Effect of enrofloxacin on gene expression profiles of Escherichia coli

The effect on gene expression and cell morphology of Escherichia coli strain ATCC 25922 of exposure to the antibiotic enrofloxacin was studied. The growth rate of the cells was compromised, and the cells took on a filamentous shape. Microarray analysis showed that the expression of 519 genes was altered by the treatment, of which 239 were up- and 280 down-regulated. The transcription of 34 genes was increased at least three fold, and that of 32 genes decreased at least three fold. The functions of these differentially expressed genes included the SOS response, cell division, the stress response, biosynthesis, metabolism, transport and transcription regulation. The overall response was consistent with the notion that exposure to enrofloxacin initiated the SOS response and inhibited cell division. Although there was extensive physiological tolerance to the stress, there was no evidence for any mutation to resistance.