Affiliation: Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13 Prospekt Entuziastov, Saratov 410049, Russian Federation.
The effect of sulfonamide drugs on the electrophysical properties of Escherichia coli strains B-878 and K-12 was investigated by the example of sulfacetamide sodium (sulfacyl sodium). Substantial changes in the orientational spectra of cell suspensions incubated with various concentrations of sulfacetamide sodium occurred only at the first five frequencies of the orienting electric field (740–2800 kHz). Sulfacetamide sodium at 0.08 µg/ml changed the magnitude of the electro-optical signal of the suspensions. A study of the time course of sulfacetamide sodium effect on the cells showed that the signal magnitude decreased by 57% of the no-drug control after 5 min of exposure to the drug and that on subsequent exposure, the signal magnitude remained almost unchanged (changes no greater than 5% of the no-drug control). The spectral changes differed significantly for the sensitive and resistant strains. The orientational spectral changes induced by sulfonamides may be useful for testing the resistance of bacteria to this family of drugs.