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Volume 48, Number 1, February 2015

Clonal dissemination of extensively drug-resistant Acinetobacter baumannii producing an OXA-23 β-lactamase at a teaching hospital in Shanghai, China 

Ying Li, Qinglan Guo, Peng Wang, Demei Zhu, Xinyu Ye, Shi Wu, Minggui Wang

Received: March 21, 2014    Revised: April 5, 2014    Accepted: April 7, 2014   


Corresponding author:

Corresponding author. Institute of Antibiotics, Huashan Hospital, Fudan University, 12 Middle Wulumuqi Road, Shanghai, China.
E-mail address: (M. Wang). 


Background and purpose: 

Extensively drug-resistant (XDR) Acinetobacter baumannii presents a serious therapeutic and infection control challenge. This study aimed to explore the causes for the rapid increase of XDR A. baumannii at a teaching hospital in Shanghai. 



All consecutive clinical isolates of XDR A. baumannii were collected from January to December 2010 at Huashan Hospital in Shanghai. The prevalence of carbapenemase genes was investigated by polymerase chain reaction (PCR) amplification. Genetic relatedness of the isolates was determined by enterobacterial repetitive intergenic consensus-PCR and multilocus sequence typing. A retrospective case–control study was performed for the identification of risk factors of XDR A. baumannii infections. 



All 106 XDR A. baumannii isolates carried the blaOxA-23 gene and were resistant to all antimicrobial agents tested, except colistin, tigecycline and cefoperazone-sulbactam. One hundred and five of the strains belonged to clonal complex 92 by multilocus sequence typing, and 78 were classified as clone A1 by enterobacterial repetitive intergenic consensus-PCR. Intensive care unit residency at the time of isolation, recent general anesthesia, the number of previous antibiotic classes administered and previous hospitalization were identified as risk factors by case-control study. Efficacy rates were 62.5% (5/8), 47.4% (9/19), and 42.9% (3/7) when the XDR patients were treated with cefoperazone–sulbactam, carbapenems, or both cefoperazone–sulbactam and carbapenem, alone or in combination with other agents, respectively. 



XDR A. baumannii producing OXA-23 β-lactamase was clonally disseminated at a university hospital in Shanghai. Cefoperazone–sulbactam and carbapenems alone or combined with other antibiotics may benefit XDR A. baumannii infections in the absence of other effective antibiotics. 


Key words:

Acinetobacter baumannii, Clonal dissemination, Extensively drug-resistant, Risk factor