Genetic basis of quinolone resistance and epidemiology of resistant and susceptible isolates of porcine Campylobacter coli strains

Abstract

Aims: The aims of this study were to investigate the epidemiology of quinolone-resistant and -susceptible porcine isolates of Campylobacter coli and to characterize the genetic basis of quinolone resistance. Methods and Results: Penner serotyping and flagellin gene sequence polymorphisms were used to investigate the epidemiology of the C. coli isolates. A total of 55 isolates were included, of which 30 were paired resistant and susceptible isolates from 15 pigs. Amplification of gyrA, gyrB and parC, followed by direct sequencing of amplicons was used to identify mutations in the targets of quinolones. Overall, 31 of the isolates were resistant to ciprofloxacin (minimum inhibitory concentrations (MIC), 2- ‡ 32 lg ml )1 ). Thirteen DdeI-flaA profiles were observed and resistant and susceptible strains were identified for nine profiles. The majority of resistant strains exhibited either profile 1 or 6. While profile 1 comprised susceptible and resistant strains, all of the strains with profile 6 were resistant to ciprofloxacin. The serogroup (O:24) of the profile 6 strains was identical. The only other serogroup to be uniformly associated with quinolone resistance was O:5. Strains with this phenotype comprised a number of genotypes, including profile 1. Only four of the paired isolates from individual pigs had the same profile. The genetic basis of quinolone resistance was investigated in two strains with ciprofloxacin MICs of 2 and ‡ 32 lg ml )1 , respectively. The amino acid substitution of isoleucine for threonine at position 86 was identified in the GyrA proteins from both strains. No mutations were identified in the GyrB proteins. Conclusions: There was an association between two of the genotypes, serotypes 5 and 24, and quinolone resistance. The association between genotype, serotype and resistance in C. coli isolates has not been reported previously. Only the mutation in GyrA associated with quinolone resistance was identified. No mutations in GyrB were identified.

Relative contribution of target gene mutation and efflux to fluoroquinolone and erythromycin resistance, in French poultry and pig isolates of Campylobacter coli

“…This confirms the predominance of this GyrA modification in the field strains [15][16][17][18][19][20].…”

“…Several mechanisms of bacterial resistance have been described: target alterations, decreased accumulation and DNA gyrase protection [14]. In Campylobacter, a modification at amino acid 86 of GyrA (Thr to Ile) was reported as the main mechanism of resistance to fluoroquinolones [15][16][17][18][19][20]. No mutation in gyrB was found to be associated with resistance [18][19][20] and there is increasing evidence that the alternative target of quinolones (topoisomerase IV) is absent in Campylobacter [17][18][19][20].…”

Antimicrobial susceptibility and mechanism of quinolone resistance in Campylobacter jejuni strains isolated from diarrheal patients in a hospital in Tokyo

“…Failure to detect the parC gene by PCR or in the whole genome database has been mentioned in many other reports, in which it has been suggested that campylobacters lack genes for topoisomerase IV. 12,14,[25][26][27] Lou et al 10 have demonstrated the involvement of an effl ux pump in the acquisition of resistance to CPFX. Accordingly, we examined the inhibitory effect of the effl ux pump inhibitor L-phenylalanine-arginine-N-naphthylamide (PAβN; Sigma-Aldrich, St. Louis, MI, USA), on the resistance of C. jejuni strains to CPFX by determining the MIC of CPFX in the presence of PAβN.…”

Enhanced in vivo fitness of fluoroquinolone-resistant Campylobacter jejuni in the absence of antibiotic selection pressure

“…Specifically, the T86I change [mediated by the C257 3 T (C257T) mutation in the gene] is the most commonly observed mutation in FQ R Campylobacter isolates and has been associated with high-level [ciprofloxacin minimal inhibitory concentration (MIC) Ն 16 g͞ml] resistance to FQ, whereas the D90N and T86K mutations are less common and are associated with intermediate-level FQ resistance (16,(20)(21)(22). No mutations in gyrB have been associated with FQ resistance in Campylobacter (18,23,24), and the lack of parC (16,18,(23)(24)(25)(26) in Campylobacter has excluded the role of parC mutations in Campylobacter resistance to FQ antimicrobials. Although the function of multidrug efflux pump CmeABC is essential for FQ resistance, overexpression of cmeABC is not observed in FQ R isolates (16).…”