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Conjugal transfer of antibiotic resistances and plasmids from Campylobacter jejuni clinical isolates
1Department of Genetics and Cellular Biology, University of Malaya, Kuala Lumpur, Malaysia.
Abstract:
Six Campylobacter jejuni clinical isolates were examined for the occurrence of plasmids in association with antibiotic resistances as well as conjugal transfer. All the isolates were found to carry three similar plasmids of 78 kb, 12.6 kb and 3.3 kb in size. Multiple resistance to at least three of the antibiotics tested was observed with resistance to tetracycline most common. En bloc transfer of donor resistances at frequencies ranging from 10(-8) to 10(-4) were seen in all but one of the isolates during conjugation. The conjugal transfer of erythromycin, neomycin and streptomycin were observed to occur at frequencies similar to that of chloramphenicol, kanamycin and tetracycline. In isolate ABA94, three different antibiotic resistance phenotypes of the transconjugants were seen. In addition to en bloc transfer of the donor resistances, in approximately 10% of the transconjugants the streptomycin resistance was lost although these transconjugants carried the donor complement of three plasmids. In a further 1% of the transconjugants, resistance to kanamycin only was detected and these transconjugants did not carry any plasmids.
Insights
This study found that Campylobacter jejuni clinical isolates commonly carry plasmids conferring multiple antibiotic resistances. These resistances were frequently transferred together during conjugation experiments.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Campylobacter jejuni is a leading cause of bacterial gastroenteritis worldwide.
- Antibiotic resistance in C. jejuni is a growing public health concern.
- Plasmids are known to play a role in the dissemination of antibiotic resistance genes.
Purpose of the Study:
- To investigate the presence and characteristics of plasmids in C. jejuni clinical isolates.
- To determine the association between plasmids and antibiotic resistance.
- To assess the conjugal transfer of antibiotic resistance.
Main Methods:
- Isolation and characterization of plasmids from C. jejuni clinical isolates.
- Antibiotic susceptibility testing.
- Conjugation experiments to evaluate the transfer of resistance.
Main Results:
- All six C. jejuni isolates contained three similar plasmids (78 kb, 12.6 kb, and 3.3 kb).
- Multiple antibiotic resistances were common, with tetracycline resistance being most prevalent.
- En bloc transfer of donor resistances occurred at frequencies of 10(-8) to 10(-4) during conjugation.
Conclusions:
- Plasmids in C. jejuni clinical isolates are associated with multiple antibiotic resistances.
- Conjugal transfer facilitates the spread of antibiotic resistance within C. jejuni populations.
- plasmid-mediated resistance transfer can be complex, with instances of resistance loss or plasmid absence in transconjugants.