Marcos Fábio Gadelha Rocha

Antifungal activity of essential oils of Croton species from the Brazilian Caatinga biome

Aims:  To find new antifungal agents among essential oils from Brazilian Croton species.

High rate of Microsporum canis feline and canine dermatophytoses in Northeast Brazil: epidemiological and diagnostic features.

Over a one year period (November 2000–December 2001), clinical specimens from 189 dogs and 38 cats, from the city of Fortaleza, Ceará, Brazil, were examined at the Specialized Medical Mycology Center at the Federal University of Ceará to detect animals with dermatophytoses. The mycological analyses were conducted by direct microscopy and by fungal culture on Sabouraud agar, Sabouraud chloramphenicol agar and Mycosel agar. Dermatophytes were isolated from 27 of the 189 (14.3%) canine specimens and 14 of the 38 (36.8%) feline specimens. The identified dermatophytes were Microsporum canis (95%), M. gypseum (2.5%) and Trichophyton mentagrophytes var. mentagrophytes (2.5%). Microsporum canis was the most common species isolated (92.6% and 100%, for dogs and cats respectively). The percentage of positive direct microscopic examinations of clinical specimens and positive cultures was 61%. There was a high proportion of positive cultures from cats less than 1 year of age, but in dogs no significant differences were detected. There were no significant differences between the sexes. Dermatophytes were more frequently isolated in March, April and May, but no significant differences were detected in the seasonal distribution of canine and feline dermatophytoses.

Onychomycosis in Ceará (Northeast Brazil): epidemiological and laboratory aspects

Knowledge of epidemiological and mycological characteristics of onychomycosis has been noted by many authors as being an important tool for control of these fungal infections. This study seeks to improve knowledge of onychomycosis epidemiology and mycological features. Samples were taken from infected fingernails and toenails of 976 patients undergoing treatment at a respected Dermatology Center in Ceará, Fortaleza, CE, Brazil. Specimens from 512 patients (52%) were positive for onychomycosis. From the culture-positive samples, yeasts of the genus Candida (C. albicans, C. tropicalis, C. krusei, C. parapsilosis) were dominant. The dermatophytes isolated (Trichophyton rubrum, T. tonsurans, T. mentagrophytes var. mentagrophytes) were dominant in 46 patients (12.99%). The mould Fusarium spp. was isolated from 29 patients (8.19%). Yeast of the genus Candida is the main causal factor in onychomycosis in our region. Also, the study showed the importance of performing direct examination and culture in diagnosis of onychomycosis.

The anatomical distribution and antimicrobial susceptibility of yeast species isolated from healthy dogs.

The aim of this work was to identify the predominant yeast species present at different anatomical sites in healthy dogs and to determine their in vitro antimicrobial susceptibility using a broth microdilution assay. Samples were collected from the preputial, vaginal, oral and perianal mucosae and the isolates cultured were identified according to their morphological characteristics and biochemical profile. Malassezia pachydermatis was the most commonly isolated yeast, followed by Candida parapsilosis, Candida tropicalis, Candida albicans, Saccharomyces cerevisiae and Rhodotorula spp. Minimum inhibitory concentrations of the azole derivatives ketoconazole, itraconazole and fluconazole against Candida spp. were 0.03-16 microg/mL, 0.06 to >16 microg/mL and 0.5-64 microg/mL, respectively and Candida isolates were sensitive to caspofungin and amphotericin B. Although all isolates of M. pachydermatis were sensitive to itraconazole, fluconazole, ketoconazole and amphotericin B, they were found to be resistant to caspofungin. The study has highlighted that Candida spp., M. pachydermatis, S. cerevisiae and Rhodotorula spp. are part of the normal canine surface microbiota and some of these organisms exhibit in vitro resistance to commonly used antimicrobials.

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.O presente estudo teve como objetivo testar os extratos hexânico e metanolico das sementes do abacate, a fim de determinar sua toxicidade em Artemia salina, avaliar a atividade larvicida frente ao Aedes aegypti, bem como verificar o potencial antifungico in vitro contra cepas de Candida spp, Cryptococcus neoformans e Malassezia pachydermatis, atraves da tecnica de microdiluicao. Os extratos hexânico e metanolico das sementes de abacate apresentaram no teste de toxicidade frente a Artemia salina, valores de LC50 2,37 e 24,13mg L-1, respectivamente; contra as larvas do Aedes aegypti os resultados obtidos foram LC50 16,7mg L-1 para o extrato hexânico e 8,87mg L-1 para o extrato metanolico das sementes do abacate. Os extratos testados tambem foram ativos contra todas as cepas de leveduras, testadas in vitro, apresentando diferentes resultados, onde o MIC do extrato hexânico variou de 0,625 a 1,25mg mL-1, de 0,312 a 0,625mg mL-1 e de 0,031 a 0,625mg mL-1 para as cepas de Candida spp., Cryptococcus neoformans e Malassezia pachydermatis, respectivamente. O intervalo de MIC para o extrato metanolico foi de 0,125 a 0,625mg mL-1, 0,08 a 0,156mg mL-1 e de 0,312 a 0,625mg mL-1, para as exemplares de Candida spp., Cryptococcus neoformans e Malassezia pachydermatis, respectivamente.

Tinea capitis in a dermatology center in the city of Fortaleza, Brazil: the role of Trichophyton tonsurans

Background  Over a 3‐year period (March 1999 to March 2002), 944 patients with scalp lesions attended a dermatology reference center in the city of Fortaleza, Ceará, Brazil. Clinical specimens were examined at the Specialized Medical Mycology Center, Federal University of Ceará, Fortaleza‐CE, Brazil, to detect patients with tinea capitis.

Candida species isolated from the gastrointestinal tract of cockatiels (Nymphicus hollandicus): in vitro antifungal susceptibility profile and phospholipase activity.

Over the past years, the incidence of yeast infections, especially candidiasis, has increased. It is known that birds, including cockatiels, harbor potentially pathogenic yeasts to human beings in their gastrointestinal tract. Thus, this work aims at determining the in vitro antifungal susceptibility and phospholipase activity of Candida spp. isolated from the gastrointestinal tract and stools of cockatiels. Sixty cockatiels were assessed and samples were collected from oral cavity, crop and cloaca and stools were collected from cages where birds were kept. Yeast species were identified according to morphological and biochemical characteristics. Amphotericin B, itraconazole and fluconazole were tested against 39 C. albicans; 12 C. tropicalis; 7 C. parapsilosis and 1 C. krusei, through broth microdilution test. These same isolates were also tested for phospholipase production, on egg yolk agar. For amphotericin B, itraconazole and fluconazole, MICs were 0.25-1 μg/mL, 0.03125 to ≥16 μg/mL and 0.5 to ≥64 μg/mL, respectively, and resistance to itraconazole and fluconazole was observed in 14 (35.89%) and 4 (10.26%) C. albicans isolates, respectively. All C. albicans were positive for phospholipase production, out of which 74.36% presented high enzymatic activity. Among non-albicans Candida species, 40% produced phospholipase. The results show that cockatiels might represent a hazard to human health, as sources of infections caused by resistant Candida spp., especially to immunocompromised individuals, children and elderly.

Histoplasmosis in HIV-positive patients in Ceará, Brazil: clinical-laboratory aspects and in vitro antifungal susceptibility of Histoplasma capsulatum isolates

This study contains a descriptive analysis of histoplasmosis in AIDS patients between 2006 and 2010 in the state of Ceará, Brazil. Additionally, the in vitro susceptibility of Histoplasma capsulatum isolates obtained during this period was assessed. We report 208 cases of patients with histoplasmosis and AIDS, describing the epidemiological, clinical, laboratory and therapeutic aspects. The in vitro antifungal susceptibility test was carried out by the microdilution method, according to Clinical and Laboratory Standards Institute, with H. capsulatum in the filamentous and yeast phases, against the antifungals amphotericin B, fluconazole, itraconazole, voriconazole and caspofungin. In 38.9% of the cases, histoplasmosis was the first indicator of AIDS and in 85.8% of the patients the CD4 cell count was lower than 100 cells/mm(3). The lactate dehydrogenase levels were high in all the patients evaluated, with impairment of hepatic and renal function and evolution to death in 42.3% of the cases. The in vitro susceptibility profile demonstrated there was no antifungal resistance among the isolates evaluated. There was a significant increase in the number of histoplasmosis cases in HIV-positive patients during the period surveyed in the state of Ceará, northeastern Brazil, but no antifungal resistance among the recovered isolates of H. capsulatum.

Epidemiologia e ecologia das dermatofitoses na cidade de Fortaleza: o Trichophyton tonsurans como importante patógeno emergente da Tinea capitis

Dermatophytosis is the most common skin infectious disturbance in the world. In this research 2.297 patients were evaluated with suspected clinical lesions of dermatophytosis. It was observed that, 534 (23.2%) patients tested positive for dermatophytes. T. rubrum was the most prevalent specie (49.6%; p £ 0.05), followed by T. tonsurans (34.4%), M. canis (7%) and T. mentagrophytes (6.2%). When the species isolated was correlated with the respective anatomical localization, it was observed that T. tonsurans was the most frequent isolated in scalp lesions (73,9%; p £ 0.01). On the other hand, T. rubrum was the main specie involved in body lesions (72.8%; p £ 0.05). Therefore, in scalp infections it was observed that, there was an absolute prevalence of T. tonsurans. This evidence is different from the statistical data collected in the southeast and south of Brazil, as well as from other areas of the world, which still show M. canis as the most frequent microorganism isolated in Tinea capiti.Dermatophytosis is the most common skin infectious disturbance in the world. In this research 2,297 patients were evaluated with suspected clinical lesions of dermatophytosis. It was observed that, 534 (23.2%) patients tested positive for dermatophytes. T. rubrum was the most prevalent specie (49.6%; p < or = 0.05), followed by T. tonsurans (34.4%), M. canis (7%) and T. mentagrophytes (6.2%). When the species isolated was correlated with the respective anatomical localization, it was observed that T. tonsurans was the most frequent isolated in scalp lesions (73.9%; p < or = 0.01). On the other hand, T. rubrum was the main specie involved in body lesions (72.8%; p < or = 0.05). Therefore, in scalp infections it was observed that, there was an absolute prevalence of T. tonsurans. This evidence is different from the statistical data collected in the southeast and south of Brazil, as well as from other areas of the world, which still show M. canis as the most frequent microorganism isolated in Tinea capitis.

The involvement of macrophage‐derived tumour necrosis factor and lipoxygenase products on the neutrophil recruitment induced by Clostridium difficile toxin B

Clostridium difficile (Cd) toxins appear to mediate the inflammatory response in pseudomembranous colitis and/or colitis associated with the use of antibiotics. In contrast to Cd Toxin A (TxA), Cd Toxin B (TxB) has been reported not to promote fluid secretion or morphological damage in rabbits and hamsters and also does not induce neutrophil chemotaxis in vitro. However, TxB is about 1000 times more potent than TxA in stimulating the release of tumour necrosis factor‐α (TNF‐α) by cultured monocytes. In the present study, we investigated the ability of TxB to promote neutrophil migration into peritoneal cavities and subcutaneous air‐pouches of rats. We also examined the role of resident peritoneal cells in this process as well as the inflammatory mediators involved. TxB caused a significant and dose‐dependent neutrophil influx with a maximal response at 0·1 μg/cavity after 4 hr. Depleting the peritoneal resident cell population by washing the peritoneal cavity or increasing this population by pretreating the animals with thioglycollate blocked and amplified the TxB‐induced neutrophil migration, respectively. Pretreating the animals with MK886 (a lipoxygenase inhibitor), NDGA (a dual cyclo‐ and lipoxygenase inhibitor) or the glucocorticoid, dexamethasone, but not with indomethacin (a cyclo‐oxygenase inhibitor), or BN52021 (a platelet‐activating factor antagonist), inhibited the neutrophil migration evoked by TxB. Pretreatment with dexamethasone or the administration of anti‐TNF‐α serum into the air‐pouches also significantly reduced the TxB‐induced neutrophil migration. Supernatants from TxB‐stimulated macrophages induced neutrophil migration when injected into the rat peritoneal cavity. This effect was attenuated by the addition of either MK886 or dexamethasone to the macrophage monolayer and by preincubating the supernatants with anti‐TNF‐α serum. TxB also stimulated the release of TNF‐α by macrophages. Overall, these results suggest that TxB induces an intense neutrophil migration which is mediated by macrophage‐derived TNF‐α and lipoxygenase products.