Epigallocatechin-gallate enhances the activity of tetracycline in staphylococci by inhibiting its efflux from bacterial cells.
Epigallocatechin-gallate (EGCg), the major catechin present in green tea extracts, has been shown to have several antibacterial activities, limiting bacterial growth and invasion and acting in synergy with beta-lactam antibiotics. In this article, we report that EGCg at doses half and below its calculated MIC of 100 microg/ml, is able to reverse tetracycline resistance in staphylococcal isolates expressing the specific efflux pump Tet(K) and appears to improve the MICs of tetracycline for susceptible staphylococcal isolates as well. The visible effect of EGCg is an increased accumulation of tetracycline inside bacterial cells. This effect is likely due to the inhibition of pump activity, and it is evident not only for Tet(K) pumps but also for efflux pumps of a different class [Tet(B)]. In summary, our data indicate that the observed dramatic enhancement by EGCg of tetracycline activity for resistant staphylococcal isolates is caused by impairment of tetracycline efflux pump activity and increased intracellular retention of the drug, suggesting a possible use of EGCg as an adjuvant in antibacterial therapy.
Sudano Roccaro
Andrea
A
SIFI SpA, Research and Development Department, Via E. Patti 36, 95020 Lavinaio, Catania, Italy.
Blanco
Anna Rita
AR
Giuliano
Francesco
F
Rusciano
Dario
D
Enea
Vincenzo
V
D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004357:Drug Synergism; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D008826:Microbial Sensitivity Tests; D013050:Spectrometry, Fluorescence; D013210:Staphylococcus / Q000187:drug effects* / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000187:drug effects; D013212:Staphylococcus epidermidis / Q000187:drug effects; D013752:Tetracycline / Q000378:metabolism* / Q000494:pharmacology*; D013753:Tetracycline Resistance
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008565:Membrane Proteins; C084212:tet(K) protein, Staphylococcus aureus; D002392:Catechin; C045651:epigallocatechin gallate; D013752:Tetracycline