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
2
Q
causes of invasive diarrhea
A
Shigella spp;
Camplobacter jejuni
Entamoeba histolytica
3
Q
Screening tests for invasive diarrhea
A
fecal smear for leukocytes: positive in most cases;
order stool culture and stool for O&P
4
Q
characteristics of secretory diarrhea
A
loss of isotonic fluid;
high volume diarrhea;
no inflammation in bowel mucosa
5
Q
mechanisms causing secretory diarrhea
A
laxatives;
enterotoxins STIMULATE CL- channels regulated by cAMP and cGMP;
serotonin increases bowel motility (carcinoid)
6
Q
How may laxative use be dangerous?
A
danger of melanosis coli (black bowel syndrome) w/ use of phenanthracene laxatives
7
Q
What enterotoxins will produce secretory diarrhea?
A
Vibrio cholerae;
Enterotoxigenic E. coli
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
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
10
Q
causes of osmotic diarrhea
A
disaccharidase deficiency;
“stunned gut” in giardiasis;
ingestion of poorly absorbable solutes (Mg sulfate laxatives)
11
Q
screening tests for Dx of osmotic diarrhea
A
fecal smear for leukocytes: negative
stool osmotic gap > 100mOsm/kg
12
Q
What are the viruses that may cause diarrhea?
A
CMV;
norwalk virus;
rotavirus
13
Q
When will CMV cause diarrhea?
A
AIDS pts when CD4 Th cell count < 50-100cells/mm
14
Q
what is Tx for CMV causing diarrhea?
A
ganciclovir
15
Q
What is the most common cause of adult gastroenteritis? how is it transmitted?
A
norwalk virus;
fecal oral transmission
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
17
Q
Tx for norwalk virus diarrhea
A
supportive
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
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
20
Q
How is rotavirus diagnosed? can it be prevented?
A
rotazyme test on stool establishes Dx;
oral vaccine highly effective
21
Q
Tx for rotavirus diarrhea
A
oral hydration;
nitazoxanide
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
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
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)
25
How does campylobacter jejuni present? what types of diarrhea?
invasive and secretory;
dysentery w/ crypt abscesses & ulcers resembling UC;
high fever & cramping abdominal pain;
organisms in stool w/ blood & leukocytes
26
Complications for campylobacter
Guillain-Barre syndrome => Abs cross-react w/ neurons;
Hemolytic uremic syndrome;
HLA-B27+ seronegative spondyloarthropathy
27
Tx for campylobacter
erythromycin
28
What bacteria may cause floppy baby w/ constipation? How does this occur?
clostridium botulinum;
| infant food poisoning from eating spores in honey
29
What type of organism is clostridium botulinum? How does it cause its pathology and diarrhea?
Gram + rod;
| adult food poisoning w/ preformed toxin causing descending paralysis, mydriasis, dry mouth
30
What is the mechanism for clostridium botulinum leading to diarrhea?
blocks ACh release in presynaptic terminal of neuromuscular jxn in ANS
31
Tx for clostridium botulinum
trivalent antitoxin
32
What is the most common cause of nosocomial diarrhea? what type?
Clostridium difficile;
| secretory
33
what is the Gram stain characteristics of Clostridium difficile? what is it associated w/?
gram + rod;
| pseudomembranous colitis
34
What is the primary reason that Clostridium difficile causes disease?
ABx induced cause leading to overgrowth of toxin producing C. diff in colon
35
What are the toxins associated w/ Clostridium difficile? what do they cause?
toxins A and B release proinflam mediators and cytokines that attract neutrophils and stimulate excess fluid secretion => watery diarrhea
36
What is the pseudomembrane caused by Clostridium difficile composed of?
cellular debris, leukocytes, fibrin, mucin
37
How is Clostridium difficile usually transmitted?
nosocomial => fecal oral
can be person to person
38
what are some lab findings w/ Clostridium difficile even though they are nonspecific?
neutrophilic leukocytosis w/ left shift;
fecal leukocytes;
decreased serum albumin
39
as far as the stool is concerned, which is better cytotoxin assay or stool culture for Clostridium difficile?
cytotoxin assay has greater specificity
40
Tx of Clostridium difficile
metronidazole =>
| vancomycin causes resistant strains
41
What is bacteria causing diarrhea that ABx are not recommended for? why?
E. coli
| may enhance toxin release
42
What is a gram neg rod that produces multiple serotypes leading to diarrhea? what are the serotypes?
E. coli;
| ETEC and STEC
43
What is probable cause of diarrhea by eating undercooked beef?
E. coli => STEC (O157:H7 serotype)
44
How does the ETEC of E. coli lead to traveler's diarrhea? what type of diarrhea is this?
strains produce toxin that activates adenylate or guanylate cyclase causing SECRETORY DIARRHEA
45
If not treated w/ this Rx, what may be the cause of E.coli infection?
ciprofloxacin;
| may produce hemolytic uremic syndrome
46
What is on the differential Dx for Traveler's diarrhea?
E. coli;
Campylobacter;
Salmonella;
Shigella
47
What is an acid fast rod that causes diarrhea w/ malabsorption in AIDS patients? What disease does it simulate and how?
Mycobacterium avium-intracellulare complex;
| foamy macs in lamina propria simulate WHIPPLE DISEASE
48
How does Mycobacterium Tb cause diarrhea? what type of organism and where is primary focus?
Acid fast=> primary focus in lung;
| invades Peyer's patches causing circumferential spread in lymphatics leading to stricture formation
49
What is a gram - rod w/ turtles, hamsters and lizards as animal reservoirs?
salmonella spp
50
What are the pathogenic salmonella spp?
S. typhi;
S. paratyphi;
S. enteritidis
51
What is the 2nd most common food borne illness in US? how is it contracted?
Salmonella enteritidis;
| eating raw or undercooked egg products, raw milk (products), poultry, drinking contaminated water
52
Tx for Salmonella enteritidis enterocolitis
ciprofloxacin or levofloxacin
53
What is Typhoid fever caused by? what is the Tx?
S. typhi;
| Tx is Sx w/ fluoroquinolone => ABx do NOT shorten illness and may increase freq of carrier states
54
What is the disease process of Typhoid fever from S. typhi?
Week 1: invades Peyer's patches causing sepsis;
| Week 2: diarrhea (+ stool culture) w/ CLASSIC TRIAD OF BRADYCARDIA, NEUTROPENIA, SPLENOMEGALY
55
Who is likely to be a chronic carrier of S. typhi? Tx for them
gallbladder disease;
| cholecystectomy
56
What are the culture characteristics and disease characteristics caused by Shigella?
gram - rod;
| mucosal ulceration, pseudomembranous inflammation in rectosigmoid colon; dysentery
57
How is Shigella transmitted?
NO animal reservoirs
| highly infectious and found in day care centers and mental institutions
58
Genetic susceptibility for Shigella?
yes=> HLA-B27+ seronegative spondyloarthropathy
59
Tx for shigella
symptomatic w/ fluoroquinolone or azithromycin
60
What is a gram + coccus that causes gastroenteritis 1-6hr after eating? How is it Tx? what should be cultured?
S. aureus;
self limited disease;
food poisoning w/ preformed toxin so culture food not stool
61
Gram characteristics of Vibrio cholerae and how does it lead to entercolitis?
Gram - comma shaped rod;
| enterotoxin stimulates adenylate cyclase in small bowel
62
When is vibrio cholerae contracted?
drinking contaminated water or eating contaminated seafood (esp crustacea)
63
Tx for vibrio cholerae?
Fluid replacement;
glucose and Na+ required in oral supplements as a cotransport for reabsorption;
doxycycline or fluoroquinolone
64
What is a gram - coccobacillus w/ bipolar staining?
Yersinia enterocolitica
65
Who is susceptible for diarrhea from Yersinia enterocolitica? what are associated findings?
children=> mesenteric lymphadenitis (granulomatous microabscesses) that simulate acute appendicitis
66
Genetic susceptibility for Yersinia enterocolitica?
yes=> HLA-B27+ seronegative spondylarthropathy
67
Tx for Yersinia enterocolitica
TMP-SMX
68
What are the protozoa and type associated w/ diarrhea?
```
Balantidium coli => ciliate
Cryptosporidium parvum=> sporozoa
Cyclospora, Microsporidia, isospora belli=> sporozoa
entamoeba histolytica=> amoeba
Giardia lamblie=> flagellate
```
69
How is Balantidium coli transmitted? what does it produce? Tx?
ingestion of cysts in food or water;
produces colonic ulcers w/ bloody diarrhea;
Tx is tetracycline
70
How is Cryptosporidium parvum transmitted? Who is likely to get it? Tx? how is it diagnosed
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
How are Cyclospora, Microsporidia, isospora belli transmitted?
fecal-oral transmission
72
Who is likely to get Cyclospora, Microsporidia, isospora belli leading to diarrhea?
AIDS pts
73
How would Cyclospora, Microsporidia, isospora belli be ID'd?
cyclospora=> contaminate rasberries and partially acid fast
microsporidia=> NOT partially acid fast
isospora=> oocysts partially acid fast
74
Tx for Cyclospora, Microsporidia, isospora belli
cyclospora=>TMP-SMX double strength;
microsporidia=> albendazole;
Isospora=> TMP-SMX double strength
75
What of the entamoeba histolytica causes diarrhea?
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
Describe the mechanism from transmission to systemic disease from entamoeba histolytica
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
Word association for entamoeba histolytica causing liver abscesses
anchovy paste abscess
78
What is typically feasted on from a entamoeba histolytica infection?
trophozoites phagocytoses RBCs
79
How is entamoeba histolytica Dx? what is Tx?
stool antigen test;
| metronidazole
80
How is the most common protozoal cause of diarrhea in US transmitted?
Giardia lamblia;
| transmitted by ingestion of cysts in food and water
81
Where and who is more common to suffer from Giardia lamblia infection?
day care centers; mental hospitals; hikers; water supplies (chlorination does not kill cysts); gay men (oral-anal contact);
IgA deficiency; common variable immunodeficiency
82
What type of disease does Giardia present w/?
produces acute and chronic diarrhea w/ malabsorption (cysts in formed stool; trophozoites in loose stool)
83
How to Dx Giardia? Tx?
stool antigen test;
| tinidazole or nitazoxanide
84
What are the intestinal nematode helminths that lead to diarrhea?
```
Anisakis simplex;
enterobius vermicularis;
Trichuris trichiura;
ascaris lumbricoides;
necator americanus;
strongyloides stercoralis
```
85
What is an intestinal cestode helminth that causes diarrhea?
diphyllobothrium latum
86
How does Anisakis simplex cause diarrhea?
eating raw fish or pickled herring causing larvae to penetrate gastric & intestinal mucosa
87
Sx associated w/ Anisakis simplex?
cramping abdominal pain; epigastric distress w/ N/V and diarrhea w/in few hrs after eating
88
How to Dx Anisakis simplex? Tx?
endoscopy and IgE Ab test;
| Tx is removal by endoscope or surgery
89
What is most common helminth in US? how is it transmitted?
Enterobius vermicularis;
| transmitted by egg ingestion from eggs being deposited in anus by adult worms causing pruritis ani
90
What is unique about enterobius vermicularis infection?
NO eosinophilia bc adult worms are NOT invasive
91
Other than enterocolitis, what other infections can enterobius vermicular cause?
girls=> urethritis
| anyone=> acute appendicitis
92
Tx for enterobius vermicular
albendazole or mebendazole
93
What is a significant complication if Trichuris trichiura infection occurs? how is it transmitted?
ingestion of eggs
| produces diarrhea that may lead to rectal prolapse in children
94
How to Dx for trichuris trichiura? Tx?
stool for ova and parasites along w/ eosinophilia;
| Tx: albendazole
95
differentiate the 2 different modes of ascaris lumbricoides infection?
larval phase through lungs=> cough, pneumonitis, eosinophilia (invasion of tissue);
bowel obstruction in adult phase=> no eosinophilia (no tissue invasion)
96
Tx for Ascaris lumbricoides
albendazole and mebendazole
97
What does a Necator americanus infection cause?
adults attach to villi resulting in blood loss and iron deficiency
98
Tx for necator americanus
albendazole or mebendazole
99
How is Strongyloides stercoralis transmitted?
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
How may an autoinfection occur w/ strongyloides stercoralis?
if filariform larvae in intestine penetrate mucosa and migrate to lungs to repeat cycle
101
What is likely to occur in immunocompromised pts w/ strongyloides stercoralis?
massive reinfection occurs w/ dissemination throughout the body
102
Tx for strongyloides stercoralis
ivermectin
103
How is diphyllobothrium latum transmitted? what does it cause?
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
Dx of diphyllobothrium latum? Tx?
eggs in stool;
| Tx is praziquantel
