Conserved mobile genetic contexts associated with bla NDM-1 and bla NDM-5 in Acinetobacter baumannii isolated from two hospitals in Thailand
4 affiliations
- 1Department of Oriental Medicine, Chiang Rai College, Chiangrai, Thailand
- 2Microbiology and Parasitology, Naresuan University, Phitsanulok, Thailand
- 3Department Clinical, Microbiology, Chiangrai Prachanukroh Hospital, Chiang Rai, Thailand
- 4Office of Disease Prevention and Control Region 3 Nakhon Sawan, Department of Disease Control, Ministry of Public Health, Nakhon Sawan, Thailand
Abstract
Background: Acinetobacter baumannii has emerged as a major nosocomial pathogen due to its remarkable ability to develop resistance to multiple classes of antimicrobial agents. The emergence and dissemination of the bla NDM gene among multidrug-resistant A. baumannii (MDRAB) are closely associated with mobile genetic elements (MGEs), which facilitate horizontal gene transfer and accelerate the spread of carbapenem resistance. This study investigated the distribution of bla NDM -positive A. baumannii isolates, characterized their antimicrobial resistance phenotypes and genetic determinants, and elucidated the genetic context surrounding bla NDM alleles using whole-genome sequencing (WGS).
Methods: A total of 286 clinical A. baumannii isolates collected from a tertiary hospital in Thailand were screened for metallo- β -lactamases encoding genes( bla NDM ), OXA carbapenemase-encoding genes, IS Aba1 , and IS Aba125 using polymerase chain reaction (PCR). The bla NDM variants were characterized by gene sequencing, and antibiotic susceptibility profiles were determined. Whole-genome sequencing (WGS) was performed on eight representative bla NDM -positive isolates, comprising four isolates from the present study and four isolates obtained from another hospital in Thailand.
Results: Among the 286 A. baumannii isolates, 55 (19.23%) carried bla NDM . All bla NDM -positive A. baumannii isolates were identified as carbapenem-resistant A. baumannii (CRAB), and 90.91% were classified as MDRAB strains. The prevalence of bla OXA-23 and bla OXA-58 was 85.45% and 16.36%, respectively. The insertion sequences IS Aba1 and IS Aba125 were detected in 89.09% and 81.82% of the isolates, respectively. Sequence analysis revealed that 49 (89.09%) bla NDM -positive A. baumannii harbored bla NDM-1 , whereas six (10.91%) showed sequence identity with bla NDM-5 . WGS analysis of eight bla NDM -positive A. baumannii demonstrated variability in K-locus and OC-locus types. MLST analysis revealed that the four bla NDM-1 -positive isolates belonged to three distinct sequence types (ST16, ST23, and ST213), while predominance of bla NDM-5 -positive isolates were ST2. Comparative genomic analysis of the genetic environments surrounding the bla NDM genes revealed highly conserved genetic organization, with strong synteny among isolates belonging to the same bla NDM type.
Conclusion: These findings demonstrate the emergence and persistence of multiple resistance determinants among A. baumannii isolates in Thailand, thereby underscoring the urgent need to strengthen antimicrobial stewardship program and infection prevention control strategies.
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BibTeX
@article{kitti2026conserved,
title = {{Conserved mobile genetic contexts associated with bla NDM-1 and bla NDM-5 in Acinetobacter baumannii isolated from two hospitals in Thailand}},
author = {Thawatchai Kitti and Kritnarin Kaewphu and Akachai Khuekankaew and Chalermchai Boonlao and Supat Khongfak and Sutthirat Sitthisak},
journal = {PeerJ},
year = {2026},
month = oct,
doi = {10.7717/peerj.21848},
url = {https://peerj.com/articles/21848},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Conserved mobile genetic contexts associated with bla NDM-1 and bla NDM-5 in Acinetobacter baumannii isolated from two hospitals in Thailand
AU - Thawatchai Kitti
AU - Kritnarin Kaewphu
AU - Akachai Khuekankaew
AU - Chalermchai Boonlao
AU - Supat Khongfak
AU - Sutthirat Sitthisak
PY - 2026
DA - 2026/10/27
JO - PeerJ
DO - 10.7717/peerj.21848
UR - https://peerj.com/articles/21848
AB - Background: Acinetobacter baumannii has emerged as a major nosocomial pathogen due to its remarkable ability to develop resistance to multiple classes of antimicrobial agents. The emergence and dissemination of the bla NDM gene among multidrug-resistant A. baumannii (MDRAB) are closely associated with mobile genetic elements (MGEs), which facilitate horizontal gene transfer and accelerate the spread of carbapenem resistance. This study investigated the distribution of bla NDM -positive A. baumannii isolates, characterized their antimicrobial resistance phenotypes and genetic determinants, and elucidated the genetic context surrounding bla NDM alleles using whole-genome sequencing (WGS). Methods: A total of 286 clinical A. baumannii isolates collected from a tertiary hospital in Thailand were screened for metallo- β -lactamases encoding genes( bla NDM ), OXA carbapenemase-encoding genes, IS Aba1 , and IS Aba125 using polymerase chain reaction (PCR). The bla NDM variants were characterized by gene sequencing, and antibiotic susceptibility profiles were determined. Whole-genome sequencing (WGS) was performed on eight representative bla NDM -positive isolates, comprising four isolates from the present study and four isolates obtained from another hospital in Thailand. Results: Among the 286 A. baumannii isolates, 55 (19.23%) carried bla NDM . All bla NDM -positive A. baumannii isolates were identified as carbapenem-resistant A. baumannii (CRAB), and 90.91% were classified as MDRAB strains. The prevalence of bla OXA-23 and bla OXA-58 was 85.45% and 16.36%, respectively. The insertion sequences IS Aba1 and IS Aba125 were detected in 89.09% and 81.82% of the isolates, respectively. Sequence analysis revealed that 49 (89.09%) bla NDM -positive A. baumannii harbored bla NDM-1 , whereas six (10.91%) showed sequence identity with bla NDM-5 . WGS analysis of eight bla NDM -positive A. baumannii demonstrated variability in K-locus and OC-locus types. MLST analysis revealed that the four bla NDM-1 -positive isolates belonged to three distinct sequence types (ST16, ST23, and ST213), while predominance of bla NDM-5 -positive isolates were ST2. Comparative genomic analysis of the genetic environments surrounding the bla NDM genes revealed highly conserved genetic organization, with strong synteny among isolates belonging to the same bla NDM type. Conclusion: These findings demonstrate the emergence and persistence of multiple resistance determinants among A. baumannii isolates in Thailand, thereby underscoring the urgent need to strengthen antimicrobial stewardship program and infection prevention control strategies.
SN - 2167-8359
ER -