Microbial Diseases of the Digestive System

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Microbial Diseases of the Digestive System

• Chapter 25
• Lecture 23

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Introduction

• Diseases of the digestive system are
  __________only to diseases of the respiratory
  system
• Result from
• Ingestion of the microorganisms
• Ingestion of their toxins in ____ __ _______
• F______-O____transmission can be broken with
• Proper disposal and treatment of sewage
• Disinfection of drinking water
• Proper food preparation and storage

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Structure and Function of the Digestive System

• The gastrointestinal (GI) tract (or alimentary
  canal) consists of the mouth, pharynx, esophagus,
  stomach, small intestine and large intestine
  (essentially a tube)
• __________ structures teeth, tongue, salivary
  glands, liver, gallbladder, and pancreas

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The Digestive System
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The Digestive System

• Functions with __________ and _______ means,
  large food molecules are broken down into smaller
  ones that can then be transported in blood or
  lymph and reach ____________ cells
• Undigested materials, and large quantities of
  normal ____________ are eliminated as feces
  through the anus

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Normal Microbiota

• The mouth is home to a wide variety of bacteria
• The stomach and small intestine have ______ _____
  residents
• In the large intestine, ___ of the mass is
  microbial cells
• Help break down food materials and synthesize
  vitamins
• Lactobacillus, Bacteroides, Esherichia coli,
  Enterobacter, Klebsiella, and Proteus

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Bacterial Diseases of the Mouth

• Tooth decay
• Strep. mutans uses ____________ to form a sticky
  ________ which helps it to adhere to teeth
  forming dental plaque
• From glucose and fructose it forms ______ acid
  which destroys enamel
• Next G rods and filamentous bacteria can
  penetrate and destroy __________ tooth
• Other carbos arent used to make dextran
• Tooth decay (caries) are prevented by limiting
  ____________ and removal of plaque

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Periodontal Disease

• Bacteria living at the base of the tooth cause an
  _____________ response that can lead to bone
  destruction and tooth loss
• Streptococci, Actinomycetes and G- anaerobic
  (____ __________) bacteria
• Acute necrotizing ulcerative gingivitis is caused
  by spirochetes and Prevotella
• (trench mouth)

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Bacterial Disease of the lower Digestive System

• _________ is growth of pathogen in the intestines
• Incubation times can range from 12 hours to 2
  weeks
• Usually accompanied by a fever
• ___________ is from ingestion of preformed toxins
  (_________ us.with Fever) and symptoms appear
  1-48 hours
• Both infection and intoxication cause diarrhea,
  dysentery or gastroenteritis
• Treatment with fluid and electrolyte replacement

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Staphylococcal Food Poisoning

• Enterotoxin is produced in improperly stored
  foods when Staph. aureus in introduced into foods
  and allowed to grow at room temperature
• Boiling _______ ____ denature the enterotoxin
• Foods with high osmotic pressure (salts an
  sugars) and not cooked ____________ before
  consumption are most often causes
• Symptoms nausea, vomiting, diarrhea beginning
  ______ _____ hours after ingestion lasting up to
  24 hours.

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Staph Food Poisoning
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Shigellosis (Bacillary Dysentery)

• Four different species of Shigella
• Symptoms include ________ and mucous in stools,
  cramps, and fever
• S. dysenteriae results in _________ of the
  intestinal mucosa from the action of
  __________toxin, an unusually virulent toxin
• Tropical areas-death rate as high as 20

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Shigellosis
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Salmonellosis

• Many different species of Salmonella
• Nausea, abdominal pain, diarrhea, __________
  hours after ingesting the organism
• Septicemia can occur in infants and the elderly
• An endotoxin is suspected of causing the fever
• Mortality is lower than 1, recovery can result
  in a ___________ state
• Heating foods to 68ºC will us. kill Salmonella

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Salmonellosis
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Typhoid Fever

• Salmonella typhi transmitted by fecal oral
  contamination
• 2 week incubations, fever and malaise, last 2-3
  weeks
• Carriers have S. typhi in the ___________

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Cholera

• Vibrio cholerae produces an ___________ that
  alters membrane permeability of the intestinal
  mucosa
• Results in vomiting and watery diarrhea and a
  significant loss of body fluids _____ gallons
  per day!
• (rice-water stools)
• _____ mortality rate if untreated, ____ if
  fluids are replaced
• 3 day incubation period, symptoms last a few days
• Another form causes gastroenteritis in the US in
  contaminated seafood

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Epidemiology of a Cholera Outbreak in S. America
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Vibrio gastroenteritis

• Caused by two vibrio halophiles
• Symptoms begin within ___ _____ after eating
  contaminated mollusks or crustaceans
• Symptoms last a few days

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E. coli gastroenteritis

• Virulent strains of E. coli
• Enterotoxigenic
• Enteroinvasive
• Enterohemorrhagic
• Epidemic diarrhea in nurseries and underdeveloped
  countries, traveler's diarrhea, and (most severe)
  hemorrhagic colitits
• ________________ E. coli have Shiga-like toxins
  which cause inflammation and bleeding of the
  large intestine and can effect the kidneys to
  cause hemolytic uremia syndrome

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Other Bacterial Diseases

• Campylobacter second most common cause of
  diarrhea in US
• Transmitted in cows milk
• Helicobacter Peptic Ulcer Disease bacteria
  produces ammonia which neutralizes stomach acid,
  bacteria colonize the intestinal mucosa and cause
  peptic ulcers
• Bismuth compounds and several antibiotics are
  useful in treating peptic ulcers caused by
  Helicobacter
• 30-50 infected, of those, 15 go on to develop
  ulcers-type ____ __________ are more susceptible

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Helicobacter and Ulcers
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More Bacterial Diseases

• Yersinia ( not pestis) sp. are transmitted in
  meat and milk
• Can grow at refrigerator temperatures
• Clostridium perfringes (gas gangrene)
• A self-limiting ________________
• Spores germinate when us. meats are stored at
  room temp.
• Exotoxin produced when grows in intestines causes
  symptoms
• B. cereus (common soil organism) food
  contaminated with it can cause diarrhea, nausea
  and vomiting

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Viral Diseases of the Digestive System

• Mumps portal of entry-__________ tract
• _____ _________ days after exposure ?
  inflammation of the parotid gland, fever, pain
  while swallowing and after 4-7 days,
  ______________may occur
• Virus is shed in blood, saliva and urine
• MMR vaccine includes Mumps

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More Viral Diseases

• CMV inclusion disease very prevalent virus with
  infection approaching ______
• Cause is a large Herpes virus ___________________
  
• Transmitted in saliva, urine, cervical
  secretions, semen, breast milk
• Us. produces a subclinical or mild illness
• Severe in the immunosuppressed or when a _____
  _________ mother contracts the disease during
  pregnancy when death or severe damage to the
  fetus may result

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Viral Prevalence
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Hepatitis

• Inflammation of the liver
• Loss of appetite, malaise, fever, jaundice
• Viral causes include Hepatitis A D and maybe E
  and F, also CMV, EB viruses

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Hepatitis A

• Infectious Hepatitis
• _________ of all cases are sub-clinical
• Spread by contaminated food or water
• Virus grows in the cells of the intestinal mucosa
  and spreads to liver, kidneys and spleen
• Incubation period is _______ weeks, illness lasts
  for 2-21 days
• Virus is shed in feces
• A vaccine is available

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Hepatitis B

• A more serious hepatitis
• Transmitted by blood transfusions, syringes,
  saliva, sweat, breast milk and semen
• Blood is now tested _____ being given in
  transfusion
• Incubation period is 3 months
• Most people recover, but a ______ ____________
  course can occur
• The carrier state is also possible

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Other forms of Hepatitis

• Type C transmitted by blood, now also tested for
  before transfusion
• Incubation period 2-22 weeks
• Mostly the disease is mild, but also may take the
  chronic aggressive course
• Type ___________ emerging forms
• See Table 25-1

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Fungal Diseases of the Digestive System

• Disease Symptoms may result from the release of
  toxins called ______________
• __________ affect blood, nervous system, kidneys
  or liver
• Ergot poisoning a fungal disease on cereal
  crops, a smut cause hallucinations (like LSD)
  and restriction of blood flow in the limbs so
  severe that gangrene develops was common in the
  Middle Ages and known as St. Anthonys fire
  because of the blackening of affected limbs
• ??Salem witch trials

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More Fungal Diseases

• Aflatoxin produced by Aspergillus (common mold)
  and one which most commonly infects ___________
• Overall risk to humans is unknown, but
• Strong evidence to support the causal status in
  cirrhosis of the liver and liver cancer in other
  parts of the world where aflatoxin contamination
  is more common

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Protozoan Diseases

• Usually ingested as resistant ________ and shed
  in the same form after the protozoan completes
  its life cycle
• Giardiasis attach to intestinal mucosa
• Produce a prolonged diarrheal disease
• Malaise, nausea, gas, weakness, weight loss and
  cramps
• Odor of _________ __________ is distinctive
• 7 of the US popn are carriers and many wild
  animals, esp. beavers disease of backpackers
  who drink contaminated waters
• Cysts are relatively _____________ to chlorine,
  so boiling or filtration is nec. to remove from
  water

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Protozoan Diseases (cont.)

• Crytosporidiosis oocysts in water contaminated
  with animal wastes, esp. cattle. Filtration and
  chlorination both sometimes fail. _____ oocysts
  may be an infective dose!
• Cholera-like diarrhea of 10-14 days duration
• Becomes life threatening in the
  ______________________
• Cyclospora
• Another protozoan few days of watery diarrhea,
  but may persist and again threaten the
  immunosuppressed person
• Uncooked foods, berries presumed contaminated
• By human wastes or possibly _____ ____________

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Amoebic Dysentery

• Entamoeba histolytica grows in large intestine
  and may invade, resulting in abscesses
• Severe dysentery with ________
• Secondary infections can result ,and invasion of
  other organs even of __________, can result
• Sometimes abscesses must be treated surgically
• _________ of US are asymptomatic carriers

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Helminthic Diseases of the Digestive System

• Tapeworms from undercooked meat, or fish
• Eggs and___________are shed
• Beef tapeworm can live for ____ years and reach
  lengths of _____ feet!
• Pork tapeworm-similar except eggs may hatch into
  larva which invade tissues, even brain and eye
  and cause damage
• Endemic in Mexico and Central America
• Symptoms mimic _________ _______ CT scan are
  differentiating
• Fresh water fish tapeworm- dont eat Sushi or
  Sashimi made from _______ ___________ fish!

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Helminthic Diseases

• Hydatid Disease from a very _______tapeworm, but
  larval cyst forms in any locations, these can
  damage tissue as they grow, liver and lungs are
  common, but heart, brain and interior of bones
  can also be the sites
• Adult tapeworm in dog or wolf, eggs are shed or
  human can get from eating the flesh of infected
  sheep or deer
• If unrestricted can grow to enormous size! (
  _______ gallons!)
• If rupture can cause anaphylaxis and seed the
  body with __________ of daughter Cysts
• Surgical removal must be done with great care

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Nematode Diseases

• Pinworm
• Ingesting eggs
• Adults live in lower bowel
• Hookworm
• Larva penetrate skin
• Travel through lung to be coughed up and
  swallowed to live in intestine and shed eggs
  which hatch into larva on the outside
• Can lead to _________ unusual craving for laundry
  starch and soils containing clay-due to iron
  deficiency
• Ascaris usually mild symptoms, relatively
  common, can have _______ ________ from the body!

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Trichinosis

• Trichinosis ________ ______ usually from
  undercooked pork (but can be from any meat eating
  animal-like bears!)-larva are encysted in tissue,
  are released in digestive tract. They develop
  into adults and then shed more larva which
  penetrate and encyst to damage tissue.
• Upon autopsy about _______ of US popn. have
  cysts in diaphagm muscle.
• Large infections can be fatal.

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Trichinosis
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World Helminth Infections