The aim of this study was to determine the presence of blaCTX-M-2 in our A. baumannii population and their putative role as an alternative mechanism of resistance to third-generation cephalosporins in this species. The blaCTX-M-2 gene is widespread among the Enterobacteriaceae isolates from our country; however, it was not found in 76 isolates A. baumannii non-epidemiologically related clinical isolates resistant to third-generation cephalosporins isolated since 1982 in hospitals from Buenos Aires City. A plasmid isolated from Proteus mirabilis that possesses the complex class 1 integron In35::ISCR1::blaCTX-M-2 was used to transform the natural competent A. baumannii clinical strain A118. PCR, plasmid extraction, DNA restriction, and susceptibility test confirmed that A118 could gain and maintain the plasmid possessing In35::ISCR1::blaCTX-M-2, the genetic platform where the blaCTX-M-2 gene is dispersing in Argentina.