Resistência primária e adquirida à pirazinamida em pacientes com tuberculose pulmonar atendidos em um hospital de referência no Recife Primary and acquired pyrazinamide resistance in patients with pulmonary tuberculosis treated at a referral hospital in the city of Recife, Brazil

OBJETIVO: Verificar a resistência primária e adquirida à pirazinamida em cepas de Mycobacterium tuberculosis provenientes de amostras de escarro de pacientes com tuberculose pulmonar. MÉTODOS: Estudo prospectivo e descritivo realizado no período entre abril e novembro de 2011 em um hospital de referência para o tratamento de tuberculose em Recife (PE). Culturas, testes de sensibilidade a fármacos e testes da pirazinamidase foram realizados em um laboratório particular na mesma cidade. RESULTADOS: Dos 71 pacientes incluídos no estudo, 37 eram virgens de tratamento e 34 eram casos de retratamento. Desses, 0 (0,0%) e 14 (41,2%), respectivamente, apresentaram cepas resistentes à pirazinamida. Desses 14 isolados, 10 (90,9%) apresentaram resultados negativos no teste da pirazinamidase. Dos 60 isolados que apresentaram resultados positivos para o teste da pirazinamidase, 56 (93,3%) eram sensíveis à pirazinamida. CONCLUSÕES: A elevada frequência de cepas resistentes à pirazinamida em pacientes em retratamento da tuberculose destaca a necessidade da realização de testes de sensibilidade à pirazinamida antes de se escolher um novo esquema de tratamento.<br>OBJECTIVE: To determine primary and acquired resistance to pyrazinamide in Mycobacterium tuberculosis strains isolated in sputum samples from patients with pulmonary tuberculosis. METHODS: This was a prospective, descriptive study conducted between April and November of 2011 at a referral hospital for tuberculosis in the city of Recife, Brazil. Cultures, drug sensitivity tests, and tests of pyrazinamidase activity were conducted in a private laboratory in Recife. RESULTS: Of the 71 patients included in the study, 37 were treatment-naïve and 34 represented cases of retreatment. Pyrazinamide-resistant strains were isolated in 14 (41.2%) of the 34 patients who had previously been treated for tuberculosis and in none of the 37 treatment-naïve patients. Of the 14 isolates, 10 (90.9%) tested negative for pyrazinamidase activity. A total of 60 isolates tested positive for pyrazinamidase activity. Of those, 56 (93.3%) were found to be sensitive to pyrazinamide. CONCLUSIONS: The high frequency of pyrazinamide-resistant strains (41.2%) in patients previously treated for tuberculosis highlights the need for drug susceptibility testing prior to the adoption of a new treatment regimen

A potent antimalarial benzoxaborole targets a Plasmodium falciparum cleavage and polyadenylation specificity factor homologue

Benzoxaboroles are effective against bacterial, fungal and protozoan pathogens. We report potent activity of the benzoxaborole AN3661 against Plasmodium falciparum laboratory-adapted strains (mean IC(50) 32 nM), Ugandan field isolates (mean ex vivo IC(50) 64 nM), and murine P. berghei and P. falciparum infections (day 4 ED(90) 0.34 and 0.57 mg kg(−1), respectively). Multiple P. falciparum lines selected in vitro for resistance to AN3661 harboured point mutations in pfcpsf3, which encodes a homologue of mammalian cleavage and polyadenylation specificity factor subunit 3 (CPSF-73 or CPSF3). CRISPR-Cas9-mediated introduction of pfcpsf3 mutations into parental lines recapitulated AN3661 resistance. PfCPSF3 homology models placed these mutations in the active site, where AN3661 is predicted to bind. Transcripts for three trophozoite-expressed genes were lost in AN3661-treated trophozoites, which was not observed in parasites selected or engineered for AN3661 resistance. Our results identify the pre-mRNA processing factor PfCPSF3 as a promising antimalarial drug target