Macrolide Resistance in Campylobacter jejuni and Campylobacter coli : Molecular Mechanism and Stability of the Resistance Phenotype

Abstract

A collection of 23 macrolide-resistant Campylobacter isolates from different geographic areas was investigated to determine the mechanism and stability of macrolide resistance. The isolates were identified as Campylobacter jejuni or Campylobacter coli based on the results of the hippurate biochemical test in addition to five PCR-based genotypic methods. Three point mutations at two positions within the peptidyl transferase region in domain V of the 23S rRNA gene were identified. About 78% of the resistant isolates exhibited an A3G transition at Escherichia coli equivalent base 2059 of the 23S rRNA gene. The isolates possessing this mutation showed a wide range of erythromycin and clarithromycin MICs. Thus, this mutation may incur a greater probability of treatment failure in populations infected by resistant Campylobacter isolates. Another macrolideassociated mutation (A3C transversion), at E. coli equivalent base 2058, was detected in about 13% of the isolates. An A3G transition at a position cognate with E. coli 23S rRNA base 2058, which is homologous to the A2142G mutation commonly described in Helicobacter pylori, was also identified in one of the C. jejuni isolates examined. In the majority of C. jejuni isolates, the mutations in the 23S rRNA gene were homozygous except in two cases where the mutation was found in two of the three copies of the target gene. Natural transformation demonstrated the transfer of the macrolide resistance phenotype from a resistant Campylobacter isolate to a susceptible Campylobacter isolate. Growth rates of the resulting transformants containing A-20583C or A-20593G mutations were similar to that of the parental isolate. The erythromycin resistance of six of seven representative isolates was found to be stable after successive subculturing in the absence of erythromycin selection pressure regardless of the resistance level, the position of the mutation, or the number of the mutated copies of the target gene. One C. jejuni isolate showing an A-20583G mutation, however, reverted to erythromycin and clarithromycin susceptibility after 55 subcultures on erythromycin-free medium. Investigation of ribosomal proteins L4 and L22 by sequence analysis in five representative isolates of C. jejuni and C. coli demonstrated no significant macrolide resistance-associated alterations in either the L4 or the L22 protein that might explain either macrolide resistance or enhancement of the resistance level.

Molecular mechanisms of quinolone, macrolide, and tetracycline resistance amongCampylobacterisolates from initial stages of broiler production

“…The most prevalent are the mutations at positions 2074 and 2075 (domain V) in the rrn gene, which encodes for 23S rRNA (Gibreel et al, 2005). Transversion A2075G is the most commonly found, in most cases, in homozygosis where the three copies of rrn gene possess the mutation (Gibreel et al, 2005).…”

Characterization of Macrolide-Resistant Campylobacter coli Isolates from Food-Producing Animals on Farms Across Japan during 2004

“…[3][4][5]. However, there is little information available on the characteristics of the resistance mechanism of EM-resistant C. coli isolates from food-producing animals in Japan.…”

The Absence of Intervening Sequences in 23S rRNA Genes of Campylobacter coli Isolates from Turkeys Is a Unique Attribute of a Cluster of Related Strains Which Also Lack Resistance to Erythromycin

“…It is possible that additional genes in the vicinity of aspA, or in other genomic regions, are of C. jejuni origin and that some of these genes may be related to the extensively documented scarcity of erythromycin resistance in C. jejuni from meat animals (1, 3, 8, 13). C. jejuni can be transformed to erythromycin resistance in the laboratory, using as donor DNA the 23S rRNA fragment from a resistant C. coli strain that harbors the A2075G erythromycin resistance determinant (14). However, it is possible that other C. jejuni genetic determinants negatively impact the competitive fitness of these erythromycinresistant organisms in natural environments or in the animal host.…”

“…IVSs are absent from all three 23S rRNA gene copies of C. jejuni NCTC 11168 (32) but were detected in other strains of C. jejuni and C. coli (29,33,41) and were also identified in all three copies of the 23S rRNA gene in the recently sequenced genome of C. coli RM2228 (12). When present, the IVS is located only 891 nucleotides (nt) upstream from the site in the 23S rRNA gene where a point mutation (A2075G) has been associated with high-level resistance to erythromycin in Campylobacter (12,14,20). Surveys of C. jejuni from broilers showed that only a minority of strains (approximately 10%) contained IVSs (29,33).…”

“…For example, Luangtongkum et al reported that for samples from conventional poultry farms, 89% of C. coli and 19% of C. jejuni isolates were resistant to erythromycin (23). For Campylobacter, erythromycin resistance has been found to be due to a base substitution in the 23S rRNA gene (A2075G, based on the sequence of the 23S rRNA gene of C. jejuni NCTC 11168) that alters the ribosome target site (14,20); erythromycin resistance can be disseminated by natural transformation among strains from turkeys and swine (21). Thus, erythromycin-resistant C. coli strains of animal origin may present treatment challenges, should such strains become implicated in human illness.…”