CM- GI Tract Infections Flashcards
What is the route of infection for MOST GI pathogens?
What are the notable exceptions?
Majority of GI infections are fecal-oral transmission [person-to-person or animal-to-person] .
Penetration of Skin:
- strongyloides
- schistosoma
- Hookworm
Blood:
- Hep B
- Hep C
What are the four major defense mechanisms of the body against enteric pathogens?
- Stomach acid [hypochlorhydria or meds to reduce acid increase incidence of vibrio]
- Secretion of IgA
- Endogenous flora [prevent overgrowth of C. diff]
- Gut motility [prevent adherence to surface mucosa]
What are the 6 general syndromes of GI infection?
- Food poisoning
- Acute infectious diarrhea [secretory]
- Dystentery
- Hemorrhagic colitis
- Typhoid [enteric] fever
- Chronic [infectious] diarrhea in AIDs patients
What are the 4 non-inflammatory pathogens?
- ETEC/EPEC/EAEC
- viruses
- parasites [except amebiasis]
- V. cholera
What are the 7 inflammatory pathogens for the GI tract?
- EIEC
- EHEC
- shigella
- salmonella
- yersinia
- campylobacter
- E. histolytica
What part of the bowel is affected by food posioning?
What is the onset of illness?
What 4 pathogens can cause it?
Food poisoning affects the upper GI tract and has more vomiting than diarrhea.
It is rapid onset.
- S. aureus
- B. cereus
- C. perfringens
- C. botulinum [with peripheral nerve abnormality]
What part of the GI tract is affected by acute infectious diarrhea?
What are the 6 pathogens that can cause it?
It affects the small bowel. There is watery diarrhea and no leukocytes.
- ETEC/EPEC/EAEC
- Rotavirus
- Norovirus
- Giardia lamblia
- Cryptosporidium
- vibrio cholera
What part of the GI tract does dysentery affect?
What are the symptoms?
What are the 8 bugs that can cause it?
It affects the colon.
Fever, pain, bloody mucopurulent diarrhea [heavy fecal leukocytes]
- campylobacter
- shigella
- salmonella
- yersinia enterocolitica
- EIEC
- E. histolytica
- Strongyloides
- C. difficile
What part of the GI tract does hemolytic colitis affect?
What are the symptoms?
What bugs cause it?
It affects the colon.
Painful, bloody diarrhea, HUS, few or absent leukocytes
EHEC O157:H7
What part of the GI tract is affected by typhoid fever?
What are the symptoms?
What 3 bugs cause it?
It enters via the SB but then has systemic illness
(monocytic leukocytosis)
- S, typhi
- S. paratyphi
- Y. enterocolitica
What part of the GI tract is affected by chronic diarrhea in AIDS and immunocompromised patients?
What are the symptoms?
What 5 bugs cause it?
It affects the SB.
Watery diarrhea with no leukocytes
- cryptosporidium parvum
- microsporidia
- cyclospora cayetanensis
- CMV
- MAC
What are the 3 causes of GI infections that affect the small bowel?
- Acute infectious Diarrhea
- Chronic infectious diarrhea (HIV/immuno)
- Typhoid fever (enters SB then systemic)
Which 2 causes of GI infections affect the colon?
- Dysentery
2. hemolytic colitis
Which causes of GI infections cause watery diarrhea with few to no fecal leukocytes?
- Acute infectious diarrhea
- hemolytic colitis
- chronic infectious diarrhea
What causes pathogenesis in food poisoning? What is the notable exception?
What are symptoms? How long does it last?
The ingestion of preformed bacterial toxins in food (it is NOT the organism that causes it).
The exception is infant botulism where the spores of C. botulinum are ingested and transform into vegetative form.
The toxins cause nausea and vomiting that is rapid onset (1-3 hours) and is self-limiting (12-36 hrs)
What is the only food poisoning that can be life threatening without appropriate supportive care?
What symptoms does it present with?
C. botulinum - it causes descending paralysis and no risk for other infections
Diarrhea is the most common manifestation of GI infection. What are the 3 major types and how do they differ in presentation?
- Secretory - watery
- dysentery, diarrhea- fever and bloody diarrhea with mucus
- Hemorrhagic colitis- frank bloody diarrhea
What generally the cause of secretory diarrhea?
What 4 viruses cause it?
What 2 bacteria?
What 3 protozoan parasites?
Viruses are generally the cause and they are usually self-limited.
Viruses: rotavirus, norovirus, adenovirus, astrovirus
Bacteria: ETEC (traveler’s diarrhea), vibrio cholera
Protozoa parasite: Giardia, cryptosporidium, cyclospora
Pathologically, how do pathogens cause diarrhea?
They colonize the small bowel and stimulate fluid and electrolyte secretion by pharmacologic imbalance
What are typical routes of exposure of protozoa that cause secretory diarrhea (crypto, giardia, cyclospora) ?
Daycare centers
Food
Water