Complete Sequence of pOZ176, a 500-Kilobase IncP-2 Plasmid Encoding IMP-9-Mediated Carbapenem Resistance, from Outbreak Isolate Pseudomonas aeruginosa 96

Pseudomonas aeruginosa 96 (PA96) was isolated during a multicenter surveillance study in Guangzhou, China, in 2000. Whole-genome sequencing of this outbreak strain facilitated analysis of its IncP-2 carbapenem-resistant plasmid, pOZ176. The plasmid had a length of 500,839 bp and an average percent G+C content of 57%. Of the 618 predicted open reading frames, 65% encode hypothetical proteins. The pOZ176 backbone is not closely related to any plasmids thus far sequenced, but some similarity to pQBR103 ofPseudomonas fluorescens SBW25 was observed. Two multiresistant class 1 integrons and several insertion sequences were identified. Thebla IMP-9 -carrying integron containedaacA4 →bla IMP-9 →aacA4 , flanked upstream by Tn21 tnpMRA and downstream by a completetni operon of Tn402 and amer module, named Tn6016 . The second integron carriedaacA4 →catB8a →bla OXA-10 and was flanked by Tn1403 -liketnpRA and asul1 -type 3′ conserved sequence (3′-CS), named Tn6217 . Other features include three resistance genes similar to those of Tn5 , a tellurite resistance operon, and twopil operons. The replication and maintenance systems exhibit similarity to a genomic island ofRalstonia solanacearum GM1000. Codon usage analysis suggests the recent acquisition ofbla IMP-9 . The origins of the integrons on pOZ176 indicated separate horizontal gene transfer events driven by antibiotic selection. The novel mosaic structure of pOZ176 suggests that it is derived from environmental bacteria.