GI bugs 1 - Parasites

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GI bugs 1 - Parasites
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NGR GI Bugs 1
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  1. Small Intestine
    Enterobius vermicularis "Pinworm"
    1. Transmission?
    2. Infective form?
    3. Diagnostic form?
    • 1. Ingestion of embryonated eggs; Direct contact; autoinfection
    • 2. embryonated eggs
    • 3. Eggs collected in perianal area "Scotch test" (egg flat on one side)
  2. Small Intestine
    Enterobius vermicularis "Pinworm"
    1. Pathogenesis
    1. Gravid female migrates to perianal region to lay eggs
  3. Small Intestine
    Enterobius vermicularis "Pinworm"
    1. Disease
    2. Clinical picture
    3. Treatment
    • 1. Enterobiasis
    • 2. Perianal pruritus especially at night
    • 3. Pyrantel pamoate (treat the entire family)
  4. Small Intestine
    Ascaris lumbricoides "The largest roundworm"
    1. Transmission?
    2. Infective form?
    3. Diagnostic form?
    • 1. Ingestion of contaminated food or water
    • 2. Egg
    • 3. Eggs in stool (bile-stained, thick shell, round/oval knobby eggs); Occasionally adult worms in stool or coming out from mouth & nose
  5. Small Intestine
    Ascaris lumbricoides "The largest roundworm"
    1. Pathogenesis:
    1. In small intestine: egg --> larvae --> invade intestinal mucosa --> blood --> lungs --> alveoli --> up to throat --> swallowed --> back to small intestine --> adults worms multiplication
  6. Small Intestine
    Ascaris lumbricoides "The largest roundworm
    1. Disease
    2. Clinical picture
    3. Treatment
    • 1. Ascariasis
    • 2. Abdominal pain and intestinal obstruction when high worm burden; peritonitis; Cough, pneumonitis during lung phase of larval migration
    • 3. Albendazole or Mebendazole
  7. Small Intestine
    Trichuris trichiura "Whipworm"
    1. Transmission?
    2. Infective form?
    3. Diagnostic form?
    • 1. Ingestion of soil-contaminated food
    • 2. Embryonated egg
    • 3. Eggs in stool (bile-stained, barrel-shaped with bipolar plugs)
  8. Small Intestine
    Trichuris trichiura "Whipworm"
    1. Pathogenesis
    1. Multiplication in large intestine; possible penetration of intestinal mucosa
  9. Small Intestine
    Trichuris trichiura "Whipworm"
    1. Disease
    2. Clinical picture
    3. Treatment
    • 1. Trichuriasis
    • 2. Depend on worm burden; Heavy infections --> abdominal pain, bloody diarrhea, appendicitis and rectal prolapse
    • 3. Mebendazole
  10. Small Intestine
    Necator americanus "Hookworm"
    1. Transmission?
    2. Infective form?
    3. Diagnostic form?
    • 1. Larva penetrates intact skin; Direct contact with contaminated soil
    • 2. Filariform larva
    • 3. Eggs in stool (ellipsoidal shade, thin shell, non-bile stained)
  11. Small Intestine
    Necator americanus "Hookworm"
    1. Pathogenesis
    1. Larvae --> invade intestinal mucosa --> blood --> lung --> alveoli --> up to throat --> swallowed --> back to small intestine --> adults worms mouthparts designed for sucking blood
  12. Small Intestine
    Necator americanus "Hookworm"
    1. Disease
    2. Clinical picture
    3. Treatment
    • 1. -
    • 2. Skin manifestations at site of entry; Pneumonitis during lung phase; Gastrointestinal symptom: nausea, vomiting, diarrhea; iron deficiency anemia
    • 3. Albendazole or Mebendazole
  13. Small Intestine
    Strongyloides stercoralis "Threadworm"
    1. Transmission?
    2. Infective form?
    3. Diagnostic form?
    • 1. Larva penetrates intact skin; autoinfection
    • 2. Filariform larva; autoinfection
    • 3. Rhabditiform larvae in stool
  14. Small Intestine
    Strongyloides stercoralis "Threadworm"
    1. Pathogenesis
    1. Larvae --> invade intestinal mucosa --> blood --> lungs --> alveoli --> up to throat --> swallowed --> back to small intestine --> adults worms
  15. Small Intestine
    Strongyloides stercoralis "Threadworm"
    1. Pathogenesis
    • 1. Strongyloidiasis
    • 2. Skin manifestations at site of entry; Pneumonitis during lung phase; Gastrointestinal symptom: nausea, vomiting, diarrhea
    • 3. Ivermectin
  16. Small Intestine
    Taenia saginata "Beef tapeworm"
    1. Transmission?
    2. Infective form?
    3. Diagnostic form?
    • 1. Ingestion of raw beef containing cysticerci
    • 2. Cysticerci
    • 3. Proglottids and/or eggs in stools
  17. Small Intestine
    Taenia saginata "Beef tapeworm"
    1. Pathogenesis
    1. Intermediate host = cattle; Definitive host = humans
  18. Small Intestine
    Taenia saginata "Beef tapeworm"
    1. Disease
    2. Clinical picture
    3. Treatment
    • 1. Taeniasis
    • 2. Asymptomatic or mild abdominal pains
    • 3. Praziquantel
  19. Small Intestine
    Taenia solium "Pork tapeworm"
    1. Transmission?
    2. Infective form?
    3. Diagnostic form?
    • 1. Ingestion of water or food contaminated with eggs
    • 2. Egg
    • 3. Cysticercus in the tissue; antibody detection
  20. Small Intestine
    Taenia solium "Pork tapeworm"
    1. Pathogenesis
    1. Eggs hatch in stomach, release oncosphere --> penetrate intestinal wall --> circulation --> different tissues to develops into cysticercus
  21. Small Intestine
    Taenia solium "Pork tapeworm"
    1. Disease
    2. Clinical picture
    3. Treatment
    • 1. Cysticercosis
    • 2. Cysticerci in the muscles: No symptoms; Cysticerci in the eyes: blurry or disturbed vision; Neurocysticercosis: seizures, and headaches
    • 3. Albendazole; surgery
  22. Small Intestine
    Diphyllobothrium "Fish tapeworm"
    1. Transmission?
    2. Infective form?
    3. Diagnostic form?
    • 1. Ingestion of raw fish containing sparganum (plerocercoid)
    • 2. Plerocercoid
    • 3. Eggs in stool
  23. Small Intestine
    Diphyllobothrium "Fish tapeworm"
    1. Pathogenesis
    1. two intermediate hosts = crustaceans then fish; definitive host = humans
  24. Small Intestine
    Diphyllobothrium "Fish tapeworm"
    1. Disease
    2. Clinical picture
    3. Treatment
    • 1. Diphyllobothriasis
    • 2. Asymptomatic to abdominal pain, diarrhea, vomiting, Vit B12 deficiency
    • 3. Praziquantel + Vit B12
  25. Small Intestine
    ETEC: EnteroToxigenic E.coli
    1. Disease
    2. Dx
    3. Infecting dose
    4. Clinical presentaion
    5. Tx
    • 1. Traveler's Diarrhea
    • 2. Culture, Immunassays (toxin detection)
    • 3. High
    • 4. Watery diarrhea, abdominal cramps
    • 5. Fluoroquinolones (ciprofloxacin)
  26. Small Intestine
    All E. coli
    1. Key characteristics
    2. Reservoir
    3. Transmission
    • 1. Enterobacteriaceae: gram (-) motile rods, facultative anaerobes, oxidase(-), lactose (+)
    • 2. Human's intestine
    • 3. Fecal-oral; ingestion of contaminated food or water
  27. Small Intestine
    ETEC EnteroToxigenic E.coli
    1. Pathogenesis
    • Cfa (colonization factor antigen) - adherence
    • ST (heat stable toxin) - guanylate cyclase activation --> ↑cGMP
    • LT (heat labiletoxin, AB toxin) - ADP ribosylates G-protein --> constant activation of adenylate cyclase --> ↑cAMP
    • High cGMP or cAMP --> hypersecretionof H2O and Cl, decrease in Na reabsorption
  28. Small Intestine
    EPEC EnteroPathogenic E.coli
    1. Disease
    2. Dx
    3. Infecting dose
    4. Clinical presentaion
    5. Tx
    • 1. Watery diarrhea
    • 2. Culture, Immunassays (toxin detection)
    • 3. Low in infants (person-to-person); high in adults
    • 4. Watery diarrhea, abdominal cramps
    • 5. Fluoroquinolones (ciprofloxacin)
  29. Small Intestine
    EPEC EnteroPathogenic E.coli
    1. Pathogenesis
    • Bfp (Bundle-forming pilus) - adherence
    • TypeIII secretion system --> cytoskeleton proteins modification
    • in host cell
    • Attaching and effacing lesions --> changes in microvilluðmalabsorption
  30. Small Intestine
    EAEC EnteroAggregative E.coli
    1. Disease
    2. Dx
    3. Clinical presentaion
    4. Tx
    • 1. Chronic diarrhea
    • 2. Culture, Immunassays (toxin detection)
    • 3. Chronic watery diarrhea (in AIDS patients), abdominal cramps
    • 4. Fluoroquinolones (ciprofloxacin)
  31. Small Intestine
    EAEC EnteroAggregative E.coli
    1. Pathogenesis
    AAF (Aggregative Adherence Fimbriae) --> autoagglutination in “stacked-brick” arrangement + biofilm --> malabsorption
  32. Small Intestine
    All Vibrio
    1. Key Characteristics
    2. Infecting dose
    • 1. Curved gram(-) rods; facultative anerobes, oxidase(+), motile (polar flagella)
    • 2. High
  33. Small Intestine
    Vibrio Cholerae (serogroups O1 and O139)
    1. Dz
    2. Reservoir
    3. Transmission
    4. Clinical presentation
    5. Dx
    6. Tx
    • 1. Cholera
    • 2. Warm costal water
    • 3. Ingestion of contaminated water or shellfish
    • 4. Profuse watery diarrhea; "rice-water" stools; severe dehydration
    • 5. TCBS (Thiosulfate citrate bile salts sucrose agar) - yellow colonies
    • 6. Azithromycin
  34. Small Intestine
    Vibrio parahaemolyticus
    1. Dz
    2. Reservoir
    3. Transmission
    4. Clinical presentation
    5. Dx
    6. Tx
    • 1. Watery diarrhea
    • 2. Warm costal water (marine life)
    • 3. Ingestion of contaminated seafood
    • 4. Watery diarrhea, abdonimal cramps, nausea
    • 5. TCBS - blue-green colonies; Halophilic
    • 6. Self-limiting
  35. Small Intestine
    Vibrio Cholerae (serogroups O1 and O139)
    1. Pathogenesis
    • Tcp (toxin coregulated pilus) - adherence
    • Ctx (cholera toxin, AB-toxin, on lysogenic CTX phage) - ADP ribosylates G protein--> constant activation of adenylate cyclase --> ↑cAMP --> hypersecretion of H2O and Cl; decrease in Na reabsorption
  36. Small Intestine
    Vibrio parahaemolyticus
    1. Pathogenesis
    Enterotoxin - chloride & water secretion
  37. Small Intestine
    Clostridium perfringens
    1. Dz
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Watery diarrhea
    • Necrotizing enteritis in New Guinea natives
    • 2. Soil and human colon
    • 3. Ingestion of contaminated meat
    • 4. High
  38. Small Intestine
    Clostridium perfringens
    1. Clinical presentation
    2. Dx
    3. Tx
    • 1. Watery diarrhea, abdominal cramps
    • Abdominal pain, vomiting, bloody diarrhea in New Guinea natives
    • 2. Culture; Immunoassay (enterotoxin detection)
    • 3. Self-limiting or Penicillin in New Guinea
  39. Small Intestine
    Clostridium perfringens
    1. Pathogenesis
    • Enterotoxin or
    • Beta-toxin (lethal toxin): necrotizing destruction of jejunum (NG natives)
  40. Small Intestine
    Bacillus cereus
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Gram(+) rods, motile; spore forming
    • 2. Ubiquitous
    • 3. Emetic Gastroenteritis - Ingestion of preformed toxin (rice) or Diarrheal Gastroenteritis - Ingestion of food contaminated with spore
    • 4. High
  41. Small Intestine
    Bacillus cereus
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Emetic gastroenteritis and
    • Diarrheal gastroenteritis
    • 2. Onset <6h after ingestion - Vomiting, nausea, abdominal cramps and
    • Incubation time >6h - Watery diarrhea, nausea, abdominal cramps
    • 3. Isolation of organism from implicated food
    • 4. Self-limiting
  42. Small Intestine
    Bacillus cereus
    1. Pathogenesis
    • Emetic gastroenteritis: Heat-stable enterotoxin (if spore survive cooking --> germination + toxin production in non-refrigerated food)
    • Diarrheal gastroenteritis: Heat-labile enterotoxin (germination of spore + toxin production in intestinal tract)
  43. Small Intestine
    Staphylococcus aureus
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    • 1. Gram(+) cocci in cluster, catalase(+); coagulase(+)
    • 2. Normal human flora
    • 3. Ingestion of preformed toxin (potato salad, custard…)
  44. Small Intestine
    Staphylococcus aureus
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Staphylococcal food poisoning
    • 2. Onset <6h after ingestion - Vomiting, nausea, abdominal cramps and watery diarrhea
    • 3. Isolation of toxin producing bacteria (mannitol salt agar)
    • 4. Self-limiting
  45. Small Intestine
    Staphylococcus aureus
    1. Pathogenesis
    Heat stable enterotoxin
  46. Large Intestine
    EHEC EnteroHemorrhagic E. coli (O157:H7)
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Enterobacteriaceae: gram(-) rods, facultative anaerobes, oxidase(-) and Motile; lactose(+), sorbitol(-)
    • 2. Intestine of cattle
    • 3. Fecal-oral; ingestion of contaminated food or water
    • 4. Low --> person-to-person transmission
  47. Large Intestine
    EHEC EnteroHemorrhagic E. coli (O157:H7)
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Hemorrhagic Colitis; Hemolytic Uremic Syndrome (HUS)
    • 2. Bloody diarrhea (no leucocytes), abdominal cramps, vomiting; oliguria+renal failure (HUS)
    • 3. Culture on Sorbitol containind MacConkey agar (sorbitol(-)); Immunassays
    • 4. Antibiotic therapy not recommended; dialysis in HUS cases
  48. Large Intestine
    EHEC EnteroHemorrhagic E. coli (O157:H7)
    1. Pathogenesis
    • Attaching & Effacing lesions (no invasion)
    • Shiga toxin (AB toxin) - cleaves rRNA --> blocks protein synthesis --> cell death; circulating shiga toxin can bind to renal tissue --> renal failure (HUS)
  49. Large Intestine
    EIEC EnteroInvasive E. coli
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Enterobacteriaceae: gram(-) rods, facultative anaerobes, oxidase(-) and Motile; lactose(+)
    • 2. Human's intestine
    • 3. Fecal-oral; ingestion of contaminated food or water
    • 4. High
  50. Large Intestine
    EIEC EnteroInvasive E. coli
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Dysentery
    • 2. Bloody diarrhea with pus, fever, abdominal cramps, nausea
    • 3. Immunassays
    • 4. Fluoroquinolones (ciprofloxacin), TMP/SMX
  51. Large Intestine
    EIEC EnteroInvasive E. coli
    1. Pathogenesis
    Invasion (Ipa: invasion plasmid antigen) and destruction of colonic epithelium
  52. Large Intestine
    Shigella spp. (S. sonnei)
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Enterobacteriaceae: gram(-) rods, facultative anaerobes, oxidase(-) and Non-motile; lactose(-)
    • 2. Human's intestine
    • 3. Fecal-oral; ingestion of contaminated food or water
    • 4. Low --> person-to-person transmission
  53. Large Intestine
    Shigella spp. (S. sonnei)
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Dysentery
    • 2. Bloody diarrhea with pus, fever, abdominal cramps, nausea
    • 3. Hektoen enteric agar: lac(-), H2S(-)ð green colonies
    • 4. Fluoroquinolones (ciprofloxacin), TMP/SMX
  54. Large Intestine
    Shigella spp. (S. sonnei)
    1. Pathogenesis
    • Invasion (Ipa) of colonic mucosa through M cells
    • Invade basal surface of enterocytes --> cell death + inflammation; shiga-toxin
  55. Large Intestine
    Salmonella enterica (enteritidis & typhimurium)
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Enterobacteriaceae: gram(-) rods, facultative anaerobes, oxidase(-) and Motile; lactose(-)
    • 2. Intestinal tracts of animals and humans
    • 3. Fecal-oral; ingestion of comtaminated food (eggs, poultry) or water; direct contact with reptiles
    • 4. High
  56. Large Intestine
    Salmonella enterica (enteritidis & typhimurium)
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Dysentery-like diarrhea; possible bacteremia
    • 2. Bloody diarrhea with pus, fever, abdominal cramps, nausea
    • 3. Hektoen enteric agar: lac(-), H2S(+)ð blue colonies with dark center
    • 4. Fluoroquinolones (ciprofloxacin), TMP/SMX
  57. Large Intestine
    Salmonella enterica (enteritidis & typhimurium)
    1. Pathogenesis
    Ruffles, invasion, inflammation
  58. Large Intestine
    Yersinia enterocolitica
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Enterobacteriaceae: gram(-) rods, facultative anaerobes, oxidase(-) and Bipolar staining; lactose (-)
    • 2. Animal's intestine
    • 3. Fecal-oral; ingestion of contaminated food or water
    • 4. High
  59. Large Intestine
    Yersinia enterocolitica
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Dysentery-like diarrhea
    • 2. Bloody diarrhea, abdonimal cramps, fever; mesenteric lymphadenitis (mimics acute appendicitis)
    • 3. lac(-), H2S(-); Stool culture at 25°C
    • 4. Gentamycin (alt: fluoroquinolones...)
  60. Large Intestine
    Yersinia enterocolitica
    1. Pathogenesis
    Invade M cells: Yops and Type III secretion system; spread --> microabscesses in lymph nodes
  61. Large Intestine
    Campylobacter jejuni
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Thin gram(-) rods; gull-wing shaped; microaerophile; oxydase(+)
    • 2. Animal's intestine
    • 3. Fecal-oral; ingestion of contaminated food (poultry), milk or water; direct contact with pets
    • 4. Moderate to Low (but person-to-person transmission unusual)
  62. Large Intestine
    Campylobacter jejuni
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Dysentery-like diarrhea
    • 2. Bloddy diarrhea with pus, fever, abdominal pain; Complications: Guillain-Barre syndrome, Reactive arthritis
    • 3. Culture (microaerophilic conditions)
    • 4. Erythromycin (alt:ciprofloxacin)
  63. Large Intestine
    Campylobacter jejuni
    1. Pathogenesis
    Damage to intestinal mucosa (toxin production, translocation, invasion); virulence factors poorly defined
  64. Large Intestine
    Entamoeba histolytica
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Protozoa
    • 2. ?
    • 3. Fecal-oral;Ingestion of contaminated food or water; Direct contact
    • 4. Low
  65. Large Intestine
    Entamoeba histolytica
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Amebiasis
    • 2. Amoebic dysentery; Liver abscess, lung abscess, brain infection…
    • 3. diagnostic form: Cysts and trophozoites in stool
    • 4. Tinidazole (asymptomatic infec.); Metronidazole then iodoquinol (symptomatic intestinal or extraintestinal infec.)
  66. Large Intestine
    Entamoeba histolytica
    1. Pathogenesis
    Infecive form: cyst --> excystation in small intestine --> trophozoites multiply and produce cysts in large intestine; possible invasion to extraintestinal sites via bloodstream
  67. Salmonella typhi
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    4. Infecting dose
    • 1. Enterobacteriaceae; Non-motile; lactose(-), H2S(+)
    • 2. Humans only
    • 3. Fecal-oral; ingestion of contaminated food or water
    • 4. Moderate-low (possible person-to-person transmission)
  68. Salmonella typhi
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Typhoid fever
    • 2. Sustained fever and headache; possible rash and/or diarrhea, dark stool; persistent bacteremiað myocarditis, encephalopathy
    • 3. Culture from blood or feces
    • 4. Fluoroquinolones (ciprofloxacin)
  69. Salmonella typhi
    1. Pathogenesis
    Invasion of M cells; Multiply in macrophages; bacteremia and invasion of RES (mesenteric lymph node, liver, spleen); infection of gallbladder (carrier state); Capsule (Vi polysaccharide); endotoxin
  70. Helicobacter pylori
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    • 1. Gram(-) rods; bacillary or spiral shape; microaerophile; oxydase(+); urease (+)
    • 2. Stomach of humans and animals
    • 3. Fecal-oral; oral-oral
  71. Helicobacter pylori
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Gastritis, peptic ulcer, gastric adenocarcinoma, lymphomas
    • 2. ?
    • 3. Biopsy=> microscopy, culture, urease test; Stool antigen test; Urea breath test; PCR
    • 4. Proton pump inhibitor + clarithromycin + amoxicillin
  72. Helicobacter pylori
    1. Pathogenesis
    Mucous layer invasion (Mucinase, flagella) + Alteration of gastric acid production (urease --> ammonium production) ðInflammation of gastric mucosa --> Tissue destruction
  73. Clostridium difficile
    1. Key Characteristics
    2. Reservoir
    3. Transmission
    • 1. Large gram(+) rods; Spore forming; Strict anaerobes
    • 2. Vegetative form: human carrier; Spore in environment (hospital rooms)
    • 3. Often endogenous infection
  74. Clostridium difficile
    1. Dz
    2. Clinical presentation
    3. Dx
    4. Tx
    • 1. Antibiotic-associated diarrhea or Antibiotic-associated pseudomembranous colitis
    • 2. Watery diarrhea or Profuse diarrhea, abdominal cramps, fever
    • 3. Immunoassays (toxins detection); colonoscopy (pseudomembrane)
    • 4. Discontinue implicated antibiotic; Vancomycin or Metronidazole
  75. Clostridium difficile
    1. Pathogenesis
    Exposure to antibiotics --> overgrowth of C.difficile or

    • Toxin A - Enterotoxin: disrupts tigh junctions between enterocytes + induces inflammation --> watery diarrhea
    • Toxin B - cytotoxin: modification of enterocyte cytoskeleton --> cell death

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