Lecture 4: Diseases Affecting the Digestive System; Learning Objectives Flashcards
Explain the digestive systems defense mechanism (3 types); its indigenous microbiota, and how the microbiota is shaped.
Defenses:
- oral cavity-mechanical forces, salivary flow, lysozyme, antibodies
- Stomach-low pH
- Intestines- mucous, antibodies, bile and enzymes
Indigenous Microbiota: varies depending on where in GI
Microbiota shaped by: Diet, medication, probiotics, prebiotics, fecal transplant
Defenses of oral cavity (4)`
- mechanical forces
- salivary flow
- lyzosyme
- antibodies
Defenses of stomach (1)
- low pH
Defense of intestines (4)
- mucous
- antibodies
- bile
- enzymes
Factors influencing GI microbiota (5) [adult]
- Diet
- Medication
- Probiotics
- Prebiotics
- Fecal Transplant
Factors shaping microbiota (3 stages)`
- Birth- Cesarian vs. vaginal
- cesarian (streptococcus, corynebacterium, cutibacterium) *derived from skin
- Vaginal (lactobacillius and Prevotella) * derrived from vagina - Infancy
- Breast Fed; oligosaccharides drive lactobacillus and bifidobacterium
- Bottle fed: enteroccus, bacteriodes, clostridia, streptococcus - Beyond: diet remains key, abx, lifestyle choices and genetics play a role
Dental Caries causes (3)`
- Tooth Decay
- Dietary carbohydrates
- Acidogenic bacteria
main acidogenic bacteria for dental caries
- streptococcus mutans
- streptococcus sobrinus
*ferment dietary carbohydrates into acids
Prevention for dental caries
fluoride
Periodontal disease (PD) stages and their causes (2)`
- Gingivitis: early stage, reversible*
- biofilm forms on teeth
- fusobacterium, prophyromonas, prevotella, and streptococcus injure periodontal tissue leading to gingivitis - Periodontitis- seroius disease of soft tissue and teeth
- P. gingivalis is key driver
PD clinical presentation
- ulcers and bleeding along ginigval margin
- degradation of periodontal ligaments and bone
- loosened or lost teeth
- Assoc. with CVD, Alzheimer’s, RA
Intoxicants vs. infection
-give examples of both
intoxicants: illnesses where bacterial toxins are ingested with food and water
infections: illnesses where live bacterial pathogens are ingested and grow in body
S. aureus vs. Clostridial* vs. B. cereus
SA: toxins in protein rich foods (meat and fish, dairy)
- incubation: 1-6 hrs.
- Gastroenteritis caused by enterotoxin
- cramps. nausea, vomiting, weakness, diarrhea
Clost: contamininates meat, poultry, fish
- resistant to heat, UV light, drying, disenfectants**
- req. high infectious dose takes 8-24 hours to appear
- abdominal pain, cramping, diarrhea
- produces enterotoxin
B. Cereus:
- enterotoxin: meats, poultry, vegies
- diarrhea - Heat-stable toxin: rice
- vomiting
Primary problem with cholera
extreme dehyrdration: up to 1 liter an hour
-fluid loss can thicken blood, leading to shock and coma
explain v. cholerae characteristics (7) and transmission mechanisms
Virbrio Cholerae
- non-invasive (not bloody)
- motile, aerobic, gram (-), curved rods
- secrete cholera toxin: loss of fluids and electrolytes through diarrhea *extreme dehydration
- cells susceptible to stomach acid
- Spread through poor sanitation and water supplies contaminated by feces
Name 4 types of E. coli Diarrheas and their clinical manifestations
- Traveler’s Diarrhea: enterotoxic e. coli (ETEC)- 2 enterotoxins
- ETEP: enteropathogenic e coli- potentially fatal diarrhea in infants
- EIEC: Enteroinvasitve e. coli- bloody diarrhea like shigella
- EHEC: enterohemorrhagic e. coli
- animal reservoir increasing chance of human contact
Transmission and and clinical syndrome caused by C. diff and how spores contribute to hospital outbreaks
Gram +
watery diarrhea, fulminant colitis, rupture of intestine (megacolon)
abx eliminate normal flora and allow c. diff to grow uncrontrolably
spores: hard to clean
trans: spores
Know the (2) types of Salmonella and differentiate based on clinical syndromes, transmission, and typical clinical course
- S. typhi
- causes typhoid fever= blood infection - Salmonella enterics serotype enteritidis
Shigella Soneri
Know the agents, transmission, and clinical syndrome
- gram (-) rod (closely related to e.coli)
- causes S. dysenteriae: bloody diarrhea
- transmission: contaminated eggs, shellfish, diary
Hepatitis
transmission
vaccine?
clinical manifestations
prevention strategies
-transmitted Hep A) through food or water contaminated by feces of contaminated person OR raw shellfish
Hep B) through direct/indirect contac with body fluid like blood or semen (mother-child or sexually)
Hep C: blood transmission, innjection drug use, blood transfusions
- 3 vaccines: HAVRIX and VAQTA -contain hep A only and TWINRIX contains hep B as well
clin: anorexia, nausea, vomiting, fever, enlargement of liver, jaundice
Prev:
Rotavirus
transmission
vaccine?
clinical manifestations
prevention strategies
*RNA virus
T: fecal-oral route
Vax: oral for infants
Clin: infects and damages and cells in small intestines, causes gastroenteritis and diarrhea
P: vaccine
Noroviurs
transmission
vaccine?
clinical manifestations
prevention strategies
*RNA Virus
T: Fecally contaminated food or water, person-person, aerolization of vomited virus, contamination of surfaces
vax: none
Clin: most common cause of viral gastroenteritis in humans
P: hand washing and disenfectants
Giardiasis
transmission
clinical manifestations
prevention strategies
Protozoan Parasite
Inflammatory
t: food or water contaminated with sewage containing dormant cysts also natural bodies of water
Clin: nausea, cramps, flatulence, diarrhea
*trophozoites emerge and attach to intestinal lining using a sucking disk
Tape worm
transmission
life cycle
symptoms
infections
t: eggs enter human host through food- raw or undercooked especially
s: liver infection, abdominal pain, rupture of cysts can cause anaphylaxis
eggs hatch and parasite enters intestinal wall -> travel by blood to liver, lungs, and brain
