Is the efflux pump inhibitor Verapamil a potential booster for isoniazid against Mycobacterium tuberculosis?

The membrane-based efflux pump systems are recognized to have an important role in pathogenicity and drug resistance in Mycobacterium tuberculosis by the extrusion of toxic substrates and drugs from the inner bacillus. This study aimed to investigate the in vitro interaction of Verapamil (VP), an efflux pump inhibitor, with the classical first-line anti-tuberculosis drug isoniazid (INH) in resistant and susceptible M. tuberculosis clinical isolates. Seven multidrug-resistant (MDR), three INH monoresistant and four susceptible M. tuberculosis clinical isolates were tested for the INH and VP combination by modified Resazurin Microtiter Assay Plate (REMA). Fractional Inhibitory Concentration (FIC) and Modulation Factor (MF) were determined. The INH plus VP combination showed no significant change in the Minimum inhibitory concentration (MIC) values of INH (FIC≥ 0.5; MF=1 or 2).The use of VP in tuberculosis therapy should be managed carefully, considering the resistance caused by specific mutation in katG and inhA genes, in which the use of these EPIs may have no success. The use of EPIs as an adjunctive drug in the anti-tuberculosis therapy should be further investigated on a larger number of M. tuberculosis clinical isolates with different resistant profile.

Suscetibilidade a antifúngicos in vitro de Candida spp. em pacientes do Hospital Universitário Regional de Maringá-PR / Antifungal susceptibility of Candida spp. in vitro among patients from Regional University Hospital of Maringá-PR

INTRODUÇÃO: No ambiente hospitalar, são frequentes as infecções por leveduras do gênero Candida spp., o que torna esse assunto um importante alvo de estudos. OBJETIVO: Avaliar o perfil de suscetibilidade aos antifúngicos de espécies de Candida de pacientes internados no Hospital Universitário Regional de Maringá-PR (HURM). MATERIAL E MÉTODOS: As amostras foram submetidas ao teste de microdiluição em caldo (MD), segundo o documento M27-A3 para determinação da concentração inibitória mínima (CIM), e ao teste de difusão em disco de acordo com o documento M44-A2, ambos do Clinical Laboratory Standarts Institute (CLSI). RESULTADOS E DISCUSSÃO: Foram obtidos 91 isolados provenientes de amostras de urina, hemocultura, ponta de cateter, secreção orotraqueal, entre outros, sendo 38 Candida albicans, 23 C. tropicalis, 16 C. gabrata, 10 C. parapsilosis e quatro C. krusei. Dos antifúngicos testados, anfotericina B, voriconazol e anidulafungina foram os mais eficazes. CONCLUSÃO: A comparação entre as metodologias de microdiluição em caldo e disco difusão (DD) mostrou boa correlação para fluconazol para a maioria das espécies de Candida spp., sendo possível destacar que a DD é útil para triagem dos principais antifúngicos usados na prática clínica. No entanto, casos de resistência detectados por DD devem ser confirmados por meio do método de MD, evitando, assim, resultados falsos resistentes, melhorando a eficácia e a segurança do tratamento.

INTRODUCTION: Due to the ubiquity of nosocomial yeast infections of the genus Candida spp., studies in this area have become increasingly relevant. OBJECTIVE: To evaluate the antifungal Candida spp. susceptibility profile of hospitalized patients from the Regional University Hospital of Maringá-PR (HURM). MATERIAL AND METHODS: The samples were submitted to broth microdilution test (MD) according to protocol M27-A3 in order to determine the minimum inhibitory concentration (MIC) and disk diffusion test according to protocol M44-A2, both from Clinical Laboratory Standards Institute (CLSI). RESULTS AND DISCUSSION: We obtained 91 isolates from urine samples, blood culture, catheter tip, endotracheal secretions, among others, from which 38 were Candida albicans, 23 were C. tropicalis, 16 were C. gabrata, 10 were C. parapsilosis, and four were C. krusei. Among the tested antifungal medications, amphotericin B, voriconazole and anidulafungin proved to be the most effective. CONCLUSION: In the comparison between broth microdilution and disk diffusion (DD) methods, fluconazole showed good correlation for most Candida spp., which corroborates the usefulness of DD in the screening of main antifungal agents used in clinical practice. Nonetheless, cases of resistance detected by DD need to be confirmed by MD method, which avoids false-resistant results and maximizes the treatment efficacy and reliability.