Exploring the association between capsular types, sequence types, and carbapenemase genes in Acinetobacter baumannii

Abstract Acinetobacter baumannii is the main cause of nosocomial infections, and the treatment of such infections has become more difficult due to the emergence of carbapenem resistance. This study focused on major carbapenemase genes and explored the association between carbapenemase genes, sequence types (ST types), and capsular types (K types). A total of 98 carbapenem-resistant A. baumannii (CRAB) strains were collected from two hospitals, the Chang Gung Memorial Hospital-Lin Kou branch (LCGMH) in northern Taiwan and the CGMH-Kaohsiung branch (KCGMH) in southern Taiwan, from 2015–2017. Major carbapenemase genes of class A, B, and D β-lactamases were detected by polymerase chain reaction. All strains except 1 were positive for blaOXA-51-like, 76 strains (77.6%) carried blaOXA-23-like, and 25 strains (25.5%) carried blaOXA-24-like. The regional distribution showed that blaOXA-23-like was more predominant than blaOXA-24-like in both hospitals (85.3% and 60% in LCGMH and KCGMH, respectively); however, blaOXA-24-like displayed a much higher percentage in KCGMH (46.7%) than in LCGMH (16.2%). Oxford multilocus sequence typing and global optimal eBURST analysis were conducted for 59 strains. We revealed the association between blaOXA gene patterns, ST types, and K types and demonstrated that four major K types, KL2, KL10, KL22, and KL52, which were associated with specific ST types, were mainly clustered into clonal complexes CC208 and CC549 (a unique clonal complex found in Taiwan). These findings provide important information for monitoring the epidemiology and dissemination of this pathogen.