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Naturally occurring plasmids in Acinetobacter calcoaceticus: a P class R factor of restricted host range
Abstract:
A naturally occurring transmissible plasmid, designated pAV1, has been isolated in Acinetobacter calcoaceticus. It specifies resistance to sulphonamides and is capable of mobilizing two non-transmissible resistance determinants for tetracycline and neomycin, respectively, within strains of A. calcoaceticus. It is incompatible with the P class R factors RP4 and R751 in A. calcoaceticus. On this basis we conclude that pAV1 is a member of the P incompatibility group. However, unlike most other P group R factors, pAV1 is not transmissible to strains of Escherichia coli, Pseudomonas aeruginosa, Klebsiella or Proteus mirabilis.
Insights
A novel plasmid, pAV1, found in Acinetobacter calcoaceticus confers sulphonamide resistance. This plasmid can mobilize other resistance genes but shows limited transmissibility to other bacterial species, unlike typical P group plasmids.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Plasmids are extrachromosomal DNA elements that play a crucial role in bacterial adaptation and evolution.
- Antibiotic resistance is a growing global health concern, often mediated by plasmid-borne genes.
- Understanding plasmid biology, including their transfer mechanisms and host range, is vital for combating resistance.
Purpose of the Study:
- To characterize a newly isolated transmissible plasmid, pAV1, from Acinetobacter calcoaceticus.
- To determine the resistance profile and mobilization capabilities of pAV1.
- To investigate the incompatibility and host range of pAV1.
Main Methods:
- Isolation and characterization of plasmid DNA from Acinetobacter calcoaceticus.
- Conjugation experiments to assess plasmid transfer and mobilization.
- Incompatibility testing with known plasmid groups.
- Testing transmissibility to various bacterial species.
Main Results:
- The isolated plasmid, pAV1, confers resistance to sulphonamides.
- pAV1 can mobilize non-transmissible resistance determinants for tetracycline and neomycin within A. calcoaceticus.
- pAV1 is incompatible with P group plasmids RP4 and R751.
- pAV1 belongs to the P incompatibility group.
- pAV1 exhibits restricted transmissibility, failing to transfer to Escherichia coli, Pseudomonas aeruginosa, Klebsiella, and Proteus mirabilis.
Conclusions:
- pAV1 is a novel P incompatibility group plasmid isolated from Acinetobacter calcoaceticus.
- pAV1 possesses unique characteristics, including limited inter-species transmissibility, distinguishing it from other P group plasmids.
- The findings contribute to the understanding of plasmid diversity and antibiotic resistance dissemination.