Integrones y su relación con el fenotipo de resistencia en bacilos gramnegativos aislados en el Hospital Torres Galdames de Iquique, Chile

Abstract

The antimicrobial resistance is coded in genetic elements which generate a horizontal flow of information, particularly in conditions that are under strong selective pressure like the nosocomial environment. In that sense, in the last decades, gram negative bacilli have become important agents of nosocomial infection. In order to investigate the presence of integrons among clinical isolates of gram negative bacilli and their relationship with their resistance profile, we studied 88 strains isolated from clinical specimens of different wards of the Hospital Torres Galdames, during the June-December period, 2004. They were identified according to biochemical tests. The antimicrobial susceptibility was evaluated by agar diffusion method. The integron presence was investigated by polymerase chain reaction (PCR). A cluster analysis was carried out to study the relationship between the presence of integrons and the resistance profile. The genotyping of the isolates was carried out by ERIC-PCR technique. Results: Of the isolated strains, 18% corresponded to Proteus mirabilis, 17% to Escherichia coli, and 32% to Non Fermentative Gram Negative bacilli. Most isolates presented high resistance to the antibiotics studied: 83% to ampicillin, 85% to cephalotin, 82% to ceftriaxone, 82% to ciprofloxacin, 81% to gentamycin and 82% to cotrimoxazole. Seventy-five % of the 88 strains presented integrons. Class 2 integrons were found to be the most common. The results of the cluster analysis did not show a clear relationship among the presence of the integrons and the resistance profile. With the available information it is not possible to relate the integron presence with a certain resistance pattern. The patterns of bands obtained with the technique ERIC-PCR revealed a great genetic variety among the analyzed isolations, defining diverse genotypes, distributed in the different services of the hospital where they were isolated.