Diseases of the Digestive System Flashcards
Chapter 25
How do microbes enter the digestive system?
fecal-oral route
What are examples of the fecal-oral route?
contaminated food & water (microbes + toxins)
How can we prevent microbes from entering
humans via the fecal-oral route? (3)
- good sewage treatment
- disinfection of drinking water
- proper food handling & cooking
Describe the microbes found in the mouth:
over 400 species of normal flora
Describe the microbes and pH of the stomach and small intestines (2):
- low pH
- few microbes
The lower the pH….. (the < or > the microbes)
the less (<) microbes
Describe the microbes in the large intestine (3):
- large # of bacteria
- anaerobes
- facultative anaerobes
What are the Bacterial Diseases of the Lower GI Tract? (4)
- Staphylococcal Food Poisoning
- Typhoid Fever
- Cholera
- Traveler’s Diarrhea (E. coli gastroenteritis)
What are the Viral Diseases of the Lower GI Tract? (2)
- Hepatitis
- Viral Gastroenteritis
Define Food Infection:
pathogen enters GI tract & multiplies
What happens if a microbe remains in the GI Tract?
infection becomes systemic
Define Food Intoxication:
ingestion of an exotoxin
What is another name for food intoxication?
food poisoning
What is another name for food poisoning?
food intoxication
Are symptoms in food intoxication caused by the microbe or by the toxin?
the toxin
What causes the symptoms of food poisoning?
the toxin
Define Gastroenteritis:
inflammation of stomach & intestinal mucosa
What are the common symptoms of microbes in the GI tract? (3)
- diarrhea or dysentery (diarrhea with blood & mucus)
- abdominal cramps
- nausea, vomiting
Which Bacteria causes Staphylococcal Food Poisoning?
Staphylococcus aureus
What is Staphylococcus aureus relatively resistant to?
drying
Describe Staphylococcus aureus (3):
- found in nasal passages & skin lesions
- tolerate high salt, organic compounds, & higher temps
- grows in custards, creamy salad dressing, sauces, ham
What is the incubation time for Staphylococcal Food Poisoning?
~2-6 hours
What are the Symptoms of Staphylococcal Food Poisoning? (3)
- diarrhea
- stomach cramps
- vomiting
How long does Staphylococcal Food Poisoning last in a healthy person?
24 hours
What does Staphylococcus aureus secrete?
an exotoxin that is an enterotoxin
What is an enterotoxin?
a toxin that affects the intestines
How are enterotoxins inactivated?
heat stabile: boil food 30 minutes
What Bacteria causes Salmonellosis?
Salmonella sp.
Describe Salmonella sp. (2):
- gram (-)
- rod
Where is Salmonella sp. found? (4)
- intestines of many animals
- eggs + egg products
- poultry
- pet reptiles (turtles & iguanas)
What does Salmonella enteritica cause?
salmonellosis
What does S. typhi cause?
typhoid fever
What bacteria causes Typhoid Fever?
S. typhi
How do we differentiate between different species of bacteria?
cell surface antigens
What is Vi Ag?
Capsule Ag
What is H Ag?
Flagella
What is the incubation period for a Food Infection?
12-36 hours
What are the steps of a Food Infection? (3)
- microbe enters GI and epithelial cells lining intestines
- multiplies within cells + enters lymphatics
- moves to blood + other organs
What are the symptoms of Food Infection? (4)
- fever
- nausea
- abdominal cramps
- diarrhea
How long do Food Infections typically last?
a few days
What bacteria causes Typhoid Fever?
Salmonella typhi
Where is Salmonella typhi found?
In humans only (no animals)
What are the Virulence Factors of Salmonella typhi? (3)
- endotoxins
- can replicate within macrophages
- can enter intestinal epithelial cells
How is Typhoid Fever spread? (2)
- ingested
- fecal-oral route
What is the incubation period for Typhoid Fever?
~2 weeks
What is the path that Typhoid Fever takes in the body? (4)
- microbe enters intestines + penetrates intestinal lining
- enters lymphatic
- re-enters intestines + pierces intestinal wall leading to bleeding
- microbe shed in feces
What are the Symptoms of Typhoid Fever? (4)
- fever
- weakness
- “rose spots” on trunk
- diarrhea (appears weeks later)
How long does Typhoid Fever last for?
2-3 weeks
Is Typhoid Fever fatal?
It can be because of internal bleeding (intestinal wall)
Who are the typical carriers of Typhoid Fever?
food handlers
Where is Typhoid Fever found in the human body?
Gallbladder (1-3%)
Who is an example of a Typhoid Fever Outbreak?
Typhoid Mary: asymptomatic food handler that caused various outbreaks
What are the Four F’s of Typhoid Fever?
- Feces
- Flies
- Fingers
- Food
How is Typhoid Fever Prevented? (3)
- proper sewage treatment
- proper water treatment
- proper food handling
What Vaccines are available for Typhoid Fever? (2)
- subunit vaccine
- live oral vaccine
What bacteria causes Cholera?
Vibrio cholera
Describe Vibrio cholera (3):
- gram (-)
- rod (comma shaped)
- high pH
What is the most common serotype of Vibrio cholera?
O:1
What is O:1 serotype divided into?
2 major biovars (based on biochemical properties)
What are the 2 biovars serotype O:1 is divided into?
- El Tor (South America)
- Classical
How is Cholera spread? (2)
- ingestion of contaminated water
- improperly cooked seafood
What is the path that Cholera takes in the body? ()
- microbe enters intestines (stays there)
- adheres to intestinal lining (exotoxin = choleragen)
Is Cholera an invasive pathogen?
No
Does Cholera release and endotoxin or an exotoxin?
Exotoxin
What is the Exotoxin that Cholera releases?
Choleragen
What does Choleragen do?
- activates Adenyl Cyclase (enzyme): increases cAMP production
What does Adenyl Cyclase do?
Increases cAMP production
What is c-AMP?
increases secretion of chloride + bicarbonate out of blood into lumen of intestines
What happens when sodium cannot leave intestines into blood?
Diarrhea
What are the Symptoms of Cholera? (5)
- vomiting
- severe “rice water” diarrhea
- coma
- convulsion
- fever
What is the Incubation period for Cholera?
few hours - few days
Why would someone die from Cholera?
Dehydration within 48 hours if untreated
What Treatments are there for Cholera? (2)
- replace electrolytes + water
- tetracycline
How is Cholera prevented? (2)
- proper water treatment
- proper food cooking + storage (seafood)
What Vaccines are there for Cholera? (2)
- killed cell vaccine (part of toxin)
- oral vaccine (not very effective)
What bacteria causes Traveler’s Diarrhea?
E. coli
Describe E. coli (3):
- facultative anaerobic
- gram (-)
- rod
(T/F) E. coli is an Enterobacteriaceae
True
(T/F) Most E. coli are pathogenic
False
What do most pathogenic strains of E. coli contain?
Fimbriae (for attachment to intestinal cells)
Do all E. coli produce toxins?
No, only some
What are the symptoms of Enterotoxigenic E. coli?
watery diarrhea
What is the major cause of Enterotoxigenic E. colli?
contaminated water
Is Enterotoxigenic E. coli an invasive form?
No
What type of E. coli is in Enterohemorrhagic E. coli?
serotype O158:h7
What does Enterohemorrhagic E. coli (EHEC) release?
enterotoxin = Shiga like toxin
What is the cause of Enterohemorrhagic E. coli?
ingestion of undercooked meats or raw milk
What is the path of Enterohemorrhagic E. coli?
Vero toxin -> hemorrhage -> dysentery
What is dysentery?
bloody diarrhea
What is the major reservoir for Enterohemorrhagic E. coli?
Cattle
What is the major complication for Enterohemorrhagic E. coli?
hemolytic - uremic syndrome = leads to kidney failure
What is Hepatitis?
inflammation fo the liver
What are the 5 different types of hepatitis?
- A
- B
- C
- D
- E
Which virus causes Hepatitis A?
Picorna Virus (RNA)
Which virus causes Hepatitis B?
Hepadna Virus (DNA)
Which virus causes Hepatitis C?
Flaviviridae (RNA)
What virus causes Hepatitis D?
(RNA)
What virus causes Hepatitis C?
Caliciviridae (RNA)
What is the second most frequent reported infectious disease in the U.S.?
Hepatitis
Describe the Picorna Virus (5):
- hepatitis A
- naked
- icosahedral
- single stranded
- RNA
Where does the Picorna Virus replicate in?
the intestines
Which Hepatitis is known as the infectious Hepatitis?
Hepatitis A
How does Hepatitis A spread in the body?
intestines -> blood -> liver, spleen etc.
How is Hepatitis A spread?
fecal-oral route
What are the main causes of Hepatitis A? (2)
- contaminated water
- contaminated food (shellfish)
How is Hepatitis A shed from the body?
through feces
What are the Symptoms of Hepatitis A? (3)
- fever
- headache
- jaundice
What is the incubation period of Hepatitis A?
~ 2- 6 weeks
Is Hepatitis A chronic or acute?
Acute
What Vaccines are available for Hepatitis A?
killed vaccine (2 doses)
Describe Hepadnaviridae (5):
- hepatitis B
- enveloped
- icosahedral
- double stranded
- DNA
Which Hepatitis is known as the Serum Hepatitis?
Hepatitis B
How is Hepatitis B spread? (4)
- sexual intercourse (anal/oral)
- blood transfusions
- contaminated needles
- mother to child
How is Hepatitis B spread in the body?
virus -> liver replicates (also lymphoid tissues)
What are the Symptoms of Hepatitis B? (3)
- fever
- joint pain
- loss of appetite (leads to jaundice)
How long is the incubation period for Hepatitis B?
~4 - 26 weeks
Hepatitis B is Chronic in what percent of infected people?
10%
What characteristics do Chronic Carriers of Hepatitis B have? (2)
- virus source
- increased risk of liver cancer
What is Hepatocellular carnicoma?
liver cancer
What treatment is there for Hepatitis B?
alpha interferon
How is Hepatitis B prevented?
recombinant subunit vaccine (surface antigen)
Describe Flavivirdae (4):
- hepatitis C
- enveloped
- icosahedral
- RNA
Which Hepatitis is known as the NANB (non-A, non-B virus) Hepatitis?
Hepatitis C
How is Hepatitis C spread? (5)
- transfusions
- sexual
- needles
- razors
- tattoo
What are the Symptoms of Hepatitis C? (2)
- milder than other hepatitis in acute form
- causes high blood concentrations of alanine transferase
What is the Incubation Period for Hepatitis C?
2 - 4 weeks and 8 - 12 weeks
What percent of infected develop Chronic Hepatitis C?
50%
What is the Treatment for Hepatitis C?
combination of antivirals for various months (too expensive)
What Vaccines are there for Hepatitis C?
None (no immunity develops)
Describe Hepatitis D Virus (3):
- enveloped
- RNA
- defective
Can Hepatitis D cause infection by itself?
No, must co-infect with HBV
How is Hepatitis D spread?
similar to HBV
What are the Symptoms of Hepatitis D?
intensifies symptoms of HBV
What is the incubation period of Hepatitis D?
2 - 12 weeks
What can HBV and HDV do together?
extensive liver damage + higher mortality rate
Describe Caliciviridae (4):
- Hepatitis E
- naked
- single stranded
- RNA
Which Hepatitis is known as the Infectious NANB Hepatitis?
Hepatitis E
How is Hepatitis E spread?
fecal - oral route
Where is Hepatitis E found?
areas with poor sanitation
What are the Symptoms of Hepatitis E? (2)
- similar to HAV
- no chronic stage
In what group is Hepatitis E virus more common in?
adults
In what group does Hepatitis E have a higher mortality rate in?
pregnant women
What Vaccines are there for Hepatitis E?
None (no immunity produced)