Abstract
Background The spread of carbapenem-resistant A. baumannii (CrAb) is gaining worldwide attention. The spread of this pathogen is largely due to its ability to acquire various resistance genes of intrinsic and extrinsic origins that confer unpredictable susceptibility to β-lactams. The aim of this study was to analyze β-lactamase genetic compositions of CrAb in Malaysia. Methods Whole-genome sequencing (WGS) was carried out on 13 CrAb isolates from clinical samples in Malaysia from 2011 to 2016. Results Endotracheal aspirate was the dominant clinical sample source (n = 6), and only one isolate was obtained from wound swab. A total of 6 sequence types (STs) of the Oxford scheme were identified, including 4 reported STs and 2 novel STs. Eleven isolates were classified into clonal complex 92 (CC92/ICII), among which ST195 and ST208 were the most prevalent STs. All 13 CrAb isolates harbored multiple β-lactamase genes. blaOXA-23 (n = 13) and blaOXA-66 (n = 11) were the dominant carbapenemase gene families found in these isolates. All isolates harbor blaADC, blaOXA-51-like, and blaOXA-23-like genes. blaTEM (n = 7), blaNDM-1 (n = 3), blaCARB-8 (n = 1), and blaPER-3 (n = 1) are amongst other β-lactamase genes found in this study. ISAba1 was found upstream to blaOXA-23 (n = 13), blaOXA-66 (n = 1), and blaADC (n = 11). All blaNDM-1 isolates had ISAba125 (mobile genetic element) upstream to the genes. All isolates were positive for Tn2006/2008 and Tn2009 but were negative for Tn2007. Conclusion Most of the isolates were grouped under the CC92 clonal complex which belongs to international clonal lineage 2. These findings predict that carriage of carbapenem-resistant genes possibly constitutes the underlying basis of high level of international clone II prevalence. Therefore, molecular surveillance and antimicrobial stewardship are essential in implementing policies to prevent and control the spread of CrAb in hospital settings.
Highlights
Acinetobacter baumannii (A. baumannii) is an infectious agent that has been the leading cause of hospital-acquired infections [1]
A. baumannii of nosocomial origin has been the leading cause of hospital-acquired infections [1]. e nature of this bacterium is that it can be found in the environment, intrinsically carrying the antibiotic resistance gene and posing a significant threat to public health due to its unpredictable antibiotic susceptibility [2, 4, 5]. is study was aimed to determine the genetic mechanisms conferring carbapenem resistance in our local strains
Most of the clinical isolates in this study obtained from respiratory secretion were similar to the Malaysian local surveillance study
Summary
Acinetobacter baumannii (A. baumannii) is an infectious agent that has been the leading cause of hospital-acquired infections [1]. A. baumannii belongs to a group of clinically important organism, known as ESKAPE. It is predominantly found among health care-associated organisms that have the potential of substantial antibiotic resistance [6]. According to the National Surveillance Antibiotic Resistance database, CrAb prevalence in Malaysia ranges from 50 to 60% and remained static since year 2008 up to 2016 [11]. Nonjudicious use of antibiotics has led A. baumannii to rapidly acquire antimicrobial resistance genes from the environment. E expression of this gene may vary with the presence of ISAba as a promoter [14] It acquires certain blaOXA and blanon-OXA group genes from plasmids [15]. Is study is aimed to analyze the molecular characteristics of 13 A. baumannii isolates obtained from hospitalized patients in Malaysia with underlying carbapenemresistant phenotype
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