| Abstrakt: |
ABSTRACTThe carbenicillin, gentamicin, kanamycin, streptomycin, spectinomycin, sulfonamide, and tobramycin resistance determinants found on Pseudomonas aeruginosaplasmid R151 have previously been shown to translocate to another plasmid, R388, and it was inferred that a transposon, Tn1404, carried the resistance determinants. Sequencing of the cassette array from the plasmid known as R388::Tn1404revealed two known gene cassettes, oxa10and aadB, and a previously unidentified cassette determining resistance to streptomycin and spectinomycin, here designated aadA10, in the order oxa10-aadB-aadA10.These cassettes replaced the dfrB2-orfAcassette array of R388, indicating that movement of the resistance determinants from R151 to R388 resulted from recombinational exchange between two class 1 integrons rather than transposition. The AadA10 protein is most closely related to AadA6 (85% identical) and AadA7 (80% identical). The aadA10cassette found here has only a simple site containing a 7-bp spacer derived from attI1in place of a 59-base element and is likely to represent a derivative of the complete cassette. IntI1-mediated deletion of the aadA10cassette was not detected, indicating that this single simple site is either inactive or only weakly active. |
