Prevalence of Genes of OXA-23 Carbapenemase and AdeABC Efflux Pump Associated with Multidrug Resistance of Acinetobacter baumannii Isolates in the ICU of a Comprehensive Hospital of Northwestern China

International Journal of Environmental Research and Public Health

Wei Jia²  Caiyun Li²  Haiyun Zhang¹  Gang Li²  Xiaoming Liu²  Jun Wei² 

[1] Center of Laboratory Medicine, the General Hospital of Ningxia Medical University, Yinchuan, Ningxia 750004, China; E-Mail:;Ningxia Key laboratory of Clinical and Pathogenic Microbiology, Yinchuan, Ningxia 750004, China; E-Mails:

关键词: Acinetobacter baumannii;    multidrug resistance;    nosocomial infections;    oxacillinase;    efflux pump;   

DOI  :  10.3390/ijerph120810079

来源: mdpi

【 摘 要 】

The objective of this study was to explore the molecular epidemiology and the genetic support of clinical multidrug resistant (MDR) Acinetobacter baumannii (A. baumannii) isolates in an ICU ward of a comprehensive hospital. A total of 102 non-duplicate drug-resistant A. baumannii isolates were identified and 93 (91.1%) of them were MDR strains. Molecular analysis demonstrated that carbapenemase genes bla_OXA-23 and bla_OXA-51 were presented in all 93 MDR isolates (100%), but other carbapenemase genes, including bla_OXA-24, bla_OXA-58, bla_IMP-1, bla_IMP-4, bla_SIM, and bla_VIM genes were completely absent in all isolates. In addition, genes of AdeABC efflux system were detected in 88.2% (90/102) isolates. Interestingly, an addition to efflux pump inhibitor, reserpine could significantly enhance the susceptibility of MDR isolates to moxifloxacin, cefotaxime, and imipenem (p < 0.01). Clonal relationship analysis further grouped these clinical drug-resistant isolates into nine clusters, and the MDR strains were mainly in clusters A, B, C, and D, which include 16, 13, 25, and 15 isolates, respectively. This study demonstrated that clinical isolates carrying carbapenemase-encoding genes bla_OXA-23 and AdeABC efflux pump genes are the main prevalent MDR A. baumannii, and the co-expression of oxacillinase and efflux pump proteins are thus considered to be the important reason for the prevalence of this organism in the ICU of this hospital.

【 授权许可】

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© 2015 by the authors; licensee MDPI, Basel, Switzerland.