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

Abstract

Pseudomonas aeruginosa 96 (PA96) was isolated during a multicenter surveillance study in Guangzhou, China, in 2000. Wholegenome 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 of Pseudomonas fluorescens SBW25 was observed. Two multiresistant class 1 integrons and several insertion sequences were identified. The bla IMP-9 -carrying integron contained aacA4¡bla IMP-9 ¡aacA4, flanked upstream by Tn21 tnpMRA and downstream by a complete tni operon of Tn402 and a mer module, named Tn6016. The second integron carried aacA4¡catB8a¡bla OXA-10 and was flanked by Tn1403-like tnpRA and a sul1-type 3= conserved sequence (3=-CS), named Tn6217. Other features include three resistance genes similar to those of Tn5, a tellurite resistance operon, and two pil operons. The replication and maintenance systems exhibit similarity to a genomic island of Ralstonia solanacearum GM1000. Codon usage analysis suggests the recent acquisition of bla 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.

Elucidating the Role of Residue 67 in IMP-Type Metallo-β-Lactamase Evolution

“…Second, the activity profiles of the enzymes against a range of ␤-lactams allow for an interesting hypothesis: that the original enzyme IMP-1 that appeared in the early 1990s was a broad-spectrum enzyme that efficiently inactivated all older ␤-lactam antibiotics, i.e., penicillins, the first-generation cephalosporin cephalothin, the neutral third-generation cephalosporin cefotaxime, the cephamycin cefoxitin, and, moderately, the early carbapenem imipenem (hence its name imipenemase). Over time, possibly selected by exposure to newer ␤-lactams, variants with mutations at position 67 appeared, including IMP-9 with I67 in 2000 (57) and IMP-10 with F67, isolated from different strains from 1997 to 2000 (19). Both residues increased resistance to imipenem, the charged third-generation cephalosporin ceftazidime, and, especially for F67, the more recently introduced carbapenems meropenem and doripenem, which were FDA approved in 1996 and 2007, respectively.…”

Multidrug-Resistant Sequence Type 235 Pseudomonas aeruginosa Clinical Isolates Producing IMP-26 with Increased Carbapenem-Hydrolyzing Activities in Vietnam

“…1), was 93% identical to that in an IMP-9-producing P. aeruginosa PA96 plasmid pOZ176 (accession no. KC543497; nt 409845 to 414689), which was isolated in 2000 in China (39).…”

Presence of VIM-Positive Pseudomonas Species in Chickens and Their Surrounding Environment

“…1B). Further analysis of the flanking regions revealed that it was very similar to the Tn6217 region in the bla IMP-9 -carrying plasmid pOZ176 from a clinical P. aeruginosa isolate from Guangzhou, China (20). The upstream and downstream regions of bla VIM-48 contained the aacA4-intI1-Tn1403-like and sul1-hp-IS6100 gene clusters, respectively.…”