Susceptibility of species within the Sporothrix schenckii complex to a panel of killer yeasts.

The Sporothrix schenckii complex is the etiologic agent of sporotrichosis, a subacute or chronic mycosis which can affect humans and animals. Killer yeasts have been used in the medical field for development of novel antimycotics and biotyping of pathogenic fungi. The action of 18 killer yeasts on the growth of 88 characterized S. schenckii, Sporothrix globosa, Sporothrix brasiliensis, and Sporothrix mexicana clinical and environmental isolates was evaluated. Killer studies were performed on Petri dishes containing cheese black starch agar. The yeasts Candida catenulata (QU26, QU31, QU127, LV102); Trichosporon faecale (QU100); Trichosporon japonicum (QU139); Kluyveromyces lactis (QU30, QU99, QU73); Kazachstania unispora (QU49), Trichosporon insectorum (QU89), and Kluyveromyces marxianus (QU103) showed activity against all strains of the S. schenckii complex tested. Observation by optical microscopy of S. brasiliensis 61 within the inhibition haloes around the colonies of the killer yeasts QU100, QU139, and LV102 showed that there was no conidiation, but there was hyphal proliferation. The toxins were fungistatic against S. brasiliensis 61. There was no difference in susceptibility to the toxins among the S. schenckii species complex. Further investigations are necessary to clearly establish the mechanism of action of the toxins.

Prevalência de carbapenemases em enterobactérias resistentes a carbapenêmicos em quatro hospitais terciários de Porto Alegre / Prevalence of carbapenemases in carbapenem-resistant Enterobacteriaceae in four tertiary care hospitals in Porto Alegre

INTRODUÇÃO: A disseminação de Klebsiella pneumoniae carbapenemase (KPC) no Brasil e a recente detecção de bactérias produtoras de New Delhi metalo-β-lactamase (NDM-1) em hospital terciário do sul do Brasil indicam a necessidade da avaliação da presença destas enzimas em enterobactérias resistentes a carbapenêmicos (ERC).OBJETIVO: Avaliar prevalência de carbapenemases nas ERC em quatro hospitais terciários de Porto Alegre, por meio de PCR multiplex em tempo real. MÉTODOS: Estudo descritivo, período de abril a dezembro de 2013. Isolados bacterianos de pacientes internados foram identificados pelo sistema automatizado VITEK 2, com realização do teste de suscetibilidade aos antimicrobianos. Amostras com isolados de ERC foram encaminhadas ao laboratório de referência para análise por PCR em tempo real para identificação de carbapenemases. RESULTADOS: Total de 701 isolados. As ERC predominantes foram K. pneumoniae (47% das amostras positivas) e Enterobacter cloacae (18%). As carbapenemases mais frequentes foram KPC (48%), OXA-48-like (3%) e NDM (2%). Em 47% das amostras não foi identificado o mecanismo de resistência. Isolados originados de culturas de vigilância foram associados com maior positividade para carbapenemases do que isolados de amostras clínicas (p<0,0001). Isolados de ERC pertencentes ao grupo Proteae (Proteus spp., Morganella spp., Providencia spp.) foram associados a menor positividade para carbapenemase do que isolados de outras ERC (p<0,0001). CONCLUSÃO: KPC foi a carbapenemase mais frequentemente detectada. A circulação de uma enzima OXA-48-like foi demonstrada, um achado novo e preocupante. O achado da carbapenemase NDM também é preocupante devido ao seu potencial de disseminação. Esses dados e outros estudos poderão contribuir para um entendimento maior da epidemiologia das ERC.

BACKGROUND: The spread of Klebsiella pneumoniae carbapenemase (KPC) in Brazil and the recent detection of bacteria producing New Delhi metallo-β-lactamase (NDM-1) in a tertiary care hospital in Porto Alegre indicate the need to evaluate the presence of these enzymes in carbapenem-resistant Enterobacteriaceae (CRE). AIM: To evaluate the prevalence of carbapenemases in CRE in four tertiary care hospitals in Porto Alegre using multiplex real-time PCR.METHODS: Descriptive study from April to December 2013. Bacterial isolates from hospitalized patients were identified by VITEK 2 automated system, with antimicrobial susceptibility testing. Samples with CRE isolates were sent to the reference laboratory for analysis using real-time PCR for identification of carbapenemases. RESULTS: Total of 701 isolates. The predominant CRE were K. pneumoniae (46% of positive samples) and Enterobacter cloacae (18%). The most frequent carbapenemases were KPC (48%), OXA-48-like (3%), and NDM-1 (2%). In 47% of the samples no carbapenemase was identified. Isolates originated from surveillance cultures were associated with higher positivity for carbapenemases than isolates from clinical samples (p<0.0001). CRE isolates belonging to the Proteae group (Proteus spp., Morganella spp., Providencia spp.) were associated with less positivity for carbapanemase than isolates of other CRE (p<0.0001). CONCLUSION: KPC was the most frequently detected carbapenemase. The movement of an OXA-48-like enzyme was demonstrated, a novel and worrisome finding. The finding of carbapenemase NDM is also worrisome due to its dissemination potential. These data and further studies may contribute to a better understanding of the epidemiology of CRE.

Comparison between two culture media for in vitro evaluation of antifungal susceptibility of the Sporothrix schenckii complex.

BACKGROUND: The standard methodology for determining the antifungal sensitivity against the Sporothrix schenckii complex recommends the use of the 1640 Roswell Park Memorial Institute culture medium (RPMI) buffered with morpholinepropanolsulfonic acid (MOPS). However, while this is a high-cost medium which requires a laborious implementation and sterilization by filtration, the Sabouraud dextrose broth is a low-cost medium, widely used in mycology, sterilized by autoclave. OBJECTIVE: To evaluate the performance of the Sabouraud dextrose broth culture medium as a substitute for the RPMI 1640-MOPS in determining the antifungal sensitivity of S. schenckii. METHODS: Forty-eight clinical isolates were evaluated against five antifungal agents: itraconazole, ketoconazole, fluconazole, amphotericin B and terbinafine, using the method of broth microdilution advocated by the M38-A2 protocol of the Clinical and Laboratory Standards Institute. RESULTS: There were no significant differences between the Minimum Inhibitory Concentrations obtained in the two culture media for all the antifungals, with the exception of the amphotericin B. Regarding this drug, the Minimum Inhibitory Concentration range obtained were wider for the Sabouraud dextrose broth than for the Roswell Park Memorial Institute morpholinepropanelsulfonic acid. CONCLUSIONS: The Sabouraud dextrose broth showed potential to be used in the in vitro evaluation of the S. schenckii complex antifungal activity.

Comparison between two culture media for in vitro evaluation of antifungal susceptibility of the Sporothrix schenckii complex / Comparação entre dois meios de cultura para avaliação in vitro da suscetibilidade a antifúngicos do complexo Sporothrix schenckii

BACKGROUND: The standard methodology for determining the antifungal sensitivity against the Sporothrix schenckii complex recommends the use of the 1640 Roswell Park Memorial Institute culture medium (RPMI) buffered with morpholinepropanolsulfonic acid (MOPS). However, while this is a high-cost medium which requires a laborious implementation and sterilization by filtration, the Sabouraud dextrose broth is a low-cost medium, widely used in mycology, sterilized by autoclave. OBJECTIVE: To evaluate the performance of the Sabouraud dextrose broth culture medium as a substitute for the RPMI 1640-MOPS in determining the antifungal sensitivity of S. schenckii. METHODS: Forty-eight clinical isolates were evaluated against five antifungal agents: itraconazole, ketoconazole, fluconazole, amphotericin B and terbinafine, using the method of broth microdilution advocated by the M38-A2 protocol of the Clinical and Laboratory Standards Institute. RESULTS: There were no significant differences between the Minimum Inhibitory Concentrations obtained in the two culture media for all the antifungals, with the exception of the amphotericin B. Regarding this drug, the Minimum Inhibitory Concentration range obtained were wider for the Sabouraud dextrose broth than for the Roswell Park Memorial Institute morpholinepropanelsulfonic acid. CONCLUSIONS: The Sabouraud dextrose broth showed potential to be used in the in vitro evaluation of the S. schenckii complex antifungal activity.

FUNDAMENTOS: A metodologia padronizada para a determinação da sensibilidade aos antifúngicos frente ao complexo Sporothrix schenckii preconiza a utilização do meio de cultura Roswell Park Memorial Institute (RPMI) 1640 tamponado com ácido morfolinopropanosulfônico (MOPS). No entanto, este meio possui custo elevado, execução trabalhosa e esterilização por filtração. Já o caldo Sabouraud-dextrose é amplamente utilizado em micologia, de baixo custo e pode ser esterilizado por autoclavagem. OBJETIVO: Avaliar o desempenho do meio de cultura caldo Sabouraud-dextrose em substituição ao RPMI 1640-MOPS na determinação da sensibilidade de S. schenckii a antifúngicos. MÉTODO: Foram avaliados 48 isolados clínicos frente a cinco antifúngicos: itraconazol, cetoconazol, fluconazol, anfotericina B e terbinafina, utilizando a metodologia da microdiluição em caldo preconizada pelo protocolo M38-A2 do Clinical and Laboratory Standards Institute. RESULTADOS: Não houve diferenças significativas nas Concentrações Inibitórias Mínimas obtidas nos dois meios de cultura para todos os antifúngicos, com exceção da anfotericina B. Para este fármaco, foram obtidas faixas mais amplas de Concentrações Inibitórias Mínimas para caldo Sabouraud-dextrose do que para Roswell Park Memorial Institute-morfolinopropanosulfônico. CONCLUSÕES: O caldo Sabouraud-dextrose mostrou potencial para ser utilizado na avaliação in vitro da atividade antifúngica do complexo S. schenckii.

Antifungal susceptibility of dermatophytes isolated from patients with chronic renal failure.

BACKGROUND: The prevalence of dermatophytosis in the general population is high, particularly in patients with chronic renal failure. Treatment requires the use of topical and/or systemic antifungal drugs. The efficacy of antifungal agents for the treatment of dermatophytosis has yet to be evaluated. Studies evaluating the in vitro activity of antifungal agents are rare, particularly in filamentous fungi. OBJECTIVE: To evaluate the susceptibility profile of different species of dermatophytes isolated from patients with chronic renal failure to nine antifungal drugs available on the market for the treatment of dermatophytosis. METHODS: Twenty-six isolates of dermatophytes obtained from patients with chronic renal failure were analyzed with respect to their susceptibility to nine antifungal agents (ketoconazole, ciclopirox olamine, fluconazole, griseofulvin, itraconazole, miconazole, piroctone olamine, terbinafine and tioconazole), using the broth microdilution method proposed by the Clinical and Laboratory Standards Institute (CLSI) and adapted for dermatophytes. RESULTS: Of the antifungal agents tested, the best results in terms of sensitivity were found with terbinafine and tioconazole, while the antifungal activity of fluconazole was found to be weak, particularly against strains of M. gypseum. Ciclopirox olamine, although less effective than terbinafine, also yielded satisfactory results. CONCLUSIONS: In general, the sensitivity profile of the antifungal agents tested in this study was similar to results obtained in previous studies, confirming the need to determine which species is causing the dermatophytosis given that antifungal susceptibility varies from one species to another. Furthermore, the present findings show the importance of conducting in vitro sensitivity tests, since the sensitivity profile may differ among isolates of the same species.

Perfil de suscetibilidade a antifúngicos de dermatófitos isolados de pacientes com insuficiência renal crônica / Antifungal susceptibility of dermatophytes isolated from patients with chronic renal failure

FUNDAMENTOS: As dermatofitoses apresentam alta prevalência na população em geral e, principalmente, em pacientes com insuficiência renal crônica, necessitando tratamento com antifúngicos tópicos e/ou sistêmicos, cuja eficácia precisa ser avaliada. Estudos in vitro para avaliar a ação de antifúngicos são raros, especialmente, em fungos filamentosos. OBJETIVO: Avaliar o perfil de suscetibilidade de diferentes espécies de dermatófitos, isolados de pacientes com insuficiência renal crônica, em relação a nove antifúngicos disponíveis comercialmente para o tratamento de dermatofitoses. MÉTODO: Analisaram-se 26 isolados de dermatófitos de pacientes com insuficiência renal crônica em relação a nove antifúngicos (cetoconazol, ciclopirox olamina, fluconazol, griseofulvina, itraconazol, miconazol, piroctona olamina, terbinafina e tioconazol) pelo método de microdiluição em caldo proposto pelo Clinical and Laboratory Standards Institute (CLSI), com modificações para dermatófitos. RESULTADOS: Entre os antifúngicos testados, a terbinafina e o tioconazol obtiveram os melhores resultados de sensibilidade e o fluconazol apresentou baixa atividade, especialmente para as amostras da espécie M. gypseum. O ciclopirox olamina, apesar de menos eficaz que a terbinafina, também mostrou resultados satisfatórios. CONCLUSÕES: De modo geral, o perfil de sensibilidade dos antimicóticos testados seguiu o padrão de resultados mostrados por estudos anteriores, ratificando a necessidade de conhecimento da espécie causadora de dermatofitose, devido à variação do perfil de suscetibilidade entre as espécies. Além disso, nossos resultados demonstram a importância da realização de ensaios de sensibilidade in vitro, pois alguns isolados da mesma espécie apresentaram diferente perfil de sensibilidade.

BACKGROUND: The prevalence of dermatophytosis in the general population is high, particularly in patients with chronic renal failure. Treatment requires the use of topical and/or systemic antifungal drugs. The efficacy of antifungal agents for the treatment of dermatophytosis has yet to be evaluated. Studies evaluating the in vitro activity of antifungal agents are rare, particularly in filamentous fungi. OBJECTIVE: To evaluate the susceptibility profile of different species of dermatophytes isolated from patients with chronic renal failure to nine antifungal drugs available on the market for the treatment of dermatophytosis. METHODS: Twenty-six isolates of dermatophytes obtained from patients with chronic renal failure were analyzed with respect to their susceptibility to nine antifungal agents (ketoconazole, ciclopirox olamine, fluconazole, griseofulvin, itraconazole, miconazole, piroctone olamine, terbinafine and tioconazole), using the broth microdilution method proposed by the Clinical and Laboratory Standards Institute (CLSI) and adapted for dermatophytes. RESULTS: Of the antifungal agents tested, the best results in terms of sensitivity were found with terbinafine and tioconazole, while the antifungal activity of fluconazole was found to be weak, particularly against strains of M. gypseum. Ciclopirox olamine, although less effective than terbinafine, also yielded satisfactory results. CONCLUSIONS: In general, the sensitivity profile of the antifungal agents tested in this study was similar to results obtained in previous studies, confirming the need to determine which species is causing the dermatophytosis given that antifungal susceptibility varies from one species to another. Furthermore, the present findings show the importance of conducting in vitro sensitivity tests, since the sensitivity profile may differ among isolates of the same species.

In vitro antifungal activity of dihydroxyacetone against causative agents of dermatomycosis.

Dihydroxyacetone (DHA), a three-carbon sugar, is the browning ingredient in commercial sunless tanning formulations. DHA preparations have been used for more than 50 years and are currently highly popular for producing temporary pigmentation resembling an ultraviolet-induced tan. In this work, the in vitro antifungal activity of dihydroxyacetone was tested against causative agents of dermatomycosis, more specifically against dermatophytes and Candida spp. The antifungal activity was determined by the broth microdilution method according to the Clinical and Laboratory Standards Institute guidelines for yeasts and filamentous fungi. The data obtained show that the fungicidal activity varied from 1.6 to 50 mg ml(-1). DHA seems to be a promising substance for the treatment of dermatomycosis because it has antifungal properties at the same concentration used in artificial suntan lotions. Therefore, it is a potential low-toxicity antifungal agent that may be used topically because of its penetration into the corneal layers of the skin.