In this study, we analyzed the frequency of the AbGRI1-type genomic island (GI) and its association with genotypes. We obtained 130 A. baumannii isolates causing bloodstream infections from patients in Korea. Antimicrobial susceptibility testing and multilocus sequence typing were performed. The presence of AbGRI1-type GIs and their structure were determined by sequential PCR and sequencing. Ninety-eight isolates (75.3%) representing 14 sequence types (STs) belonged to CC208, corresponding to global clone 2 (GC2). AbGRI1-type GIs interrupted the comM gene in 107 isolates (82.4%). Four types of GIs were identified: Tn6022 (50 isolates, 46.7%), AbaR4 (23 isolates, 21.5%), Tn6166 (10 isolates, 9.3%), and Tn6166/Tn2006 (24 isolates, 22.4%). In the 50 isolates with Tn6022, Tn2006 or Tn2008B, both containing ISAba1-blaOXA-23, were present in sites other than GIs in three and 28 isolates, respectively. In the ten isolates with Tn6166, Tn2008B was identified in one isolate. AbGRI1-type GIs were identified nearly exclusively in CC208 isolates, with the exception of nine non-CC208 isolates (AbaR4 in eight ST229 isolates and Tn6022 in one ST1244 isolate). Within CC208 isolates, there was evidence of frequent recombination events, both in housekeeping genes and AbGRI1-type GIs, contributing to genotype diversification and the emergence of carbapenem resistance.
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