In169, a new class 1 integron that encoded bla(IMP-18) in a multidrug-resistant Pseudomonas aeruginosa isolate from Mexico.
OBJECTIVE
Carbapenem resistance in Pseudomonas aeruginosa may be due to the presence of metallo-beta-lactamases (MbetaL). The genes that encode these enzymes can be located in association with aminoglycoside-modifying enzymes on class 1 integrons. This study describes the bla(IMP-18) class 1 integron array (In169) from a carbapenem-resistant P. aeruginosa clinical isolate obtained at the Centro Medico Nacional La Raza (CMNR) in Mexico City and compares it to other bla(IMP)-type producers.


METHODS
Twenty six multiresistant P. aeruginosa clinical isolates were recovered between June and December 2004 and tested by MicroScan and CLSI agar dilution methods. The MbetaL production was screened by a disk approximation test and MbetaL Etest strips, whereas MbetaL genes and integrons were detected using PCR primers. DNA sequence analysis was carried out by BLAST, and epidemiological typing was performed by pulsed-field gel electrophoresis (PFGE). A Southern hybridization analysis was performed with a bla(IMP) specific DNA probe.


RESULTS
Nine of 26 P. aeruginosa isolates were imipenem-resistant with unique PFGE patterns (no clonal relation), and only one strain (5106) was positive for MbetaL production, corresponding to the IMP-type. The class 1 integron encoding the MbetaL was characterized: it contained the IMP-18, two copies of aadA2 and OXA-2 genes, corresponding to a new class 1 integron array, denoted In169. P. aeruginosa isolate 5106 is genetically related to bla(IMP-18) positive P. aeruginosa isolate from a distant hospital (Hospital Infantil de Morelia).


CONCLUSIONS
This report is the first to describe the bla(IMP-18) in two genetically related isolates from two different institutions.
Sánchez-Martinez
Guillermina
G
Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México.
Garza-Ramos
Ulises Jesús
UJ
Reyna-Flores
Fernando Luis
FL
Gaytán-Martínez
Jesús
J
Lorenzo-Bautista
Isaí Guillermo
IG
Silva-Sanchez
Jesús
J
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D017931:DNA Primers; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D016521:Electrophoresis, Gel, Pulsed-Field; D032023:Integrons; D016133:Polymerase Chain Reaction; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics
D000900:Anti-Bacterial Agents; D017931:DNA Primers