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[The Transmission of KPC-2 Gene in Klebsiella Species]
Li-Juan Wu1, Ting-Ting Wang1, Qing-Yan He1
1Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041,China.
Objectives:
To explore the mechanisms of imipenem resistance inKlebsiella spp. and the transmission of Klebsiella pneumoniae Carbapenemase-2(KPC-2) gene in Klebsiella species.
Methods:
The imipenem resistant Klebsiella pneumoniae and Klebsiella oxytoca were isolated in the West China Hospital of Sichuan University in 2009/2010 and 2012/2013. Their minimal inhibitory concentration (MIC) was determined by agar dilution method. CARB ChromID plate and improved Hodge test were undertaken to detect carbapenemases resistant phenotype. PCR method was used for detecting KPC-2 gene. Plasmid transmission was detected by plasmid conjugation tests. The homology of the plasmids and the strains was analyzed using random amplified polymorphic DNA (RAPD) and enterobacterial repetitive intergenic consensus PCR(ERIC-PCR) methods.
Results:
Three strains of Klebsiella oxytoca collected in 2009/2010 and 7 Klebsiella pneumoniae collected in 2012/2013 developed carbapenemases resistance, all of which carried KPC-2 gene. The 3 KPC-2 positive plasmids isolated from Klebsiella oxytoca transited to recipient organisms and showed homology with the 7 KPC-2 gene positive plasmids isolated from Klebsiella pneumoniae. The ERIC-PCR showed homology of the 7 KPC positive Klebsiella pneumoniae.
Conclusions:
Carbapenemases inKlebsiella spp with expressed KPC-2 gene contribute to the development of resistance in this hospital. The transmission of KPC-2 plasmid in Klebsiella oxytoca may cause imipenem resistance in Klebsiella pneumonia. The horizontal transmission may be the main mechanism in the spread of imipenem resistance inKlebsiella spp.
Insights
Klebsiella species developed imipenem resistance due to the Klebsiella pneumoniae Carbapenemase-2 (KPC-2) gene. Horizontal transmission of the KPC-2 plasmid is the primary mechanism driving this resistance spread in hospitals.
Area of Science:
- Microbiology
- Infectious Diseases
- Molecular Biology
Background:
- Carbapenem resistance in Klebsiella species poses a significant threat to public health.
- Imipenem resistance is often mediated by carbapenemase enzymes, such as KPC-2.
- Understanding resistance mechanisms and gene transmission is crucial for infection control.
Purpose of the Study:
- To investigate the mechanisms of imipenem resistance in Klebsiella species.
- To determine the role of the Klebsiella pneumoniae Carbapenemase-2 (KPC-2) gene in resistance.
- To explore the transmission dynamics of the KPC-2 gene within Klebsiella populations.
Main Methods:
- Isolation and identification of imipenem-resistant Klebsiella pneumoniae and Klebsiella oxytoca.
- Determination of minimal inhibitory concentrations (MICs) using agar dilution.
- Detection of carbapenemase production and KPC-2 gene presence via CHROMID CARBA, Hodge test, and PCR.
- Plasmid conjugation assays and molecular typing (RAPD, ERIC-PCR) to analyze gene transmission and strain homology.
Main Results:
- Carbapenemase resistance was observed in 3 Klebsiella oxytoca (2009/2010) and 7 Klebsiella pneumoniae (2012/2013) strains, all harboring the KPC-2 gene.
- KPC-2 positive plasmids from K. oxytoca successfully transferred to recipient organisms and showed homology with plasmids from K. pneumoniae.
- ERIC-PCR analysis confirmed homology among the KPC-2 positive K. pneumoniae strains, indicating clonal spread.
Conclusions:
- The presence of KPC-2 gene-expressing carbapenemases is a key factor in imipenem resistance development in Klebsiella spp. within the studied hospital.
- Plasmid-mediated transmission of KPC-2 from Klebsiella oxytoca to Klebsiella pneumoniae likely contributes to imipenem resistance.
- Horizontal gene transfer is identified as the predominant mechanism responsible for the spread of imipenem resistance among Klebsiella species.
