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Remarkable Synergies between Baicalein and Tetracycline, and Baicalein and β‐Lactams against Methicillin‐Resistant Staphylococcus aureus
Author(s) -
Fujita Mai,
Shiota Sumiko,
Kuroda Teruo,
Hatano Tsutomu,
Yoshida Takashi,
Mizushima Tohru,
Tsuchiya Tomofusa
Publication year - 2005
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2005.tb03732.x
Subject(s) - tetracycline , baicalein , staphylococcus aureus , efflux , microbiology and biotechnology , minimum inhibitory concentration , methicillin resistant staphylococcus aureus , antimicrobial , escherichia coli , tetracycline hydrochloride , biology , antibacterial agent , antibiotics , bacteria , pharmacology , biochemistry , gene , genetics
During the screening of compounds that potentiate the effect of antimicrobial agents against methicillin‐resistant Staphylococcus aureus (MRSA), we found that an extract of thyme ( Thymus vulgaris L) leaves greatly reduced the minimum inhibitory concentration (MIC) of tetracycline against MRSA. We isolated the effective compound and identified it as baicalein (5, 6, 7‐trihydroxyflavone). One of the clinically isolated MRSA strains possessed tetK , a gene encoding active efflux pump for tetracycline. We examined the effect of baicalein on the efflux of tetracycline, using Escherichia coli KAM32/pTZ1252 carrying the tetK . The E. coli KAM32/pTZ1252 showed 8 to 16 times higher MIC than E. coli KAM32. We observed strong inhibition of transport of tetracycline by baicalein with membrane vesicles prepared from E. coli KAM32/pTZ1252. Baicalein also showed synergy with tetracycline in a MRSA strain that doesn't possess tetK , or with β‐lactams. Thus, mechanisms of the synergies seem to be versatile.