High Expression of Metallo-β-Lactamase Contributed to the Resistance to Carbapenem in Clinical Isolates of Pseudomonas aeruginosa from Baotou, China
Authors Xu Y, Niu H, Hu T, Zhang L, Su S, He H, Wang H, Zhang D
Received 9 October 2019
Accepted for publication 17 December 2019
Published 6 January 2020 Volume 2020:13 Pages 35—43
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 2
Editor who approved publication: Dr Sahil Khanna
Yanfeng Xu,1,* Haiying Niu,1,* Tongping Hu,2 Lixia Zhang,2 Shanna Su,1 Huijie He,1 Huimin Wang,1 Dong Zhang1
1Department of Pulmonary Medicine, The First Afﬁliated Hospital of Baotou Medical College, Baotou, People’s Republic of China; 2Department of Clinical Laboratory, The First Afﬁliated Hospital of Baotou Medical College, Baotou, People’s Republic of China
*These authors contributed equally to this work
Correspondence: Dong Zhang
Department of Pulmonary Medicine, The First Afﬁliated Hospital of Baotou Medical College, Baotou, People’s Republic of China
Background: Bacterial resistance to antibiotics has become a major public health concern. This study aimed to determine the resistance mechanisms to carbapenem in clinical isolates of Pseudomonas aeruginosa.
Methods: A total of 62 clinical isolates of carbapenem-resistant P. aeruginosa (CRPA) were collected from 2015 to 2017. Imipenem (IPM)–EDTA disk synergy test was used to screen strains that produced metallo-β-lactamase. In addition, the genes for outer membrane protein OprD2, metallo-β-lactamase and mexR gene were amplified and sequenced. Expression of mexA was detected by real-time PCR.
Results: Disk synergy test showed that 51.6% (32/62) of the strains were positive for metallo-β-lactamase. PCR showed that 84.4% of the strains were SIM-positive (27/32), 15.6% of the strains were IMP-positive (5/32), and 12.5% of the strains were VIM-positive (4/32). SPM-positive and GIM-positive strains were not detected. In addition, 5 of the 62 strains had small deletions and/or point mutations in OprD2. Three strains had a high expression of mexA, while eight strains were positive for the regulatory gene mexR with no mutations detected by DNA sequencing.
Conclusion: Expression of metallo-β-lactamase is the main resistance mechanism of P. aeruginosa to carbapenem. Mutations in OprD2 and/or the overexpression of efflux pump MexAB-OprM may contribute to P. aeruginosa resistance to carbapenem.
Keywords: Pseudomonas aeruginosa, carbapenem, metallo-β-lactamase, outer membrane protein OprD2, efflux pump MexAB-OprM
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