Acinetobacter baumannii (Ab) circulating in Argentina and Uruguay

MORALES A., RAMÍREZ M.S., VILACOBA E., NARDELLI M., MÁRQUEZ C., ARGENTINIAN STUDY GROUP, CENTRÓN D.

San Diego, CA

Jornada; San Diego Microbiology Group Day-Long Meeting; 2011

Background: Ab has emerged as a serious problem in the hospital environment over the world. Previous results of our laboratory showed a particular dispersion of class 2 integrons (In2) in Ab clinical isolates from Argentina. To reveal the current epidemiology of In2, a molecular surveillance analyzing 78 MDR Ab isolates from Argentina and Uruguay collected during the years 2008-2010 was performed. Methods: PCR reactions using specific primers and sequence analysis were carried out to determine the presence and characterization of In2. PFGE and REP-PCR were used to determine clonal relationships. Results: The intI2 gene was present in 27 Ab isolates (36,61%), being the typical array, Tn7::In-7, present in 19 out of 27. In 7 isolates none of the gene cassettes usually described in the context of class 1 and 2 integrons were detected. At least one of the Tn7 transposition genes was present in 74% of the isolates, and only 30% of the intI2 positive isolates enclosed the 5 genes of the module. The genetic localization of In2 in the attTn7 site was also determined, resulting 18 isolates positive for the reaction. Clonal relationship analysis exposed the presence of 2 predominant clones (I and IV), which were widespread in our region and did not correspond to the European clones. Conclusion: A dissemination of MDR clones of Ab carrying In2 was exposed in our region. The results showed two predominant clones endemic to the South Cone carrying In2, which could explain the high frequency of In2 in Ab isolates circulating in our region. Analysis of the tns genes of Tn7, showed a significant decrease in the presence of the Tn7 module linked to the class 2 integron which is in agreement with our previous proposal that the class 2 integrons and the transposition module of Tn7 are evolving independently.