Transmission Dynamics of Carbapenemase Genes in CREC, 2022–2
2026-04-12
Transmission Dynamics of Carbapenemase Genes in CREC, 2022–2024
Study Background and Research Question
Carbapenem-resistant Enterobacter cloacae (CREC) represents one of the most clinically challenging multidrug-resistant organisms in China and worldwide. The COVID-19 pandemic has exacerbated antimicrobial resistance by altering antibiotic usage patterns and straining healthcare infrastructure. Despite the growing threat posed by CREC, detailed investigations into the specific genetic mechanisms, especially the transmission dynamics of carbapenemase-encoding genes (CEGs), have been limited in scope and depth. The reference study by Chen et al. (2025) addresses this critical gap by analyzing the characteristics and dissemination pathways of CEGs in CREC isolates from eight teaching hospitals in Guangdong Province between 2022 and 2024 [source_type: paper][source_link: https://doi.org/10.1186/s12866-025-04300-0].Key Innovation from the Reference Study
The principal innovation of Chen et al. lies in the integrated genotypic and phenotypic characterization of CEGs within a multi-institutional clinical cohort during the COVID-19 era. The study not only identifies the predominant resistance genes (notably blaNDM-1) but also elucidates their chromosomal and plasmid distribution, transmission rates, and association with mobile genetic elements. Critically, the research quantifies the transferability of these resistance determinants via horizontal gene transfer, offering granular insights into the real-world spread of multidrug resistance among clinical Enterobacter strains [source_type: paper][source_link: https://doi.org/10.1186/s12866-025-04300-0].Methods and Experimental Design Insights
Chen et al. employed a multi-pronged molecular and microbiological approach:- Sample Collection: 54 non-redundant CREC isolates were prospectively collected from eight major teaching hospitals over an 18-month period (Dec 2022 – June 2024).
- Genotyping and CEG Detection: PCR amplification and sequencing targeted three major carbapenemase genes: blaNDM-1, blaIMP, and blaKPC-2.
- Plasmid Analysis: The variable temperature SDS plasmid elimination method distinguished chromosomal from plasmid-borne CEGs.
- Antibiotic Susceptibility Testing: Broth microdilution assays assessed resistance profiles for multiple antibiotic classes.
- Transmission Studies: Plasmid conjugation experiments quantified the transfer success rates of CEGs between strains.
- Mobile Genetic Element Typing: Six types of insertion sequences were identified, with ISEcp1 being the most prevalent (87.04% of isolates) [source_type: paper][source_link: https://doi.org/10.1186/s12866-025-04300-0].
- Clonal Diversity Analysis: ERIC-PCR and NTSYS software clustered the isolates into 17 genotypes, highlighting both clonal expansion and inter-hospital dissemination.
Protocol Parameters
- assay | Broth microdilution | 1–64 μg/mL range | Determines MICs for resistance profiling | paper [https://doi.org/10.1186/s12866-025-04300-0]
- assay | Plasmid conjugation | 95.65% transfer success (44/46) | Assesses horizontal gene transfer efficiency of CEGs | paper [https://doi.org/10.1186/s12866-025-04300-0]
- assay | PCR genotyping | 100% of isolates | Detects and differentiates blaNDM-1, blaIMP, blaKPC-2 | paper [https://doi.org/10.1186/s12866-025-04300-0]
- assay | ERIC-PCR | 17 genotypes resolved | Evaluates clonal diversity and transmission | paper [https://doi.org/10.1186/s12866-025-04300-0]
Core Findings and Why They Matter
The study's key findings reshape our understanding of carbapenem resistance dissemination in hospital settings:- High Prevalence of CEGs: 85.19% of CREC isolates harbored at least one carbapenemase gene; blaNDM-1 was predominant, present in 79.63% of isolates (33.33% both chromosomal and plasmid, 46.30% plasmid-only). [source_type: paper][source_link: https://doi.org/10.1186/s12866-025-04300-0]
- Efficient Gene Transfer: Plasmid conjugation achieved a 95.65% success rate for CEG transfer, with blaNDM-1 and blaIMP showing the highest mobilization rates; blaKPC-2 was not successfully transferred in this cohort. [source_type: paper][source_link: https://doi.org/10.1186/s12866-025-04300-0]
- Mobile Genetic Elements: ISEcp1 and other insertion sequences facilitate CEG dissemination, with many isolates carrying multiple mobile elements simultaneously (up to four per isolate in 40.74%). [source_type: paper][source_link: https://doi.org/10.1186/s12866-025-04300-0]
- Multidrug Resistance: CEG-positive strains exhibited significantly higher resistance rates to imipenem, cefepime, and other key antibiotics compared to CEG-negative strains (P<0.05). [source_type: paper][source_link: https://doi.org/10.1186/s12866-025-04300-0]
- Clonal and Epidemiological Trends: The most prevalent genotypes (E and G, each 20.37%) were shared across different hospital departments, underscoring the potential for inter- and intra-hospital spread.
- Patient and Sample Risk Factors: Higher detection rates were noted in male patients, the elderly, respiratory medicine wards, and sputum samples, suggesting target areas for surveillance and intervention.
Comparison with Existing Internal Articles
Several internal resources provide complementary perspectives on approaches to multidrug-resistant bacteria, particularly regarding the experimental use of glycylcycline antibiotics:- Tigecycline: Glycylcycline Antibiotic for Multidrug-Resistant Bacteria highlights the bacteriostatic mechanism of Tigecycline via 30S ribosomal subunit inhibition, relevant for designing infection models targeting plasmid-mediated resistance [source_type: workflow_recommendation][source_link: https://fezolinetantchem.com/index.php?g=Wap&m=Article&a=detail&id=122].
- Tigecycline: Advancing Multidrug-Resistant Bacteria Research discusses the strategic use of Tigecycline against MRSA and VRE, supporting the utility of glycylcycline antibiotics in models of multidrug resistance (including carbapenemase producers) [source_type: workflow_recommendation][source_link: https://annexin-v-cy3.com/index.php?g=Wap&m=Article&a=detail&id=226].
- These internal articles collectively align with the reference study by emphasizing the importance of targeting both chromosomal and plasmid resistance determinants in experimental workflows and clinical translational research.
Limitations and Transferability
While robust, the study does have certain limitations:- Geographic Scope: The sample is limited to hospitals in Guangdong Province, so findings may not generalize to regions with different epidemiological pressures.
- Gene Coverage: The focus was on three major CEGs; rare or novel carbapenemases may have been missed.
- Clinical Correlation: While resistance profiles were well-characterized, direct clinical outcome data were not included.
- Temporal Window: The study covers 18 months during the COVID-19 pandemic; transmission dynamics may shift as healthcare practices normalize.