title: Dissemination of blaOXA-23 in Acinetobacter spp. in China: main roles of conjugative plasmid pAZJ221 and transposon Tn2009.
abstract: Production of the OXA-23 carbapenemase is the most common reason for the increasing carbapenem resistance in Acinetobacter spp. This study was conducted to reveal the genetic basis of blaOXA-23 dissemination in Acinetobacter spp. in China. A total of 63 carbapenem-resistant OXA-23-producing Acinetobacter sp. isolates, representing different backgrounds, were selected from 28 hospitals in 18 provinces for this study. Generally, two patterns of plasmids carrying blaOXA-23 were detected according to S1-nuclease pulsed-field gel electrophoresis and Southern blot hybridization. A ca. 78-kb plasmid, designated pAZJ221, was found in 23 Acinetobacter baumannii and three Acinetobacter nosocomialis isolates, while a novel ca. 50-kb plasmid was carried by only two other A. baumannii isolates. Three of these isolates had an additional copy of blaOXA-23 on the chromosome. Transformation of the two plasmids succeeded, but only pAZJ221 was conjugative. Plasmid pAZJ221 was sequenced completely and found to carry no previously known resistance genes except blaOXA-23. The blaOXA-23 gene of the remaining 35 isolates was chromosome borne. The blaOXA-23 genetic environments were correlated with Tn2009 in 57 isolates, Tn2008 in 5 isolates, and Tn2006 in 1 isolate. The MIC values for the carbapenems with these isolates were not significantly associated with the genomic locations or the copy numbers of blaOXA-23. Overall, these observations suggest that the plasmid pAZJ221 and Tn2009 have effectively contributed to the wide dissemination of blaOXA-23 in Acinetobacter spp. in China and that horizontal gene transfer may play an important role in dissemination of the blaOXA-23 gene.
authors.affiliation: Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Li-Lin
authors.initials: LL
authors.lastname: Liu
authors.affiliation: Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Shu-Juan
authors.initials: SJ
authors.lastname: Ji
authors.affiliation: Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Ruan
authors.affiliation: Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Department of Respiratory Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Yi-Qi
authors.initials: YQ
authors.lastname: Fu
authors.affiliation: Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Yan-Fei
authors.initials: YF
authors.lastname: Wang
authors.affiliation: Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China yvys119@163.com.
authors.forename: Yun-Song
authors.initials: YS
authors.lastname: Yu
mesh_terms: D000150:Acinetobacter / Q000187:drug effects* / Q000235:genetics*; D000151:Acinetobacter Infections / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics*; D002681:China; D002876:Chromosomes, Bacterial / Q000235:genetics; D003227:Conjugation, Genetic / Q000235:genetics*; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D001618:beta-Lactamases; C000599728:beta-lactamase OXA-23, Acinetobacter baumannii