Transcriptional analysis of C. jejuni response to FQ treatment

Fluoroquinolones (FQs) are one class of commonly used antimicrobials in clinical therapy of diseases caused by Campylobacter and other foodborne pathogens. The molecular mechanisms underlying the response of Campylobacter to FQ treatment is of interest because unlike other enteric bacteria, Campylobacter lacks many genes encoding components of DNA repair systems and SOS response. To understand how Campylobacter survive antibiotic treatment, DNA microarray was used to compare the gene expression profiles of C. jejuni 11168 in the presence and absence of ciprofloxacin. Our analysis identified 45 genes that showed ≥1.5-fold (p<0.05) changes in expression in the presence of ciprofloxacin. The up-regulated genes (13) are involved in cell membrane biosynthesis and DNA repair or have unknown functions, while the majority of the down-regulated genes (32) are involved in cellular process and energy metabolism. These findings suggest that C. jejuni modulates membrane biosynthesis, increases spontaneous mutation rates, and decreases metabolism in response to fluoroquinolone treatment. Keywords: 0.06 µg/ml (0.5X MIC) or 1.2 µg/ml (10X MIC) ciprofloxacin treated campylobacter VS. untreated campylobacter, the bacterial cells were treated for 0.5 hour The design utilized a commercially available two color microarray slide for the entire transcriptome of Campylobacter jejuni. Six hybridizations were performed each with independently extracted samples of either untreated C. jejuni cDNA samples or ciprofloxacin-treated (0.06 µg/ml or 1.2 µg/ml) C.jejuni cDNA samples. A dye swap was utilized to help minimize dye dependent bias. Thus there were six biological replicates of each sample.