Upload
mansooreh-jami
View
842
Download
0
Embed Size (px)
Citation preview
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 1
Listeria monocytogenes in seafood
Mansooreh Jami, Ph.D Student
Institute of Food Science
Department of Food Science and Technology
BOKU-University of Natural Resources and Life Sciences
A Presentation forSpecific and Emerging Topics in Food Microbiology
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 2
Six identified species
L. monocytogenes, L. innocua, L. welshimeri, L. seeligeri, L. ivanovii, and L. grayi
Primary human pathogen
L. monocytogenes
• Gram (+), non-spore, motile, rod
Aerobic and facultative anaerobic
Psychotropic and halo-tolerant
The Listeria genus
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 3
Ubiquitous presenceWidely distributed in the environmentL. monocytogenes is found in relatively low number but under certain conditions facilitate higher numberSoil & vegetationFecal waterAnimal feed
Foodborne pathogen that causes listeriosisListeriosis is a serious infection caused by eating foods contaminated with the bacterium L.monocytogenes.
Significance of L. monocytogenes
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 4
This disease affects primarily pregnant women, newborn,
and adults with weakened immune systems.
Pregnant women
Flu-like illness, fever, muscular pain, headache or asymptomatic
Spontaneous abortion, stillbirth, septicemia, meningitis.
Non-pregnant adults
Mild gastroenteritis, septicemia, meningitis.
Symptoms
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 5
Foodborne illness caused by L. monocytogenes
14 serotypes of L. monocytogenes have been designated
1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a,4b, 4bX, 4c, 4d, 5, 6a, 6b
Serotype 1/2a, 1/2b, and 4b account for 96% of human infections in the United States
Food-borne listeriosis
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 6
Circulation of L. monocytogenes
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 7
Temperature
Growth range = -1 to 45°C
Optimum = 30 to 37°C
Psychrotrophic (refrigeration temperature; <5 °C)
Mesophilic (room to body temperature; 18-38 °C)
Temperatures < 0 moderately inactivate LM
LM can survive freezing
Factors affecting growth and survival
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 8
Acidity
Typical pH range is 5.0 to 9.6
Optimum =neutral conditions ~6.0 - 7.0
Growth at pH of <4.3 has not been demonstrated
LM can tolerate lower pH when kept at near refrigeration temperatures
(vs. room & body temperatures)
Most strains of LM are unlikely to grow in food products with pH < 5.2
Factors affecting growth and survival
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 9
Water activity
Water activity (aw)
LM grows well at aw of >0.95; can multiply at aw of 0.90
Some LM can survive at aw of <0.90
Salt concentration
Growth at 10%
Survival at 25.5%
Factors affecting growth and survival
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 10
Fresh seafoodRaw fishRaw molluscRaw crustacean
Ready to eat seafoodCold smoked fishHot smoked fishGravad
Semi processed seafood
L. monocytogenes in seafood
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 11
Listeria as indigenous pathogens in aquatic environment
The prevalence of L. monocytogenes in raw fish is quite low, ranging from 0 to 1% (Autio et al., 1999) to 10% (Jemmi & Keusch, 1994). An overall prevalence 3% of L. monocytogenes was observed in European fish (Davies et al., 2001). Swetha et al., 2012; L. monocytogenes was isolated from 8 % fish samples.
Different geographical area, Different type of products
The problems can arise when handling, processing or storing conditions provide favourable conditions for the growth of the pathogenic bacteria.
Fresh seafood products
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 12
• Cold smoked fish: Aw (0.89 – 0.99), pH (3.1-7.2), Temperature (25-28 ºC)
• Hot smoked fish: Aw (0.89 – 0.99), pH (4.1 – 8.4), Temperature (70-90 ºC)
• Gravad: Aw (0.97-0.99), pH (6.1-6.3)
L. monocytogenes in lightly preserved seafood
15,000 samples
1988-2007
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 13
Seafood/lightly preserved seafood implicated in human listeriosis
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 14
a n = number of units comprising the sample; c = number of sample units giving values over m or between m and M b m = M
EU criteria for L. monocytogenes
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 15
ConclusionThe prevalence of L. monocytogenes generally increases along the food production chain, mainly due to cross-contamination in the production plants making this pathogen a major threat to the seafood industry.
Attention must be paid to the design of food-processing equipment and to the effectiveness of the cleaning and disinfecting procedures in the production facilities, based on the known imperative preventive measures, such as Good Agricultural Practices (GAP) in the primary production, Good Hygiene and Manufacturing Practice (GMP) and also Hazard Analysis and Critical Control Points (HACCP).
Specific Emerging Topics in Food Microbiology I Listeria monocytogenes in seafood I 27, May 2013-SS 16
Thanks for Your Attention!