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Imprint
Molecular typing of Listeria monocytogenes in food as basis for an efficient risk assessment and control of listeriosis in Germany
Project
Project code: BfR-BIOS-08-1322-668
Contract period: 01.01.2016
- 31.12.2018
Purpose of research: Applied research
Listeriosis is a serious, partly life-threatening bacterial infectious disease. The case fatality rate is relatively high in comparison to other zoonotic diseases. The number of cases notified in Germany continuously increased in the last years with 662 cases in 2015 (incidence rate 0.8/100,000 population) which has been the highest number since the introduction of the German Protection against Infection Act in 2001. The case fatality rate was 7 %. Human listeriosis is caused by the infection with Listeria monocytogenes (Lm) that is usually transmitted by the consumption of contaminated food. Beside epidemiological investigations, high-resolution molecular typing methods are an important tool for the control and clarification of listeriosis outbreaks. Identification of causative foods by explorative interviews of patients or by examination of retained samples is often impossible due to the long incubation time of listeriosis of up to 70 days and the partly serious aetiopathology. Furthermore, most listeriosis infections in Germany are sporadic, non-epidemic cases. The molecular typing of Lm isolates enabling us to assign sporadic cases to outbreak clusters that occur over months or several years. To date, the Pulsed-Field Gel Electrophoresis (PFGE) was used as gold standard for the comparison of Lm isolates in outbreak investigations due to its high discriminatory power for the pathogen and existing worldwide quality standards for analysis. Nevertheless, the genetic resolution of the PFGE method is restricted as only a small part of the genome is analysed for the comparison of isolates. This can lead to an incorrect assignment of frequently found and very similar PFGE pattern to outbreak clusters. With the whole genome sequencing (WGS) a new typing method is available which dissolves the limits of PFGE analysis and provides maximum genomic information for isolates. Here, Single Nucleotide Polymorphism (SNP) analysis and Multi Locus Sequence Typing (MLST) analysis based on whole genome (wgMLST) or core genome (cgMLST) are used depending on the relatedness of isolates. The comprehensive typing of Lm isolates from food and human and the use of standardized methods for whole genome sequencing play an important role for the control and reduction of human listeriosis, but that is currently missing in Germany. The aim of the present research project is to set up the whole genome sequencing for use in the surveillance of Lm in Germany and to generate representative typing data for isolates from food and food producing environments. The findings should give a better understanding about diversity, virulence, resistance and persistence of Lm isolates and allow tracing back human infections to outbreak sources (molecular mapping). The prospective use of WGS in listeriosis surveillance will facilitate the clarification of outbreaks and will contribute to the risk assessment of Lm.
The comprehensive typing of Listeria monocytogenes (Lm) isolates from food and human and the use of standardized methods for whole genome sequencing play an important role for the control and reduction of human listeriosis, but that is currently missing in Germany. The aim of the present research project is to set up the whole genome sequencing for use in the surveillance of Lm in Germany and to generate representative typing data for isolates from food and food producing environments. The findings should give a better understanding about diversity, virulence, resistance and persistence of Lm isolates and allow tracing back human infections to outbreak sources (molecular mapping). The prospective use of whole genome sequencing in listeriosis surveillance will facilitate the clarification of outbreaks and will contribute to the risk assessment of Lm.
Section overview
Subjects
- Animal health
- Biotechnology
- Toxicology
