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Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes
Published on: August 9, 2011
Weak phospholipase-positive Listeria monocytogenes: a challenge for the diagnostic laboratory
Marc J A Stevens1, Joseph Wambui1, Sabrina Corti1
1Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Abstract:
Listeria monocytogenes isolates from environmental samples of a food producing company harboured a C424G mutation in the prfA gene that results in a G141A substitution in PrfA. This mutation results in strongly decreased phospholipase activity and is therefore challenging for culture-based detection of L. monocytogenes and may even lead to misidentification.
Insights
A specific mutation in the Listeria monocytogenes prfA gene reduces phospholipase activity. This genetic change challenges accurate, culture-based detection and identification of this foodborne pathogen.
Area of Science:
- Food safety microbiology
- Bacterial genetics
- Molecular diagnostics
Background:
- Listeria monocytogenes is a significant foodborne pathogen.
- Accurate detection is crucial for public health.
- The prfA gene is essential for virulence in L. monocytogenes.
Purpose of the Study:
- To investigate the impact of a specific prfA gene mutation on L. monocytogenes detection.
- To assess the functional consequences of the C424G mutation in the prfA gene.
- To evaluate the implications for culture-based diagnostic methods.
Main Methods:
- Genetic sequencing of prfA gene from environmental isolates.
- Analysis of C424G mutation and G141A PrfA substitution.
- Assessment of phospholipase activity in mutated isolates.
Main Results:
- Environmental L. monocytogenes isolates carried a C424G mutation in the prfA gene.
- This mutation led to a G141A substitution in the PrfA protein.
- Phospholipase activity was significantly reduced in these isolates.
Conclusions:
- The identified prfA mutation impairs L. monocytogenes phospholipase activity.
- This impairment poses challenges for standard culture-based detection methods.
- Misidentification of L. monocytogenes may occur due to this mutation.
