Unit 4 flashcards
(275 cards)
1
Q
what classifies fermentations?
A
by either the substrate fermented or the products formed
2
Q
What is a benefit of fermentation
A
a main method of food preservation
3
Q
What can inhibit the growth of spoilage organisms and food borne pathogens?
A
- acid produced in yogurt, cheese, and pickled vegetables from fermentation
- bacteriocins and some secondary metabolites
4
Q
What are other methods of preservation?
A
- salting
- drying
- addition of various herbs or spices (own antimicrobial compounds)
- canning
5
Q
What causes the tastes of yogurt, pickles, sharp cheeses, and some sausages to be special?
A
- production of lactic and/or acetic acid by fermenting bacteria
- other molecules produced during fermentation and/or secondary metabolism
6
Q
True or False: milk is sterile in a cow’s udder.
A
True
7
Q
Why/how does a cow’s milk become contaminated if it is sterile inside the udder?
A
- rapid contamination during milking and handling
- skin microbiome (lactic acid bacteria on the cow’s udder)
- from where milk is held
temperature
8
Q
What causes changes in the aesthetic features of milk?
A
- production of acid, proteases, exopolysaccharides and flavor compounds (secondary metabolites)
9
Q
What are some changes in the aesthetic features of milk?
A
- milk proteins coaggulating or curdling
- sours flavor
- thickens/gels the liquid
10
Q
What are some characteristics of Kefir?
A
- a fermented milk drink similar to a thin yogurt
- contains live probiotics
11
Q
True or false: you can drink raw milk because it has more nutritional benefits.
A
false- a lot of contaminants in non-pasteurized milk
12
Q
true or false: lactic acid bacteria are the only way to get fermentation to occur in milk products.
A
false: starter cultures can be added to milk
13
Q
What are starter cultures?
A
a preparation of living microorganisms, which are deliberately used to assist the beginning of fermentation, producing specific changes in the chemical composition and the sensorial properties of the substrate
- strains are specifically selected to produce desirable flavors and textures
14
Q
Why must starter cultures be carefully maintained?
A
- they can easily get contaminated by other microbes
15
Q
What are the levels of cheese classification?
A
- very hard
- hard
- semi-soft
- soft
16
Q
What determines the hardness of cheese?
A
- based on percentage of water content
17
Q
What cheese is the easiest to make?
A
cottage cheese
18
Q
How do you make cottage cheese?
A
- pasteurized milk is inoculated with starter culture
- culture causes milk proteins to coagulate
- curds are the protein coagulates
- curd is heated and cut into small pieces to facilitate drainage of liquid
19
Q
What is whey?
A
the liquid strained out from cottage cheese production
20
Q
True or false: most cheeses undergo further microbial processing called ripening or curing.
A
true
21
Q
How are cheeses ripened?
A
- added enzyme, rennin (chymosin), is a protease added to fermenting milk to hasten protein coagulation
- curds are salted after whey is separated and pressed
- curds are ripened to encourage changes in texture and flavor
- ripening can take from weeks to years
22
Q
What does longer ripening do to cheeses?
A
- produces more acidic, sharper cheeses
23
Q
True or False: all organisms produce the same characteristics in cheeses and fermentations.
A
false - certain organisms produce certain characteristics
24
Q
What does propionibacterium shermanii produce?
A
swiss cheese
25
What type of cheese(s) does penicillium roquefortii produce?
- roquefort
- gorgonzola
26
What types of bacteria are prominent in yogurt production?
- streptococcus thermopiles
- lactobacillus bulgaricus
- other lactobacillus species
27
How is yogurt made?
- milk is inoculated with starter culture (high temperature heating, 180 degree F)
- mixture is incubated at 40-45 degree C for several hours (optimum growth temperatures for bacteria in yogurt production
- controlled incubation ensures proper levels of acid production, proteolytic activity and flavor compound
28
What are probiotics?
live microbes that confer a health benefit when ingested in sufficient quantities
29
What are the most common types of probiotics?
- lactobacillus species
- bifidobacterium species
- bacillus coagulans
- saccharomyces boulardii ssp. lyo
30
What are other (food microbes) types of probiotics?
- propionibacterium freudenreichii ssp shermanii
- other lactic acid-producing bacteria:
- streptococcus thermophilus
- leuconstoc
- lactococcus
- bacillis subtilis natto
31
What are other non-food probiotics?
- E. coli nissle 1917
- enterococcus faecium SF68
32
True or False: each strain and species of probiotic microbe has a different activity in probiosis.
true
33
How does pickling work?
uses naturally occurring lactic acid bacteria residing on vegetables
- vegetables are packing in vinegar (acetic acid) to pickle them
34
What are the characteristics of kimchi and how it's made?
- traditionally fermented in a semi-permeable vessel called an onggi
- very long shelf life
- length of fermentation changes the flavors
35
How does fermentation for alcohol occur?
- some yeasts ferment sugars to produce ethanol and carbon dioxide
- yeasts are used to make variety of alcoholic beverages, vinegar, and bread
36
How does fermentation occur in bread?
- bread rises due to carbon dioxide produces through fermentation of sugars by baker's yeast
- alcohol produced during fermentation evaporates during baking
37
What is baker's yeast?
saccharomyces cervisiae
38
What is the characteristics of fermentation in sourdough bread?
characteristic flavor of sourdough bread is due to adding lactic acid bacteria and other yeast to the bread making mixture
- sourdough uses a starting culture
39
what are intrinsic factors in food spoilage?
conditions naturally present in food that influence growth of microorganisms
40
What are extrinsic factors in food spoilage?
environmental conditions that influence the growth of microorganisms on food
41
What are some examples of intrinsic factors?
- water availability
- pH
- Nutrients
- biological barriers
- antimicrobial chemicals
42
What is the best environment for microorganisms to grow on food?
- microbes multiply most rapidly in moist, nutritionally rich, pH neutral foods
43
What foods have high water availability?
fresh meats and milk
44
What foods have low water availability?
breads, nuts, and dried foods
- defined populations can grow in these conditions
45
What is used to designate amount of water available in foods?
- water activity (aw)
- also referred as osmolarity of food
46
What is the aw of pure water?
1.0
47
What is the required aw for bacterial growth?
above 0.90
48
What is the required aw for fungal growth?
above 0.80
49
what type of pH conditions inhibit growth of many microorganisms?
acidic conditions
50
what types of bacteria are not inhibited by low pH?
lactic acid bacteria (LAB)
- LAB used in fermentation for food production
- LAB can also cause spoilage of unpasteurized milk and other foods
51
What other types of microorganisms are able to survive at low pH?
yeast
other fungi
52
True or false: most acid foods spoil from fungal contamination.
true
53
What are types of biological barriers that can prevent microbe growth?
- rinds, shells, other outer coverings
- can be eventually broken down and cause spoilage
54
What are some types of antimicrobial compounds?
-clove
- oregano
- thyme
- cinnamon
- cumin
- garlic
55
What is the best extrinsic factors that promote microbe growth?
- largely depends on storage of food
- best in warm, oxygen-rich environments
- can also grow under anaerobic and low-oxygen conditions (improperly canned foods)
56
What are some examples of extrinsic factors?
- storage temperatures
- oxygen levels
- humidity
57
What does storing food below freezing do?
- decreases water availability significantly
- water crystalizes and is unavailable to microbes
58
What does storing food at low temps, but above freezing do?
- enzymatic action is very slow or non-existent
- unable to allow microbe growth
59
How does humidity impact microbe growth?
more moistures = more microbe growth of spoilage microorganisms
60
What do preservation methods do?
interfere with intrinsic and extrinsic factors
61
What are some preservation methods?
- canning
- pasteurization
- cooking
- refrigeration
- freezing
- drying/reducing water availability
62
What does cooking do to prevent microorganism growth?
can destroy non-spore forming organisms
63
What is a con of cooking?
if the heat is uneven, microbes can still survive in the undercooked portion
64
What does refrigeration do to prevent microorganism growth?
- slowing growth rate of microbes
65
What is a negative to freezing to prevent spoilage?
portion of organisms remaining can grow when food is thawed
66
what is a negative to drying foods to prevent spoilage?
Molds can grow on dry food eventually
67
What does irradiation do to prevent microorganism growth?
Damages microbial DNA and kills them
68
What does filtering do in spoilage prevention?
- will not remove viruses
- 0.2 micron filter will remove microbes
- cheesecloth only removes particulates
69
What does heating do in spoilage prevention?
- efficacy depends on temperature and time heated
- boiling may not kill endospores
70
what is pasteurization?
the process of heating a liquid for a specific period of time to destroy pathogenic microorganisms
- developed by Louis pasteur
71
What are some milk borne illnesses?
typhoid fever, undulant fever (brucellosis), scarlet fever, septic sore throat (strep throat), diphtheria, diarrheal diseases, and tuberculosis
72
Who demonstrated the unpasteurized milk could transmit the bacterial diseases?
Alice Catherine Evans in 1918
73
What percentage of all food and waterborne illnesses were caused by milk products in 1938?
25%
74
What percentage of all food and waterborne illnesses were caused by milk products in 2016?
- way less than 1%
75
What is a benefit of pasteurization other than cleaning milk?
reduced pathogenic bacteria in milk without changing the flavor
76
What does cooking milk at high temperatures for a long period of time do?
- micelles of the milk protein casein irreversibly aggregates and imparts a cooked flavor to the milk
- turns it to custard
77
What is flash pasteurization?
- high-temperature, short-time (HTST)
- milk is forced between heated metal plates or pipes
- the milk is heated to 72 degrees C for 15 seconds
78
What are the other types of pasteurization?
- ultra-pasteurization
- ultra-heat-treating (UHT)
79
What is ultra-pasteurization?
holds the milk at a temp of 140 degrees C for 2 seconds
- allows for extended storage in the refrigerator
80
What is UHT?
- processing holds the milk at a temp of 140 degrees C for 4-15 seconds
- milk is sterilized and not pasteurized
- lets consumers to store milk or juice for several months without refrigeration
81
Is juice on the shelf pasteurized or sterilized?
sterilized
82
What is required of pasteurized juices?
they need to be refrigerated
83
What are some other products that may be pasteurized?
- fruit juices
- almonds
- cider
- some beers
84
Does boiling sterilized liquid?
depends on:
- what was in the liquid to begin with
- how long it is boiled for
- what temperature it is boiled at
85
Will boiling sterilize a liquid if heat-resistant endospores are present?
no unless it is sterilized at autoclave conditions
86
Is heat-induced microbial death instantaneous?
no
- a function of time, temperature, and microbial species.
87
What are cardinal temperatures?
- the minimum, optimum, and maximum temperatures a microorganism can grow in
88
What are the groups that microorganisms are classified into according to growth temperature optimum?
- psychrophile
- mesophile
- thermophile
- hyperthermophile
89
What are psychrotolerant microorganisms?
- can grow at 0C, but has an optimum of 20-40C
- more widely distributed in nature than psychrophilic microorganisms
- responsible for cold-storage spoilage of foods
90
True or false: food spoilage is always harmful.
false - generally not harmful, but can be
91
What bacteria is responsible for refrigerator milk spoilage and blue growth on cheese
- pseudomonas spp
92
what types of organisms can survive cooking and canning?
endospore-forming organisms
93
what are some types of spore-forming organisms?
- clostridium species
- bacillus species
94
what is the range that fungi can spoil food in?
- in acidic and low-moisture conditions
95
What is food borne illness or food poisoning?
- results from a failure in proper use of preserving, preparation, or cooking techniques to avoid growth of microbial pathogens
96
What is intoxication?
- disease resulting from he consumptions of foods containing microbial toxins
- microbes that produced the toxin do not have to infect the host
- symptom onset is typically 4-12 hours
97
What is infection from food poisoning?
- microbial infection from the ingestion of pathogenic food followed by growth of pathogen in the host
- symptom onset is typically 24-48 hours
98
What are the factors for determining the risk of developing food borne illness?
- type of microbe or toxin ingested
- inoculum size (number of microbes/ amount of toxin ingested
- inadequate stomach acidity
- reduction of change in normal microbiota of host (use of antibiotics)
- susceptible populations (young, old, and hospitalized/immunocompromised)
99
true or false: in intoxication, the toxin is responsible for the illness not the organism
true
100
What are common causes of food borne intoxication?
- staphylococcus aureus
- E. coli
- clostridium botulinum
101
What kinds of microorganisms produce heat stable enterotoxins?
- staphylococcus aureus
- e. coli
- vibrio cholera
102
How long and at what temp are heat stable enterotoxins stable for?
- heating at 100C for 30 min
103
What are other special characteristics of heat stable enterotoxins?
- protected from hydrolysis by duodenal and jejunal enzymes
- elicit net secretion of ions and water = watery diarrhea and abdominal cramping (no fever or blood in stool, onset of diarrhea is less than 12 hours)
104
What are physical and chemical barriers for your body's immune system?
- skin
- tears
- stomach acid
- earwax
- mucus
- hairs in your nose
105
What are some examples of your innate defenses?
- inflammation (swelling, fever)
- chemical signals
- WBCs eat invaders (phagocytosis)
- generalized threat response to all invaders
- ramp up attack against intruders
106
What are some examples of your body's adaptive defenses?
- specific responses tailored to threat
-T cells
- B cells
- Antibodies
- memory (immunity)
107
What is the innate defense system/ innate immunity?
- occurs immediately after something breaches past a barrier
- evolved in early invertebrates
- includes anatomic/physical barriers, chemical barriers, non-specific cellular defense
- present at birth
108
What is adaptive immunity?
- slower response than innate immunity
- only exists in vertebrates
- reacts to antigens
- body has to see/detect antigens before a response is launched
- develops overtime after birth
109
What is an infection?
invasion of an organism's body tissues by disease-causing agents, the multiplication or metabolically-active persistence of agents, and the reaction of host tissues to the infectious agents and any toxic compounds they produces
110
what is an infectious disease?
- the disease that results from infection by a transmissible agent
111
What is a transmissible agent?
an agent that can be passed from host to host, including via abiotic or biotic intermediates
112
True or false: all infectious diseases are infections, but not all infections are infectious diseases.
True
113
What are some types of infectious microbes?
- bacteria
- viruses
- parasites (protozoa and worms)
114
What are some types of modes of entry into the body for infectious microbes?
- ingestion
- zoonotic
- entry through open wounds
115
What are characteristics of intracellular infection?
- pathogen lives and reproduces within the cells
- within cytoplasm and vesicles
116
What are characteristics of extracellular infections?
- pathogens lives in the body but outside of individual cells
- interstitial space
- blood
- lymph
- epithelial surfaces
117
True or false: an infectious agent entering the body does not guarantee disease.
true
118
What must first happen in order for an infection agent to cause disease?
- not just enter the body, but must first breach anatomic and chemical barriers to gain entry
- must survive innate defenses
- must survive adaptive immune responses
119
What are some passive barriers to protect against infection?
- removal of particles/microorganisms by cilia in the nasopharynx
- skin produces antimicrobial fatty acids and antibacterial peptides, RNase production prevents infection
- lysozyme in tears
- mucus and cilia lining the trachea
- stomach acidity pH of 2
- surfactant in lungs prevent infections
- blood and lymph proteins
- Rapid pH changes
- normal microbiota competes with pathogens in the gut and on the skin
- flushing of urinary tract
- epithelial cells have tight junctions
120
What are some characteristics of Epithelial cells as anatomic barriers?
- barrier between internal systems and microbes in the environment (skin)
- lining of tubular structures (respiratory tract, urogenital tract, GI tract)
121
What are internal epithelia called?
- mucosal epithelia
- they are specialized to secrete mucus
122
What are some examples of gut-associated lymphoid tissues?
- Peyer's patch
- M cell: antigens/bacteria that enter and leave are phagocytosed by macrophages
123
What are some examples and characteristics of chemical barriers?
- enzymes in phagocytes, tears, saliva (Lysozymes phospholipase)
- acidic pH in the stomach via digestive enzymes, bile salts, lysoplipids, fatty acids
- antimicrobial peptides (defenses, cathelicidins, and histatins)
124
What are anti-microbial peptides (AMPs)?
- small, typically (+), peptides with potent antimicrobial activities
- produced by many cells in the body like neutrophils and cells of the mucosa (paneth)
- many display a direct and rapid antimicrobial activity by causing disruption of the physical integrity of the microbial membranes and/or by translocating across the membrane into the cytoplasm of bacteria to act on intracellular targets
125
What all contributes to the host defense?
- pH
- temperature of the body
- nutrient availability
- fluid flow
- adherence
126
Where is a common place to find immune cells?
Blood!!!!
127
Where are immune cells found in the blood?
- in the Buffy coat layer, which makes up <1% of the whole blood
- contains leukocytes and platelets (WBCs)
128
What do unstained WBCs look like?
- larger, colorless, and more granular
129
What do RBCs look like?
- smaller, red-tinged from hemoglobin
130
What are leukocytes?
WBCs
- formed by differentiation of hematopoietic stem cells in the bone marrow
- have two main lineages (Myeloid = innate response, lymphoid = adaptive response
131
what are the main 4 types of WBCs and some of their characteristics?
- Neutrophils: have many nuclei
- eosinophil: have 2 nuclei
- monocyte
- lymphocyte: has a large nucleus, involved in the adaptive immune response
132
What does bone marrow do?
- the source of the WBCs that are the major mediators of host defense
133
What immune cells are a part of the adaptive immune response?
- T-cells (processed in the thymus)
- B-cells (processed in the bone marrow)
*Which are both lymphocytes
134
What are some examples of innate immune cells?
- Polymorphonuclear leukocytes (PMNs)/granulocytes = neutrophils, eosinophils, basophils
- Monocytes
- Macrophages
- dendritic cells (a bridge between 2 immune responses)
- Mast cells
- Natural killer cells (part of lymphoid lineage)
135
What do macrophages do?
- phagocytosis and activation of bactericidal mechanisms
- antigen presentation
136
What do eosinophils do?
- killing of antibody-coated parasites
137
What do dendritic cells do?
Antigen uptakes in peripheral sites
- antigen presentation
138
What do basophil cells do?
- promotion of allergic responses and augmentation of anti-parasitic immunity
139
What do neutrophil cells do?
- phagocytosis and activation of bactericidal mechanisms
140
What do mast cells do?
release of granules containing histamine and active agents
141
What is phagocytosis?
- the process of engulfing microbe via extrusion of pseudopods (attach to the antigen and pull it in)
- once microbes are engulfed (a phagosome), they are killed by lysozymes
142
What types of cells have phagocytic capabilities?
- macrophages
- monocytes
- neutrophils
- dendritic cells
143
What can mediate the attachment of a phagocyte to a microbe?
specific receptor interactions or by charge interactions
144
How are phagocytosed microbes killed in a phagosome?
- oxygen radicals by oxidizing key cellular constituents of the ingested microbe
- respiratory burst
- degradative enzymes in the phagolysosome
145
What is the respiratory burst?
- a series of catalyzed reactions in the phaglyosome that. creates ROS metabolites like peroxide, hypochlorite, nitric oxide, superoxide, and hydroxyl
- occurs within the phagocytic vacuole of phagocyte, which is not damage by ROS products
146
How do neutrophils kill microbes?
- throw neutrophil extracellular traps (NETs), spews a lattice of DNA containing antimicrobial compounds into the immediate area
- traps pathogen and prevents it from spreading
- antimicrobial compounds kill the microbe
147
What types of microbes can escape NETs?
- Group B Strep
- Neisseria Gonorrhea
by secreting extracellular nucleases
148
How do eosinophils and basophils kill microbes?
- release products toxic to the microbe
- release chemical mediators that affect the diameter and permeability of blood vessels (vasoactive agents)
- eosinophils play major roles in multicellular parasite infections + allergic responses (Helminths)
- Basophils play a major role in inflammation and wound healing (have IgE receptors fro allergic responses)
149
How do mast cells kill microbes/what is their role?
- similar structure of basophils
- residents of connective tissues and mucosa = don't circulate in the blood
- play a role in inflammation and wound healing by releasing antihistamines
- contains IgE allergic response receptors
150
How do monocytes and macrophages kill microbes/ what is their role?
-widely distributed throughout the body
- mononuclear, likely to make first contact with pathogens
- phagocytose microbes and other foreign particles , clear them from the blood stream
151
What are some additional types of macrophages?
- kupffer cells: immobile, reside in capillaries
152
What bridges innate and adaptive immune responses?
- macrophages and monocytes produce antigens derived from the microbes they degraded
- antigens are used in adaptive immune response
- also take antigens and trains the immune system
153
How do dendritic cells kill microbes/ what is their role?
- also antigen presenting
- present in: skin, mucosal tissue, lymph nodes and spleen
- phagocytose microbes
- take up small antigens from their surroundings
154
How do natural killer cells kill microbes/ what is their role?
- kill host cells instead of microbes (intracellular parasites, cancer cells)
- recognize changes in cell surface proteins (major histocompatibility complex)
- degranulate onto target and kill the cell (triggers apoptosis, looks for absence of MHC or presence of antibodies)
- antibody-dependent cell-mediated cytotoxicity (Fc receptors link)
155
What does inflammation do in immune defense?
Provides the opportunity for phagocytic cells to move from the bloodstream to the infected tissue. (aka Extravasation/diapedesis)
156
What are 5 signs of inflammation?
-Red
-Heat
-Edema (swelling)
-Pain
-Altered function
157
What does fever do for fighting infections
-Elevated body temp produced by metabolism in response to pyrogens (molecules on some bacterial cell walls)
-Reduces microbial growth with optimal temps at 37
158
How do pattern recognition receptors work in immune response?
-Microbes have unique structures that are tagged by the immune system as foreign
-Microbe associated molecular patterns (MAMPS) are recognized by receptors on or within the cell. They are toll or NOD like
159
What are cytokenes?
-Proteins that bind to a specific receptor.
-They are intercellular signaling molecules that act locally or systemically
-Have multiple effects depending on target cell binding the cytokine
160
How are cytokines produced?
-By many different immune cells
-Can have local or systemic effects
-Turn immune responses up or down
161
What is a Cytokine Storm?
-Hyperactive immune cell activity due to out of control cytokine production
-Leaking blood vessels,
-Multiple organ failure
-death
-one of the major causes of death from covid
162
WHat are interferons?
-A soluble factor that can interfere with viral replication
-Host species specific but NOT pathogen specific
-Activates NK cells, dendritic cells, and macrophages
163
What are the THREE types of Interferons
Type 1:
Alpha, beta, and others
-High antiviral potency
Type 2:
Gamma. (Immunomodulatory)
-Activate white blood cells
-Increase MHC antigen presentation
Type 3:
Antiviral responses in epithelial cell
164
What are methods of pathogen avoidance of complements (proteins that try to make bacteria more susceptible to phagocytosis)
-Neisseria menigitidis- Inactivates bound C3b via membrane and secrete proteins
-Borrelia burgdorferi- Inactivates bound C3b via membrane proteins
-Staph aureus- Inactivated bound C3b via membrane proteins
-Binds antibodies preventing c1 activation
-Cleaves antibodies
-Inhibits convertase pathways
165
What are the
166
What is the avian flu?
H5N1 strain of influenza, fast-mutating
167
How is the avian flu spread?
- epizootic (an epidemic in non-humans)
- panzootic (a disease affecting animals of many species)
- infected cows shed virus in their milk
- pasteurization should kill the virus. unpasteurized milk poses a threat?
168
What is staphylococcus aureus' role in food poisoning?
- source is generally from a human carrier
- skin and nasal commensal microbe in humans
- organism is inoculated into food during preparation
- food left at room temperature allows organism to grow and produce toxin, making them heat stable = cooking won't kill them
- due to intoxication
169
What are the principles of canning?
- heat processing at high temperature for a fixed period of time
- destroys microbes
- inactivates endogenous "spoilage" enzymes
- oxygen is driven out = reduced microbial and oxygen-driven spoilage chemistry
- a vacuum is formed upon cooling that prevents recombination
170
What happens when canning is done improperly?
- can promote germination and growth of endospores
- occurs when the temperature of canning isn't high enough or held long enough
- home canning is a major concern
- can cause botulism
171
What is botulism?
- a paralytic disease caused by ingestion of a neurotoxin
- caused by intoxication
- produced by clostridium botulinum (gram +, spore-forming, anaerobic rod)
- growth of organism or production of toxin may not result in changes in taste or appearance of food.
172
What are the disease characteristics of Botulism?
- symptoms hit 12-24 hours after ingestion in adults
- nausea and vomiting
- visual impairment
- loss of mouth and throat function
- fatigue and loss of coordination
- respiratory impairment
- abdominal pain and either diarrhea or constipation
173
What are the botulism disease characteristics in infants?
- constipation: days to week
- generalized weakness and a weak cry (cause of chest paralysis)
- poor feeding and sucking reflex
- lack of facial expressions
- floppiness
- respiratory arrest may occur although death is rare
174
Why should children younger than 12 months never consume honey?
- C. botulinum spores are found in soil, dust, and honey
- when infants swallow the spores, they can germinate in there immature GI tract and begin producing botulinum toxin
- adults or children >12months are almost never affected
175
What is Bacillus cereus?
- causes intoxicaton
- gram +, spore-forming, facultative anaerobic, rod
- found in soil
- can be found in feces of healthy individuals
- can cause fried rice syndrome, a diarrheal disease
- at least 3 enterotoxins have been described
- may be found in grains, especially rice
- incubation period 8-16 hours; duration one to several days
- heat stable
- environmental contaminant
176
What causes food borne infection?
- requires consumption of living organisms (invasion of the large intestine mucosal surface by the infection)
177
What are symptoms of food borne illnesses?
- do not appear for at least 1 day after ingestion
- major symptom is diarrhea
- fecal blood
- fecal leukocytes
- body aches
- fever
178
What are food borne illnesses commonly caused by?
- salmonella species
- campylobacter species
- E. coli diarrheagenic strains
179
What bacteria are in raw flour?
- E. coli
- salmonella
180
What are salmonella and campylobacter commonly found in?
- inadequately cooked poultry products
- cross-contamination can result in transfer of pathogens to other foods
- type of infection
181
What is salmonellosis?
- salmonella species (non-typi): motile, gram (-), enterobacteria
- many different species and strains
182
What are symptoms of salmonellosis?
- gastroenteritis and food poisoning
- nausea, vomiting, abdominal pain, fever, and diarrhea 24-48 hours after ingestion
type of infection
- can get rid of it yourself over time
183
What is campylobacter jejuni?
- most common of bacterial diarrhea
- from inadequately cooked poultry, untreated water, unpasteurized milk, and exposure to animals with diarrhea
- self-limiting, antibiotics typically not needed
184
what are the symptoms of campylobacter jejuni?
high fever
- headache
- malaise
nausea
- abdominal cramps
- bloody stools
- replicates in the small intestine
- low infectious dose
185
what are some characteristics of campylobacter jejuni?
- curved s-shaped gram (-) rods
- motile with one polar flagellum
- microaerophile
- grows best at 42C
- has 2 main toxins (adenyl cyclase activating cholera toxin like enterotoxin, cytotoxin)
186
What is true of most pathogenic E.coli strains?
- are intestinal parasites
- some produce potent enterotoxins
- can cause either intoxication or infections
187
What are characteristics of E. coli O157:H7?
- causes bloody diarrhea
- responsible for large food poisoning outbreaks
- typically found in ground meat
- also found in unpasteurize milk and juices
- cows can be carriers
- use of their manure can casue crop contamination
188
What is listeria
- tolerates high salt concentration 10-12%
- 4.4-9.6 pH range
found on:
- deli meats and hot dogs
- pates or meat spreads
- unpasteurized milk and dairy
- soft cheeses from unpasteurized milk
- refreigerated smoked seafood
-mortality rate is high
type of infection
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What are higher-risk groups of listeriosis?
- pregnant women
- newborn infants
- persons with immunocompromising conditions
- older adults
190
What are other causes of foodborne or waterborne illnesses?
- vibrio cholerae
- amoebic dysentery
- travelers diarrhea
- clostridium perfringens
-norovirus
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What is a virus?
- genetic element that cannot replicate independently of a living host cell
- can infect all domains
192
What is a viron?
- extracellular form of a virus
- exists outside of the host and facilitates transmission from one host cell to another
- contains nucleic acid genome surrounded by a protein coat and other layers of material
193
What encapsulates a viron?
- consists of a nucleocapsid
- capsid (protein coat)
- nucleic acid
194
what are the 2 main categories of virons?
- naked
- enveloped (surrounded by a lipid envelope)
195
What are characteristics of envelope viruses?
- Have membrane surrounding nucleocapsid
- lipid bilayer with embedded proteins
- envelope makes initial contact with the host cell
- much of the membrane is picked up from the host cell during exit
- most infect animal cells
196
True or false: because viruses are obligate parasites, they do not carry their own enzymes with them between host cells.
- false, some need to carry enzymes with them to carry out certain functions
197
What enzymes might viruses carry with them?
- lysozyme-like enzymes
- enzymes that aid in cleaving virus from host cell during release (like neuramidase in influenza)
198
What are RNA replicases?
- enzymes that copy RNA from RNA in viruses + host cells
199
What are the phases of viral replication?
- attachement (adsorption)
- entry (penetration)
- synthesis
- assembly
- release
200
What is a common fact for all types of viruses?
no matter what the viral genome is, mRNA must be made from it somehow.
201
What are the types of viral genomes?
- dsDNA: transcription of minus strand
- ssDNA (+): synthesis of minus strand, has a dsDNA intermediate (replicative form)
- dsRNA: Transcription of the minus strand
- ssRNA (+): used directly as mRNA
- ssRNA (-): Transcription of minus strand
- ssRNA (+) retrovirus: reverse transcription, forms dsDNA intermediate -> transcription of minus strand
202
How are ssRNA (+) translated?
- directly translated into viral proteins
- it is 5'-3' as the host mRNA, allowing for protein synthesis
203
How are ssRNA (-) translated?
- not readable by the host ribosome
- 3'-5' RNA is converted to 5'-3' by viruses' RNA-dependent RNA Polymerase
- positive sense RNA functions as mRNA and is translate into protein by the ribosome
204
What are characteristics of positive strand RNA viruses?
- the sequence of the genome and the mRNA are the same
- this mRNA can be translated immediately after entering the cell by host RNA polymerase
- genomes encode RNA replicase which is an enzyme that replicates viral RNA
205
What are some examples of ssRNA (+) viruses?
- poliovirus
- COVID
- West Nile virus
- dengue virus
206
What are characteristics of the influenza virus?
- causes infection of the upper and lower respiratory tract
- enveloped
- ssRNA (-)
- family: orthomyxoviridae
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What types of influenza cause seasonal epidemics?
- influenza A and B
208
What are characteristics of influenza A?
- exist in many species
- different strains infect different species
- pig often acts as an intermediate host
- considered zoonotic pathogens
-constantly changing its genome and is generally responsible for the large flu epidemics
209
Why are influenza A viruses considered zoonotic pathogens?
- genetic reassortment in an intermediate host allows emergence of new hybrid strains
210
What are characteristics of influenza B?
- only found in humans and maybe seals
- may cause less severe reaction than type A
- responsible for 1/3 of influenza virus infections
- more limited host-range
211
What is the structure of the influenza virus?
- virons of type A and V have 8 different RNAs
- in influenza A, they encode for 11 proteins
- virus replicates in the cell nucleus like DNA viruses
- virus requires the host machinery to cap the mRNAs
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What determines the subtype of influenza virus?
surface glycoproteins (H & N)
213
What does the H stand for in surface glycoproteins?
- hemagglutinin
- binds to sialic acid on the surface of a host
214
What does the N stand for in surface glycoproteins?
- neuraminidase - cleaves sialic acid
215
What does antigenic drift mean?
- small genetic changes in surface-exposed proteins that alter a few individual epitopes on an antigen
- continuous and occurs often
- can cause small mutations
216
What is antigenic shift?
- large genetic change that allows the virus to evade host immunity, resulting in an epidemic/pandemic
- can cause a new sub type
217
When is antigenic shifting likely to occur?
when multiple virus strains infect the same organism
218
What types of influenza does antigenic drift occur?
- all types because it occurs in only humans
219
what types of influenza virus are antigenic drifting?
- only in type A because it infects more than just humans
220
What kind of damage can influenza do to the body?
- the adaptive immune response can induce damage to lung tissues like ciliated epithelial cells that line the respiratory tract
221
What causes the symptoms of the flu?
- inflammation in the bronchial tree and Cytokine storm during the inflammatory response
222
What does inflammation and damage to the epithelial cells from the flu result in?
- increased susceptibility to secondary bacterial infection due to an unregulated inflammatory response in the lungs
223
What type of bird flu is becoming newly transmitted between cattle and humans?
- H5N1
224
What are generic definitions of vaccines?
-- manipulation of adaptive immune system in an antigen-specific manner to mimic infection by a specific pathogen
- results in stimulation of protective immunity against a pathogen without causing the disease of that pathogen
225
What are the 5 types of modern vaccines?
1. Attenuated/weakened microbes (live vaccine where virulence has been artificially reduced)
2. Killed microorganisms
3. Sub-cellular microbial fragments or toxins
4. Microorganism DNA (genetically engineered into a "delivery construct" eg. replication defective viral shell)
5. Microorganism RNA (genetically engineered into a "delivery construct" eg. a liposome) mRNA vaccines have the greatest potential and fewest drawbacks
226
How do you make a weakened virus for a viral vaccine?
Being passed through animal or human cells until it picks up mutations and is less able to cause disease.
227
How would you inactivate a virus for a viral vaccine?
Virus is exposed to chemicals or heat that render it uninfectious
228
How would you replicate a viral vector for a viral-vector vaccine?
Replicates within cells. Usage of this vaccine when existing immunity is present will weaken the effectiveness of the vaccine.
229
How is a non-replicating viral vector vaccine used?
-No licenced vaccines use this
-Used in gene therapy
-Booster shots needed for long term immunity
230
How does the COVID vaccine work?
1. Lipid nanoparticles surround the viral mRNA
2. The immune system recognizes the spike proteins as foreign. Antigen-presenting cells will present fragments to helper T cells
3. Antibodies mark infected cells for destruction and prevent spikes from COVID virons from attaching to our cells
231
What are some side effects of the COVID vaccine?
-Headache
-Fever and chills
-Body aches
232
What are the types of viruses ranging from quickest recovery to longest?
- infection virus (acute - most RNA viruses)
- viral RNA viruses (Acute)
- latent (comes back randomly in the future, sedentary until then - herpesvirus)
- persistent (slowly declines over the course of recovery, but can take years - HIV)
233
What happens in latent viruses?
- may produce infectious visions months, years or decades later to infect a new group of people
- some can evade immune control and continuously produce virons (RNA)
234
What are examples of latent DNA viruses?
- Varicella (chickenpox) to shingles
- herpes simplex to ulcers
- epstein-barr to viral shedding (mononucleosis)
235
where are the places that shingles can arise and how serious are they?
- side of face (more serious)
- eyes or mouth (emergency)
- shoulders (common)
- ribs and waist (common)
236
What are the characteristics of shingles during the early stage?
- Days 1-5
- smaller rash
-bumps with less depth
237
What are the characteristics of shingles during the mid stage?
- Days 5-7
- larger rash
- fluid-filled bumps
238
What are the characteristics of shingles during the late stage?
- Days 7-10
- blisters are crusted over
239
What are examples of latent RNA viruses?
- Hepatitis C (HCV)
- Human immunodeficiency virus (HIV)
- Sars-CoV-2
240
What are symptoms of ME/CFS?
- overwhelming fatigue that is not improved by rest
- may worsen after any activity whether physical or mental (PEM)
241
How many Americans are estimated to suffer from ME/CFS?
- 836,000 to 2.5 million
242
What percentage of people with ME/CFS have not been diagnosed?
- 90%
243
How much money does ME/CFS cost the U.S. economy annually?
$17-$24 billion
244
What are the potential causes of ME/CFS?
- people with ME/CFS often have their illnesses begin in a way that resembles flu
- 1 in 10 people who become infected with epstein-barr virus, ross river virus, or coxiella brunette will develop ME/CFS symptoms
- viral incidence, but mechanism is unknown
245
Why is it hard to get help for ME/CFS?
-med schools don't offer training on it
-Illness is misunderstood
-More education for doctors on making a timely diagnosis and approprate care for patients
-no specific tests exist
-no definitive cause
-no cure
246
What was info on ME virus like prior to 2020?
-Hard to find
-underfunded
-Unrest film advocated and spurred better care and research funding and visibility
247
What is long COVID (PASC)?
-Ongoing, relapsing, or new symptoms or other health effects after the acute phase of COVID
-can last weeks months or years
-mostly people who had severe covid, but can impact ANYONE WHOS BEEN INFECTED
-EVEN IN PEOPLE WITH MILD ACUTE PHASES
248
True or false: People not vaccinated for covid have a higher risk of developing long covid
true
249
true or false: People can be reinfected with covid and each time they have a risk of developing long covid
true
250
True or False: in july 2021, long covid was added as a recognized condition that could result in disability under the ADA.
true
251
Which organ systems does long covid affect?
-Heart
-Lungs
-Immune system
-Pancreas
-GI Tract
-Neurological system
-Kidneys, spleen, and liver
-Blood vessels
-reproductive system
252
How does long covid affect heart
Symptoms: Chest pain, palpitations
Pathology: POTS, Cardiac impairments, mycocardinal inflammation
253
How are lungs affected by long covid
Symptoms: Cough, Dyspnoea
Pathology: Abnormal gas exchange
254
How does long covid affect Immune system
Pathology: MCAS, autoimmunity
255
How does long covid affect pancreas
Pathology: diabetes, pancreas injury
256
How does long covid affect GI tract
Symptoms: Abdominal pain, Nausea
Pathology: Gut dysbiosis, Viral persistence/ vrial resivoir
257
How does long covid affect neurological system?
Symptoms: Cognitive impairment, fatigue, Disordered sleep, memory loss, tinnitus
Pathology: DYseutonomia, ME/CFS, neuroinflammation, reduced cerebral blood flow, small fibre neuropathy
258
How does long covid affect kidneys, liver, and spleen?
Pathology: organ injury
259
How does long covid affect blood vessels
Symptoms: Fatigue
Pathology: Coagulopathy, deep vein thrombosis, endothelial dysfunction, microangiopathy, microclos, pulmonary embolism, stroke
260
How does long covid affect the reproductive system?
SYmptoms: erectile dysfunction, increased severity and number of premenstral symptoms, irregular mentration
Pathology: reduced sperm count
261
What is a competent outsider?
- a non-expert who posses the skills to evaluate credibility of:
+ source of information
+ expertise of information giver
+ reputation of information (not = to success)
+ trustworthiness
+ track record
+ who has what to gain?
262
What is the definition of misinformation?
- claims that are false but not deliberately designed to deceive
263
What is the definition of disinformation?
- falsehoods that are spread deliberately
264
who reviews scientific information in order for it to be credible?
- scientists with expertise in the relevant domain
265
What is the definition of scientific consensus?
- the answer to empirical questions is so universally agreed that it is no longer of any great interest to investigate, and the field has moved on?
266
What are the 2 main types of knowledge?
- Consensus science
- science-in-the-making/cutting edge
267
What is consensus science?
- tested/validated independently over Long periods of time
- broad agreement among experts
- additional contributions are refinements
268
What is science-in-the-making/cutting edge type of science?
- ideas/questions where we lack consensus.
- knowledge that is open to question
- advanced by experts who may disagree
- resolution requires further investigation, time, more studies
- additional contributions can be paradigm shifting or breakthroughs
269
What are characteristics of misinformation?
- inciting doubt and simeoultaneously demanding 100% certainty from science
- using uncertain language (maybe, possibly, could)
- misrepresents data
- misinterprets data
- correlation/causation confusion
- leveraging the limits off science into an unjustified skepticism
270
What are some of the best qualities and biggest risks of social media?
- information travels fast
- accessible - anyone can post/share anything
- free to users
- minimally regulated
- open forum for the exchange of ideas and experiences
271
What are the primary goals of social media?
- generate ad revenue
- get many views/users
- have users spend a lot of time on the platform
272
What are 3 main questions one should ask when confronted with science on social media?
1) who is the source
2) how do they know this/what are their credentials?
3) what are they trying to sell me?
273
How do you establish credibility of a source?
-who is it
-any ideological or political bias
-algorithm will just show you what you want to see based on ur history
-domains outside of .gov can be purchased
274
How do you establish expertise for a source?
-Theres usually no both sides to science
-Qualifications
-expertise must be relevant
-reputation not the same as expertise
275
How can you tell if someone is trying to sell something to you?
-supplements
-building a following/lifestyle
-posts are ads
-product placement
