Asunto(s)
Foliculitis/microbiología , Dermatosis del Cuero Cabelludo/microbiología , Infecciones Cutáneas Estafilocócicas , Staphylococcus aureus , Adulto , Anciano , Antibacterianos/uso terapéutico , Enfermedad Crónica , Femenino , Foliculitis/tratamiento farmacológico , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Dermatosis del Cuero Cabelludo/tratamiento farmacológico , Adulto JovenRESUMEN
Aqueous extracts of teas (Camellia sinensis) of different types and from various sources inhibited a wide range of pathogenic bacteria, including methicillin-resistant Staphylococcus aureus. Tea extracts were bactericidal to staphylococci and Yersinia enterocolitica at well below 'cup of tea' concentrations. Activity was confined to one of four fractions obtained from a green tea extract by partition chromatography. Testing of pure tea compounds and closely related chemicals suggested that the antibacterial activity of extracts of green tea can be explained by its content of epigallocatechin, epigallocatechin gallate and epicatechin gallate. In black tea extracts, theaflavin and its gallates are additional antibacterially active components.
Asunto(s)
Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Té , Extractos Vegetales/farmacologíaRESUMEN
Major errors arise if E test strips are placed upside down. Asymmetric zones, or no zone at all, may result. MICs indicated by upside-down tests were almost always considerably higher than true values. This situation differs markedly from that for conventional testing, where orientation of disks is not important.
Asunto(s)
Pruebas de Sensibilidad Microbiana/instrumentación , Bacterias/efectos de los fármacos , Errores Diagnósticos , Farmacorresistencia Microbiana , Humanos , Pruebas de Sensibilidad Microbiana/métodos , Pruebas de Sensibilidad Microbiana/estadística & datos numéricosRESUMEN
Extracts of tea (Camellia sinensis) can reverse methicillin resistance in methicillin-resistant Staphylococcus aureus (MRSA) and also, to some extent, penicillin resistance in beta-lactamase-producing S. aureus. These phenomena are explained by prevention of PBP2' synthesis and inhibition of secretion of beta-lactamase, respectively. Synergy between beta-lactams and tea extracts were demonstrated by disc diffusion, chequerboard titration and growth curves. Partition chromatography of an extract of green tea on Sephadex LH-20 yielded several fractions, one of which contained a virtually pure compound that showed the above-mentioned activities, at concentrations above about 2 mg/L. The observed activities are novel and distinct from the previously reported direct antibacterial activity of tea extracts. Prevention of PBP2' synthesis offers an interesting possible new approach for the treatment of infections caused by MRSA.