Lec 22: Digestive infections Flashcards
what is the #2 major portal of entry?
the digestive tract
how do pathogens enter through to the digestive system?
-Direct contact with oral bacteria of other people
-Fecal-oral route
what does the fecal-oral route contain?
-Consumption of food or water contaminated with feces.
-Direct contact with feces (hands to mouth)
-Oral-anal sex
-Source of feces: animal or human
what does the digestive system comprise of?
Digestive tube organs and accessory organ
what is stomatitis?
inflammation of the mouth
what is gingivitis?
inflammation of the gingiva (gums)
what is periodontitis?
inflammation of the periodontal membrane
what is esophagitis?
inflammation of the esophagus (food pipe)
what is gastritis?
inflammation of the stomach
what are the upper digestive tract accessory organs?
teeth, gums, periodontal membrane, tongue, and salivary glands
what is enteritis?
inflammation of the small intestine
what is colitis?
inflammation of the large intestine
what is pancreatitis?
inflammation of the pancreas
what is hepatitis?
inflammation of the liver
what are the accessory organs of the lower digestive tract?
pancreas, liver, and gall bladder
what are the flushing actions of the digestive system?
-Peristalsis
-Vomiting
-Diarrhea
-Dysentery
what is peristalsis?
rhythmic contraction and relaxation of intestine muscles, sent to anus
what is vomiting?
expulsion of food through mouth
what is diarrhea? what does it indicate?
increasing in the expulsion of feces through the anus (this indicates abnormal functioning of the small intestine)
what is dysentery? what does it include?
diarrhea + blood, mucus, or pus in feces. (this indicates abnormal functioning of the large intestine)
what is the difference between diarrhea and dysentery?
Diarrhea is just diarrhea, whereas dysentery is diarrhea with blood, mucus, or pus.
Diarrhea is the abnormal functioning of the small intestine, whereas dysentery is the abnormal functions of the large intestine.
how is stomach acid a defense mechanism?
by killing most pathogens
is the normal microbiota in the digestive tube a defense mechanism?
yes
what are two examples of upper digestive infections?
- Dental caries or cavities
- Periodontal disease
what are dental caries?
they are cavities
what disease of dental caries?
it is the disease of the crown of tooth
what is the crown of the tooth?
the part of the tooth above the gumline
what is the etiology of dental caries? (what is it caused by?)
-Streptococcus spp. especially S. mutans (which are Gram + cocci).
-Lactobacillus spp. (which are Gram + rods)
Other bacteria
what is the epidemiology of dental caries? how is it spread, which population does it affect, and what can cause it?
-You get it via direct contact with oral bacteria of other people, especially parents.
-Age is a factor: you have fissures in your tooth when you are young and old
-Genetics is a factor as well
-Diet high in sucrose can cause dental caries as well
how does a diet high in sucrose cause dental caries?
A high-sugar diet:
-Promotes capsule formation (attachment)
-Promotes lactic acid production (creates holes)
what is the pathogenesis of dental caries?
Initiation: attaches to teeth using capsules; it forms plaque, which is a biofilm
Progression: dissolves enamel with acids
what are the symptoms of dental caries?
-holes
-pain if the hole reaches the pulp since the pulp has nerves
-abscess due to inflammation
-if it is bad, the crown may break off
what is the treatment like for dental caries?
-Fillings
-Root canal
what is the prevention like for dental caries?
-Dental care
-Fluoride treatment
-Low sucrose diet
-Sealants in children
what is the periodontal membrane?
It holds to tooth to the bone
what is the etiology of periodontal disease?
It is caused by primarily Gram (-) anaerobic rods
what is the epidemiology of periodontal disease?
-you get it via contact, esp with parents and partners
-Age: common in over 35 years of age
-genetics is a factor
-smoking: nicotine lowers the blood flow to the teeth
-pregnancy: immunocompromised, so the oral bacteria overgrow leading to inflammation
what is the pathogenesis of periodontal disease?
Before the periodontal disease, inflammation starts.
-Plaque forms at the gum-tooth junctions
-Plaque and Ca salts = calculus or tartar
-Gingivitis starts initially, which is pink in the sink
-Later periodontitis can cause the tooth to fall
what are the symptoms of periodontal disease?
-Red swollen gums initially
-Gums start to recede from tooth over time
-Tooth will eventually fall out
what is the treatment of periodontal disease?
-Deep cleaning under the gums
-Gingival flap surgery: cut the gums, flip them over, clean up, and sow them back
-Antibiotics
what is prevention for periodontal disease?
-Similar to caries
-Stop smoking
-Flossing in key!!
what can be some possible complications of periodontal disease?
-Endocarditis if heart disease is present
-It can cause premature birth
Periodontal disease: Researchers think that oral bacteria can cause diseases like…
-Rheumatoid arthritis: joints
-Alzherimer’s: brain
-Atherosclerosis: heart vessels
-Evidence: fewer cases of respiratory-induced pneumonia if patients’ oral hygiene is good
which of the following is not a risk factor for dental caries and periodontal disease?
1. Contact with oral bacteria from parents
2. Winter season
3. Diet high in sucrose
4. Genetics
- Winter season
what are 4 lower digestive tract infections?
- Bacterial gastroenteritis
- Viral gastroenteritis
- C. difficile colitis
- Hepatitis A, B, and C
what is bacterial gastroenteritis?
inflammation of the small intestine
what causes bacterial gastroenteritis?
E. coli (gram - rod)
Salmonella enterica (gram - rod)
Campolybacter jejuni (gram - curved rod)
Other bacteria including typhoid, cholera, etc.
what are two types of E. coli toxins that cause bacterial gastroenteritis? what happens?
- Enterotoxigenic E. coli (ETEC):
-Produces toxins
-Spreads via fecally contaminated food and water
-Major cause of diarrhea among travelers and children in developing countries - Shiga-toxin-producing E. coli (STEC): O157:H7:
-Spreads via consumption of improperly cooked cattle meat
how does Salmonella enterica cause bacterial gastroenteritis? like how do you contract it
you usually get it via improperly cooked eggs/chicken
how do you contract campolybacter jejuni when causing bacterial gastroenteritis?
by improperly cooked chicken
what is the epidemiology of bacterial gastroenteritis?
-Fecal-oral route from animals or people
-Contaminated food (esp. beef, poultry, eggs), water, or milk
-Petting zoos, pet birds, and reptiles
what is the leading cause of bacterial diarrhea in the US and is found on 90% or more of raw poultry?
Campolybacter jejuni
what is the pathogenesis of bacterial gastroenteritis? what does it affect and what does the severity depend on
-It affects the small and large intestine
-The severity depends on the virulence factors
what are the symptoms of bacterial gastroenteritis?
-Vomiting/diarrhea or Dysentery
-Cramps
-may or may not have fever
what is the treatment for bacterial gastroenteritis?
-Fluid and electrolyte replacement (IV or oral)
-Sometimes antibiotics, some have resistance
-Usually self-limiting within 7-10 days
should you take anti-diarrheal drugs when you have bacterial gastroenteritis?
No, it’s not the best idea if you are a healthy person. It varies case to case
what is the prevention like for bacterial gastroenteritis?
-Proper precautions while cooking meat and eggs
-Drink clean water, milk, and juices
-Wash hands after handling or petting animals
what are 2 possible complications of bacterial gastroenteritis?
-Hemolytic uremic syndrome (with O157:H7)
-Guillain-Barre syndrome (with C. jejuni)
what happens with hemolytic uremic syndrome?
It is a possible complication of bacterial gastroenteritis with the strain O157:H7.
-The toxin affects capillaries in kidneys promoting inflammation and clotting
-As RBCs pass through these semi-clogged capillaries, they get shredded
-This can lead to kidney failure
what happens with Guillain-Barre syndrome?
It is a possible complication of bacterial gastroenteritis with C. jejuni.
-It is an autoimmune disorder
-When Abs attack the myelin sheaths of neurons causing progressive paralysis
what is the etiology of viral gastroenteritis?
It is caused by norovirus and other viruses including rotavirus.
what is the epidemiology of viral gastroenteritis? how is it transmitted, is it contagious, and where is it common?
-It is highly contagious!
-It is transmitted through the fecal-oral route and aerosolized vomit
-It is a common HAI
what is the pathogenesis of viral gastroenteritis? (what part of the body does it affect)
it affects the stomach and upper small intestine
what are the symptoms of viral gastroenteritis?
Vomiting/diarrhea.
Often called the stomach flu
what is the treatment of viral gastroenteritis?
-Anti-emetics as needed to prevent dehydration
-Self-limiting within 2-3 days
what is the prevention of viral gastroenteritis?
-it is hard to prevent
-hand-washing
-isolation
what is the most important treatment for gastroenteritis of any cause?
1. Fluid and electrolytes
2. Antibiotics
3. Antidiarrheal medications
4. Bland diet
- Fluid and electrolytes
what is Clostridiodes difficile colitis?
the inflammation of the large intestine
what is the etiology of Clostridiodes difficile colitis?
Caused by C. diff - which is a Gram + anaerobic rod and forms endospores
what is the epidemiology of Clostridiodes difficile colitis?
-It is transmitted through the fecal-oral route
-It is the most common cause of HAI infectious diarrhea
-Associated with previous antibiotic use (esp. broad spectrum) that destroys the normal microbiota
-THere is an increased risk with age, immunocompromise, prolonged hospital stay, or GI disease/surgery
how is Clostridiodes difficile colitis an HAI?
-Healthcare workers can transmit to patients.
-Environmental contamination with endospores
are there asymptomatic carriers of Clostridiodes difficile colitis?
yes
why aren’t antibiotics that successful for Clostridiodes difficile colitis?
because antibiotics cannot kill the endospores
what is the pathogenesis of Clostridiodes difficile colitis? what does it affect?
it affects the large intestine
what are the symptoms of Clostridiodes difficile colitis?
-Diarrhea/dysentery with distinct color
-Cramps
-May or may not cause fever
what is the treatment for Clostridiodes difficile colitis?
-Stop using underlying antibiotics
-Use alternate antibiotics such as metronidazole, vancomycin, and fidaxomicin - but endospores are not killed!
-Some resistant strains are emerging
can you use probiotics for Clostridiodes difficile colitis?
yes, after antibiotics are taken
can there be a fecal transplantation for Clostridiodes difficile colitis?
yes
in Clostridiodes difficile colitis, are you likely to get infected with C. diff again after the first exposure?
Yes, the 1st recurrence is in 20% of the cases and 2nd recurrence in 40% of the cases, and so on
what are 2 possible complications of Clostridiodes difficile colitis?
- Pseudomembranous colitis
- Toxic megacolon
what happens with Pseudomembranous colitis?
Pseudomembranous colitis is a complication of C. diff: It causes -
-Inflammation of the lining of the colon which causes the formation of yellow pseudomembrane (this is dead colon cells + mucus + WBCs)
-Colon function declines and it is painful
what happens with Toxic megacolon?
Toxic megacolon: inflated colon that is a complication of C. diff:
-Due to the production of toxins by C. diff that inhibit smooth muscle contraction
-The colon becomes flaccid and blows up
-It can rupture and be life-threatening
-Colectomy is used to remove the affected colon
what is hepatitis?
the inflammation of the liver
what is hepatitis A caused by? AKA what is its etiology?
Hepatitis A virus (HAV)
what is the epidemiology of Hepatitis A? How is it spread?
It is spread through the fecal-oral route.
-Contact with fecal-contaminated food, water, or fomites.
-Oral-anal sex (via feces NOT semen)
what type of disease is Hepatitis A?
It is an Acute disease ONLY, no long-term carriers
what is the pathogenesis of Hepatitis A?
-It invades liver cells, causes damage, and is removed via bile into feces.
can Hepatitis A be asymptomatic?
yes
what are the symptoms of Hepatitis A?
Pain in abdomen
V/D
fever
fatique
jaundice (yellowing of skin)
what is the treatment of Hepatitis A?
None, recovery is usually 2-6 months
what is the prevention for Hepatitis A?
Inactivate vaccine
Immune globulin pre- or post-exposure
what is the etiology of Hepatitis B?
Caused by Hepatitis B virus (HBV)
what is special about the viral replication cycle of the Hepatitis B virus?
-HBV is a DNA virus, but doesn’t use the usual DNA-dependent DNA-polymerase replication cycle.
Instead, HBV gets replicated from DNA to RNA to DNA again.
Using DNA-dependent RNA-polymerase and Reverse Transcriptase
what type of virus is HBV?
retrovirus
how do we use the replication cycle of HBV to our advantage?
By targeting reverse transcriptase
what is the epidemiology of Hepatitis B? What does it contaminate?
It is contaminated blood or semen
It can be sexually transmitted (STD)
can Hepatitis B be transmitted to babies?
yes, at birth
are there chronic carriers of Hepatitis B?
yes, but not all pts go chronic. some are acute
what is the acute phase, and what amount of cases can become chronic in adults and infants in Hepatitis B?
-The acute phase is asymptomatic or sever
-It can become chronic in 10% of cases in adults
-It can become chronic in 90% of infants
what are the symptoms of Hepatitis B?
same as Hepatitis A
what is the treatment of Hepatitis B?
It is ONLY for chronic patients
-Reverse transcriptase inhibitors
-Interferon (secreted by virus-infected cells)
-Liver transplant
what is the prevention for Hepatitis B?
-Blood-borne precautions (similar to HIV)
-Protein subunit vaccine (as soon as the baby is born)
-Immune globulin post-exposure (anti-serum with Abs against Hepatitis B)
what are the possible complications of Hepatitis B?
Chronic cases can develop cirrhosis or liver cancer
what is the etiology of Hepatitis C? what virus causes it?
caused by Hepatitis C virus (HCV)
what is contaminated in Hepatitis C?
Contaminated blood, rarely semen.
This is how is spreads
can Hepatitis C be transmitted at birth?
Yes, it can be transmitted to babies at birth
are there acute or chronic carriers of Hepatitis C?
chronic carriers (most cases)
what is the acute and chronic phase of Hepatitis C? what is the percentage for chronic cases?
-Acute phase is asymptomatic or mild
-Can become chronic in over 80% of cases
what are the symptoms of Hepatitis C?
same as Hepatitis A and B
what is the treatment like for Hepatitis C?
ONLY for chronic pts:
-Antivirals
-Interferon
-Liver transplant
what is prevention like for Hepatitis C?
Blood-borne precautions (similar to HIV) to stop transmission
Vaccines are being developed
what are the possible complications of Hepatitis C?
Chronic cases can develop cirrhosis or liver cancer
which type of viral Hepatitis is the one that goes chronic in the majority of the cases?
Hepatitis C
what is the difference between Hepatitis A, B, and C?
A:
-Acute
-Spreads through poop
-Vaccine
B:
-Spreads through blood
-STD
-Vertically transmitted
-Vaccine
C:
-Chronic
-Spreads through blood
-Vertically transmitted
-No vaccine yet
Most of the normal flora of the digestive system are found in the:
1. Mouth
2. Stomach
3. Small intestine
4. Esophagus
5. Large intestine
- Large intestine
Streptococcus mutans can produce dental caries because it:
1. Causes gingival inflammation
2. Destroys the periodontal ligaments around teeth
3. Produces a biofilm where lactic acid bacteria can thrive
4. Resists fluoride treatments
5. Adheres to the mucosal surfaces inside the mouth
- Produces a biofilm where lactic acid bacteria can thrive
The source most commonly associated with Salmonella and Campylobacter gastroenteritis is:
1. Unwashed vegetables
2. Unpasteurized juice
3. Undercooked poultry
4. Unchlorinated water
5. Uncooked fish (sushi)
- Undercooked poultry
Which of the following is a common cause of “stomach flu?”
1. Salmonella enterica
2. Norovirus
3. Campylobacter jejuni
4. Influenza A
5. E. coli
- Norovirus
What is unique about the hepatitis B replication cycle?
1. It needs neuraminidase to release from host cells
2. It synthesizes DNA from RNA
3. It cannot attach to host cells without a co-receptor
4. It synthesizes RNA directly from RNA
5. It forms resistant endospores
- It synthesizes DNA from RNA
Escherichia coli is normally found in the large intestine of humans. So, how can this bacterium be an etiologic agent of infectious gastroenteritis? How do you treat E. coli gastroenteritis if you get it? How can you prevent it?
E. coli comes in different forms. The strains that live in our large intestine are not pathogenic; in fact, they help protect us against pathogenic bacteria. However, there are also pathogenic strains that come from human and animal reservoirs. They are transmitted through the fecal-oral route and can cause gastroenteritis. These strains have specific virulence factors including potent toxins. Enterotoxigenic E. coli commonly affects the small intestine and causes “traveler’s diarrhea.” Shiga-toxin producing E. coli (O157:H7) commonly affects the large intestine, causing dysentery and potentially leading to the complication, hemolytic uremic syndrome (HUS). If you get E. coli gastroenteritis, you will need fluid and electrolyte replacement and possibly antibiotics. With HUS, hospitalization and aggressive treatment is required, but death still may occur. Prevention methods for E. coli gastroenteritis include: sanitary food handling and preparation (e.g. washing hands after handling meat, using separate cutting boards for meat and other foods, cleaning cutting boards well and cooking meat), drinking clean water, drinking pasteurized beverages, especially milk, and washing hands after touching petting zoo or farm animals.
How are digestive infections transmitted?
Direct contact with oral bacteria of other bacteria.
Fecal-oral route (including consumption of contaminated food/water, direct contact with feces, oral-anal sex, and the source of feces can be either animal or human).
What are the innate immune defenses in the digestive tract to get rid of pathogens?
Peristalsis, vomiting, and normal microbiota
Differentiate between hepatitis A, B, and C in terms of their transmission and course of
the disease (acute or chronic)
-Hepatitis A:
Acute
Transmitted through poop
Vaccine available
-Hepatitis B:
In adults, 90% acute & in infants, 90% chronic
Transmitted through blood and STD
Vaccine available
Vertically transmitted
-Hepatitis C:
Chronic
Transmitted through blood
Vaccine not available
Vertically transmitted
