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)
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
http://bioinfo.bact.wisc.edu/themicrobialworld/Listeria.html
Special adaptations : Multi-resistance island on plasmid of Listeria
(1998-1999 hot dog outbreak) confers resistance to quaternary
ammonium compounds
0075
IS1216
IS1216left
Heavy metal…
(natural and industrial pollution)
0074
0067
Disinfectant…
(food processing plants, healthcare)
0065
Dyes…
(textile effluents &
aquaculture)
Zealand, MI
http://pics2.city-data.com/city/maps/fr5445.png
IS1216right
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, http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0076835
Unique regions:
Thermoregulated phage resistance in
Epidemic Clone II
L. monocytogenes H7858 (4b, ECII)
C
RE
MT
2753
GC%
2748
GC%
38
2754
32
32
2749
40
2757
31
2752
41
35
34
37
2765
46
2759
27
2766
40
37
33
2767
2768
41
39
2764
35 33 35 30
2769
2770
42
40
34
2771
39
2772
38
2773
37
L. monocytogenes EGDe (1/2a)
2591
2592
2595
2596 2597
2598
2599 2600
2601
2602
2603
2604
Kim J et al. Appl. Environ.
Microbiol. 2012;78:1995-2004
L. monocytogenes F2365 (4b, ECI)
2564
2565
2568
2569 2570
2571
2572 2573
2574
2575
2576
2577
Virulence
• Further discoveries: infection impacts on host
cell’s methylation, organelle fragmentation
• Galleria mellonella as alternative, user-friendly
animal model
http://bioinfo.bact.wisc.edu/themicrobialworld/Listeria.html
Listeria virulence: host-pathogen interactions
Lebreton et al 2015http://www.sciencedirect.com/science/article/pii/S0962892415000148
Listeria interactions with host: “patho-epigenetics”, organelle fragmentation
Lebreton et al 2015http://www.sciencedirect.com/science/article/pii/S0962892415000148
Galleria mellonella,
Alternative model system
for virulence assessments
BB. Fuchs et al., Virulence. 2010;1:475–82. doi: 10.4161/viru.1.6.12985.
80
OUTBREAK STRAINS LINKED TO MEAT PRODUCTS
Virulence assessments using Galleria
L1306A
H7750
J0161
60
40
100
20
DAY 2
DAY 5
107 CFU/larva
DAY 7
80
L1306A
H7750
J0161
60
40
100
20
L1306A
0
DAY 2
DAY 5
106 CFU/larva
DAY 7
% MORTALITY
0
% MORTALITY
% MORTALITY
100
80
H7750
60
J0161
40
20
0
DAY 2
DAY 5
105
CFU/larva
DAY 7
100
L1306A
2011L-2858
OUTBREAK STRAINS LINKED TO PRODUCE
Virulence assessments using Galleria
2011L-2857
2011L-2875
2010-1723
60
100
L1306A
40
80
0
DAY 2
DAY 5
DAY 7
WASHED CELLS 10^7 CFU/larva
2011L-2858
2011L-2857
60
2011L-2875
2010-1723
100
40
L1306A
80
20
0
DAY 2
DAY 5
DAY 7
1:10 DILUTION 10^6 CFU/larva
% MORTALITY
20
% MORTALITY
% MORTALITY
80
2011L-2858
2011L-2857
60
2011L-2875
2010-1723
40
20
0
DAY 2
DAY 5
DAY 7
1:100 DILUTION 10^5 CFU/larva
Virulence assessments using Galleria: low virulence for certain outbreak strains (e.g. 08-5923)
Kuenne et al 2013, http://www.biomedcentral.com/content/pdf/1471-2164-14-47.pdf
Host susceptibility factors influence Galleria
virulence assessments
100
80
% Survival
60
Compromised Galleria
40
Regular Representative Trial
20
0
0
-20
1
2
3
4
Day
5
6
7
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
http://bioinfo.bact.wisc.edu/themicrobialworld/Listeria.html
Listeria ecology: environment-food-host (“A down-to-earth pathogen”)
Vivatn et al 2013 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3842520/figure/F1/
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): e75969.
doi:10.1371/journal.pone.0075969
http://127.0.0.1:8081/plosone/article?id=info:doi/10.1371/journal.pone.0075969
Listeria monocytogenes ecology and downstream impacts: breakdown of chitin as model system
M. H. Larsen et al. Appl. Environ. Microbiol. 2010;76:6470-6476
Extensive analysis of serotypes and genotypes from RTE
food, processing facilities: 2010
• 501 isolates (1999-2008, 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 73:861-869
http://bioinfo.bact.wisc.edu/themicrobialworld/Listeria.html