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Detection of KPC enzyme by MALDI-TOF MS from bacteria impregnated in filter paper
Camila M Wilhelm1, Natália K Moreira1, Maiara S Carneiro1
1Programa de Pós-Graduação em Ciências Farmacêuticas - Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Laboratório de Pesquisa em Resistência Bacteriana (LABRESIS) - Hospital de Clinicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil.
Abstract:
The main mechanism that causes resistance to carbapenem, one of the most potent antibiotic available, in Enterobacterales bacterial isolates, is due to Klebsiella pneumoniae carbapenemase (KPC) production by the bacterium. KPC is spread worldwide, requiring laboratories to be capable of identifying this enzyme, however some methods can be expensive for small laboratories, especially in developing countries. Therefore, the development of methods with low cost of reagents for the detection of KPC enzyme is necessary. The objective of this study was to evaluate the detection of KPC enzyme by MALDI-TOF MS from inactivated bacteria impregnated in filter paper. A total of 129 Enterobacterales isolates were impregnated in filter paper, and after 7 days at room temperature, they were subjected to a protein extraction protocol and spectra acquisition, in triplicates, by MALDI-TOF MS. The spectra were evaluated and KPC was identified according to the presence of a peak of 28,712.62 ± 27.80 m/z. Considering the presence of the KPC peak in at least one spectrum of the triplicates, this method presented 60.8% sensitivity and 96.4% specificity. However, considering the presence of KPC peak in at least two spectra of the triplicate, a specificity of 100% was achieved. The detection of KPC enzyme from inactivated bacteria impregnated in filter paper can be used as a method to confirm the presence of KPC, which could be very significant for small laboratories with limited resources.
Insights
This study introduces a cost-effective method for detecting Klebsiella pneumoniae carbapenemase (KPC) using MALDI-TOF MS on filter paper. This approach aids in identifying carbapenem resistance in Enterobacterales, crucial for resource-limited laboratories.
Area of Science:
- Microbiology
- Biochemistry
- Analytical Chemistry
Background:
- Carbapenem resistance in Enterobacterales is a growing global health threat.
- Klebsiella pneumoniae carbapenemase (KPC) is a primary mechanism of carbapenem resistance.
- Existing KPC detection methods can be costly, limiting access for smaller laboratories.
Purpose of the Study:
- To evaluate MALDI-TOF MS for detecting KPC enzyme from inactivated Enterobacterales on filter paper.
- To develop a low-cost, accessible method for KPC identification.
Main Methods:
- 129 Enterobacterales isolates were impregnated onto filter paper.
- Protein extraction and MALDI-TOF MS spectra acquisition were performed in triplicates.
- KPC identification was based on a specific m/z peak (28,712.62 ± 27.80).
Main Results:
- Using KPC peak in at least one replicate yielded 60.8% sensitivity and 96.4% specificity.
- Requiring the KPC peak in at least two replicates achieved 100% specificity.
- The method successfully identified KPC from bacteria stored on filter paper for 7 days.
Conclusions:
- MALDI-TOF MS detection of KPC from inactivated bacteria on filter paper is a viable method.
- This approach offers a significant advantage for resource-limited laboratories needing to confirm KPC presence.
- Further optimization could enhance sensitivity for broader applicability.
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