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
Roundworm
transmission
life cycle
symptoms
infections
eggs hatch and larvae penetrate skin -> larvae enter blood stream -> move through lungs and get swallowed -> adults enter intestins -> lay eggs -> eggs ingested -> back to lungs
Hookworm
transmission
life cycle
symptoms
infections
- Necator Americanus & Ancylostoma duodenale
t: larvae in soil: penetrate skin of bare feet and enter blood stream
s: cause itchy dermatitis
eggs hatch -> enter bloodstream through skin -> travel to lungs (causes mild pneumonia) -> swallow larvae
*suck blood from intestinal cappilaries- causes blood loss and anemia
How is pinworm diagnosed
tape touched to anal region, tape placed on slide and examined under microscope for pinworm eggs
Cryptosporidiosis
transmission
clinical manifestations
prevention strategies
Protozoan Parasite
Inflammatory
t: contaminated water, physical contact
clin: diarrhea lasting 1-2 weeks If immunocompromised cholera like dairrhea can occur
- following ingestion oocysts dissolve and release sporozites that enter intestinal epithelial cells
- asexual then sexual cycles produce infective oocytes
- oocytes excreted in stool and contaminate water and food
Cyclosporiasis
transmission
clinical manifestations
prevention strategies
Protozoan Parasite
Inflammatory
t: contaminated fresh produce and water
- make oocytes in intestine but aren’t infective (no fecal-oral transmission**)
clin: dairrhea, nausea, vomiting, bloating, cramping
- symptoms can last more than a month
* *Trimethoprim-sulfamethoxazole (TMP-SMX) treatment
Amoebiasis
transmission
clinical manifestations
prevention strategies
Protozoan Parasite
Invasive
t: cysts enter body through food or water contaminated with feces
* caused by entamoeba hystolytica
- trophozoites emerge in the intestines
clin: trophozites cause loose stool, stomach cramping and pain
- lesions may form causing: pain, bloody stools, fever
