Oral

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Chapter 22

• Oral Gastrointestinal Diseases

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Overview of Digestive System

• Organs are separated into 2 groups
• Alimentary canal (GI tract)
• Continuous muscular tube (30 ft) open to
  external environment at both ends
• Site of digestion and absorption
• Includes mouth, pharynx, esophagus, stomach and
  the intestines
• Accessory organs
• Teeth, tongue, liver, gallbladder, pancreas and
  salivary glands
• Glands are outside GI tract connected by ducts
  produce digestive enzymes and various other
  secretions

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Digestive Processes

• Six essential activities
• Ingestion
• Propulsion
• Involves peristalsis wave-like contractions
• Mechanical digestion
• Chewing of food in mouth stomach
• Churning and segmentation in stomach
• Chemical digestion
• Series of catabolic steps facilitated by enzymes
• Absorption
• Passage of foodstuffs from GI tract into blood
  and lymph
• Defecation
• Elimination of indigestible substances

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• Mouth oral cavity
• Common portal of entry for microbes has normal
  flora
• Lined with stratified squamous epithelium,slightly
  keratinized to protect against abrasions,
  produces defensins
• Contains tongue, teeth and salivary glands
• Primary functions mastication and chemical
  digestion
• Salvia has several functions
• cleans mouth, dissolves food chemicals for taste,
  contains enzymes like lysozymes to destroy
  microbes
• Each tooth has a crown covered with enamel above
  the gum and a root covered with cementum below
  the gum
• Under these coverings is a porous substance
  called dentin, a central pulp cavity and the root
  canals where blood vessels and nerves are located

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A section through a typical tooth and gum
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• Pharynx throat has three divisions
• Oropharynx, laryngopharynx (common passages for
  air and food) and the nasopharynx (plays no role
  in digestion)
• Has external muscle layer to propel food into
  esophagus below
• Esophagus muscular tube that is collapsed when
  not involved in food propulsion
• Pierces diaphragm and empties into the stomach
• Heartburn occurs when acidic stomach juice (pH 4)
  is regurgitated into esophagus

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• Stomach site of protein digestion and more
  mechanical digestion
• Food is converted into a creamy paste called
  chyme
• The epithelial lining has goblets cells which
  produce a protective alkaline mucus coating
• Lining is doted with millions of gastric glands
  which produce hydrochloric acid pepsin (protein
  digesting enzyme)
• Alcohol and aspirin and some lipid-soluble drugs
  pass across the mucous barrier to blood

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• Small intestine is the bodys main digestive
  organ
• Site of virtually all absorption
• Three subdivisions
• Duodenum beginning portion drains stomach
  curves around pancreas bile duct and main
  pancreatic duct converge here
• Jejunum middle portion
• Ileum end portion joins large intestine
• Villi finger-like projections
• Increase surface area form absorption, contain
  blood lymph vessels
• Microvilli tiny folds in plasma membranes of
  absorptive cells
• Secrete enzymes that complete the digestive
  process

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• As food enters the duodenum it is mixed with
  secretions from the liver and pancreas
• The liver secretes bile cholesterols which help
  digest fats
• The pancreas produces a broad spectrum of enzymes
  that help complete digestion of starches
  proteins
• Sugars amino acids are absorbed into the blood
  while fats are absorbed into the lymph
• The ileum contains special lymphoid tissues
  called Pyers patches to filter out microbes

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• Large Intestines (colon) major function is to
  absorb water from indigestible foods and
  eliminate them from body as feces
• The beginning portion is a sac-like cecum, with a
  worm-like appendix extending off the back
• Most bacteria entering the large intestine are
  dead the few that survive and those entering
  the anus make up the bacterial flora of the colon
• Ferment indigestible carbohydrates releasing
  acids and gasses
• They also produce vitamin K needed for the liver
  to produce clotting factors and complex B
  vitamins
• In addition to absorbing water the colon absorbs
  these vitamins

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Normal Flora of the Digestive System

• Mouth has over 400 species of bacteria
• Esophagus has no permanent flora
• Stomach is usually too acidic for bacteria to
  colonize
• Some G- anaerobes colonize the lower small
  intestine and into the colon
• E. coli, Bacteroides, Clostridium
• Food may remain in the colon for over 60 hours
  allowing lots of time for colonization
• About 50 of the weight of feces is bacteria

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Bacterial Diseases of Mouth

• Dental plaque
• continuously formed coating of the teeth with
  microbes and organic matter
• 1st step in tooth decay and gum disease
• May become so firmly attached it requires
  professional removal
• Plaque consists of over 30 different genera of
  bacteria and their metabolic products
• Plaque forming bacteria include Streptococcus
  mutans and Streptococcus sanguis
• May accumulate near the gum line and cause
  gingivitis
• Actinomyces, Veillonella, Fusobacterium and
  Streptococci
• May mineralize causing the formation of tarter
  (calculus)

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• Dental caries (tooth decay)
• Chemical dissolution of enamel, dentin and pulp
• The most common infectious disease in developing
  countries because of refined sugar in diet
• May form an abscess that damages the peridontal
  ligaments and bone supporting the tooth
• Periodontal disease
• Sugars diffuse through plaque then the acids
  produced by bacteria from fermentation of the
  sugars becomes trapped against tooth
• Preventable by reducing sugar, frequent brushing
  and fluoride treatment
• Hardens surface enamel
• Water supply, toothpaste, mouthwash, gel
  treatments

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Viral Diseases of the Mouth

• Mumps caused by paramyxovirus
• Transmitted in saliva droplets
• Swelling of parotid glands (salvia glands)
• Common in children (6-10 yrs)
• Preventable with MMR vaccine
• May cause orchitis in post-pubertal males
• Inflammation of testes that predisposes them to
  testicular cancer
• Other complications include inflamation of
  ovaries and pancrease, eye and ear infections,
  and meningoencephalitis

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paramyxovirus
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• Other diseases of the mouth
• Herpes simplex
• Primarily HHV type 1
• cause fever blisters or cold sores
• Thrush
• Caused by the yeast Candida albicans
• Characterized by milky patches of inflammation on
  oral mucus membranes
• Prevalent in infants, diabetics and
  immunosuppressed individuals

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Bacterial Gastrointestinal Diseases

• Bacterial food poisonings
• Food poisoning is caused by ingesting food
  contaminated with bacterial toxins, pesticides,
  heavy metals or other toxic substances
• Preventable by following proper food handling
  procedures
• If bacteria are consumed they can continue to
  produce toxins
• Tissue damage is a result of the action of the
  toxin not the growth of the bacteria
• Bacteria producing such toxins include
  Staphylococcus aureus, Campylobacter jejune,
  Clostridium species and Bacillus cereus

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• S. aureus causes enterotoxicosis by releasing
  enterotoxins A or D which are actually exotoxins
• damages intestinal wall and inhibits water
  reabsorbtion causing abdominal pain, vomiting and
  diarrhea usually within 1-6 hrs of ingestion
• Usually clears itself up in healthy adult no
  immunity
• C. perfringens releases an enterotoxin only
  during sporulation under anaerobic conditions
• Main symptom is diarrhea usually 8-24 hrs after
  exposure
• May also be transmitted by introducing spores to
  open wounds causing gangrene
• C. botulinum produces the botulism neurotoxin
  which mainly affects the nervous system
• B. cereus secretes a toxin that induces vomiting
• often associated with contaminated rice
• Symptoms occur within 12 hrs of exposure and are
  short lived

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S. aureus
C. botulinum
C. perfringens
B. cereus
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• Peptic ulcers gastritis
• Etiological agent Helicobacter pylori
• Peptic ulcers are lesions in membrane lining GI
  tract
• Require 46,000 surgeries cause 14,000 deaths
  annually
• Correlated to 89 of stomach cancers
• Chronic gastritis is stomach inflammation may
  lead to ulceration
• H. pylori generates ammonia from urea ammonia
  neutralizes acidic stomach juices
• Unclear portal of exit or route of infection
• Experimental antibiotic treatments and antacids

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Helicobacter pylori

Knobs at end of flagella help it move through
mucus that traps other normally flagellated
bacteria
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• Bacterial enteritis enteric fevers
• Enteritis is an inflammation of the intestine
• bacteria invade and damage the intestinal lining
  and deeper tissues
• Infection not intoxication like food poisoning
• Mainly affects the small intestine causing
  diarrhea
• If it affects the colon it is often called
  dysentery
• Severe diarrhea usually contains mucus, blood or
  pus
• Some infections spread to the blood and cause
  systemic infections called enteric fevers
• Salmonellosis, Typhoid Fever, Shigellosis,
  Cholera, Vibriosis, Travelers Diarrhea
  (Montezumas revenge) and Yersiniosis

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• Salmonellosis
• Etiological agent Salmonella species
• S. typhi, S. choleraeusuis S. enteritidis
• Various harmless animal hosts
• Transmitted through contaminated food, water and
  chicken eggs
• Abdominal pain, fever and diarrhea with blood or
  mucus
• No vaccine antibiotics may induce a carrier
  state
• Health adults usually recover within a week with
  no treatment
• Certain serovars have the ability to enter the
  blood and cause enterocolitis enteric fever
• Chronic infections are not uncommon

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Salmonella enteriditis
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• Typhoid Fever
• One of the most serious epidemic enteric
  infections
• Etiological agent Salmonella typhi
• Common in areas with poor water sewage
  treatment
• Transmitted in contaminated food or water and
  invades small intestine and lymphoid tissue
• Survive and multiply in phagocytes
• Headache, fever, malaise, enlargement of spleen,
  abdominal distension tenderness but no diarrhea
  
• May result in internal hemorrhage, perforation of
  bowel and pneumonia
• Treatment chloramphenicol (some strains are
  resistant)
• Vaccine is available but requires booster every 3
  yrs.

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Salmonella typhi--the cause of typhoid fever
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• Typhoid Mary
• Mary Mallon an immigrant, Irish woman who made
  her way as a cook
• Well liked and respected ("good with the
  children")
• Probably exposed to typhoid fever around 1900
• Between 1900 and 1907, she infected 22 people
  with typhoid fever one died
• Quarantined on North Brother Island (age 37) for
  three years
• Released by the new health officer after
  promising never to cook again
• Traced to Sloan Maternity Hospital as cook!
• 25 more people infected
• 2 died
• Returned to quarantine on North Brother Island
• Died of a stroke 23 years later (in 1938)

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• Shigellosis (bacillary dysentery)
• Etiological agent several species of Shigella
• S. dysenteriae, S. flexneri, S. sonnei, S. boydii
  
• Transmitted by contaminated food, fingers, water,
  flies, feces and fomites only 10 organisms are
  enough to cause infection
• Cramps, fever extreme diarrhea with blood
• All strains produce fever inducing endotoxins but
  S. dysenteriae produces a neurotoxin as
  well
• Combination of antibiotics is used to treat
• Ampicillin, tetracycline and nalidixic acid (DNA
  synthesis inhibitor)
• Temporary immunity follows recovery an oral
  vaccine is being developed

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A colorized TEM ofShigella--the causeof
shigellosis
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• Asiatic Cholera
• Etiological agent Vibrio choleae
• Problematic in areas with poor sewage water
  treatment
• Enterotoxin (choleragen) binds to cells of small
  intestine making them highly permeable to water
• Severe diarrhea, nausea and vomiting, death due
  to shock from fluid loss
• Treatment fluid and electrolyte replacement
• No effective vaccine immunity is temporary
• Vibriosis
• Caused mainly by Vibrio parahaemolyticus
• Most common in Japan where raw fish is frequently
  consumed
• Can also infect skin wounds
• Releases endotoxin causing nausea, vomiting,
  diarrhea
• No vaccine usually no treatment is given

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A colorized SEM of Vibrio choleraethe cause of
Asiatic cholera
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• Travelers Diarrhea (Montezuma's revenge)
• Most commonly caused by E. coli (40-70)
• Different from the strains found in colon
• Transmitted in contaminated food water
• Mild to severe diarrhea, vomiting, nausea,
  bloating and malaise
• May become irritable bowel syndrome persist for
  years
• Enter-hemorrhagic strains (E. coli O157H7) cause
  deadly outbreaks of bloody diarrhea (no more rare
  hamburger)
• May lead to kidney failure (leading cause in
  children)
• Yersiniosis
• Caused by Yersinia entercolitica most common in
  Western Europe
• Transmitted in contaminated food (especially
  chitlins)
• Releases endotoxin causing severe abdominal pain
  increase in WBCs

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Yersinia enterocolitica
E. coli
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Viral Gastrointestinal Diseases

• Viral enteritis
• major cause in children is the rotavirus
• Double stranded RNA virus
• Transmitted by the oral-fecal route, common in
  small children
• Damages GI lining, causes watery diarrhea
• Major cause of infant mortality in under
  developed countries
• About ½ US cases caused by Norwalk virus
• Affects mostly older children and adults

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rotavirus
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• Hepatitis
• Inflammation of liver usually caused by viruses
  but also by an amoeba various toxic chemicals
• Most common viral form is Hepatitis A (infectious
  hepatitis) caused by hepatitis A virus (HAV)
• Single RNA transmitted by fecal-oral route
  contaminated food
• Hepatitis B (serum hepatitis) caused by HBV
• Double stranded DNA transmitted by blood
  intravenous direct contact contaminated body
  secretions
• Hepatitis C caused by more than 1 RNA virus (not
  HAV)
• Transmitted parenterally by blood
• Hepatitis D (delta hepatitis) particularly severe
  caused by both HDV and HBV
• Hepatitis E caused by HEV
• Transmitted by fecal-oral route fecally
  contaminated water
• 3 more viruses have been identified as potential
  hepatitis viruses

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Hepatitis B viruses
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Protozoan Gastrointestinal Diseases

• Giardiasis caused by flagellated Giardia
  intestinalis
• Inflammation of bowel, frothy diarrhea due to
  decreased fat absorption, dehydration weight
  loss
• Transmitted by contaminated food, water hands
• Giardia cysts are not killed by ordinary
  chlorination
• Amoebic dysentery caused by Entamoeba
  histolytica
• Becomes chronic but can revert to acute
• Transmitted through cyst infected water food
• Cryptosporidiosis Cryptosporidium species
  transmitted from cyst infested feces of puppies
  kittens
• Opportunistic infection with no available
  treatment
• Severe diarrhea and fluid loss
• Cyclosporiasis Cyclospora cayentanenisis
• Transmitted by contaminated fruits and vegetables
• Flu like symptoms, often with relapse

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Giardia intestinalis
Cryptosporidium lining the intestinal tract
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Effects of Fungal Toxins on GI Tract

• Fungi produce large numbers of toxins
• Most come from species of Aspergillus
  Penicillium
• Various effects include loss of muscle
  coordination, tremors, weight loss and cancers
• Aflatoxins produced by Aspergillus flavus
• Most potent carcinogen known
• Transmitted from mold infected grain
• Ergot produced by Claviceps purpurea
• Transmitted on contaminated rye and wheat
• Causes fever, hallucinations, gangrene and death

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Claviceps purpurea
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Helminth Gastrointestinal Diseases

• Helminthes that infect humans have complex life
  cycle with 1 or more intermediate hosts
• Acquired mainly in tropical regions
• Fluke infections
• Tapeworm infections
• Trichinosis
• Hookworm infections
• Ascariasis
• Pinworm infections

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• Fluke infections
• Affect 40 million people worldwide
• Sheep liver fluke (Fasciola hepatica)
• Intermediate host is snail
• Cercaria encyst on water vegetation forming
  metacercaria
• Diagnosed by eggs in stool
• Treated with bithionol or other antihelminth
• Prevented by avoiding uncooked water vegetation
• Chinese liver fluke (Clonorchis sinensis)
• Has a second intermediate host fish or
  crustacean
• Diagnosed by eggs in stool
• No effective treatment
• Prevented by avoiding uncooked fish or
  crustaceans

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• Tapeworm infections
• Caused by several species- most found worldwide
• Contracted by eating undercooked pork, beef or
  fish and by contact with infected dogs
• Pork tapeworm (Taenia solium) and Beef tapeworm
  (Taenia saginata)
• Enter as larvae in undercooked meat
• Develop into adult in intestine stealing
  nutrients from host
• May form masses that block intestines
• Eggs may invade blood stream and spread to other
  body sites
• Echinococcus granulosus
• Contracted through contact with infected dogs
• Eggs produces cysts called hydatid cysts
  containing hundreds of immature worms
• Diagnosed by eggs or proglottids in stool
• Treated with niclosamide and other antihelminths

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Liver Fluke
Pork Tapeworm
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• Trichinosis
• Caused by round worm Trichinella spiralis
• Enters as encysted larvae in undercooked pork,
  horse or game meat
• Adults penetrate intestinal mucosa releasing
  toxins
• Wandering larvae damage blood vessels an other
  tissues
• Hard to diagnose muscle biopsy or immunological
  tests may be effective
• Treatment is restricted to alleviating symptoms
• Prevented by thoroughly cooking meat
• Average of 100 cases/yr in US

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• Hookworm infections
• Often caused by 1 of 2 species of roundworms
• Necator americanus or Ancylostoma duodenale
• Complex life cycle with a single host
• Free-living larvae burrow through skin and travel
  to heart or lungs
• May be coughed up and swallowed where they reach
  the intestines mature, lay eggs and start the
  cycle again
• 500 million cases worldwide
• Diagnosed by worms or eggs in feces
• Treatment Tetrachloroethylene for Necator only
  Bephenium and mebendazole effective for both
  worms
• Preventable through sanitary disposal of human
  waste

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• Ascariasis
• Caused by the large roundworm Acaris lumbricoides
• Spread through water or food contaminated with
  eggs
• Eggs hatch and larvae travel to lymph vessels and
  results in systemic immune response
• Mature in small intestine and begin laying eggs
• Single female lays 200,000 eggs/day and 26
  million/ lifetime
• Worldwide 25 of population is infested
• Ascaris worms cause three forms of damage
• Burrowing into lungs causes Ascaris pneumonitis
• Malnutrition by stealing host nutrients
• Wandering worms for abscess in liver and other
  organs

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• Pinworm infections
• Caused by small round worm Enterobius
  vermicularis
• Humans are the only known host
• Has the greatest geographical distribution of all
  human worm parasites
• 209 million infested worldwide (18 million in US
  and Canada)
• Adults attach to intestinal wall
• Females carrying 15,000 eggs travel to anus and
  lay the eggs on the exterior then travel back to
  intestines
• Eggs are ealisly transmitted through contaminated
  bedding, clothing and hands
• Eggs may become airbourne
• Usually not debilitating, but very uncomfortable
• Diagnosed by eggs around anus
• Treated with piperazine or other antihelminth
• All personal items (bedding, clothing) should by
  cleaned

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Round Worm
Hookworm
Adult Pin Worm
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Hydatid cysts in brain
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Ascaris lumbricoides mass