Sensitization of Campylobacter jejuni to fluoroquinolone and macrolide antibiotics by antisense inhibition of the CmeABC multidrug efflux transporter

Objectives: The aim of this study was to investigate the feasibility and efficacy of antisense-mediated gene silencing by peptide nucleic acid (PNA) for specific inactivation of the CmeABC multidrug efflux transporter in Campylobacter jejuni. Methods: PNA was designed to bind to the cmeA transcript and to inhibit the translation of CmeA, the periplasmic component of the RND-type CmeABC efflux transporter of C. jejuni. Inhibition of CmeA production was determined by western blotting. MICs of clinically important antibiotics, including ciprofloxacin and erythromycin, were measured in the presence of the CmeA-specific PNA (CmeAPNA). Results: CmeA-PNA greatly reduced the expression level of CmeA. Consistent with the reduced CmeA production, CmeA-PNA rendered C. jejuni strains more susceptible to ciprofloxacin and erythromycin. At a concentration of 2 mM, CmeA-PNA resulted in 8- and 4-fold reductions in the MICs of ciprofloxacin and erythromycin, respectively, in C. jejuni NCTC 11168. CmeA-PNA also increased the susceptibility to the antibiotics in C. jejuni strains that were resistant to ciprofloxacin or erythromycin. Conclusions: Antisense technology is a feasible method to suppress the function of the CmeABC multidrug efflux transporter, which may be further exploited to control antibiotic-resistant Campylobacter.