Yihan Mao1, Qiucheng Shi1, Ping Zhang1, Yan Jiang1, Yunsong Yu2. 1. Department of Infectious Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China; Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, Zhejiang, China. 2. Department of Infectious Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China; Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, Zhejiang, China. Electronic address: yvys119@zju.edu.cn.
Abstract
OBJECTIVES: Tigecycline is an antibacterial agent restricted for use against carbapenem-resistant Klebsiella pneumoniae (CRKP). This study aimed to identify the tigecycline resistance mechanism in clinical CRKP isolates obtained from a 60-year-old femalepatient during tigecycline treatment. METHODS: Three K. pneumoniae isolates obtained during tigecycline treatment were subjected to antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, and whole-genome sequencing and analysis. The function of ramR was confirmed by gene complementation. RESULTS: Three K. pneumoniae isolates (W814, W112 and W113) were collected from the patient on Days 0, 10 and 13, respectively, of ongoing tigecycline treatment. Antimicrobial susceptibility testing showed resistance to all antibiotics except tigecycline and ceftazidime/avibactam. The tigecycline minimum inhibitory concentration (MIC) for strains W814 and W112 was 4 mg/L compared with 16 mg/L for strain W113. The three strains belonged to sequence type 11 (ST11) and had a similar PGFE pattern. Insertion sequence (IS) element ISKpn18 in ramR was identified in strain W113. A parent strain transformed with plasmid pCR2.1-Hyg carrying ramR enhanced tigecycline susceptibility, thus confirming that a loss-of-function insertion in ramR contributes to tigecycline resistance. CONCLUSION: ISKpn18 insertion in the ramR gene contributes to the tigecycline resistance mechanism in the isolated K. pneumoniae strains.
OBJECTIVES: Tigecycline is an antibacterial agent restricted for use against carbapenem-resistant Klebsiella pneumoniae (CRKP). This study aimed to identify the tigecycline resistance mechanism in clinical CRKP isolates obtained from a 60-year-old femalepatient during tigecycline treatment. METHODS: Three K. pneumoniae isolates obtained during tigecycline treatment were subjected to antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, and whole-genome sequencing and analysis. The function of ramR was confirmed by gene complementation. RESULTS: Three K. pneumoniae isolates (W814, W112 and W113) were collected from the patient on Days 0, 10 and 13, respectively, of ongoing tigecycline treatment. Antimicrobial susceptibility testing showed resistance to all antibiotics except tigecycline and ceftazidime/avibactam. The tigecycline minimum inhibitory concentration (MIC) for strains W814 and W112 was 4 mg/L compared with 16 mg/L for strain W113. The three strains belonged to sequence type 11 (ST11) and had a similar PGFE pattern. Insertion sequence (IS) element ISKpn18 in ramR was identified in strain W113. A parent strain transformed with plasmid pCR2.1-Hyg carrying ramR enhanced tigecycline susceptibility, thus confirming that a loss-of-function insertion in ramR contributes to tigecycline resistance. CONCLUSION: ISKpn18 insertion in the ramR gene contributes to the tigecycline resistance mechanism in the isolated K. pneumoniae strains.
Authors: Melissa J Martin; Brendan W Corey; Filomena Sannio; Lindsey R Hall; Ulrike MacDonald; Brendan T Jones; Emma G Mills; Casey Harless; Jason Stam; Rosslyn Maybank; Yoon Kwak; Katharina Schaufler; Karsten Becker; Nils-Olaf Hübner; Stefania Cresti; Giacinta Tordini; Marcello Valassina; Maria Grazia Cusi; Jason W Bennett; Thomas A Russo; Patrick T McGann; Francois Lebreton; Jean-Denis Docquier Journal: Proc Natl Acad Sci U S A Date: 2021-11-30 Impact factor: 11.205