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Rapid and Specific Detection of Acinetobacter baumannii Infections Using a Recombinase Polymerase Amplification/Cas12a-based System
Published on: April 25, 2025
Dissemination of multidrug-resistant Acinetobacter baumannii carrying BlaOxA-23 from hospitals in central Taiwan
Mei-Hui Lee1, Te-Li Chen2, Yi-Tzu Lee3
1Division of Infectious Diseases, Taipei Veterans General Hospital, Taipei, Taiwan.
Background:
Imipenem-resistant Acinetobacter baumannii (IRAB) poses a great threat to healthcare systems. Production of carbapenem-hydrolyzing class D β-lactamases (CHDLs) is the major mechanism for imipenem resistance. In this study, we found a high prevalence of IRAB carrying a gene encoding CHDL, bla(OxA-23), in central Taiwan and elucidated the molecular characteristics and possible mechanisms of the spread of these isolates.
Methods:
During 2007, we collected 291 nonrepetitive A baumannii isolates from 10 teaching hospitals in Taiwan. The antimicrobial susceptibility of the isolates was determined by agar dilution or Etest. The genes encoding carbapenemase and related structure were detected by polymerase chain reaction mapping and sequencing, and the clonal relationship of the isolates was analyzed by pulsed-field gel electrophoresis. Plasmid localization of bla(OxA-23) was determined by extraction of plasmid with commercial kit and Southern blot analysis.
Results:
Among 142 IRAB isolates, 30 harbored the bla(OxA-23). The prevalence of IRAB with bla(OxA-23) was highest in central Taiwan compared to other areas [24.8% (27/109) vs. 1.6% (3/182); p < 0.001]. These IRAB with bla(OxA-23) were also resistant to other antimicrobial agents, except colistin. The PCR methods showed the presence of bla(OxA-51) in all isolates. We could exclude clonal spreading due to the diversity of the pulsotype. The bla(OxA-23) gene was detected in the plasmids of 6 isolates. Tn2006 was present in 22 (73.3%) isolates, and Tn2008, in 6 other isolates (26.7%). Two strains had bla(oxa-23)-ΔATPase but lacked upstream ISAba1.
Conclusion:
The high prevalence of bla(OxA-23)-harboring IRAB in central Taiwan might be attributed to the transposition event of Tn2006.
Insights
Imipenem-resistant Acinetobacter baumannii (IRAB) carrying the bla(OxA-23) gene is highly prevalent in central Taiwan. The spread of these resistant bacteria may be linked to the Tn2006 transposon.
Area of Science:
- Medical Microbiology
- Antimicrobial Resistance
- Molecular Epidemiology
Background:
- Imipenem-resistant Acinetobacter baumannii (IRAB) presents a significant healthcare challenge.
- Carbapenem-hydrolyzing class D β-lactamases (CHDLs), particularly bla(OxA-23), are primary drivers of imipenem resistance in A. baumannii.
- A high prevalence of IRAB harboring bla(OxA-23) was identified in central Taiwan.
Purpose of the Study:
- To investigate the prevalence and molecular characteristics of IRAB isolates in Taiwan.
- To elucidate the mechanisms contributing to the spread of bla(OxA-23)-positive IRAB.
Main Methods:
- Collected 291 A. baumannii isolates from 10 teaching hospitals in Taiwan (2007).
- Determined antimicrobial susceptibility, detected carbapenemase genes (PCR, sequencing), and analyzed clonal relationships (PFGE).
- Investigated bla(OxA-23) plasmid localization and identified mobile genetic elements (Tn2006, Tn2008).
Main Results:
- Among 142 IRAB isolates, 30 harbored bla(OxA-23), with highest prevalence in central Taiwan (24.8%).
- These isolates were resistant to multiple agents except colistin; bla(OxA-51) was universally present.
- Diverse pulsotypes indicated non-clonal spread; bla(OxA-23) was plasmid-located in 6 isolates, and Tn2006/Tn2008 were frequently identified.
Conclusions:
- The high prevalence of bla(OxA-23)-harboring IRAB in central Taiwan is notable.
- The transposition of Tn2006 is a likely contributor to the spread of these resistant isolates.
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