New plasmid-borne antibiotic resistance gene cluster in Pasteurella multocida

Abstract

A new antibiotic resistance gene cluster comprising genes for sulfonamide (sul2), streptomycin (strA-strB), and tetracycline [tetR-tet(H)] resistance was detected on plasmid pVM111 from Pasteurella multocida. The tetR-tet(H) gene region was inserted between sul2 and strA, possibly by illegitimate recombination. Two potential recombination sites of 18 and 25 bp were identified.

FIG. 1.

Comparative analysis of restriction maps and structural organizations of plasmids RSF1010 (14), pVM111 (this study), pSTOJO1 (13), and pMVSCS1 (11). Restriction endonucleases are abbreviated as follows: B, BclI; D, DraI; E, EcoRI; Ev, EcoRV; H, HindIII; Hp, HpaI; K, KpnI; P, PstI; Pv, PvuII; S, SacI; and Sf, SfuI. A distance scale (in kilobases) is presented below each map. The reading frames for genes sul2, strA, ΔstrA, strB, ΔstrB, tet(H), tetR, dfrA14, catA3, mobA to mobC, ΔmobA, rep, and repA to repC are shown as arrows, with the direction of transcription indicated by the arrowhead. The black bar in the map of pVM111 indicates the sequenced part.

FIG. 2.

Presentation of the two potential recombination sites downstream of tet(H) and tetR probably involved in the integration of a Tn5706-like tetR-tet(H) gene region in an RSF1010-like spacer region between sul2 and strA. Identical bases with respect to the pVM111 sequence are indicated by vertical bars. The original translational stop codon of the sul2 gene in the RSF1010 sequence and the alternative stop codon in the pVM111 sequence are underlined. The two putative recombination sites are displayed as boxes.