Incidence of antibiotic resistance in Campylobacter jejuni isolated in Alberta, Canada, from 1999 to 2002, with special reference to tet(O)-mediated tetracycline resistance.
Of 203 human clinical isolates of Campylobacter jejuni from Alberta, Canada (1999 to 2002), 101 isolates (50%) were resistant to at least 64 microg of tetracycline/ml, with four isolates exhibiting higher levels of tetracycline resistance (512 microg/ml). In total, the MICs for 37% of tetracycline-resistant isolates (256 to 512 microg/ml) were higher than those previously reported in C. jejuni (64 to 128 microg/ml). In the tetracycline-resistant clinical isolates, 67% contained plasmids and all contained the tet(O) gene. Four isolates resistant to high levels of tetracycline (MIC = 512 microg/ml) contained plasmids carrying the tet(O) gene, which could be transferred to other isolates of C. jejuni. The tetracycline MICs for transconjugants were comparable to those of the donors. Cloning of tet(O) from the four high-level tetracycline-resistant isolates conferred an MIC of 32 microg/ml for Escherichia coli DH5alpha. In contrast, transfer to a strain of C. jejuni by using mobilization conferred an MIC of 128 microg/ml. DNA sequence analysis determined that the tet(O) genes encoding lower MICs (64 to 128 microg/ml) were identical to one other, although the tet(O) genes encoding a 512-microg/ml MIC demonstrated several nucleotide substitutions. The quinolone resistance determining region of four ciprofloxacin-resistant isolates (2%) was analyzed, and resistance was associated with a chromosomal mutation in the gyrA gene resulting in a Thr-86-Ile substitution. In addition, six kanamycin-resistant isolates contained large plasmids that carry the aphA-3 marker coding for 3'-aminoglycoside phosphotransferase. Resistance to erythromycin was not detected in 203 isolates. In general, resistance to most antibiotics in C. jejuni remains low, except for resistance to tetracycline, which has increased from about 8 to 50% over the past 20 years.
Department of Medical Microbiology and Immunology, 1-28 Medical Sciences Building, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
Amera
A
Gibreel
Dobryan M
DM
Tracz
Lisa
L
Nonaka
Trinh M
TM
Ngo
Sean R
SR
Connell
Diane E
DE
Taylor
D000416:Alberta / Q000453:epidemiology; D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002169:Campylobacter Infections / Q000453:epidemiology* / Q000382:microbiology*; D016123:Campylobacter jejuni / Q000187:drug effects* / Q000254:growth & development; D002352:Carrier Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D027081:DNA Gyrase / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005822:Genetic Vectors; D006801:Humans; D007612:Kanamycin / Q000494:pharmacology; D019868:Kanamycin Kinase / Q000235:genetics; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D011804:Quinolines / Q000494:pharmacology; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013753:Tetracycline Resistance / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D011804:Quinolines; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; C083139:Tet O resistance protein, Bacteria; D007612:Kanamycin; D019868:Kanamycin Kinase; D027081:DNA Gyrase