Structure of In31, a bla _IMP -Containing Pseudomonas aeruginosa Integron Phyletically Related to In5, Which Carries an Unusual Array of Gene Cassettes

Abstract

The location and environment of the acquiredbla IMP gene, which encodes the IMP-1 metallo-β-lactamase, were investigated in a JapanesePseudomonas aeruginosa clinical isolate (isolate 101/1477) that produced the enzyme. In this isolate,bla IMP was carried on a 36-kb plasmid, and similar to the identical alleles found in Serratia marcescens and Klebsiella pneumoniae clinical isolates, it was located on a mobile gene cassette inserted into an integron. The entire structure of this integron, named In31, was determined. In31 is a class 1 element belonging to the same group of defective transposon derivatives that originated from Tn402-like ancestors such as In0, In2, and In5. The general structure of In31 appeared to be most closely related to that of In5 from pSCH884, suggesting a recent common phylogeny for these two elements. In In31, the bla IMP cassette is the first of an array of five gene cassettes that also includes anaacA4 cassette and three original cassettes that have never been described in other integrons. The novel cassettes carry, respectively, (i) a new chloramphenicol acetyltransferase-encoding allele of the catB family, (ii) a qac allele encoding a new member of the small multidrug resistance family of proteins, and (iii) an open reading frame encoding a protein of unknown function. All the resistance genes carried on cassettes inserted in In31 were found to be functional in decreasing the in vitro susceptibilities of host strains to the corresponding antimicrobial agents.

Class 1 integron containing metallo β-lactamase gene blaIMP-1 in carbapenem-resistant Pseudomonas aeruginosa in Thailand

“…Direct sequencing of the amplicons confi rmed the presence of the bla IMP allele. 9 PFGE revealed the two IMPproducing isolates' profi les to be distinct from one another (Fig. 2).…”

Emergence of resistance to antibacterial agents: the role of quaternary ammonium compounds—a critical review

“…Co-resistance may result from the acquisition of a genetic unit, such as a plasmid [40,[53][54][55][56][57][58], transposon [59] or integron [60,61], that contains two or more resistance genes or genetic units [62][63][64][65][66][67][68][69]. Cross-resistance may be due to a single efflux pump that can actively export both QACs and antimicrobial agents [26,40,[70][71][72][73][74][75][76][77][78][79][80][81][82][83][84].…”

Evaluation of genetic determinants involved in β-lactam- and multiresistance in a surgical ICU

“…The former two groups are well known and representatives of these groups were already present in our hospital during the mid-1990s [20]. Recently, VIM and IMP metallo-␤-lactamases have been described in France and Italy [19,[21][22][23][24][25]. The genes encoding these ␤-lactamases were present on integrons, which are highly predictive for multi-resistance [8].…”