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

ANTIFUNGAL POTENTIAL OF PLANT SPECIES FROM BRAZILIAN CAATINGA AGAINST DERMATOPHYTES

Trichophyton rubrum and Trichophyton mentagrophytes complex, or Trichophyton spp. are the main etiologic agents of dermatophytosis, whose treatment is limited by the high cost of antifungal treatments, their various side effects, and the emergence of resistance amongst these species. This study evaluated the in vitro antidermatophytic activity of 23 crude extracts from nine plant species of semiarid vegetation (caatinga) found in Brazil. The extracts were tested at concentrations ranging from 1.95 to 1,000.0 mg/mL by broth microdilution assay against the reference strains T. rubrum ATCC 28189 and T. mentagrophytesATCC 11481, and 33 clinical isolates of dermatophytes. All plants showed a fungicidal effect against both fungal species, with MIC/MFC values of the active extracts ranging from 15.6 to 250.0 µg/mL. Selected extracts of Eugenia uniflora (AcE), Libidibia ferrea (AE), and Persea americana (AcE) also exhibited a fungicidal effect against all clinical isolates of T. rubrum and T. mentagrophytes complex. This is the first report of the antifungal activity of Schinus terebinthifolius, Piptadenia colubrina, Parapiptadenia rigida, Mimosa ophthalmocentra, and Persea americana against both dermatophyte species

Tuberculosis-HIV treatment with rifampicin or rifabutin: are the outcomes different?

BACKGROUND Rifamycins are a group of antibiotics mainly used in the treatment of tuberculosis (TB), however they interact with antiretroviral therapy (ART). Rifabutin allows more regimens options for concomitant imunodeficiency virus (HIV) treatment compared to rifampicin. OBJECTIVE Compare the outcomes of TB-HIV co-infected patients who used rifampicin or rifabutin. METHODS We analysed data from a prospective cohort study at National Institute of Infectious Diseases Evandro Chagas, Rio de Janeiro (RJ), Brazil. Patients who were treated for TB and HIV with rifampicin or rifabutin, from February 2011 to September 2016 were included. FINDINGS There were 130 TB-HIV patients, of whom 102 were treated with rifampicin and 28 with rifabutin. All patients in the rifabutin-treated group and 55% of the rifampicin-treated group patients were ART-experienced. Patients treated with rifampicin had similar abandon and cure rates, interruptions in treatment due to adverse reactions, immune reconstitution inflammatory syndrome and a similar mortality rate as those treated with rifabutin. However, rifampicin-treated patients had higher CD4 counts and more frequently undetectable HIV viral load by the end of treatment (67% versus 18%, p < 0.001) compared to rifabutin-treated patients, even when only ART-experienced patients were evaluated (66,6% versus 36,3%, p = 0.039). CONCLUSIONS Patients who used rifabutin had worst immune and virological control. This group had more ART-experienced patients. New and simpler regimens are needed for patients who do not respond to previous antiretroviral therapies

Suscetibilidade a antifúngicos in vitro de Candida spp. em pacientes do Hospital Universitário Regional de 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

Correction: In Vitro Activity of Rifampicin and Verapamil Combination in Multidrug-Resistant Mycobacterium tuberculosis.

The aim of the present study was to evaluate the effect of the combination of rifampicin (RIF) and verapamil (VP) against the Mycobacterium tuberculosis H37Rv reference strain and six multidrug-resistant (MDR) M. tuberculosis clinical isolates by determining Time-Kill Curves and the ability to efflux drug by fluorometry. The RIF+VP combination showed synergism in one MDR clinical isolate. For the other five MDR clinical isolates, the drug combination showed no interaction. The MDR clinical isolate had lower ethidium bromide (EtBr) accumulation when exposed to the RIF+VP combination, compared with RIF and VP exposure alone. The other MDR clinical isolates showed no significant difference in EtBr accumulation. These results suggest greater efflux action in one of the MDR clinical isolates compared with the M. tuberculosis H37Rv reference strain. The other five MDR isolates may have additional mechanisms of drug resistance to RIF. The use of the RIF+VP combination made one MDR bacillus more susceptible to RIF probably by inhibiting efflux pumps, and this combination therapy, in some cases, may contribute to a reduction of resistance to RIF in M. tuberculosis

Time-kill curve of the <i>Mycobacterium tuberculosis</i> H₃₇Rv reference strain and multidrug-resistant clinical isolates 71A, 18, 19, 109, 3614, and 64A exposed to rifampicin (RIF), verapamil (VP), and RIF+VP combination for 7 days at 35–37°C.

<p>Time-kill curve of the <i>Mycobacterium tuberculosis</i> H₃₇Rv reference strain and multidrug-resistant clinical isolates 71A, 18, 19, 109, 3614, and 64A exposed to rifampicin (RIF), verapamil (VP), and RIF+VP combination for 7 days at 35–37°C.</p

Molecular characterization, drug susceptibility profile, minimum inhibitory concentration, and drug interaction in the <i>M. tuberculosis</i> H₃₇Rv reference strain and multidrug-resistant clinical isolates.

<p>R, resistant; NP, not performed; INH, isoniazid; RIF, rifampicin; EMB, ethambutol; PZA, pirazinamid; FICI, fractional inhibitory concentration index; REDCA; Resazurin Drugs Combination Microtiter Assay. VP, verapamil; EtBr, ethidium bromide. Numbers in bold represent synergism.</p><p>Molecular characterization, drug susceptibility profile, minimum inhibitory concentration, and drug interaction in the <i>M. tuberculosis</i> H₃₇Rv reference strain and multidrug-resistant clinical isolates.</p