First report of a Tn402-like class 1 integron carrying blaVIM-2 in Pseudomonas putida from Argentina

Pseudomonas putida colonizes several niches including soil, fresh water, and animal surfaces. Although rarely isolated from human infections, metallo-beta-lactamase (MBL)-containing P. putida clinical strains resistant to most beta-lactams) have recently been described and proposed to act as likely reservoirs of MBL genes [1,2]. This, in addition to the lack of an effective clinical inhibitor of these metallo-enzymes, poses a serious challenge to antimicrobial therapy [3]. blaVIM-2 represents the most widely distributed MBL gene worldwide, and is most generally present in class 1 integrons [4,5, Pasteran F et al. (2005) 45th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) Abstract C2 108/151]. These elements may be contained within transposons, and the whole arrangement subjected in turn to rapid spread among different bacterial species by the aid of wide-range plasmids [5]. It follows that the elucidation of the genetic platform(s) in which blaVIM-2 genes are contained enables us to rationally speculate on how they evolve and disseminate. We report here the identification for the first time of an unusual class 1 integron carrying blaVIM-2 and aacA4 aminoglycoside acetyl transferase gene cassettes embedded in a complete Tn402-like transposon, all elements carried in turn by a self-transferable plasmid present in a carbapenem-resistant P. putida clinical strain. © 2010 Marchiaro et al.