The goal of this study was to determine the presence of the genes implicated in resistance to agents used for chemotherapy of infectious diseases caused by Pseudomonas aeruginosa. Twenty seven P. aeruginosa isolates from the Clinical Hospital for Infectious Diseases in Cluj-Napoca, Romania, were analyzed. The bacteria were isolated over two years period, in 2008 and 2009 and serotyped at the Clinical Hospital of Infectious Disease, Cluj-Napoca. The isolates were recovered from patients with multiple types of infections, mostly respiratory tract, urinary tract and postoperative wound infections. In order to identify the genes implicated in antimicrobial resistance mechanisms, we used a direct PCR technique. DNA extraction was skipped and the bacterial cell wall denaturated in the first step of the reaction. We did not identify the presence of blaVIM or blaIMP family genes at any of the tested isolates of P. aeruginosa. We determined instead the PstS gene and from the ESBL group, we detected the presence of OXA type genes, namely OXA-50 and OXA-2. The presence of blaOXA-50 is important in order to identify and track the spread of multidrug-resistant P. aeruginosa clones since that blaOXA-50 may be another potential clonality marker. This study is the first report of presence of PstS and blaOXA type genes in P. aeruginosa isolates, in Romania.