Background: Multidrug-resistant Acinetobacter baumannii (MDRAB) is an increasing problem worldwide. We aimed to determine the antibiotic susceptibility, diversity of oxacillinases, and molecular types of MDRAB. Methods: A total of 100 non-duplicate A. baumannii blood culture isolates were evaluated. Antimicrobial susceptibilities of the isolates were determined according to the standard Clinical and Laboratory Standards Institute (CLSI) broth microdilution method. Colistin, doripenem, and tigecycline susceptibilities were analyzed by E-test. The presence of bla OXA-23-like, blaOXA-24-like, blaOXA-51-like, and blaOXA-58-like genes was investigated by multiplex polymerase chain reaction (PCR). Typing of A. baumannii isolates was performed using repetitive extragenic palindromic sequence-based PCR (rep-PCR; DiversiLab). Results: Most isolates were susceptible to colistin (98% susceptible) and tigecycline (94% susceptible), whereas fewer isolates were susceptible to imipenem, meropenem, and doripenem (17%, 17%, and 18% susceptible, respectively). Carbapenem resistance was associated with the presence of blaOXA-23-like (31% of isolates) and blaOXA-58-like (23% of isolates) genes. The occurrence of isolates carrying bla OXA-58-like genes increased between y 2004 and 2009, but decreased in 2010. In contrast, isolates with blaOXA-23-like genes increased during the 2008-2010 period. Out of 100 isolates, 62 were categorized into 13 major rep-PCR patterns, with the highest prevalence in pattern 1 (10 isolates), followed by patterns 2 and 3 (9 isolates each). Conclusions: Carbapenem-resistant invasive A. baumannii isolates carrying the bla OXA-23-like gene became more prevalent and replaced isolates carrying the blaOXA-58-like carbapenemase gene through the 7 y. Rep-PCR genotyping of these strains confirmed that ongoing MDRAB resulted from a long-term persistence and mixture of several clusters. © 2013 Informa Healthcare.