologic pathology was an important fatal complication in dengue cases.

Feline histoplasmosis in Brazil: clinical and laboratory aspects and a comparative approach of published reports

The present study described clinical and epidemiological aspects of three cases of feline histoplasmosis and compared them to previously described cases. A detailed mycological identification and antifungal susceptibility profile of each isolate are presented. Secondarily, a serological survey for anti-Histoplasma antibodies was performed with domestic and wild cats. Diseased animals presented nodular to ulcerated skin lesions and respiratory disorders as main clinical signs. H. capsulatum var. capsulatum was isolated and the strains showed to be susceptible to antifungal drugs. Considering that feline histoplasmosis is uncommonly observed in veterinary clinics, diagnosis, and clinical management in endemic areas should be improved.

Detection of the dengue non-structural 1 antigen in cerebral spinal fluid samples using a commercially available enzyme-linked immunosorbent assay

The involvement of the central nervous system in dengue infections has been reported in countries where the disease in endemic. The purpose of this study was to determine whether an enzyme-linked immunosorbent assay kit designed to detect the dengue NS1 antigen in serum was able to detect this antigen in cerebral spinal fluid (CSF) samples from patients with fatal outcomes. To evaluate the sensitivity of the kit, 26 dengue-positive CSF samples were used. The Pan-E Dengue Early kit was able to detect the NS1 antigen in 13 of 26 dengue-positive CSF samples, resulting in a sensitivity of 50% (95% confidence interval, 29.9-70.1%) and specificity of 100% (95% confidence interval, 75.3-100%). The kit was able to detect the NS1 antigen in CSF of individuals who had died of dengue. When used in combination with IgM, the detection rate rose to 92.3%. This study reports a method for rapidly detecting the dengue virus in CSF, thereby increasing the diagnosis of dengue fever cases with unusual neurological manifestations.

Mycotic aneurysm caused by Burkholderia pseudomallei: report of a Brazilian strain genetically related to Thai strains

Melioidosis, a severe infectious disease caused by Burkholderia pseudomallei that is prevalent in Southeast Asia and Northern Australia, has been sporadically reported in Brazil since 2003. We report a case of aortic aneurysm with blood culture positive for B. pseudomallei. The phylogenetic analysis of 16S ribosomal DNA showed this isolate to be evolutionarily grouped with the MSHR346 strains from Thailand.

Molecular methods for the diagnosis and characterization of Cryptococcus: a review

Cryptococcosis is a fungal infection caused by yeasts of the genus Cryptococcus, with Cryptococcus neoformans and Cryptococcus gattii as the primary pathogenic species. This disease is a threat to immunocompromised patients, especially those who have AIDS. However, the disease has also been described in healthy individuals. The tests used to identify these microorganisms have limitations that make final diagnosis difficult. However, currently there are specific gene sequences that can be used to detect C. neoformans and C. gattii from clinical specimens and cultures. These sequences can be used for identification, typing, and the study of population genetics. Among the main identification techniques are hybridization, which was the pioneer in molecular identification and development of specific probes for pathogen detection; PCR and other PCR-based methods, particularly nested PCR and multiplex PCR; and sequencing of specific genomic regions that are amplified through PCR, which is especially useful for diagnosis of cryptococcosis caused by unconventional Cryptococcus sp. Concerning microorganism typing, the following techniques have shown the best ability to differentiate between fungal serotypes and molecular types: PCR fingerprinting, PCR-RFLP, AFLP, and MLST. Thus, the accumulation of data generated by molecular methods can have a positive impact on monitoring resistant strains and treating diseases.

A diagnosis of Burkholderia pseudomallei directly in a bronchoalveolar lavage by polymerase chain reaction

Melioidosis is an infectious disease caused by the Gram-negative bacterium Burkholderia pseudomallei. Interest in the molecular identification of B. pseudomallei has increased after its classification as a category B agent by the US Centers for Disease Control and Prevention. The present article reports a diagnosis of B. pseudomallei directly in a bronchoalveolar lavage by polymerase chain reaction amplification. The results obtained show that direct detection of the 16-23s spacer sequence in bronchoalveolar lavage is a quick and specific test to diagnose melioidosis.

Fungal microbiota dynamics as a postmortem investigation tool: focus on Aspergillus, Penicillium and Candida species

AIMS

To investigate the presence of fungi during three human decomposition stages: bloated, putrefaction and skeletonization.

METHODS AND RESULTS

The samples were gathered in the city of Fortaleza, Ceará, Brazil, from the public morgue and cemeteries. The material was submitted to conventional mycological procedures by direct examination and macro/micro morphological and biochemical analyses. The main fungi isolated were Aspergillus spp., Penicillium spp. and Candida spp. in the bloated stage (n = 34 cadavers) and in the putrefaction stage (n = 6 cadavers), while in the skeletonization stage (n = 20 cadavers), the main fungi were Aspergillus spp., Penicillium spp. and Mucor sp.

CONCLUSIONS

Aspergillus, Penicillium and Candida species were associated with decomposed human cadavers.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings enable tracing out the profile of fungal communities of human cadavers for the first time. However, much more research will be necessary to develop this new segment of mycology and to enable its routine use in forensic science.

Chemical composition, toxicity and larvicidal and antifungal activities of Persea americana (avocado) seed extracts

The present study had the aim of testing the hexane and methanol extracts of avocado seeds, in order to determine their toxicity towards Artemia salina, evaluate their larvicidal activity towards Aedes aegypti and investigate their in vitro antifungal potential against strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis through the microdilution technique. In toxicity tests on Artemia salina, the hexane and methanol extracts from avocado seeds showed LC50 values of 2.37 and 24.13 mg mL-1 respectively. Against Aedes aegypti larvae, the LC50 results obtained were 16.7 mg mL-1 for hexane extract and 8.87 mg mL-1 for methanol extract from avocado seeds. The extracts tested were also active against all the yeast strains tested in vitro, with differing results such that the minimum inhibitory concentration of the hexane extract ranged from 0.625 to 1.25mg L-(1), from 0.312 to 0.625 mg mL-1 and from 0.031 to 0.625 mg mL-1, for the strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis, respectively. The minimal inhibitory concentration for the methanol extract ranged from 0.125 to 0.625 mg mL-1, from 0.08 to 0.156 mg mL-1 and from 0.312 to 0.625 mg mL-1, for the strains of Candida spp., Cryptococcus neoformans and Malassezia pachydermatis, respectively.

Ants (Hymenoptera: Formicidae) as carriers of fungi in hospital environments: an emphasis on the genera Tapinoma and Pheidole

The aim of this study was to evaluate the presence of filamentous fungi and yeasts on the external surface of ants at hospitals. From March 2007 to February 2008, 2,899 ants were evaluated in two public hospitals in the city of Fortaleza, Ceará, in northeastern Brazil. The ants were attracted by nontoxic baits, distributed within critical and semicritical hospital areas. The fungi were identified through macro- and micromorphological analysis, biochemical profile, and growth in chromogenic medium. From this study, 5 genera and 13 species of ants were identified, from critical (8% of the collected ants) and semicritical (92%) areas, during the daytime (48%) and nighttime (52%) periods. In the mycological analysis, 75% of the ants were fungi carriers, with the species Tapinoma melanocephalum and species from the genus Pheidole having the most potential as carriers of airborne fungi (75 and 18%, respectively) and yeasts (6 and 1%, respectively). In summary, ants act as carriers of airborne fungi and yeasts, including some pathogenic species.

In vitro synergistic effects of antituberculous drugs plus antifungals against Coccidioides posadasii

The aim of the present study was to evaluate the in vitro interactions of antituberculous drugs (ATDs) with antifungals against Coccidioides posadasii. Eighteen drug combinations, formed by an ATD (isoniazid, pyrazinamide or ethambutol) plus an antifungal (amphotericin B, ketoconazole, itraconazole, fluconazole, voriconazole or caspofungin), were tested using the checkerboard method. All the antimicrobial combinations inhibited C. posadasii strains and synergistic interactions were observed for 10 combinations. Antagonism between the tested drugs was not observed. Stronger synergistic interactions were seen in the combinations formed by triazoles plus ethambutol as well as itraconazole plus pyrazinamide. Further studies in animal models are needed to confirm the usefulness of these combinations.

Antifungal and marker effects of Talisia esculenta lectin on Microsporum canis in vitro

AIMS

The purpose of this study was to demonstrate the usefulness of lectin obtained from Talisia esculenta (TEL) seeds as a tool to recognize and study Microsporum canis. For this purpose, we investigated the antifungal and marker action of this lectin and the relationship of these effects with the presence of carbohydrates on the structure of this fungus.

METHODS AND RESULTS

The in vitro antifungal activity of TEL was analysed by broth microdilution assay. In addition, TEL was assessed against the arthroconidia present on hairs obtained from infected dogs and cats. The affinity of fluorescein isothiocyanate (FITC)-labelled TEL for macroconidia and arthroconidia of M. canis was also tested. The effects of TEL on the growth of the M. canis strains began with 0.125 mg ml(-1), and 100% inhibition was obtained with a concentration of 2 mg ml(-1). The addition of carbohydrates, especially N-acetyl-glucosamine and d-mannose, inhibited these antifungal effects. TEL was able to inhibit the growth of arthroconidial chitin-rich forms of M. canis obtained from hairs of infected animals and strains cultured in Sabouraud agar. FITC-labelled TEL efficiently marked macroconidial and arthroconidial forms of M. canis, as shown by fluorescent microscopy.

CONCLUSIONS

These results show that the inhibitory effects of TEL on M. canis growth may be related to the interaction of lectin with the carbohydrates present at the micro-organism's surface, mainly D-mannose and N-acetyl-glucosamine.

SIGNIFICANCE AND IMPACT OF THE STUDY

Talisia esculenta can be used as an important tool in the biochemical study of M. canis or as a molecule to recognize this dermatophyte in infected tissue.

Twelve years of coccidioidomycosis in Ceará State, Northeast Brazil: epidemiologic and diagnostic aspects

Coccidioidomycosis is an endemic infection in the Americas caused by the dimorphic fungi Coccidioides immitis and Coccidioides posadasii. Although the disease occurs in Brazil in sporadic form, little information about these cases is available. In this study, we summarize the most important clinical, epidemiologic, and diagnostic features of coccidioidomycosis in Ceará State (Northeast Brazil) during the past 12 years. In this period, 19 cases of coccidioidomycosis were diagnosed. All the patients were young males and came from semiarid areas of the state. The majority of cases were associated to armadillo hunting, and pulmonary disease was the most common clinical presentation. In our laboratory, coccidioidomycosis was confirmed by culture, serology, and polymerase chain reaction tests, which together were very suitable for the diagnosis of this disease. Based on our local experience, we believe many cases of this disease are misdiagnosed or not diagnosed in our region. Therefore, some strategies for improvement of diagnosis should be encouraged by local authorities.