Resistência às equinocandinas em pacientes com candidemia persistente
Data
2013-11-27
Autores
Siqueira, Ricardo Andreotti 
Orientadores
Colombo, Arnaldo Lopes
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Candidemia persistente tem sido descrita como uma complicação do quadro de candidemia, caracterizada pelo isolamento de Candida spp. em amostras sequenciais de hemocultura após o diagnóstico inicial, mesmo em pacientes expostos ao tratamento antifúngico adequado. Embora fatores predisponentes relacionados ao hospedeiro já estejam bem estabelecidos, poucos estudos têm analisado os atributos do patógeno envolvidos no desenvolvimento dessa complicação. O objetivo do presente estudo foi avaliar a ocorrência de resistência às equinocandinas em isolados de Candida spp. provenientes de pacientes com candidemia persistente submetidos a terapia antifúngica com esta classe de fármaco. As amostras foram identificadas através de sequenciamento da região ITS do rDNA. O perfil de susceptibilidade in vitro aos antifúngicos foi realizado utilizando metodologia de microdiluição em caldo (CLSI, documento M27-S4). Além disso, nós avaliamos a ocorrência de resistência a partir do sequenciamento do gene FKS1. Dentre 436 pacientes com candidemia, 63 (14,4%) apresentaram quadros de candidemia persistente, desses, 13 atenderam aos critérios de inclusão estabelecidos no presente estudo. Através das identificações fenotípica e molecular, foi observado 5 dos 13 pacientes (38,5%) foram infectados por isolados de C. parapsilosis (sensu stricto), 3 (23%) por isolados de C. albicans, 2 (15,4%) por isolados de C. krusei, 1 (7,7%) por isolado de C. tropicalis e 1 (7,7%) teve como agente etiológico da candidemia isolados de C. orthopsilosis. Além disso, um paciente (7,7%) apresentou episódio de infecção mista com alternância de isolamento de duas diferentes espécies, C. tropicalis e C. parasilosis (sensu stricto). Em relação ao perfil de susceptibilidade aos antifúngicos, a grande maioria dos isolados foi classificada como sensível a todos os antifúngicos testados, com exceção dos cinco isolados de C. krusei provenientes dos pacientes 2 (dois isolados) e 10 (três isolados), os quais apresentaram resistência ao fluconazol e à caspofungina, sendo que dois deles foram intermediários à anidulafungina. Não foi verificado aumento de valores de CIM entre os isolados sequenciais de um mesmo paciente a despeito do tratamento antifúngico utilizado. Nenhum dos isolados apresentou mutação nas regiões dos HS1 e HS2 do gene FKS1, sendo classificados como selvagens em relação aos genótipos de resistência já descritos. Por outro lado, os isolados de C. krusei apresentaram mutação não sinônima em região muito próxima ao HS1, o que poderia, ao menos em parte, explicar o desfecho clínico negativo durante tratamento com equinocandinas e os elevados valores de CIM observados para estes isolados. Os dados obtidos no presente estudo mostram que a ocorrência de resistência às equinocandinas ainda permanece rara em nosso meio, mesmo quando analisada em coorte de pacientes com risco elevado à ocorrência de tal fenômeno. Por fim, conclui-se que as características clínicas do paciente parecem ter maior relevância que os mecanismos de resistência às equinocandinas no que se refere à ocorrência de candidemia persistente.
Persistent candidemia refers to the continued isolation of the same Candida species in the blood of a candidemic patient despite appropriate therapy. Although a number of studies have described host risk factors which predispose to development of persistent candidemia, none have specifically identified the properties of the pathogen associated with the development of this complication. The aim of this study was to investigate the occurrence of echinocandin resistance in Candida spp. isolated from patients with persistent candidemia who received echinocandin at some point during the treatment. Microorganisms were identified to the species level by sequencing of the ITS region. Antifungal susceptibilities profile of strains was performed using the CLSI broth microdilution method. In addition, in order to investigate the echinocandin resistance, we assessed the presence of FKS mutations. Among 436 patients with candidemia, 63 (14.4%) developed a persistent candidemia and 13 of them were included in this study. Five patients (38.5%) were infected with C. parapsilosis (sensu stricto), three (23%) with C. albicans, two (15.4%) with C. krusei, one (7.7%) with C. tropicalis and one (7.7%) with C. orthopsilosis. Moreover, one (7.7%) patient have mixed infection due to C. tropicalis and C. parasilosis (sensu stricto). Most isolates were susceptible to all the antifungal drugs, with the exception of five C. krusei isolates recovered from patient 2 (two isolates) and patient 10 (three isolates). These isolates were resistant to fluconazole and caspofungin and two of them were intermediate to anidulafungin. No increase was observed in MIC values between sequential isolates from the same patient despite antifungal treatment. No mutations were detected in FKS1 of either hot spot1 or hotspot2. On the other hand, C. krusei isolates showed nucleotide and amino acid differences near HS1 region. This may explain, at least in part, the negative clinical outcome during treatment with echinocandins as well as the high MIC values against these drugs. Our findings suggest that echinocandin resistance in Candida spp. is still uncommon, even when evaluated in a cohort of patients with high risk of the occurrence of this phenomenon. Finally, the clinical features of the patient seem to have more relevance than the mechanisms of resistance to echinocandins concerning the occurrence of persistent candidemia.
Persistent candidemia refers to the continued isolation of the same Candida species in the blood of a candidemic patient despite appropriate therapy. Although a number of studies have described host risk factors which predispose to development of persistent candidemia, none have specifically identified the properties of the pathogen associated with the development of this complication. The aim of this study was to investigate the occurrence of echinocandin resistance in Candida spp. isolated from patients with persistent candidemia who received echinocandin at some point during the treatment. Microorganisms were identified to the species level by sequencing of the ITS region. Antifungal susceptibilities profile of strains was performed using the CLSI broth microdilution method. In addition, in order to investigate the echinocandin resistance, we assessed the presence of FKS mutations. Among 436 patients with candidemia, 63 (14.4%) developed a persistent candidemia and 13 of them were included in this study. Five patients (38.5%) were infected with C. parapsilosis (sensu stricto), three (23%) with C. albicans, two (15.4%) with C. krusei, one (7.7%) with C. tropicalis and one (7.7%) with C. orthopsilosis. Moreover, one (7.7%) patient have mixed infection due to C. tropicalis and C. parasilosis (sensu stricto). Most isolates were susceptible to all the antifungal drugs, with the exception of five C. krusei isolates recovered from patient 2 (two isolates) and patient 10 (three isolates). These isolates were resistant to fluconazole and caspofungin and two of them were intermediate to anidulafungin. No increase was observed in MIC values between sequential isolates from the same patient despite antifungal treatment. No mutations were detected in FKS1 of either hot spot1 or hotspot2. On the other hand, C. krusei isolates showed nucleotide and amino acid differences near HS1 region. This may explain, at least in part, the negative clinical outcome during treatment with echinocandins as well as the high MIC values against these drugs. Our findings suggest that echinocandin resistance in Candida spp. is still uncommon, even when evaluated in a cohort of patients with high risk of the occurrence of this phenomenon. Finally, the clinical features of the patient seem to have more relevance than the mechanisms of resistance to echinocandins concerning the occurrence of persistent candidemia.
Descrição
Citação
SIQUEIRA, Ricardo Andreotti. Resistência às equinocandinas em pacientes com candidemia persistente. 2013. 98 f. Dissertação (Mestrado em Medicina Trananslacional) – Escola Paulista de Medicina, Universidade Federal de São Paulo. São Paulo, 2013.