week 7- lower GI Flashcards
• What is acute intestinal perforation? Causes?
o emergency!
o Any part of GI, spill gastric, intestinal contents into abd cavity
o General causes: blunt or penetrating trauma, foreign bodies
o in SI: duodenal ulcer, corrosives, strangulation of bowel, acute appendicitis
o colon: obstruction, diverticulitis, IBD, toxic megacolon
• what are ssx of acute intestinal perforation? PE? Work-up?
o Ssx: sudden, severe general abd pn, tender, signs shock, N/V, anorexia
o PE: quiet to absent BS; peritoneal (guarding, rigidity)
o ***Note: in pts w underlying GI do, looks like “worsening” (more gradual, localized pn)
o Work-up: free air seen (usu SI) on abd xray or CT
• What is gastroenteritis? Hx?
o inflam lining of stomach, SI, LI (mc dt infx)
o usu self-limiting, mb serious in young, elderly, immunocompromised
o hx: ingest potentially contaminated food, water, travel, contact w similarly ill person, meds (eg abx)
• what are normal intestinal microflora?
o GI has 500 bacteria spp
o Stomach and proximal SI: few bacteria dt acidity
o Jejunum: lactobacilli, enterococci, gram (+) aerobes, facultative anaerobes
o Terminal ileum: enterobacteria, coliforms
o Colon: anaerobes: bacteriodes, lactobacillus, clostridium, bifidobacterium
• What are general ssx of gastroenteritis? PE? Work-up?
o Vary. Sudden N/V, anorexia, abd cramps, diarrhea. mb malaise, myalgia
o PE: distension, tender, borborymi
o Wu: Stool test (hemoccult, fecal WBCs, O&P, culture), Rapid enzyme assays (viral ags, Shiga toxin), CBC, CMP (hypokalemia; vomiting → metabolic alkalosis, diarrhea → acidosis)
• What is viral gastroenteritis?
o 30-40% infx diarrhea in US
o Viruses infect enterocytes in SI villi → transudate of fluid/salt into lumen
o →watery diarrhea, rare blood or mucus
• What is rotavirus GE?
o Mc infx diarrhea worldwide. 33% hospitalizations, 20% of GE
o Highly contagious: fecal-oral, peaks in winter
o Severe, dehydrating diarrhea in kids (peaks 3-15 mos). Mild in adults
o Ssx: vomit, fever >102°F. sxs can last 5-7 d
• What is norovirus GE? Astrovirus?
o N: older children and adults, year-round incidence, mb epidemic w water and food-borne outbreaks, highly contagious; acute onset vomit, abd cramps, diarrhea, fever, HA; lasts 1-2 d
o A: infants and young kids, winter months, fecal-oral, ssx similar to rotavirus
• What is enteric adenovirus GE? Other?
o E: kids <2, year-round/summer, fecal-oral. Diarrhea 1-2 wks → mild
o In immunocompromised, CMV and enterovirus can cause gastroenteritis
• How does exotoxin cause GE?
o Bacterial toxin → environment, pre-formed toxin ingested in contaminated food → N/V, watery diarrhea in 12hr of ingestion, minimal systemic sx (except botulinum), relief in 36 hrs; Stools have no blood or WBCs
• Describe GE caused byStaphylococcus aureus:
o MC food poisoning, dt food-handlers; Custard, milk products, potato salad, salad dressing, coleslaw, processed meat/fish at room temp
o Ssx: sudden severe vomit 2-6 hr after ingesting, explosive diarrhea, abd. cramps, rare fever; last 3-6 hours, usu complete recovery
• Describe GE dt Bacillus cereus:
o spore-forming, in soil, survive high heat of cooking; usu contaminated rice or meat
o 2 distinct syndromes:
o Emesis: 2-6 hrs after ingestion, severe vomit, abd. pain w or wo diarrhea; no fever, no systemic sxs
o Diarrhea: 8-16 hrs; foul smelling, profuse w nausea, abd pain, tenesmus
o resolves in 12-24 hours
• describe GE dt Clostridium perfringens:
o spore-forming anaerobe, in feces, soil, air, water; most toxin synthesized before ingestion, additional produced in GI; beef, beef products, poultry; food inadequately pre-cooked, reheated before served
o ssx: watery diarrhea, foul-smelling w severe, crampy abd. pn, 8-16 hr after ingestion
o self-limited, resolves in 24-36 hrs
• describe GE dt Clostridium botulinum?
o 3-exotoxin types (A, B, E); 1/3 deaths from food borne dz.
o A, B: improperly prepared home-canned non-acidic food (string beans, corn, mushroom, spinach, olives, beets, asparagus)
o E: smoked freshwater fish
o Boiling in water for 15 min can inactivate exotoxin
o Ssx: incubation 4 hr- 8 d after ingesting
o phase 1: vague, short period fatigue, N/V, abd cramps, diarrhea
o 2: visual, diplopia, ↓ acuity, PERRLA, ptosis
o 3: neuro, descending weakness or paralysis, dysarthria, dysphagia, weakness of trunk and extremities, sensorium unaffected, norm or ↓ temp; blood, urine, CSF normal
o 65% mortality 2-9 d after ingestion; with tx., < 10%- supportive to prevent respiratory impairment
o Ddx: polio, encephalitis, M gravis, curare, belladonna poisoning
• How does enterotoxin cause GE?
o Bacterial cytotoxin, specific for mucous membrane of intestine (in vivo). ↓intestinal absorption, ↑secretion water, electrolytes →watery diarrhea
• Describe GE dt cholera and non-cholera vibrio:
o endemic in Asia, fecal contaminated water or food, saltwater crabs and freshwater shrimp. incubation 1-3 d after ingestion
o ssx: sudden, painless, profuse, large volume, watery diarrhea, no blood or mucus, usu no fever vomit tenesmus
o water and electrolyte loss → thirst, oliguria, muscle cramps, weakness, cold, cyanotic skin, dehydration, hypotension, tachycardia
o recover in 7-10 w rehydration; fatal in > 50% untx severe cases
• describe GE dt Enterotoxigenic Escherichia coli:
o diarrhea dt tissue invasion or enterotoxin
o fecal/oral, contaminated water or food, traveler’s pathogen
o Incubation: 1-3 days
o SSX: Profuse, watery diarrhea, lasts 3-5 days
• Describe GE dt Clostridium difficile ( “C diff”)
o overgrowth of intrinsic organisms (post antibiotic) or infx by external source (soil, water, pets) →pseudomembranous colitis; common nosocomial dz, or iatrogenic after abx
o Ssx: watery diarrhea, cramping abd pain. N/V rare.
• What is toxin megacolon?
o Complication of C diff → pseudomembranous colitis
o Other possible causes: UC, Crohn’s, Entamoeba histolytica, Yersinia infx
o Dilated colon w fever, abd pain, tachycardia
o PE: tender abdomen, absent BS
o Work-up: ↑ WBC, distended bowel on xray. Colonoscopy is contraindicated (risk of perforation, sepsis, septic shock)
• What is mucosal invasion by microorganisms?
o by ingested organism → microscopic ulceration, bleeding, exudates, secretion of electrolytes and water
o Stool has WBCs, RBCs. mb gross bloody or watery diarrhea
o watery: > 1 L/d; usu no fever, h/a, myalgia, arthralgia
o bloody: usu abd pn, tenesmus, N/V, fever, malaise
o fever and prostration common
• describe GE dt salmonella mucosal invasion:
o undercooked chicken or eggs, unpasteurized milk, contact w reptiles
o requires large inoculum to produce infx → exudative diarrhea; (also enterotoxin causes secretory diarrhea)
o ssx: watery diarrhea mc, mb bloody, h/a, malaise, N/V, abd. pain 6-48 hr after ingestion, may have fever
o usu self-limited to 7 days
• describe GE dt Campylobacter jejuni and fetus mucosal invasion:
o mc bacterial cause of bloody diarrhea in US; pork, lamb, beef, milk products, water, infx pets
o incubation period 1-7 d
o ssx: mb prodrome of h/a, myalgia, malaise for 12-24 hr, then severe abd pain, ↑ fever, profuse watery diarrhea, then bloody diarrhea
o usu self-limited to 7-10 d
• describe GE dt Shigella mucosal invasion:
o mc 6 mos - 5 yrs; food, water, milk; person to person; highly contagious with very small inoculum
o ssx: incubation 1-3 d; usu start low abd pn, diarrhea; fever in 50%; many have biphasic illness 1) fever, abd. pain, diarrhea; 3-5 days, 2) rectal burning, tenesmus, small volume bloody D
o Course: variable, kids resolves in 1-3 d; adults resolves in 1-7 d
• describe GE dt Enterohemorrhagic Escherichia coli mucosal invasion:
o E. Coli 0157:H7 strain, produces Shiga toxin; bovine reservoir → beef, unpasteurized milk; fecal-oral toddlers diapers; usu affects several people (anyone else sick?)
o Ssx: acute onset severe abd cramps, watery diarrhea >16 hr after ingestion →bloody in 24 hr. 1-8 days if uncomplicated
o Comp in 5%: hemolytic-uremic syndrome (HUS) → hemolytic anemia, thrombocytopenia, acute renal failure
o thrombotic thrombocytopenic purpura (TTP) → HUS, fever, neurological deficits
• describe GE dt Yersinia enterocolitica mucosal invasion:
o pork, unpasteurized milk, water
o ssx: watery or bloody diarrhea and fever
o May mimic appendicitis (RLQ pn, fever, vomit, leukocytosis) if infx in terminal ileum. AKA “acute ileitis”
• What is Traveler’s Diarrhea?
o Aka Turista. GE dt organism endemic to locale visited (water, food)
o Enterotoxigenic E coli mc, also norovirus
o Ssx: N/V, borborygmi, abd pain/cramps, diarrhea, onset 12-72 hr after ingestion
o Usu self-limiting, fever and bloody diarrhea suggest more serious dz
• What are the parasitic infxs?
o Giardia lamblia
o Cryptosporidium parvum
o Entamoeba histolytica
o Isospora, microsporidia, esp immunocompromised
• Describe Giardia lamblia infx:
o Fecal-oral, water, person to person (daycare), traveling (esp low IgA, hypochlorhydria, malnutrition), ingestion of cysts which break down releasing organism
o Ssx: inc 7 d, mb asx, mild watery diarrhea, abd bloating, cramps, flatulence for 1-3 wk, stools bulky, foul smelling
o Course: mb self-limiting, chronic or recurrent dz (celiac-like lesion →lactose intolerance and malabsorption), fatigue, wt loss
• Describe Cryptosporidium parvum infx:
o Common in HIV, immune-compromised, daycare; water, food, pets (esp cats)
o Ssx: immune competent: profuse, watery diarrhea, anorexia, lo fever 5 days after ingestion; usu self-limited, lasts ~2wks
o immune-compromised: mb chronic, watery diarrhea, up to 17/d, → dehydration
• describe Entamoeba histolytica infx:
o endemic, travel, fecal-oral
o institutionalized pt, HIV, AIDS, immune-compromised
o cysts ingested, released → ulcers like IBD
o ssx: mild: crampy, abd pn, intermittent diarrhea
seere: bloody diarrhea, abd pn, tenesmus, fever, toxic megacolon
• example of Fungal overgrowth:
o Basidiobolomycosis: SE US. Contaminated food or dirt
• What is Drug and Chemical-related Gastroenteritis?
o Many agents and drugs → N/V, diarrhea o Pharmaceuticals: antacids, antibiotics, antihelminthics, colchicine, digoxin o Heavy metal poisoning o Laxative abuse o Poisonous mushrooms or plants
• What is inflammatory bowel dz?
o Crohn’s and UC o Dt loss of tolerance to normal flora o Triggers: ↑intestinal permeability: tight junctions defect dt pathogens or inflammatory mediators (cytokines, chemokines, TNF, etc) o Imbalanced microflora o Psychological stress exacerbates
• What is crohn’s dz?
o Aka Regional enteritis
o Chronic transmural inflammation of colon, involves mesentery and regional LN. May involve entire GI tract from mouth to anus, rare: stomach, duodenum, esophagus; w “skip lesions” (normal)
o Early mucosal involvement = longitudinal and transverse aphthous ulcers (cobblestone appearance). → deep fissures, sinuses and fistulas
o Typical pattern is intermittent exacerbations and periods of remission, worse w stress
• What is etio and risk factors for crohn’s?
o Unknown, genetic (assoc NOD2/CARD15), infx, immunologic, psychological…
o Smoking
o OCP, 2x risk
o diet: diary, refined sugar, ↓ fiber, ↑ animal fat
o dysbiosis, abx
o inflamed appendectomy early in life
• what is incidence of crohn’s?
o bimodal: peak 15-25, smaller peak 55-65
o 40
o 2-4X in Jewish, also higher in Caucasians
o inc in higher socioeconomic group, Type A personality
o F slightly >M
• What are ssx of crohn’s? PE?
o RLQ pain, steady, localized, fatigue
o Occult blood, in stool if colonic involvement (less common that UC)
o Stool: formed, or loose if extensive colonic involvement or terminal ileum,
o Fat malabsorption (steatorrhea) ↑ risk of gallstones, renal oxalate stones
o 1/3 have perianal dz: fissures, fistulas, perianal abscess
o PE: RLQ tenderness w assoc fullness or mass. Abdominal distention, fever, wt loss
• What are the 4 sx patterns w crohn’s?
o inflammation: RLQ pn, tender, like appendicitis (esp in young)
o obstruction: severe colic, abd distention, constipation, vomit
o diffuse jejunoileitis: both inflam and obstruction → chronic debility
o abd fistulas and abscesses: usu late, fever, painful masses, wasting
• what are complications of Crohn’s?
o Intestinal obstruction. initial from edema and inflammation, esp ileum= reversible. → fibrosis → constipation, intractable obstruction from fixed luminal narrowing
o Fistula → indolent abscess, malabsorption, cutaneous fistula, persistent UTI or pneumaturia (Enteroenteric, enterovesical, enterovaginal, enterocutaneous, retroperitoneal)
o Perforation, hemorrhage: rare, dt thickened mucosa
o ↑ risk SCC
