Multidrug-resistant Acinetobacter baumannii infections are serious challenges for clinicians because of A. baumannii
propensity to acquire resistance to a wide spectrum of antimicrobial agents. In this study, 91 A. baumannii isolates
from patients in tertiary intensive care units of three university hospitals in the north, central, and south of Iran
were selected and tested for susceptibility to 22 antimicrobials; amplified restriction fragment polymorphism and
multiplex polymerase chain reaction methods were used to determine genetic relationships and International
Clone (IC) of A. baumannii isolates, respectively. Twenty-four genotypes were identified in A. baumannii isolates.
About 91.2% of isolates categorized into 4 distinct clusters; one was more heterogeneous and observed across the
three locations. A considerable number of the isolates (27.5%) belonged to the novel IC variant, sequence group 7
(SG7), which was geographically widespread in three locations. The drug resistance pattern showed that 14.2%,
20%, and 77% of the A. baumannii isolates were resistant to colistin, tigecycline, and rifampicin, respectively. Nine
percent of isolates (8) showed simultaneous resistance to colistin, rifampicin, and tigecycline. Interestingly, all of
them were susceptible to ampicillin–sulbactam and/or tobramycin. According to our results, SG7 could be
considered as a pan-Iranian clone
