Antimicrobial resistance of Campylobacter jejuni and Campylobacter coli with special reference to plasmid profiles of Japanese clinical isolates

Abstract

A total of 111 clinical isolates of Campylobacter jejuni and 10 clinical isolates of Campylobacter coli were characterized by their susceptibility to nine antimicrobial agents and by their plasmid profiles on agarose gel electrophoresis. All of the C. jejuni isolates were susceptible to chloramphenicol, ciprofloxacin, erythromycin, kanamycin, and nalidixic acid, but 55% were tetracycline resistant. In the 10 C. coli isolates, a high prevalence of multiple-antibiotic resistance was noted. Plasmids were found in 82% of the tetracycline-resistant and 15% of the tetracycline-susceptible C. jejuni isolates. Tetracycline resistance in six randomly selected C. jejuni isolates, which contained 50-or 135-kilobase (kb) plasmids, was transferred by conjugation to a Campylobacter fetus subsp. fetus recipient with recovery of a 50-or a 45-kb plasmid from transconjugants. From one multiple-antibiotic-resistant C. coli isolate, resistance to tetracycline, kanamycin, and chloramphenicol was transferred concomitantly with a 58-kb plasmid, pNR9589. Nonconjugative 98-kb plasmids, pNR9131 and pNR9581, from C. coli isolates with resistance to tetracycline, kanamycin, and erythromycin were shown by cloning experiments to code for at least kanamycin resistance. Restriction digests revealed that 50-kb plasmids from tetracycline-resistant C. jejuni isolates were identical, although plasmids from multiple-antibioticresistant C. coli isolates shared partial DNA homology to each other. Cloning of the kanamycin and chloramphenicol resistance genes of pNR9589 into Escherichia coli showed that the two genes are closely linked or clustered. Double-digestion analysis of the fragments encoding the kanamycin resistance of pNR9131, pNR9581, and pNR9589 showed that these three plasmids contain a common fragment related to kanamycin resistance.Campylobacterjejuni is recognized as one of the common causes of acute bacterial enteritis throughout the world (2, 17). More than 200 strains of C. jejuni and a small number of C. coli strains, 60% of which are from children, are isolated every year in Tokyo Metropolitan Toshima General Hospital.Taylor et al. (19, 20) and Tenover et al. (21) demonstrated that tetracycline resistance in C. jejuni is mediated by conjugative R plasmids with a size of 60 kilobases (kb), and more recently, Tenover et al. (22) showed that all tetracycline-resistant C. jejuni harbored R plasmids. Most recently, Taylor (18) mapped the tetracycline resistance plasmid. Studies on plasmid detection in Campylobacter spp.have not yet been carried out in Japan, although clinical and epidemiological studies on Campylobacter spp. have been performed extensively. In the present study, we examined the MICs of nine antimicrobial agents against Campylobacter isolates, the plasmid carriage in these isolates, and the relationship between antimicrobial resistance and plasmid carriage in C. jejuni and C. coli. Moreover, we analyzed three plasmids isolated from multiple-antibiotic-resistant C. coli strains by restriction endonuclease digestion and c...

Campylobacter

“…resulted in the emergence of the corresponding resistant isogenic strains suggesting that this organism is hypermutatable under these conditions [87]. Horizontal transfer of such resistance determinants (acquisition) together with any genetic modification of pre-existing genes through point mutations (intrinsic) or some other genetic event, are thought to be the main mechanisms contributing to bacterial resistance [2,10,140]. Self-transmissible elements including plasmids, transposons and bacteriophage all facilitate the acquisition and subsequent dissemination of resistance determinants.…”

“…More recently, in Brazil, only 15.9% of the isolates analysed for plasmids contained these mobile elements and none of the tetracycline resistant strains were found to harbour plasmid DNA [10]. Chloramphenicol resistance, although rare in campylobacters [10], has also been reported to be plasmid mediated [140]. A chloramphenicol resistance determinant cloned from a C. coli plasmid was sequenced and found to have 43 and 57% homology with chloramphenicol acetyltransferase (CAT) proteins from other Gram-positive and -negative origins [186].…”

“…A kanamycin resistance determinant, aphA-3 was found located distal to Chromosomal: enzymatic modification of antibiotics. Integron-mediated resistance [113,175] Kanamycin Majority plasmid-borne, remainder chromosomal; resistance through enzymatic modification of kanamycin [140] Chloramphenicol Plasmid-borne, resistance through modification of the target site (ribosome) or alteration of the antibiotic [186] Ciprofloxacin Chromosomal: modification of gyrA and parC confers resistance [3,4,16] Erythromycin Chromosomally mediated, resistance through modification of the target site (ribosome) [166] β-Lactams Chromosomal; three mechanisms, decreased uptake through modification of a porin, alteration of a penicillin binding protein, or production of a β-lactamase [129] Tetracycline tetO gene, plasmid-borne in the majority of cases, resistance mediated through ribosomal protection [7,78,167] Trimethoprim dfr1 gene, chromosomal, located to the remnants of an integron dfr9 gene, chromosomal, located to the remnants of a transposon Resistance arising through modification of the trimethoprim target [53] Multidrug-resistance (MDR)…”

“…Efflux pump with a broad specificity; preventing accumulation of antibiotics [25] this cat gene and Sagara et al [140] reported a link between kanamycin and chloramphenicol resistance in Campylobacter following a number of cloning experiments involving the cat and kan resistance genes of a plasmid from a multiple-antibioticresistant C. coli isolate. Kanamycin resistance in Campylobacter is more commonly associated with C. coli than with C. jejuni [140].…”

“…Kanamycin resistance in Campylobacter is more commonly associated with C. coli than with C. jejuni [140]. Like tetracycline resistance, kanamycin resistance determinants were located both on the chromosome and on self-transmissible plasmids [168].…”