Objectives: Campylobacter infections are amongst the leading causes of foodborne bacterial gastroenteritis in the developed world. The multidrug efflux pump CmeABC described in Campylobacter jejuni has been shown to be important for bile resistance and for successful colonization of chicken intestines and seems to be involved in resistance to fluoroquinolon and macrolide. The aim of the study was to develop a real-time reverse transcriptase (RT)-PCR method to study transcript levels of the multidrug efflux pump CmeABC in Campylobacter jejuni and to apply it to compare bile salt dependent cmeABC transcription in poultry and human C. jejuni strains.
Methods and results: Ten poultry and eight human C. jejuni strains were cultured microaerobically at 42°C in Mueller-Hinton broth with or without the addition of the bile salts cholate (CA) and taurocholate (TCA). Normalization of real-time RT-PCR data to CFU revealed inconsistent transcription of 16S rRNA and low level transcription of cmeA and cmeB, which increased slightly but significantly upon addition of bile salts. Human C. jejuni strains had lower cmeA and cmeB transcription levels but could be induced in a similar manner as poultry strains.
Conclusion: Colony count normalized real-time RT-PCR was useful for determination of the cmeA and cmeB transcription on a cellular basis. The real-time RT-PCR method described is a valuable tool for future studies regarding the activity of the cmeABC operon, provides the opportunity to gather information about the transcript levels on a cellular basis and could easily by adapted to investigate other targets.