Naturally Occurring Plasmids in Acinetobacter calcoaceticus: a P Class R Factor of Restricted Host Range

Summary: A naturally occurring transmissible plasmid, designated pAVl, 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 pAVl is a member of the P incompatibility group. However, unlike most other P group R factors, pAVl is not transmissible to strains of Escherichia coli, Pseudomonas aeruginosa, Klebsiella or Proteus mirabilis.