Disease of Digestive Tract Flashcards
Digestive System
- consist of GI tract and accessory structures
- stomach and small intestine have few organisms
- large intestine has 100 billion bacteria per gram feces
norma biota
- large variety of normal biota
- oral cavity alone; more than 550 known species of microorganisms
- esophagus and stomach much more sparsely populated
- large intestine; billions of microorganisms
- Gm negative and Gm positive bacteria
- Anaerobes and facultative anaerobes
- lactobacillus, Bacteroides, E. coli, Enterobacter, Klebsiella, Proteus
Defenses
- mucus
- Secretory IgA
- Peristalsis
- fluids with antimicrobial: saliva, stomach fluid, bile
- GALT tissues (gut associated lymph tissue): tonsils, adenoids, lymphoid tissue in the esophagus, Peyer’s patches, appendix
- microbial antagonism
Dental Caries
more than 300 species on and around the teeth
- ferment sugars and carbohydrates into lactic acid which dissolves away enamel
- form biofilms on teeth
- Streptococcus mutans and other streptococci
- Protein from salvia coats the teeth and the bacteria adhere
- Bacteria produce dextrin’s from sucrose to form dental plaque
- Actinomyces may be part of the flora
Periodontitis
- initial stage: gingivitis (swelling, loss of normal contour, patches of redness, and increased bleeding of the gingival
- Gingivitis (early)- gums irritated
- plaque forms
- plaque calcifies-calculus
- if gingivitis persists, periodontitis develops
- extension of gingivitis into the periodontal membrane and cementum
- increased the size of pockets between the tooth and the gingival and can cause bone resorption enough to loosen and possible lose the tooth
Disease of Lower Digestive System
- infection-pathogen multiples in the GI tract
- intoxication- occurs when person ingests a preformed toxin which causes disease symptoms
- dysentery- blood diarrhea
- gastroenteritis- inflammation of the stomach and intestinal mucosa
exotoxin
-toxin produced and released by bacteria
enterotoxin
-type of exotoxin that affects the mucosal lining of the gut
endotoxin
-toxin that is part of the gram negative cell wall
infective dose
number of organisms needed to cause an infection
staphycoccal food poisoning
food intoxication
- S. aureus strains that produce enterotoxin (type of exotoxin)
- organisms come from nasal cavities and skin of food handlers
- resistant to heat, high salt, drying and radiation
- associated with temperature abuse of the food
Salmonellosis: food infection
- Salmonella spp.
- Heat sensitive but many contaminate food after cooking from cutting boards
- 2000 serotypes
- gastroenteritis
- invade the mucosa and multiply
- need to ingest large numbers of cells
- 12-36 hour incubation
- nausea, abdominal pain, cramps, diarrhea
- infants and old are the hardest hit
Pusled-field gel electrophoresis
- DNA from Salmonella is separated on a gel by running an electric current through gel
- different strains will have different patterns
- can “fingerprint” the DNA from strains
- type of molecular finger-printing
- CDC has national data base called PulseNet
Salmonella Outbreaks
traced to:
- milk
- peanut butter
- eggs
- poultry
- vegetables:sprouts, cantaloupe
Typhoid Fever
- Salmonella typhi and other stains
- oral route; water/food
- 2 weeks incubation
- fever, malaise, headache
- microbes don’t multiply in gut but multiply in the phagocytic cells
- Used to have high mortality rate
- chronic carriers
- vaccine, live oral or killed
E. coli gastroenteritis
- most E. coli are not causes of gastroenteritis
- there are several strains that produce toxins that can cause gastroenteritis
- named or typed by bacterial antigens
HKO antigens
H= flagellar antigen
K= capsular antigen
O= cell wall antigen
Ex. E. coli O157:H7
E.coli gastroenteritis; enterotoxin
- enterotoxigenic E. coli
- traveler’s diarrhea
- infant diarrhea
- not invasive
- enterotoxin causes watery diarrhea
E. coli gastroenteritis; Enterohemorrhagic E. coli
- STEC(shiga toxin producing E. coli)
- hemorrhagic colitis(bleeding from colon); no fever
- complication: hemolytic uremic syndrome which causes blood in urine and kidney failure
- 5-10% children develop this and mortality is high
- low infective dose
Cholera
-vibrio cholera
-exotoxin produced that causes vomiting and diarrhea
-diarrhea, “rice water” stools cause dehydration; can loose 3-5 gallons fluid/day
-shock sets in
must replace fluids and electrolytes
-spread by water; especially during major disasters
-incubation 3 days
-50% mortality unless treated with fluids
Cholera in Haiti
- outbreak in 2010, 9 months after earthquake
- used epidemiological techniques to find source:
- deaths and cases graphed by date
- case mapped
- molecular typing to compare outbreak strain with other strains
- found that the UN peace-keeping troops from Nepal had brought cholera with them from an outbreak in Nepal
- Poor sewage treatment led to contaminated rivers which served as a source for drinking water
Pseudomembraneous Colitis
- Clostridium difficile –> “C. diff”
- also called antibiotic-associated colitis
- Gm +, anaerobic, spore-former
- occurs when patient is treated by broad spectrum antibiotics
- disrupt normal flora
- superinfection
- entertoxins
- mild to serious, leading to perforations of cecum
