Effects of permeabilizers on antimicrobial susceptibility of Stenotrophomonas maltophilia and Acinetobacter spp.

Isolates of the gram-negative bacteria Stenotrophomonas maltophilia and Acinetobacter spp. are naturally resistant to many classes of antibiotics. Using the disk diffusion technique it was shown that the membrane permeabilizers ethylenediaminetetraacetic acid, sodium citrate, and sodium polyphosphate increased susceptibility to a range of antibiotics including imipenem, ciprofloxacin, tetracycline, and rifampicin. These effects are probably due to the metal chelating properties of the permeabilizers.