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GI block > GI goljan diarrhea, viral, bacterial, protozoa, helminths > Flashcards

GI goljan diarrhea, viral, bacterial, protozoa, helminths Flashcards

1
Q

characteristics of invasive diarrhea

A

pathogens invade enterocytes;
low volume diarrhea;
diarrhea w/ blood and leukocytes => dysentery

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2
Q

causes of invasive diarrhea

A

Shigella spp;
Camplobacter jejuni
Entamoeba histolytica

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3
Q

Screening tests for invasive diarrhea

A

fecal smear for leukocytes: positive in most cases;

order stool culture and stool for O&P

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4
Q

characteristics of secretory diarrhea

A

loss of isotonic fluid;
high volume diarrhea;
no inflammation in bowel mucosa

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5
Q

mechanisms causing secretory diarrhea

A

laxatives;
enterotoxins STIMULATE CL- channels regulated by cAMP and cGMP;
serotonin increases bowel motility (carcinoid)

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6
Q

How may laxative use be dangerous?

A

danger of melanosis coli (black bowel syndrome) w/ use of phenanthracene laxatives

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7
Q

What enterotoxins will produce secretory diarrhea?

A

Vibrio cholerae;

Enterotoxigenic E. coli

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8
Q

screening tests for secretory diarrhea and what will be present in them for positive Dx

A

fecal smear for leukocytes: negative
increased 5-HIAA: carcinoid syndrome
stool osmotic gap < 50mOsm/kg

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9
Q

characteristics of osmotic diarrhea

A

osmotically active substance drawing hypotonic salt solution out of bowel;
high volume diarrhea;
no inflammation in bowel mucosa

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10
Q

causes of osmotic diarrhea

A

disaccharidase deficiency;
“stunned gut” in giardiasis;
ingestion of poorly absorbable solutes (Mg sulfate laxatives)

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11
Q

screening tests for Dx of osmotic diarrhea

A

fecal smear for leukocytes: negative

stool osmotic gap > 100mOsm/kg

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12
Q

What are the viruses that may cause diarrhea?

A

CMV;
norwalk virus;
rotavirus

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13
Q

When will CMV cause diarrhea?

A

AIDS pts when CD4 Th cell count < 50-100cells/mm

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14
Q

what is Tx for CMV causing diarrhea?

A

ganciclovir

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15
Q

What is the most common cause of adult gastroenteritis? how is it transmitted?

A

norwalk virus;

fecal oral transmission

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16
Q

What is the presentation of norwalk virus diarrhea? where is it typically presented?

A

N/V, diarrhea resolving in 12-24hrs but may be fatal;

common infection on cruise ships

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17
Q

Tx for norwalk virus diarrhea

A

supportive

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18
Q

How is rotavirus transmitted? who is most susceptible to contracting it and when?

A

fecal-oral transmission;

most common childhood diarrhea in winter months

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19
Q

How does rotavirus cause damage leading to diarrhea? what type of diarrhea is caused?

A

damages ion transport pump in small intestine;

secretory diarrhea

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20
Q

How is rotavirus diagnosed? can it be prevented?

A

rotazyme test on stool establishes Dx;

oral vaccine highly effective

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21
Q

Tx for rotavirus diarrhea

A

oral hydration;

nitazoxanide

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22
Q

What type of organism is found in reheated fried rice or tacos? describe it and what is Tx

A

Bacillus cereus => G+;
food poisoning w/ preformed toxin;
disease is self-limited

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23
Q

Most common food-borne illness and invasive enterocolitis in US? how does it transmit?

A

Campylobacter jejuni;

fecal-oral via contaminated water, poultry, unpasteurized milk

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24
Q

Gram stain, shape and reservoir for campylobacter jejuni?

A

Gram - curved or S shaped rod;

animal reservoirs from chicken, cattle, puppies (source for children)

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25
Q

How does campylobacter jejuni present? what types of diarrhea?

A

invasive and secretory;
dysentery w/ crypt abscesses & ulcers resembling UC;
high fever & cramping abdominal pain;
organisms in stool w/ blood & leukocytes

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26
Q

Complications for campylobacter

A

Guillain-Barre syndrome => Abs cross-react w/ neurons;
Hemolytic uremic syndrome;
HLA-B27+ seronegative spondyloarthropathy

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27
Q

Tx for campylobacter

A

erythromycin

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28
Q

What bacteria may cause floppy baby w/ constipation? How does this occur?

A

clostridium botulinum;

infant food poisoning from eating spores in honey

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29
Q

What type of organism is clostridium botulinum? How does it cause its pathology and diarrhea?

A

Gram + rod;

adult food poisoning w/ preformed toxin causing descending paralysis, mydriasis, dry mouth

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30
Q

What is the mechanism for clostridium botulinum leading to diarrhea?

A

blocks ACh release in presynaptic terminal of neuromuscular jxn in ANS

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31
Q

Tx for clostridium botulinum

A

trivalent antitoxin

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32
Q

What is the most common cause of nosocomial diarrhea? what type?

A

Clostridium difficile;

secretory

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33
Q

what is the Gram stain characteristics of Clostridium difficile? what is it associated w/?

A

gram + rod;

pseudomembranous colitis

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34
Q

What is the primary reason that Clostridium difficile causes disease?

A

ABx induced cause leading to overgrowth of toxin producing C. diff in colon

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35
Q

What are the toxins associated w/ Clostridium difficile? what do they cause?

A

toxins A and B release proinflam mediators and cytokines that attract neutrophils and stimulate excess fluid secretion => watery diarrhea

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36
Q

What is the pseudomembrane caused by Clostridium difficile composed of?

A

cellular debris, leukocytes, fibrin, mucin

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37
Q

How is Clostridium difficile usually transmitted?

A

nosocomial => fecal oral

can be person to person

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38
Q

what are some lab findings w/ Clostridium difficile even though they are nonspecific?

A

neutrophilic leukocytosis w/ left shift;
fecal leukocytes;
decreased serum albumin

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39
Q

as far as the stool is concerned, which is better cytotoxin assay or stool culture for Clostridium difficile?

A

cytotoxin assay has greater specificity

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40
Q

Tx of Clostridium difficile

A

metronidazole =>

vancomycin causes resistant strains

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41
Q

What is bacteria causing diarrhea that ABx are not recommended for? why?

A

E. coli

may enhance toxin release

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42
Q

What is a gram neg rod that produces multiple serotypes leading to diarrhea? what are the serotypes?

A

E. coli;

ETEC and STEC

43
Q

What is probable cause of diarrhea by eating undercooked beef?

A

E. coli => STEC (O157:H7 serotype)

44
Q

How does the ETEC of E. coli lead to traveler’s diarrhea? what type of diarrhea is this?

A

strains produce toxin that activates adenylate or guanylate cyclase causing SECRETORY DIARRHEA

45
Q

If not treated w/ this Rx, what may be the cause of E.coli infection?

A

ciprofloxacin;

may produce hemolytic uremic syndrome

46
Q

What is on the differential Dx for Traveler’s diarrhea?

A

E. coli;
Campylobacter;
Salmonella;
Shigella

47
Q

What is an acid fast rod that causes diarrhea w/ malabsorption in AIDS patients? What disease does it simulate and how?

A

Mycobacterium avium-intracellulare complex;

foamy macs in lamina propria simulate WHIPPLE DISEASE

48
Q

How does Mycobacterium Tb cause diarrhea? what type of organism and where is primary focus?

A

Acid fast=> primary focus in lung;

invades Peyer’s patches causing circumferential spread in lymphatics leading to stricture formation

49
Q

What is a gram - rod w/ turtles, hamsters and lizards as animal reservoirs?

A

salmonella spp

50
Q

What are the pathogenic salmonella spp?

A

S. typhi;
S. paratyphi;
S. enteritidis

51
Q

What is the 2nd most common food borne illness in US? how is it contracted?

A

Salmonella enteritidis;

eating raw or undercooked egg products, raw milk (products), poultry, drinking contaminated water

52
Q

Tx for Salmonella enteritidis enterocolitis

A

ciprofloxacin or levofloxacin

53
Q

What is Typhoid fever caused by? what is the Tx?

A

S. typhi;

Tx is Sx w/ fluoroquinolone => ABx do NOT shorten illness and may increase freq of carrier states

54
Q

What is the disease process of Typhoid fever from S. typhi?

A

Week 1: invades Peyer’s patches causing sepsis;

Week 2: diarrhea (+ stool culture) w/ CLASSIC TRIAD OF BRADYCARDIA, NEUTROPENIA, SPLENOMEGALY

55
Q

Who is likely to be a chronic carrier of S. typhi? Tx for them

A

gallbladder disease;

cholecystectomy

56
Q

What are the culture characteristics and disease characteristics caused by Shigella?

A

gram - rod;

mucosal ulceration, pseudomembranous inflammation in rectosigmoid colon; dysentery

57
Q

How is Shigella transmitted?

A

NO animal reservoirs

highly infectious and found in day care centers and mental institutions

58
Q

Genetic susceptibility for Shigella?

A

yes=> HLA-B27+ seronegative spondyloarthropathy

59
Q

Tx for shigella

A

symptomatic w/ fluoroquinolone or azithromycin

60
Q

What is a gram + coccus that causes gastroenteritis 1-6hr after eating? How is it Tx? what should be cultured?

A

S. aureus;
self limited disease;
food poisoning w/ preformed toxin so culture food not stool

61
Q

Gram characteristics of Vibrio cholerae and how does it lead to entercolitis?

A

Gram - comma shaped rod;

enterotoxin stimulates adenylate cyclase in small bowel

62
Q

When is vibrio cholerae contracted?

A

drinking contaminated water or eating contaminated seafood (esp crustacea)

63
Q

Tx for vibrio cholerae?

A

Fluid replacement;
glucose and Na+ required in oral supplements as a cotransport for reabsorption;
doxycycline or fluoroquinolone

64
Q

What is a gram - coccobacillus w/ bipolar staining?

A

Yersinia enterocolitica

65
Q

Who is susceptible for diarrhea from Yersinia enterocolitica? what are associated findings?

A

children=> mesenteric lymphadenitis (granulomatous microabscesses) that simulate acute appendicitis

66
Q

Genetic susceptibility for Yersinia enterocolitica?

A

yes=> HLA-B27+ seronegative spondylarthropathy

67
Q

Tx for Yersinia enterocolitica

A

TMP-SMX

68
Q

What are the protozoa and type associated w/ diarrhea?

A 
Balantidium coli => ciliate
Cryptosporidium parvum=> sporozoa
Cyclospora, Microsporidia, isospora belli=> sporozoa
entamoeba histolytica=> amoeba
Giardia lamblie=> flagellate
69
Q

How is Balantidium coli transmitted? what does it produce? Tx?

A

ingestion of cysts in food or water;
produces colonic ulcers w/ bloody diarrhea;
Tx is tetracycline

70
Q

How is Cryptosporidium parvum transmitted? Who is likely to get it? Tx? how is it diagnosed

A

ingestion of oocysts in food or water;
MOST COMMON CAUSE OF DIARRHEA IN AIDS;
Tx if immunocompetent: niazoxanide;
Dx: stool antigen test and oocysts are partially acid fast

71
Q

How are Cyclospora, Microsporidia, isospora belli transmitted?

A

fecal-oral transmission

72
Q

Who is likely to get Cyclospora, Microsporidia, isospora belli leading to diarrhea?

A

AIDS pts

73
Q

How would Cyclospora, Microsporidia, isospora belli be ID’d?

A

cyclospora=> contaminate rasberries and partially acid fast
microsporidia=> NOT partially acid fast
isospora=> oocysts partially acid fast

74
Q

Tx for Cyclospora, Microsporidia, isospora belli

A

cyclospora=>TMP-SMX double strength;
microsporidia=> albendazole;
Isospora=> TMP-SMX double strength

75
Q

What of the entamoeba histolytica causes diarrhea?

A

transmitted by cyst ingestion in food and water;
cysts are nonmotile and found in stool;
trophozoites are motile and present in bloody diarrhea (dysentery)

76
Q

Describe the mechanism from transmission to systemic disease from entamoeba histolytica

A

cysts in cecum => become trophozoites who release powerful histolytic agent causing flask shaped ulcers=> can penetrate portal vein tributaries and drain to liver to produce liver abscess=> penetrate hepatic vein tributaries and produce systemic diseae

77
Q

Word association for entamoeba histolytica causing liver abscesses

A

anchovy paste abscess

78
Q

What is typically feasted on from a entamoeba histolytica infection?

A

trophozoites phagocytoses RBCs

79
Q

How is entamoeba histolytica Dx? what is Tx?

A

stool antigen test;

metronidazole

80
Q

How is the most common protozoal cause of diarrhea in US transmitted?

A

Giardia lamblia;

transmitted by ingestion of cysts in food and water

81
Q

Where and who is more common to suffer from Giardia lamblia infection?

A

day care centers; mental hospitals; hikers; water supplies (chlorination does not kill cysts); gay men (oral-anal contact);
IgA deficiency; common variable immunodeficiency

82
Q

What type of disease does Giardia present w/?

A

produces acute and chronic diarrhea w/ malabsorption (cysts in formed stool; trophozoites in loose stool)

83
Q

How to Dx Giardia? Tx?

A

stool antigen test;

tinidazole or nitazoxanide

84
Q

What are the intestinal nematode helminths that lead to diarrhea?

A 
Anisakis simplex;
enterobius vermicularis;
Trichuris trichiura;
ascaris lumbricoides;
necator americanus;
strongyloides stercoralis
85
Q

What is an intestinal cestode helminth that causes diarrhea?

A

diphyllobothrium latum

86
Q

How does Anisakis simplex cause diarrhea?

A

eating raw fish or pickled herring causing larvae to penetrate gastric & intestinal mucosa

87
Q

Sx associated w/ Anisakis simplex?

A

cramping abdominal pain; epigastric distress w/ N/V and diarrhea w/in few hrs after eating

88
Q

How to Dx Anisakis simplex? Tx?

A

endoscopy and IgE Ab test;

Tx is removal by endoscope or surgery

89
Q

What is most common helminth in US? how is it transmitted?

A

Enterobius vermicularis;

transmitted by egg ingestion from eggs being deposited in anus by adult worms causing pruritis ani

90
Q

What is unique about enterobius vermicularis infection?

A

NO eosinophilia bc adult worms are NOT invasive

91
Q

Other than enterocolitis, what other infections can enterobius vermicular cause?

A

girls=> urethritis

anyone=> acute appendicitis

92
Q

Tx for enterobius vermicular

A

albendazole or mebendazole

93
Q

What is a significant complication if Trichuris trichiura infection occurs? how is it transmitted?

A

ingestion of eggs

produces diarrhea that may lead to rectal prolapse in children

94
Q

How to Dx for trichuris trichiura? Tx?

A

stool for ova and parasites along w/ eosinophilia;

Tx: albendazole

95
Q

differentiate the 2 different modes of ascaris lumbricoides infection?

A

larval phase through lungs=> cough, pneumonitis, eosinophilia (invasion of tissue);
bowel obstruction in adult phase=> no eosinophilia (no tissue invasion)

96
Q

Tx for Ascaris lumbricoides

A

albendazole and mebendazole

97
Q

What does a Necator americanus infection cause?

A

adults attach to villi resulting in blood loss and iron deficiency

98
Q

Tx for necator americanus

A

albendazole or mebendazole

99
Q

How is Strongyloides stercoralis transmitted?

A

filariform larvae in soil penetrate feet=> larval phase through lungs=> swallowed & molt into adults that enter intestinal mucosa & lay eggs => eggs hatch into RHABDITIFORM larvae to enter intestinal lumen and passed in stool => develop into FILARIFORM larvae (infective form) in the soil

100
Q

How may an autoinfection occur w/ strongyloides stercoralis?

A

if filariform larvae in intestine penetrate mucosa and migrate to lungs to repeat cycle

101
Q

What is likely to occur in immunocompromised pts w/ strongyloides stercoralis?

A

massive reinfection occurs w/ dissemination throughout the body

102
Q

Tx for strongyloides stercoralis

A

ivermectin

103
Q

How is diphyllobothrium latum transmitted? what does it cause?

A

ingest larve in lake trout (esp Great Lakes);

produces diarrhea w/ or w/o vit B12 deficiency due to preferential uptake of vitB12 by worm

104
Q

Dx of diphyllobothrium latum? Tx?

A

eggs in stool;

Tx is praziquantel

GI block (11 decks)

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