Lida Chen1,2, Pinghai Tan3, Jianming Zeng4,5, Xuegao Yu1, Yimei Cai1, Kang Liao1, Penghao Guo1, Yili Chen1, Zongwen Wu1, Pinghua Qu4,5, Renxin Cai4,5, Cha Chen4,5, Bin Huang1. 1. Department of Laboratory Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China. 2. Department of Blood Transfusion, China-Japan Friendship Hospital, Beijing, China. 3. Department of Hematology, Zhujiang Hospital, Southern Medical University, Guangzhou, China. 4. Department of Laboratory Medicine, The Second Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, China. 5. Department of Laboratory Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.
Abstract
BACKGROUND: This study aimed to examine the impact of an intervention carried out in 2011 to combat multi-drug resistance and outbreaks of imipenem-resistant Acinetobacter baumannii (IRAB), and to explore its resistance mechanism. METHODS: A total of 2572 isolates of A. baumannii, including 1673 IRAB isolates, were collected between 2007 and 2014. An intervention was implemented to control A. baumannii resistance and outbreaks. Antimicrobial susceptibility was tested by calculating minimal inhibitory concentrations (MICs), and outbreaks were typed using pulsed-field gel electrophoresis (PFGE). Resistance mechanisms were explored by polymerase chain reaction (PCR) and whole genome sequencing (WGS). RESULTS: Following the intervention in 2011, the resistance rates of A. baumannii to almost all tested antibiotics decreased, from 85.3 to 72.6% for imipenem, 100 to 80.8% for ceftriaxone, and 45.0 to 6.9% for tigecycline. The intervention resulted in a decrease in the number (seven to five), duration (8-3 months), and departments (five to three) affected by outbreaks; no outbreaks occurred in 2011. After the intervention, only bla AMPC (76.47 to 100%) and bla TEM- 1 (75.74 to 96.92%) increased (P < 0.0001); whereas bla GES- 1 (32.35 to 3.07%), bla PER- 1 (21.32 to 1.54%), bla OXA- 58 (60.29 to 1.54%), carO (37.50 to 7.69%), and adeB (9.56 to 3.08%) decreased (P < 0.0001). Interestingly, the frequency of class B β-lactamase genes decreased from 91.18% (bla SPM- 1) and 61.03% (bla IMP- 1) to 0%, while that of class D bla OXA- 23 increased to 96.92% (P < 0.0001). WGS showed that the major PFGE types causing outbreaks each year (type 01, 11, 18, 23, 26, and 31) carried the same resistance genes (bla KPC- 1, bla ADC- 25, bla OXA- 66, and adeABC), AdeR-S mutations (G186V and A136V), and a partially blocked porin channel CarO. Meanwhile, plasmids harboring bla OXA- 23 were found after the intervention. CONCLUSION: The intervention was highly effective in reducing multi-drug resistance of A. baumannii and IRAB outbreaks in the long term. The resistance mechanisms of IRAB may involve genes encoding β-lactamases, efflux pump overexpression, outer membrane porin blockade, and plasmids; in particular, clonal spread of bla OXA- 23 was the major cause of outbreaks. Similar interventions may also help reduce bacterial resistance rates and outbreaks in other hospitals.
BACKGROUND: This study aimed to examine the impact of an intervention carried out in 2011 to combat multi-drug resistance and outbreaks of imipenem-resistant Acinetobacter baumannii (IRAB), and to explore its resistance mechanism. METHODS: A total of 2572 isolates of A. baumannii, including 1673 IRAB isolates, were collected between 2007 and 2014. An intervention was implemented to control A. baumannii resistance and outbreaks. Antimicrobial susceptibility was tested by calculating minimal inhibitory concentrations (MICs), and outbreaks were typed using pulsed-field gel electrophoresis (PFGE). Resistance mechanisms were explored by polymerase chain reaction (PCR) and whole genome sequencing (WGS). RESULTS: Following the intervention in 2011, the resistance rates of A. baumannii to almost all tested antibiotics decreased, from 85.3 to 72.6% for imipenem, 100 to 80.8% for ceftriaxone, and 45.0 to 6.9% for tigecycline. The intervention resulted in a decrease in the number (seven to five), duration (8-3 months), and departments (five to three) affected by outbreaks; no outbreaks occurred in 2011. After the intervention, only bla AMPC (76.47 to 100%) and bla TEM- 1 (75.74 to 96.92%) increased (P < 0.0001); whereas bla GES- 1 (32.35 to 3.07%), bla PER- 1 (21.32 to 1.54%), bla OXA- 58 (60.29 to 1.54%), carO (37.50 to 7.69%), and adeB (9.56 to 3.08%) decreased (P < 0.0001). Interestingly, the frequency of class B β-lactamase genes decreased from 91.18% (bla SPM- 1) and 61.03% (bla IMP- 1) to 0%, while that of class D bla OXA- 23 increased to 96.92% (P < 0.0001). WGS showed that the major PFGE types causing outbreaks each year (type 01, 11, 18, 23, 26, and 31) carried the same resistance genes (bla KPC- 1, bla ADC- 25, bla OXA- 66, and adeABC), AdeR-S mutations (G186V and A136V), and a partially blocked porin channel CarO. Meanwhile, plasmids harboring bla OXA- 23 were found after the intervention. CONCLUSION: The intervention was highly effective in reducing multi-drug resistance of A. baumannii and IRAB outbreaks in the long term. The resistance mechanisms of IRAB may involve genes encoding β-lactamases, efflux pump overexpression, outer membrane porin blockade, and plasmids; in particular, clonal spread of bla OXA- 23 was the major cause of outbreaks. Similar interventions may also help reduce bacterial resistance rates and outbreaks in other hospitals.
Authors: F C Tenover; R D Arbeit; R V Goering; P A Mickelsen; B E Murray; D H Persing; B Swaminathan Journal: J Clin Microbiol Date: 1995-09 Impact factor: 5.948
Authors: X Yu; R Wang; W Peng; H Huang; G Liu; Q Yang; J Zhou; X Zhang; J H Lv; W Lei; J Wu; J Chen Journal: Clin Microbiol Infect Date: 2019-01-16 Impact factor: 8.067