Affiliation:
1. State Key Laboratory for Diagnosis and Treatment of Infectious Disease, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
2. Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People's Republic of China
Abstract
ABSTRACT
Because of its remarkable ability to acquire antibiotic resistance and to survive in nosocomial environments,
Acinetobacter baumannii
has become a significant nosocomial infectious agent worldwide. Tigecycline is one of the few therapeutic options for treating infections caused by
A. baumannii
isolates. However, tigecycline resistance has increasingly been reported. Our aim was to assess the prevalence and characteristics of efflux-based tigecycline resistance in clinical isolates of
A. baumannii
collected from a hospital in China. A total of 74
A. baumannii
isolates, including 64 tigecycline-nonsusceptible
A. baumannii
(TNAB) and 10 tigecycline-susceptible
A. baumannii
(TSAB) isolates, were analyzed. The majority of them were determined to be positive for
adeABC
,
adeRS
,
adeIJK
, and
abeM
, while the
adeE
gene was found in only one TSAB isolate. Compared with the levels in TSAB isolates, the mean expression levels of
adeB
,
adeJ
,
adeG
, and
abeM
in TNAB isolates were observed to increase 29-, 3-, 0.7-, and 1-fold, respectively. The efflux pump inhibitors (EPIs) phenyl-arginine-β-naphthylamide (PAβN) and carbonyl cyanide 3-chlorophenylhydrazone (CCCP) could partially reverse the resistance pattern of tigecycline. Moreover, the
tetX1
gene was detected in 12 (18.8%) TNAB isolates. To our knowledge, this is the first report of the
tetX1
gene being detected in
A. baumannii
isolates. ST208 and ST191, which both clustered into clonal complex 92 (CC92), were the predominant sequence types (STs). This study showed that the active efflux pump AdeABC appeared to play important roles in the tigecycline resistance of
A. baumannii
. The dissemination of TNAB isolates in our hospital is attributable mainly to the spread of CC92.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
152 articles.
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