Comparative genomic insights into carbapenem-resistant versus susceptible Acinetobacter baumannii in Shanghai hospital settings: a multi-center molecular surveillance study
Jul 2026· Frontiers in Cellular and Infection Microbiology· Vol 16· 0 citations· 39 references
Medicine
TL;DR
The ICU environment was critical for CRAB control, and CRAB exhibited stronger resistance, harbored more putatively conjugative plasmids and richer virulence-associated genes than CSAB, highlighting the need for targeted disinfection and surveillance of prevalent clones.
Abstract
Background Carbapenem-resistant Acinetobacter baumannii (CRAB) is priority pathogen for nosocomial infection control worldwide. This study aimed to elucidate differences in distribution, genotyping and antimicrobial resistance patterns between CRAB and carbapenem-susceptible Acinetobacter baumannii (CSAB) strains isolated from healthcare environments. Materials and methods A total of 1,812 environmental samples were collected from 10 medical institutions in Pudong New Area between June and December 2024 for the identification of A. baumannii. Antimicrobial susceptibility testing, whole-genome sequencing, and bioinformatic analysis were performed to reveal molecular characteristics of A. baumannii. Results A total of 81 A. baumannii strains were detected, with 39.51% CRAB (n = 32) and 60.49% CSAB (n = 49). CRAB strains were highly prevalent in intensive care units (ICUs, accounting for 83.33%) and patient-contact items, whereas CSAB were more evenly distributed. MLST analysis identified ST2 as dominant CRAB clone (78.13%), followed by ST164 (18.75%). CRAB isolates demonstrated 100% resistance to multiple antibiotics such as piperacillin/tazobactam and ciprofloxacin, whereas all CSAB isolates were susceptible to tested antibiotics except one ampicillin/sulbactam-resistant isolate. Carbapenem resistance in CRAB was predominantly mediated by class D carbapenemases, with carriage rate of the blaOXA-23 gene reaching 96.88%. Notably, six ST164 isolates co-harbored class B and class D carbapenemase genes, which may elevate resistance severity. Bioinformatic analysis indicated that 22.20% of resistance plasmids in CRAB were predicted to be conjugative. CRAB exhibited a more diverse and extensive virulence gene profile than CSAB strains. Conclusions The ICU environment was critical for CRAB control. ST2 and ST164 represented clones worthy of attention. CRAB exhibited stronger resistance, harbored more putatively conjugative plasmids and richer virulence-associated genes than CSAB, highlighting the need for targeted disinfection and surveillance of prevalent clones.
CRAB isolates in this orthopaedic specialty hospital are dominated by the ST2/KL3 clone, which carries multiple resistance and virulence genes, exhibits a remarkably strong biofilm-forming ability, and shows a capsular switch trend from KL2 to KL3.
Tengfei Shi, Shaohan Xu, Xuexin Zheng et al.· Frontiers in Cellular and In...· 0 citations
OBJECTIVE
The prevalence of carbapenem-resistant Acinetobacter baumannii (CRAb) has been increasing globally. This study aimed to investigate the risk factors, resistance gene profiles, and molecular epidemiology of CRAb bloodstream infections (BSIs) among patients in Xi'an, China, to provide evidence for clinical prevention and targeted treatment.
METHODS
We conducted a retrospective study of 139 patients with A. baumannii BSIs. Patients were categorized into a CRAb group (n = 84) and a carbapenem-susceptible A. baumannii (CSAb) group (n = 55). Independent risk factors were identified via multivariate logistic regression analysis. Carbapenemase resistance genes were detected using polymerase chain reaction (PCR), and CRAb isolates were molecularly typed by multilocus sequence typing (MLST).
RESULTS
Multivariate logistic regression analysis identified the following as independent risk factors for CRAb BSIs: inappropriate empirical antimicrobial therapy (OR = 8.620; 95% CI: 2.078-35.751), deep venous catheterization (OR = 12.625; 95% CI: 2.263-70.429), prolonged hospitalization before the onset of BSIs (OR = 1.467; 95% CI: 1.123-1.915), and ICU admission (OR = 4.981; 95% CI: 1.898-13.065). Antimicrobial susceptibility testing showed that CRAb isolates were multidrug-resistant, exhibiting resistance rates exceeding 70% to most common clinical antibiotics, with the exception of tigecycline (5.95% resistance) and colistin (27.38% resistance). All 84 CRAb isolates carried both blaOXA-51-like and blaOXA-23-like genes, while other carbapenemase genes were not detected. MLST identified 7 sequence types (STs), with ST540 (45.24%, 38/84) being the dominant clone. eBURST analysis indicated that the major STs (ST195, ST208, etc.) belonged to the same clonal complex.
CONCLUSION
Inappropriate empirical antimicrobial therapy, deep venous catheterization, prolonged hospitalization before the onset of BSIs and ICU admission are independent risk factors for CRAb BSIs. The prevalent strains produce OXA-23-like carbapenemase, and molecular typing indicates that the ST540 clone and its related clonal complex are predominant, suggesting potential nosocomial clonal spread.
Jiahao Guan, Yajuan Ren, Xiaojun Dang et al.· Microbial Drug Resistance· 0 citations
This study substantiates an escalated incidence of carbapenem-resistant, MDR A. baumannii in post-surgical infections in Pakistan, highlighting the exigency for strengthened antimicrobial stewardship and infection control strategies in the hospitals of the region.
Sana Gul, Nawab Ali, M. Qasim et al.· Antibiotics· 0 citations
Background/Objectives: Acinetobacter baumannii is a major cause of infections in Intensive Care Units (ICUs), driving mortality through high-level antimicrobial resistance. This study utilized whole-genome sequencing (WGS) to evaluate the phenotypic, genotypic and virulence features of carbapenem-resistant A. baumannii (CRAB), which has caused ventilator-associated pneumonia/tracheobronchitis (VAP/VAT) in the ICU of the University Hospital of Split, Croatia. Methods: Over 1 year, lower respiratory tract specimens from 79 VAP/VAT patients were analyzed. CRAB isolates were identified via MALDI-TOF MS and evaluated for antimicrobial susceptibility, and a representative subset underwent WGS and multilocus sequence typing (MLST). Results: Out of 106 specimens, 18 non-duplicate CRAB strains were isolated. Five isolates underwent genomic analysis, identifying two globally distributed, high-risk Pasteur lineages: ST2 and ST492. These lineages displayed distinct resistomes: ST2 carried blaOXA-23 and blaADC-73, while ST492 harbored plasmid-borne blaOXA-72 (Rep3-T1/AB082 cluster) and blaADC-30. All isolates shared aminoglycoside/macrolide-resistance genes, conserved efflux pumps, and virulence determinants (bau, bas, ent, bar) crucial for acinetobactin synthesis and respiratory colonization. Phylogenetic analysis confirmed regional circulation and genetic links to neighboring countries. Conclusions: This study highlights the evolutionary dynamics of endemic CRAB lineages in a Croatian ICU and their global dissemination, which poses a critical threat, demanding strict infection control and novel therapeutics.
Marija Čavka, Marija Kvesić Ivanković, Ana Maravić et al.· Antibiotics· 0 citations
Background Carbapenem resistant Acinetobacter baumannii (CRAB) is recognized as one of the most critical priority pathogens by the World Health Organization due to its persistence in nosocomial settings, extensive antimicrobial resistance, and increasing dissemination at the global level. Despite the escalating availability of genomic data, genotype–phenotype integrated studies exploring the genetic determinants associated with carbapenem resistance remain limited. Methods In this study, a comprehensive comparative genomics was performed using publicly available 395 clinical A. baumannii genomes, comprising of 267 CRAB and 128 carbapenem susceptible A. baumannii (CSAB). Comparative genomic analyses included sequence types (STs), virulence factors (VFs), antimicrobial resistance genes (ARGs), and mobile genetic elements (MGEs) characterization. Pangenome-wide association study (PanGWAS) was performed to test the associations between genotypes and carbapenem resistance phenotype. Results CRAB genome subset demonstrated higher abundance of ARGs (acquired carbapenemases in particular), plasmids, carbapenem resistance-associated insertion sequences, and integrons than CSAB genomes. PanGWAS identified six positively associated genes (relE, umuC, hphA, hsmA, hphR, and fecI) significantly enriched in CRAB population. Core SNP phylogeny integrated with STs and acquired carbapenemase genes exhibited heterogeneous distribution of resistance genes across lineages, indicating potential role of both clonal dissemination and horizontal gene transfer. Conclusion This study provides an overall genomic architecture of CRAB integrating comparative genomics, PanGWAS, and phylogenomics approaches. The findings underscore the complex interplay between ARGs, VFs, and MGEs in the genomic evolution of CRAB, expanding current understanding of CRAB adaptation and may contribute toward enhanced surveillance, antimicrobial stewardship, and exploration of alternative therapeutic targets.
Sara Pearl, A. Anbarasu· Frontiers in Cellular and In...· 0 citations
It is indicated that blaOXA-23 is the predominant contributor to carbapenem resistance among A. baumannii isolates in Baghdad, while blaOXA-24 and blaOXA-58 are also increasingly prevalent.
A. A. Abdulhassan, Hiba Hazim Hamid, Sara Mahdi Al-Lami et al.· Cellular Physiology and Bioc...· 0 citations
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