Prof. H.P. R. Seeliger

Transcription

1 Prof. H.P. R. Seeliger Professor at the Institute for Hygiene and Microbiology at the University of Würzburg; Head of the Tropical Hygiene Institute in Lomé (Togo)

2 Environmental adaptations of special food safety relevance Resistance to disinfectant (quaternary ammonium compounds) via novel genes Resistance via mutations in pre-existing genes (efflux systems etc) Thermoregulated phage resistance

3 Special adaptations : Multi-resistance island on plasmid of Listeria ( hot dog outbreak) confers resistance to quaternary ammonium compounds IS1216 left Heavy metal (natural and industrial pollution) IS1216 Disinfectant (food processing plants, healthcare) Dyes (textile effluents & aquaculture) IS1216 right Zealand, MI

4 Tn6188 (mostly serotype 1/2a), chromosomal, resistance to quats and ethidium bromide Disinfectant resistance elements (bcrabc, Tn6188): Potential roles in persistence? Potential for dissemination among listeriae? Reservoir strains? Differences from resistance via mutations of pre-existing genes? Müller et al 2013,

5 Unique regions: Thermoregulated phage resistance in Epidemic Clone II L. monocytogenes H7858 (4b, ECII) RE MT C GC% GC% L. monocytogenes EGDe (1/2a) L. monocytogenes F2365 (4b, ECI) Kim J et al. Appl. Environ. Microbiol. 2012;78:

6 Virulence Further discoveries: infection impacts on host cell s methylation, organelle fragmentation Galleria mellonella as alternative, user-friendly animal model

7 Listeria virulence: host-pathogen interactions Lebreton et al 2015http://

8 Listeria interactions with host: patho-epigenetics, organelle fragmentation Lebreton et al 2015http://

9 Galleria mellonella, Alternative model system for virulence assessments BB. Fuchs et al., Virulence. 2010;1: doi: /viru

10 % MORTALITY % MORTALITY % MORTALITY L1306A H7750 J0161 OUTBREAK STRAINS LINKED TO MEAT PRODUCTS Virulence assessments using Galleria DAY 2 DAY 5 DAY L1306A H7750 J CFU/larva DAY 2 DAY 5 DAY L1306A H7750 J CFU/larva DAY 2 DAY 5 DAY CFU/larva

11 % MORTALITY % MORTALITY % MORTALITY L1306A 2011L L L OUTBREAK STRAINS LINKED TO PRODUCE Virulence assessments using Galleria DAY 2 DAY 5 DAY 7 WASHED CELLS 10^7 CFU/larva L1306A 2011L L L L1306A 2011L L DAY 2 DAY 5 DAY L :10 DILUTION 10^6 CFU/larva DAY 2 DAY 5 DAY 7 1:100 DILUTION 10^5 CFU/larva

12 Virulence assessments using Galleria: low virulence for certain outbreak strains (e.g ) Kuenne et al 2013,

13 % Survival Host susceptibility factors influence Galleria virulence assessments Compromised Galleria Regular Representative Trial Day

14 Ecology Deciphering the elements of the environmentfood-host continuum Special emphasis on soil as potential Listeria reservoir : impact of abiotic and biotic factors Breakdown of chitin: paradigm for environmenthost linkages Distribution of specific serotypes and genotypes in environment, food, illness

15 Listeria ecology: environment-food-host ( A down-to-earth pathogen ) Vivatn et al

16 Survival of Listeria monocytogenes in nine soils: non-sterile (panel A) and sterile (panel B). Locatelli A, Spor A, Jolivet C, Piveteau P, Hartmann A (2013) Biotic and Abiotic Soil Properties Influence Survival of Listeria monocytogenes in Soil. PLoS ONE 8(10): e doi: /journal.pone

17 Listeria monocytogenes ecology and downstream impacts: breakdown of chitin as model system M. H. Larsen et al. Appl. Environ. Microbiol. 2010;76:

18 Extensive analysis of serotypes and genotypes from RTE food, processing facilities: isolates ( , RTE processing facilities, mostly in US) Lineage I and II: 46 and 54%, respectively Serotypes: 1/2a, 41%; 1/2b, 40%; 1/2c, 12%; 4b, 7% Epidemic clone isolates: 9 each ECI and ECII; 14 ECIa; 6 ECIII Premature stop codons in inla: 1/2c, 86% 1/2a, 53% 1/2b, 40% 4b, not detected From: Ward et al., 2010, J,. Food Prot 73: