Identification of ciprofloxacin-resistant Campylobacter jejuni by use of afluorogenic PCR assay

Fluoroquinolones are one class of antimicrobial agents commonly used to tre at severe Campylobacter jejuni infection. C,jejuni strains resistant to hig h levels of the fluoroquinolone ciprofloxacin (MIC greater than or equal to 16 mug/ml) have been predominantly characterized with a C-->T transition i n codon 86 of gyrA. The gyrA gene encodes one subunit of DNA gyrase, which is a primary target for fluoroquinolone antibiotics. This study establishes a rapid PCR-based TaqMan method for identifying ciprofloxacin-resistant C, jejuni strains that carry the C-->T transition in codon 86 of gyrA. The as say uses real-time detection, eliminating the need for gel electrophoresis. Optimization of the assay parameters using purified Campylobacter DNA resu lted in the ability to detect femtogram levels of DNA. The method should be useful for monitoring the development of ciprofloxacin resistance in C. je juni. Compiled nucleotide sequence data on the quinolone resistance-determi ning region of gyrA in Campylobacter indicate that sequence comparison of t his region is a useful method for tentative identification of Campylobacter isolates at the species level.