Detection of gyrA Mutation Among Clinical Isolates of Campylobacter jejuni Isolated in Egypt by MAMA-PCR

Abstract

Introduction: Campylobacter spp are the major cause of enteritis in humans and more than 90% of reported infections are caused by Campylobacter jejuni. Fluoroquinolones such as ciprofloxacin are the antibiotics of choice for treatment.  An increase in the frequency of ciprofloxacin-resistant Campylobacter has been reported globally due to a single base mutation (C-257 to T) in codon 86 of the quinolone resistance determining region (QRDR) of the gyrA gene altering the amino acid sequence from threonine at position 86 to isoleucine (Thr-86 to Ile). 

Methodology: Campylobacter spp (n = 118) were selected from a collection of Egyptian isolates spanning 1998 to 2005.  The presence of C. jejuni gyrA gene was confirmed in each isolate by a PCR assay amplifying 368bp portion of the gyrA gene.  C to T alteration was detected by the mismatch amplification mutation assay MAMA PCR. The MIC of nalidixic acid (NA) and ciprofloxacin (CIP) was determined by E-test.

Results: C. jejuni gyrA gene was detected in 100 of the Campylobacter spp studied; the other 18 isolates were found to be Campylobacter coli by lpxA PCR. The mutation was detected in 89 C. jejuni resistant isolates with MIC values (NA; 8 - >256μg/ml) and (CIP; 4 - >32μg/ml). The other 11 sensitive C. jejuni isolates with MIC values (NA; 0.38 - 3μg/ml) and (CIP; 0.03 - 0.125μg/ml) were not amplified by the MAMA primers. There was 100% congruence with MAMA PCR, MIC results and gyrA gene sequence analysis.

Conclusions: In Egypt the main mechanism for resistance to fluoroquinolones is an alteration in the gyrA QRDR.  MAMA PCR provides an economical and rapid means for screening fluoroquinolone resistance.