抄録
Bacteria possess arrays of efflux systems that confer resistance to a wide variety of toxic compounds. Several of the multidrug resistance (MDR) systems exist in Streptomyces, but are normally under tight regulation. Therefore, drug resistant mutants of Streptomyces arise only through mutations that derepress the MDR genes. This enigma supports the notion that the tested drugs may only be fortuitous substrates of the MDR systems, of which the normal physiological targets may be something else.
