RESUMEN
The Pseudomonas putida group (P. putida G) is composed of at least 21 species associated with a wide range of environments, including the clinical setting. Here, we characterized 13 carbapenem-resistant P. putida G clinical isolates bearing class 1 integrons/transposons (class 1 In/Tn) carrying blaVIM-2 metallo-ß-lactamase gene cassettes obtained from hospitals of Argentina. Multilocus sequencing (MLSA) and phylogenetic analyses based on 16S rDNA, gyrB and rpoD sequences distinguished 7 species among them. blaVIM-2 was found in three different cassette arrays: In41 (blaVIM-2-aacA4), In899 (only blaVIM-2), and In528 (dfrB1-aacA4-blaVIM-2). In41 and In899 were associated with complete tniABQC transposition modules and IRi/IRt boundaries characteristic of the Tn5053/Tn402 transposons, which were designated Tn6335 and Tn6336, respectively. The class 1 In/Tn element carrying In528, however, exhibited a defective tni module bearing only the tniC (transposase) gene, associated with a complete IS6100 bounded with two oppositely-oriented IRt end regions. In some P. putida G isolates including P. asiatica, P. juntendi, P. putida G/II, and P. putida G/V, Tn6335/Tn6336 were carried by pLD209-type conjugative plasmids capable of self-mobilization to P. aeruginosa or Escherichia coli. In other isolates of P. asiatica, P. putida G/II, and P. monteiliieilii, however, these blaVIM-2-containing class 1 In/Tn elements were found inserted into the res regions preceding the tnpR (resolvase) gene of particular Tn21 subgroup members of Tn3 transposons. The overall results reinforce the notion of P. putida G members as blaVIM-2 reservoirs, and shed light on the mechanisms of dissemination of carbapenem resistance genes to other pathogenic bacteria in the clinical setting.
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/genética , Carbapenémicos/farmacología , Farmacorresistencia Bacteriana/genética , Pseudomonas putida/genética , beta-Lactamasas/genética , Elementos Transponibles de ADN/genética , Integrones/genética , Pseudomonas putida/efectos de los fármacosRESUMEN
Con el fin de analizar la presencia de metalo-ß-lactamasas en nuestro medio, se incluyeron en este estudio aislamientos de Pseudomonas aeruginosa causantes de infecciones nosocomiales en un centro hospitalario del Uruguay, en el período comprendido entre abril y setiembre de 2008. En un aislamiento se detectó la presencia del gen codificante de la metalo-ß-lactamasa VIM-2 asociado a un integrón de clase 1 y del gen codificante de una ß-lactamasa de espectro extendido CTX-M-2. Esta es la primera comunicación de la presencia de los genes blaCTX-M-2 y blaVIM-2 en un mismo aislamiento de P. aeruginosa. A pesar de que las carbapenemasas ya han sido ampliamente documentadas en varias partes del mundo, esta es la primera comunicación de una metalo-ß-lactamasa adquirida con actividad carbapenemasa en bacterias patógenas encontradas en el Uruguay.
VIM-2 metallo-ß-lactamase gen detection in a class 1 integron associated to blaCTX-M-2 in a Pseudomonas aeruginosa clinical isolate in Uruguay: first communication. In order to analyze the presence of metallo-ß-lactamase in our country, we included in this study Pseudomonas aeruginosa isolates causing nosocomial infections in a hospital from Uruguay. The presence of a metallo-ß-lactamase VIM-2 in a class 1 integron and of an extended spectrum -lactamase CTX-M-2 was detected in one isolate. This is the first report of both genes, blaCTX-M-2 and blaVIM-2,in the same P. aeruginosa isolate. Although carbapenemases have been extensively documented in the world, this is the first report of an acquired metallo-ß-lactamase with carbapenemase activity in pathogenic bacteria in Uruguay.