Background: Carbapenem-resistant Acinetobacter baumannii strains are considered as one of the most severe factors in hospital infection in the world, and the Beta-lactamase enzyme is one of the most important mechanisms of resistance in these strains. Objectives: The aim of this study was to evaluate the presence of Carbapenem-resistant beta-lactamase genes and determining antibiotic resistance patterns in clinical isolates of Acinetobacter baummanii from hospitalized patients in Shahid Kamyab hospital in Mashhad, Iran. Methods: Out of 286 collected isolates from hospitalized patients of Shahid Kamyab hospital (March 2017 to June 2017), 31 isolates confirmed to be Acinetobacter baummanii using biochemical tests. Antibiotic susceptibility testing was conducted using disc diffusion method according to CLSI standard protocols. The presence of beta-lactamase genes, blaVEB, blaPER, blaAmpC, blaVIM, blaIMP, blaSHV, and blaTEM, was investigated using Polymerase Chain Reaction. Results: In total, 31 isolates were identified as Acinetobacter baummanii, all of which showed high resistance to Ceftazidime, Cefixime, Ceftriaxone, Meropenem, Imipenem, Cefotaxime and Cephalexin, and the lowest resistance (19.35%) was observed against Polymixin B. The genes, blaAmpC, blaTEM, blaSHV, blaPER and blaVIM, were found in 93.54% (29), 51.61% (16), 48.38% (15), 41.93% (13) and 77% (24) isolates, respectively, while blaVEB, and blaIMP genes were not observed in any of the isolates. Conclusions: The results showed high levels of carbapenem resistance as well as high frequency of beta-lactamase resistance genes among clinical isolates of Acinetobacter baumannii.

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