Study published in PLoS Pathogens using C. jejuni treated with a fluoroquinolone antibiotic identified overexpression of Mfd as one cause.

Iowa State University scientists report that the protein Mfd plays an important role in the development of antibiotic resistance in a bacterial pathogen commonly associated with food poisoning. The protein is involved in DNA transcription and repair.

Previous studies have revealed that Campylobacter is highly mutable to antibiotic treatment. Also, other researchers have found that people are becoming increasingly resistant to fluoroquinolone, a broad-spectrum antimicrobial.

The scientists compared the gene-expression profiles of C. jejuni in the presence and absence of ciprofloxacin, a fluoroquinolone, using DNA microarray. The analysis revealed that multiple genes showed changes in expression in the presence of a suprainhibitory concentration of ciprofloxacin. The drug induced the expression of Mfd, which encodes a transcription-repair coupling factor involved in strand-specific DNA repair.

The Iowa State Univ. group from the College of Veterinary Medicine found that Campylobacter increases the production of Mfd in the presence of a fluoroquinolone antibiotic. Mutation of the Mfd gene resulted in 100-fold reduction in the rate of emergence of mutants resistant to fluoroquinolones, while overexpression of Mfd elevated the mutation frequency.

Mfd is not the only factor influencing the mutation frequency, though. The investigators note that more researche is needed to determine how Mfd increases the emergence of antibiotic-resistant mutants. The current study is published in the June 6 issue of PLoS Pathogens.

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