Pathogen
s
s
What pathogen causes the most foodborne illnesses?
Norovirus
Culture based: historic, golden standard, indirect measure, dependent on growth and time consuming
Non-cultured based: next generation, rapid, direct detection, detects wider spectrum of microbes, quantitative or qualitative
Name the three types of microparasites
1. Protozoans
2. Viruses
3. Prions
Clostridium spp.
Bacillus spp.
Geobacillus
Alicyclobacillus
What is Zone 1, 2, 3, 4 in regards to sanitation
Zone 1 = direct food contact surfaces (ex. grater, conveyor, gloved hands)
Zone 2 = environment outside product lines (ex. frames, railling, control pannels)
Zone 3 = food processing environment (ex. drains, floors, walls, foot baths)
Zone 4 = outside processing area but potential for contamination (ex. locker room, washroom, recreation area)
Name the top 7 foodborne bacterial pathogens in North America
1. Camphylobacter
2. Salmonella
3. Clostriudium
4. Staphylococcus aureus
5. E. coli O157:H7
6. Bacillus cereus
7. Listeria monocytogenes
Name advantages and disadvantages of pour plate agar
Advantages: allows for the growth of anaerobes, bacteria is dispersed, more rapid than spread plate, easy to perform and reliable
Disadvantages: heat from agar may damage cells, hard to count, count analyze cell morphology
Name examples of protozoan pathogens
Toxoplasma, Cyclospora, Crytosporidium, Giardia
Types of Lactic Acid Bacteria
Homofermentative
Facultative homofermenters
Heterofermentative
What are the steps for sanitation in order
1. Dry-clean
2. Pre-rinse
3. Apply detergent
4. Post-rinse
5. Sanitize
(optional 6th: post-sanitizer rinse)
Name the 3 modes of foodborne ilnesses and an example of pathogen that causes it
1. Intoxication (Staphylococcus aureus, Clostridium botulinum)
2. Infection (Salmonella, Campylobacter jejuni, Listeria monocytogenes)
3. Toxico-infection (Shiga toxin producing E. coli, Clostridium perfringens, Bacillus cereus)
How does MacConkey agar allow for the selective and differential growth of coliforms?
Contains bile salts (selective), crystal violet (selective against gram positive), pH indicator which confirms lactose fermentation (differential)
Success factors of Norovirus
- high mutation rate makes vaccination less effective
- low infectious dose
- high resistant to santizers
- high level of persistance
What are utility microbes?
Microbes that indicate spoilage (ex. total aerobic count, psychrotrophic count, lactic acid bacteria, yeasts and molds)
Name the 5 types of detergents
1. General purpose
2. Alkaline
3. Enzymatic
4. Acid
5. Chlorinated
What are the two types of disease caused by different strains of Bacillus cereus? Name the the symptoms and incubation period.
Diarrhegenic – abdominal pain, watery diarrhea, 12-24 h
Emetic syndrome – nausea, vomiting, diarrhea, 0.5-5 h
What is flow cytometry? Name some advantages and disadvantages
Flow cytometry rapidly measures and analyzes physical and chemical characteristics of individual microbial cells (often dyed with fluorescent compounds) as they flow in a fluid stream past a laser.
Advantages: can separative gram-positives/negatives, differentiate live and dead cells, count VNBC
Disadvantages: dyes can stain food particles, stain is rapidly beached by UV light
Can be carried by food handlers asymptomatically
Primarily found in humans although has been recovered in pork
Potentially lethal to pregnant women
Infection linked to jaundice
What is Hepatitis E
Key 2-class or 3-class Sampling Plan Terms
n = Number of sample units analyzed
c = Maximum number of sample units with unsatisfactory test results
m = Maximum level for good quality product: Values at or above m are marginally acceptable or unacceptable quality
M = Level for defective quality: Values at or above M are unacceptable
Characteristics of an ideal sanitizer
- destroys vegetative microorganism
- works well in different environments
- dissolves in water
- inexpensive, easy to use, readily available
- should not irritate skin
- should not have offensive odor
Name the 5 types of pathogenic E. coli and their infectious dose
Enteropathogenic (EPEC) – 108 cells
Enterotoxigenic (ETEC) – 108 cells
Enteroinvasive (EIEC) – unknown
Enteroaggregative (EAEC) – unknown
Enterohemorhagic (EHEC, STEC, VTEC) – 10 cells
What is MALDI-TOF
Matrix Assisted Laser Desorption Ionziation - Time of flight
allows for the identification of bacteria as there is a unique spectra for each strain based on mass-to-charge ratio of bacterial proteins
rapid, independent of culture media, but spectra must be in the database to identify unknowns
explain how exposure to bad prions replicate
endogenous PrPc interacts with PrPSc and causes conversion from PrP to PrPSc
Explain what the following terms mean:
1. appropriate level of protection (ALOP)
2. food safety objective (FSO)
3. performance objective (PO)
1. Appropriate Level of Protection (ALOP): Target acceptable incidence
of a foodborne hazard – cases per 100, 000
2. Food Safety Objective (FSO): Performance standard to ensure
exposure of population to a hazard will not exceed ALOP
3. Performance Objective (PO): Levels of hazard at particular stage of
the chain to ensure FSO is met
Pros and Cons of Chlorine Dioxide
Advantages: Very powerful oxidizing agent, does not produce chloroamines, relatively stable in the presence of organics
Disadvantages: Limited efficacy against viruses, unstable above 30ºC