Related Experiment Video
Updated: Aug 23, 2026
Identifying Amino Acid Overproducers Using Rare-Codon-Rich Markers
Published on: June 24, 2019
Characterization of plasmid-mediated aphA-3 kanamycin resistance in Campylobacter jejuni
Amera Gibreel1, Ola Sköld, Diane E Taylor
1Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
Abstract:
A total of 254 isolates of Campylobacter jejuni and three isolates of Campylobacter coli, isolated from Sweden, Canada, and Egypt, were screened for kanamycin resistance. Eight strains of C. jejuni contained large plasmids that carried the aphA-3 kanamycin-resistance marker. In six plasmids, the aphA-3 gene was located downstream of an apparent insertion sequence, designated IS607*, which showed a considerable similarity to IS607, characterized on the chromosome of some Helicobacter pylori strains. In contrast, the other plasmids carried the aphA-3 gene as a part of a resistance cluster. This included three resistance markers encoding 6'-adenylyltransferase (aadE), streptothricin acetyltransferase (sat), and 3'-aminoglycoside phosphotransferase type III (aphA-3). The genetic organization of this resistance cluster suggests that it has been acquired by C. jejuni from a Gram-positive organism. The IS607* element was also observed in kanamycin-susceptible strains of C. jejuni on plasmids mediating tetracycline resistance. The kanamycin-resistance phenotype transferred along with tetracycline resistance by conjugation from four representative C. jejuni strains to a recipient strain of C. jejuni. The kanamycin-resistance determinant (aphA-3) was stably transferred from one of the four C. jejuni strains to a recipient strain of Escherichia coli. However, the C. jejuni plasmid, which also carries the tetO gene, was not maintained in E. coli. Pulsed-field gel electrophoresis revealed the integration of approximately 50 kb of the plasmid into the chromosome of the E. coli recipient.
Insights
Kanamycin resistance in Campylobacter jejuni is often linked to the aphA-3 gene on plasmids. These plasmids can also carry tetracycline resistance and transfer between bacteria, highlighting potential public health concerns.
Area of Science:
- Microbiology
- Genetics
- Antimicrobial Resistance
Background:
- Campylobacter jejuni is a leading cause of bacterial gastroenteritis worldwide.
- Antibiotic resistance in Campylobacter poses a significant public health threat.
- Understanding the genetic basis of antibiotic resistance in C. jejuni is crucial for effective treatment strategies.
Purpose of the Study:
- To investigate the prevalence and genetic mechanisms of kanamycin resistance in Campylobacter isolates.
- To characterize the plasmids carrying kanamycin resistance genes.
- To examine the transferability of antibiotic resistance markers between bacterial strains.
Main Methods:
- Screening of Campylobacter jejuni and Campylobacter coli isolates for kanamycin resistance.
- Plasmid analysis, including sequencing and characterization of resistance genes (aphA-3).
- Conjugation experiments to assess the transfer of resistance phenotypes and plasmids.
- Pulsed-field gel electrophoresis (PFGE) to analyze plasmid integration.
Main Results:
- Eight C. jejuni strains harbored large plasmids with the aphA-3 kanamycin-resistance marker.
- In some plasmids, aphA-3 was associated with an insertion sequence (IS607*) similar to elements found in Helicobacter pylori.
- Other plasmids contained aphA-3 within a resistance cluster, suggesting acquisition from Gram-positive bacteria.
- Kanamycin and tetracycline resistance were transferable by conjugation.
- The aphA-3 determinant transferred to Escherichia coli, with partial plasmid integration into the host chromosome.
Conclusions:
- Plasmids play a significant role in the dissemination of kanamycin resistance in C. jejuni.
- The presence of IS607* and resistance clusters indicates complex genetic events contributing to antibiotic resistance.
- The transferability of resistance genes highlights the potential for spread between different bacterial species, including clinically relevant pathogens.
Related Concept Videos
01:25Clinical Significance of Antibiotic Resistance
01:28Plasmids
00:57Antibiotic Selection