Analysis of class 2 integrons as a marker for multidrug resistance among gram negative bacilli

Class 1 and 2 integrons are considered the paradigm of multidrug resistant (MDR) integrons. Although class 1 integrons have been found statistically associated to Enterobacteriaceae MDR isolates, this type of study has not been conducted for class 2 integrons. Escherichia coli and 3 species that were found that harbored more than 20% of class 2 integrons in clinical isolates, were selected to determine the role of intI2 as MDR marker. A total of 234 MDR/191 susceptible non-epidemiologically related isolates were analyzed. Seventy-four intI2 genes were found by PCR and sequencing. An intI2 relationship with MDR phenotypes in Acinetobacter baumannii and Enterobacter cloacae was found. No statistical association was identified with MDR E. coli and Helicobacter pylori isolates. In other words, the likelihood of finding intI2 is the same in susceptible and in MDR E. coli and H. pylori strains, suggesting a particular affinity between the mobile element Tn7 and some species. The use of intI2 as MDR marker was species-dependent, with fluctuating epidemiology at geographical and temporal gradients. The use of intI2 as MDR marker is advisable in A. baumannii, a species that can reach high frequencies of this genetic element.Fil: Rodriguez, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; ArgentinaFil: Cassini, Marcelo Hernan. Universidad Nacional de Luján; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Delgado, Gabriela del Valle. Provincia de Tucuman. Ministerio de Salud. Sistema Provincial de Salud. Hospital del Ni?o Jesus; ArgentinaFil: Argentinian Integron Study Group. No especifica;Fil: Ramirez, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; Argentina. California State University; Estados UnidosFil: Centron, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; Argentin

Characterization of Tn 6238

Here, we report that the genetic structure of Tn1331 remained conserved in Argentina from 1989 to 2013 (72 of 73 isolates), with the exception being the plasmid-borne Tn1331-like transposon Tn6238 containing a new aac(6′)-Ib-cr allele recovered from a colistin-resistant Klebsiella pneumoniae clinical isolate. A bioinformatic analysis of aac(6′)-Ib-like gene cassettes suggests that this new aac(6′)-Ib-cr allele emerged through mutation or homologous recombination in the Tn1331 genetic platform. Tn6238 is a novel platform for the dissemination of aminoglycoside and fluoroquinolone resistance determinants

Distribution and functional identification of complex class 1 integrons

The emergence of extended-spectrum b-lactamases and plasmid-mediated resistance to quinolones has been previously found to be associated with the dissemination of complex class 1 integrons in Argentina. In this study, we analyzed their distribution through time and evaluated the functionality of the Orf513 pro- tein, which is the putative recombinase of the ISCR1 mobile element. We investigated the presence of the orf513, blaCTX-M-2, dfrA3b, qnrB10 and blaDHA-1 genes by PCR and DNA sequencing as well as their linkage to class 1 integrons in 451 non-epidemiologically related nosocomial strains resistant to at least one expanded-spectrum cephalosporin and to one aminoglycoside, isolated between 1989 and 2010 from 7 hospitals from Buenos Aires City. The epidemiology of complex class 1 integrons was found to be notably different among fermenting (94/171) and non-fermenting clinical bacilli isolates (1/280). The ISCR1::qnrB10 positive isolates were found since 1993, confirming its presence in clinical isolates more than a decade before its first description. As expected, In35::ISCR1::blaCTX-M-2 was the most common complex class 1 integron among Enterobacteriaceae isolates, particularly in Proteus mirabilis. Experimental analysis corroborated the activity of the Orf513 protein, which was found to bind specific DNA sequences containing the previously suggested oriIS region. These findings showed the high dispersion and maintenance of com- plex class 1 integrons across time in our nosocomial isolates. The contribution of the ISCR1 mobile element to multidrug resistant phenotypes is significant due to its sustained association to class 1 integrons.Fil: Quiroga, María Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica; ArgentinaFil: Arduino, Sonia Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Estudios Médicos e Investigaciones Clínicas; Argentina. Laval University; Canadá;Fil: Merkier, Andrea Karina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica; ArgentinaFil: Quiroga, Cecilia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica; ArgentinaFil: Petroni, Alejandro. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; ArgentinaFil: Roy, Paul H.. Laval University; Canadá;Fil: Centrón, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica; ArgentinaFil: Argentinian Integron Study Group. No especifíca