RESUMO
Recent work has shown that the efflux genes in Streptococcus pneumoniae that are responsible for acquired macrolide resistance can be distinguished as either mef(E) or mef(A). The genetic elements on which mef(A) and mef(E) are found also carry an open reading frame (ORF) that is 56% homologous to msr(A) in Staphylococcus. The prevalence of mef(A/E) and of the msr-like ORF [msr(D)] was evaluated in 153 mef(+) S. pneumoniae clinical isolates collected in North America, Europe, Africa, and Asia from 1997 to 2002. Clinical isolates were screened with PCR primers specific for either mef(A) or mef(E) and for msr(D). mef(A), mef(E), and msr(D) were cloned from mef(+) strains and transformed into a susceptible, competent strain of S. pneumoniae. The transformants were tested for antimicrobial susceptibilities and efflux pump induction. The results of this work demonstrated that mef(A) is more often isolated in parts of Europe, with some incidence in Canada, and that the msr-like gene alone can confer the efflux phenotype.
Assuntos
Proteínas de Bactérias/análise , Proteínas de Membrana/análise , Streptococcus pneumoniae/genética , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Sequência de Bases , Primers do DNA , Farmacorresistência Bacteriana , Geografia , Humanos , Proteínas de Membrana/genética , Testes de Sensibilidade Microbiana , Sorotipagem , Streptococcus pneumoniae/classificação , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/isolamento & purificaçãoRESUMO
We report the discovery of a novel class of macrolide antibiotics that have improved antibacterial activity against Ery-resistant organisms.
Assuntos
Antibacterianos/síntese química , Bactérias/efeitos dos fármacos , Eritromicina/farmacologia , Macrolídeos/síntese química , Antibacterianos/farmacologia , Bactérias/metabolismo , Membrana Celular/metabolismo , Resistência a Medicamentos , Farmacorresistência Bacteriana , Macrolídeos/farmacologia , Testes de Sensibilidade Microbiana , Relação Estrutura-AtividadeRESUMO
We report the discovery and characterization of a novel ribosome inhibitor (NRI) class that exhibits selective and broad-spectrum antibacterial activity. Compounds in this class inhibit growth of many gram-positive and gram-negative bacteria, including the common respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and Moraxella catarrhalis, and are nontoxic to human cell lines. The first NRI was discovered in a high-throughput screen designed to identify inhibitors of cell-free translation in extracts from S. pneumoniae. The chemical structure of the NRI class is related to antibacterial quinolones, but, interestingly, the differences in structure are sufficient to completely alter the biochemical and intracellular mechanisms of action. Expression array studies and analysis of NRI-resistant mutants confirm this difference in intracellular mechanism and provide evidence that the NRIs inhibit bacterial protein synthesis by inhibiting ribosomes. Furthermore, compounds in the NRI series appear to inhibit bacterial ribosomes by a new mechanism, because NRI-resistant strains are not cross-resistant to other ribosome inhibitors, such as macrolides, chloramphenicol, tetracycline, aminoglycosides, or oxazolidinones. The NRIs are a promising new antibacterial class with activity against all major drug-resistant respiratory pathogens.
Assuntos
Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Ribossomos/efeitos dos fármacos , Aminoacil-tRNA Sintetases/genética , Animais , Bacillus subtilis/efeitos dos fármacos , DNA Girase/genética , DNA Girase/metabolismo , Desenho de Fármacos , Farmacorresistência Bacteriana , Escherichia coli/enzimologia , Escherichia coli/genética , Células Eucarióticas/metabolismo , Genes Reporter/genética , Indicadores e Reagentes , Luciferases/genética , Testes de Sensibilidade Microbiana , Plasmídeos/genética , Coelhos , Proteínas Ribossômicas/efeitos dos fármacos , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/genética , Fatores de Transcrição/genética , Transcrição Gênica , beta-Galactosidase/genéticaRESUMO
A series of novel 6-O-substituted homopropargyl ketolides was synthesized and evaluated against various erythromycin-resistant pathogens. Promising in vitro antibacterial activity was demonstrated for compounds bearing this structural motif.