GI System Flashcards
What is the digestive system composed of?
GI tract
Accessory Digestive organs
How is the GI tract protected from pathogen colonization?
Chemical, mechanical and cellular defences in place
Where in our body can you find gut bacteria?
Large Intestine
Small Intestine
Mouth
Stomach
What kind of microflora is most common in the mouth and what does it produce?
Bacteria is the most common
-some cause acid which leads to tooth cavities, tartar and calculus on teeth
Why is the esophagus and stomach largely free of microbes?
Because of its highly acidic environment (heart burn for esophagus)
-although some bacteria do survive the stomach
What bacteria survives in the stomach?
Hylicobacter pylori
- causes stomach ulcers
- Produced a compound around itself so it can survive in the acid
On the phylogenetic tree where is hylicobacter pylori?
Epsilon in the proteobacteria
Where are most microbes found in the body?
large intestines has the most species and numbers of bacteria
Which bacterium dominate fecal matter?
Bacteroides and E coli
How long does food stay in the large intestine and how does that relate to bacteria?
A long time so the bacteria have a longer time for microbial metabolic action and reproduction
What do bacteria in the large intestine produce?
Gas, acids and materials we can use such as vitamin K
Where on the phylogenictree would you find E. coli and bacteroides?
Both are gamma and apart of proteobacteria
What is dental plaque?
Coating of tooth enamel composed of polysaccharide slime materials excreted by bacteria
- mainly from streptococcus mutans
- moimized by brushing teeth and flossing
Why is dental plaque bad?
Complex bacterial communities build up and lives in the plaque, making acid as a by-product which attacks tooth enamel, leading to cavities
Why are cavities bad?
- Cosmetic problem, allows for improper processing of food
- May be an entry point for bacteria into the blood
What does dental plaque also cause?
Plaque will build up below th gum line and cause gum inflammation (gingivitis)
What is periodontitis?
Caused by gingivitis where tooth loss and bone damage in the mouth occurs
What does the term food poisoning mean?
Situations in which there is bacterial contamination of food and those bacteria grow IN the food and release toxins INTO the food which will exert their effects on the person who eats the food
-is an intoxication, NOT an infection
What does the term food borne infection mean?
Bacteria which re present in food and water which are taken into the digestive tract and which survive and grow
May be that once the bacteria are in the digestive tract that they will also produce toxins as with food poisoning situations, but the clear distinguishing feature is that in this case it is survival and growth of ingested bacteria in the digestive tract that allows disease
In terms of food poisoning, what are ways to destroy the toxin?
Heating the food prior to serving so the toxin is destroyed along with the bacteria the produced it
Does heating always work in killing toxins?
No, heating could kill bacteria that made the toxins but the toxin could NOT be destroyed. So once food is ingested it will still be poisonous
What is the key point in food poisoning?
It is bacteria that can grow in the food before it is eaten that is the problem.
-they produce toxins and it is the toxins that cause damage in the person, NOT DIRECTLY the bacterium that released the toxins
What is the major problem in food borne infections?
Bacteria contaminate the food and then those bacteria are transferred to the digestive tract when a person eats
-once bacteria are int he digestive tract disease begins
What are the 2 ways in which food borne infection agents cause damage?
- bacteria can grow in numbers and release toxins
2. Bacteria are invasive and to some degree cross the lining of the digestive tract or lodge in it to cause damage
How do you get rid of food more infections?
Usually heating the food prior to consumption kills the bacteria and there is no longer danger.
-may taste “off” so it contains no toxin and is safe to eat only IF the heating killed ALL bacteria
How do you avoid bacteria growth on food?
Once food is cooked cover it, then:
- Keep it got enough so no bacteria can live or reproduce
- Cool it fast to reduce bacteria reproduction
In food, where do bacteria like to grow?
Based on:
- Temperature
- O2 present or not
What does staphylococcus enterotoxicosis cause?
Bacterial food poisoning
- release enterotoxins into contaminated food (starch based or milk products)
- toxin is heat stable even after boiling for 30 mins
- once in intestine the toxin acts directly on the bacterium, if present, does not multiply but continues to release toxin
On the phylogenetic tree where is staphylococcus enterotoxicosis?
In the gram positive bacteria
What are the symptoms of staphylococcus enterotoxicosis and how do you avoid it?
Causes pain, diarrhea, fever, intestinal inflammation, vomiting
- self limiting and does not require specific treatment
- Avoid by proper food handling
What is wound botulism?
Occurs when toxins are produced in anaerobic tissue of wounds
What is the most common form of botulism?
INfant botulism and occurs when infants ingest endospores, commonly in honey
- causes floppy baby syndrome
- treated with penecilin
Cosmetically what is botulism used in?
Botulism toxins are used in botox
What is the difference between bacterial GI infections and intonations?
Infections have a longer incubation period because cells must establish themselves in the body after ingestion
-Ex: bacterial gastroenteritis produces inflammatory condition- dehydration is a common complication
What does clostridium botulinum cause?
Rare food poisoning
-strict anaerobe
On the phylogenetic tree where is clostridium botulinum?
Gram positive
How does c bot survive?
Survives as endospores in soil. Commonly found on root veggies
-endospores are very dry, heat resistant and lie dormant for years
How do you avoid C bot?
As long os veggie are processed properly there will be no problem and there will be enough O2 to prevent the germination of endospores
When do we see a problem with botulism?
- Food cooked on stove is allowed to cool slowly and also contains endospores
- if large enough, could have an anaerobic centre - Food canning/bottling prodecudes are not done properly. If non acidic doos are processed improperly, endospores will survive and germinate
- Improper storage of products like mushrooms which may contain contaminant spores
Where are food borne infections and food poisoning most common?
Salad bars
How are food borne infections and food poisoning the same?
Infection can also involve toxins being released by the bacteria but they are being released by live bacteria growing int he digestive tract
What does bacterial enteritis cause?
Bacteria directly inflame the lining of the intestinal tract. bacterial multiply and adhere to or invade lining and may cross into deeper tissue
-toxins not directly involved
How does bacterial enteritis cause diarrhea?
Inflammatory process interferes with water and ion absorption across the small intestine and results in water feces
What is Peyers patches?
Patches and intestinal cells on surface of lower third of small intestine are part of the lymphatic system nd have immune function, sometimes bacteria and prions actually gain entry to body through them instead of being destroyed
Where is Salmonellosis on the phylogenetic tree?
Gram positive
What are the main characteristics of salmonella?
- gram - ve
- small rods
- facultative anaerobes
- members of coliform group of bacteria
- common inhabitants of human intestine
What are common hosts of salmonella?
Intestine of poultry, wild birds, rodents
-may be deposited onto or into eggs
What are most cases of salmonella due to?
improper food preparation and preservations
What happens when you get salmonellosis?
Usually caused by S. eneritidis
- causes vomiting, fever and diarrhea
- bacteria cause fevers when their cells lyse in the digestive tract and release endotoxins from the cell wall
- antibiotics are not given
What is the story around typhoid marry?
Caused thousands of deaths in numerous outbreaks, was finally permanently jailed on an island because she refused to believe she was responsible and changed her name to continue working
What does S. typhi cause?
Spreads and grows in the blood
- Causes fever, heartache and reach the intestines and cross the intestinal lining and passed out in stools
- Not fatal in most
- can reside in gallbladder and released to the faces
- treated with chloramphenicol
What is shigellosis?
Bacterial dysentery occurs when sanitary conditions are lacking
- caused by shigella sonnei
- found in contaminated water and foods commonly in eggs veggies shellfish and diary
- toxin production in the intestinal epithelium triggers gastroenteritiis
- no vaccine available
Where on the phylogenetic tree is shigella species?
In gamma apart of the proteobacteria
What is shigellosis also known as?
Bacillary dysentery
- gram -ve rods, facultative anaerobes
- has a plasmid that codes for neuro toxin production. ends toxin is released when it lyses
- know to pass plasmids on to other bacteria like E. coli
- Can invade macrophage cells in payer patches
Where are the most common places to find shigellosis outbreaks?
In developed countries: day care centres due to improper hand washing practices
-children require active intervention due to large fluid and electrolyte loss
What does vibrio cholerae cause?
Gram -ve rods, flagella
- facultative anaerobes
- infect macrophage cells in peters patches in the lining of small intestine
- in contaminated water, intestinal tract, shells and body surfaces of marine animals
- some are bioluminescent
- produces enterotoxin
Where on the phylogenetic tree is vibrio cholerae?
In gamma within the proteobacteria
Where is vibrio cholerae most common?
In asia in contaminated food and water
What are the symptoms of vibrio cholerae ?
Copius watery diarrhea (rice water stool)
-may lead to potentially fats dehydration and Na loss
How do you treat vibrio cholerae ?
Oral replacement therapy
Sugar and salt fluid mix
What does champylobacteriosis cause?
Result from consumption of contaminated poultry or unpasturized milk
-one of the most common causes of bacterial gastroenteritis
may cause rare immune reaction (Guillain-Barre syndrome causing paralysis)
How is champylobacteriosis transmitted?
Campylobacter jejune is transmitted through the fecal-oral-route
What are characteristics of campylobacter?
Gram -ve, curved rod
- spread via food and water by touch
- causes enteritis
What does listeria monocytogenes cause?
listeriosis through fecal contaminated food, water and milk
-causes intrauterine infections, neonatal meningitis, abortions, kidney infections in transplant patients
What are characteristics of listeria?
- Does not cause enteritis
- Gram+
- affects pregnant women the most, elderly newborn and immune compromised
What does listeria do?
Crosses into blood from intestine via peters patches etc and spreads, lives in cells
Where on the phylogenetic tree does listeria reside?
Gram positive bacteria
