ABSTRACT
Rifampicin resistance is a major therapeutic challenge, particularly in tuberculosis, leprosy, P. aeruginosa and S. aureus infections, where it develops via missense mutations in gene rpoB. Previously we have highlighted that these mutations reduce protein affinities within the RNA polymerase complex, subsequently reducing nucleic acid affinity. Here, we have used these insights to develop a computational rifampicin resistance predictor capable of identifying resistant mutations even outside the well-defined rifampicin resistance determining region (RRDR), using clinical M. tuberculosis sequencing information. Our tool successfully identified up to 90.9% of M. tuberculosis rpoB variants correctly, with sensitivity of 92.2%, specificity of 83.6% and MCC of 0.69, outperforming the current gold-standard GeneXpert-MTB/RIF. We show our model can be translated to other clinically relevant organisms: M. leprae, P. aeruginosa and S. aureus, despite weak sequence identity. Our method was implemented as an interactive tool, SUSPECT-RIF (StrUctural Susceptibility PrEdiCTion for RIFampicin), freely available at https://biosig.unimelb.edu.au/suspect_rif/ .
Subject(s)
Bacterial Proteins/genetics , Drug Resistance, Bacterial/genetics , Machine Learning , Mutation, Missense , Mycobacterium leprae/genetics , Mycobacterium tuberculosis/genetics , Rifampin/pharmacology , Staphylococcus aureus/genetics , Antitubercular Agents/pharmacology , Bacterial Proteins/chemistry , Humans , Leprosy/drug therapy , Leprosy/microbiology , Mycobacterium leprae/drug effects , Mycobacterium tuberculosis/drug effects , Staphylococcal Infections/drug therapy , Staphylococcal Infections/microbiology , Staphylococcus aureus/drug effects , Tuberculosis/drug therapy , Tuberculosis/microbiologyABSTRACT
O Staphylococcus aureus (S. aureus) é um patógeno comumente isolado de amostras biológicas humanas. É encontrado com freqüência na pele e fossas nasais de indivíduos saudáveis, podendo provocar desde simples infecções ate graves enfermidades. Cerca de 40% da população adulta saudável é portadora nasal de S. aureus e esta taxa pode ser ainda maior em ambientes hospitalares, especialmente entre os pacientes internados e equipe médica. O surgimento da resistência à meticilina, uma penicilina sintética, pelo S. aureus e sua disseminação tornaram as medidas de controle epidemiológico ainda mais importantes no que diz respeito à prevenção de infecções hospitalares e, mais recentemente, comunitárias. Profissionais da área de saúde que são portadores nasais de S. aureus e Staphylococcus aureus resistentes a meticilina (MRSA) são considerados importantes fontes de disseminação do patógeno e estão intimamente envolvidos na epidemiologia dos mesmos. Investigação constante e adoção de medidas de controle na admissão dos pacientes em áreas de alta endemicidade para MRSA, tais com CTIs e centros de dermatologia, são consideradas estratégias efetivas em termos de custo-benefício contra as ionfecções hospitalares, bem como o estudo da prevalência de MRSA em profissionais de saúde que atuam nos referidos lugares. O objetivo do estudo foi verificar a colonização por S. aureus e MRSA nas fossas nasais de profissionais das equipes médicas de enfermagem e dos laborat´rios em um hospital de dermatologia de nível terciário - Instituto Lauro de Souza Lima - Bauru/SP...
Subject(s)
Methicillin/isolation & purification , Methicillin/chemical synthesis , Methicillin Resistance/physiology , Staphylococcus aureus/physiology , Staphylococcus aureus/genetics , Staphylococcus aureus/immunologyABSTRACT
OBJECTIVES: Infections caused by Staphylococcus aureus might be treated with agents whose primary indications are for other infections. Clofazimine, an established anti-mycobacterial drug, could be such a candidate. However, the anti-staphylococcal properties of clofazimine have not been fully described and its mode of action, possibly involving inhibition of both RNA polymerase and a membrane-located target, has not been explored in detail. We have now conducted experiments to address these issues. METHODS: Using established procedures, we examined the activity of clofazimine against a range of clinical isolates of S. aureus and determined whether it was bactericidal, exhibited a post-antibiotic effect (PAE), or interacted synergically with other agents. The potential for emergence of clofazimine-resistant mutants was also examined. Mode of action studies involved macromolecular synthesis assays, cross-screening against rifampicin-resistant mutants, susceptibility of RNA polymerase to clofazimine in vitro and several methods to detect drug-induced membrane damage. RESULTS: Clofazimine demonstrated good anti-staphylococcal activity encompassing MSSA, MRSA and GISA. It was bactericidal and resistant mutants could not be isolated. Clofazimine did not exhibit a PAE and failed to act synergically with other drugs. No evidence for specific inhibition of RNA polymerase was obtained. Clofazimine caused non-specific inhibition of DNA, RNA and protein synthesis, consistent with membrane-damaging activity that was detected in three independent assays for membrane disrupting agents. CONCLUSIONS: Clofazimine is a potent anti-staphylococcal agent. It appears to be a membrane-disrupting agent and does not inhibit RNA polymerase.