Acquisition of Quinolone Resistance and Point Mutation of the gyrA Gene in Campylobacter jejuni Isolated from Broilers and in vitro-Induced Resistant Strains

Abstract

ABSTRACT. A dramatic rise in the number of resistant Campylobacter to quinolones has been documented in human patients and domestic animals. In this study, the mechanism of acquisition of quinolone resistance was studied by detecting point mutations in the gyrA gene of Campylobacter strains obtained from broilers and strains with in vitro-induced resistance. The minimal inhibitory concentrations (MICs) of norfloxacin (NFLX) and ofloxacin (OFLX) for the strains that had no point mutation were slightly increased from the so urce strain (Campylobacter jejuni ATCC 33560). The MICs of nalidixic acid (NA), NFLX, and OFLX for the strains that had the point mutation at Thr-86 were 100 or 200 µg/ml, 50 µg/ml, and 25 µg/ml, respectively. The MIC of NA for the strain that had a point mutation at Asp-90 higher than those for the strains that had the point mutation at Thr-86, but the MICs of NFLX and OFLX were relatively lower than those for the strains that had point mutation at Thr-86. These findings suggest that the degree of antimicrobial resistance against NA, NFLX, and OFLX in the in vitro-induced C. jejuni strains was associated with the location of the point mutation in gyrA. On the other hand, a point mutation in all seven resistant strains isolated from broilers was located only at Thr-86, while the MICs of the three quinolones varied in each wild strain. This suggests that another mechanism might also be involved in the acquisition of quinolone resistance in C. jejuni wild strains.

Role of the CmeABC efflux pump in the emergence of fluoroquinolone-resistant Campylobacter under selection pressure

“…Asp-90!Tyr. The first three types of mutations have been reported previously, 20,22,24,40 These findings clearly indicate that FQ resistance in C. jejuni mutants is affected not only by the point mutations in GyrA but also by the expression level of CmeABC. We also tested the MICs of several other antibiotics in the FQ-resistant mutants, none of which showed cross-resistance to the tested antibiotics including erythromycin, doxycycline, gentamicin and meropenem (data not shown).…”

Emergence of Fluoroquinolone Resistance in Campylobacter jejuni in Chickens Exposed to Enrofloxacin Treatment at the Inherent Dosage Licensed in Japan

“…In the present in vitro selection study, the 23 fluoroquinoloneresistant mutants were obtained from the same parental strain, and the isolation frequency of resistant strains with mutation of Thr-86-Ile and Asp-90-Asn was almost equal. Furthermore, the existence of fluoroquinolone-resistant C. jejuni isolates in the field showing the mutation of Asp-90-Asn has been also reported (Piddock et al, 2003;Beckmann et al, 2004;Chuma et al, 2004;Griggs et al, 2005). It is generally known that an Asp-90-Asn and a Thr-86-Ile change in GyrA are associated with a low or high level of resistance to fluoroquinolones respectively (Payot et al, 2002).…”

Antimicrobial drug residues in poultry products and implications on public health: A review

“…jejuni, Salmonella sp., and Verotoxigenic Escherichia coli have been recognized as major emerging foodborne pathogens among human beings. [97] Luber et al [98] and Chuma et al [99] have ascertained contamination of poultry meat available in supermarkets with antimicrobial resistant C. jejuni, which upon consumption may lead to compylobacteriosis. C. jejuni strains isolated from poultry samples were found to be resistant to multiple antibiotics including ampicillin, cephalothin, sulfamethoxizole +trimethoprim.…”