23. Acute Diarrhea Flashcards
1
Q
Infectious diarrheal disease is the ___ leading cause of death worldwise
____ leading cause of childhood death
A
Second
First
2
Q
What is the time frame for acute diarrhea/
A
<14 days
3
Q
What is the definition for diarrhea?
A
> 200 grams per 24 hour period
3 or more loose/watery stools per day or clear increase in frequency over baseline
4
Q
When does most diarrhea occur?
A
Winter months (viral)
5
Q
WHat is the length of the SI? What is mostly absorbed there?
A
3-8 meters
Macronutrients: carbs, fat, nitrogen **absorbed in the proximal 100 to 150 cm
6
Q
How much of the 10 L of chyme that under the duodenum exits the SI?
Consequence on pathology in this area?
A
1.5 L
SI does the bulk of the absorption, therefor pathology is very dramatic there
7
Q
S/s of infections in the small bowel?
A
Large volume of watery diarrhea
Abdom cramping, bloating, gas, and weight loss
**fever is rare
**rare stool WBCs/occult blood
8
Q
S/s of infections in the large bowel?
A
Frequent, small, regular stools Painful BM of tenesmus (painful urge to have a BM) Fever Bloody and mucoid stools RBCs and WBCs on stool smear
9
Q
What is the infectious cause of most gastroenteritis?
A
Viral (cultures only positive in 1.5-5.6 cases
10
Q
What is the definition of severe, community acquired diarrhea?
A
> 4 fluid stools per day
3 days
87% bacterial
11
Q
What are the bacterial agents that commonly cause acute GI illness?
A
Salmonella Shigella Campylobacter C. difficile E. coli 0157:H7
12
Q
What are the viruses that commonly cause acute GI illness?
A
Adenovirus (40 and 41)
Rotavirus
Calcivirus
Astrovirus
13
Q
What are the protazoa that commonly cause GI illness?
A
Giardia
Cryptospoidium
Entomoeba histolytica
14
Q
What are the two viruses that cause colon infection in immunocompromised people?
A
CMV
HSV
15
Q
What are non-infectious causes of diarrhea?
A
Drugs-antibiotics, laxitives Food allergies IBD/IBS Thyoid disease Carcinoid/Neuroendocrine tumors Ischemic colitis Stool impaction-overflow diarrhea Stress
16
Q
What happens with osmotic diarrhea?
A
Neither SI nor colon can maintain an osmotic gradient
Unabsorbed ions in the lumen cause water retention
17
Q
What SHOULD the intraluminal osmolality be?
A
290 mOsm/kg
18
Q
What are some things that can cause osmotic diarrhea?
A
- Ingestion of poorly absorbed ions or sugar alcohols (mannitol, sorbitol, Mg, sulfate, phosphate)
- Disaccharidase deficiency (lactase deficiency)
19
Q
What causes cessation of osmotic diarrhea?
A
Fasting
Cessation of the offending substance
20
Q
Electrolyte concentrations in stool water with osmotic diarrhea
A
Low concentrations, because electrolyte absorption is not impaired
21
Q
What is the problem underlying secretory diarrhea?
A
- Net secretion of anions (Cl- or bicarbonate)
- Inhibition of net sodium absorbtion
22
Q
What is the most common cause of secretory diarrhea?
A
Infection
23
Q
What are three actions of enterotoxins that cause secretory diarrhea?
A
- Interact with receptors and modulate intestinal transport
- Block specific absorbative pathways in addition to stimulating secretion
- Inhibit Na+/H+ exchange in the SI and colon
24
Q
How is the osmotic gap calculated?
A
Gap=Serum Osm - estimated stool Osm (2 x ([Na]+[K]))
25
What is a normal sized osmotic gap that can result from not being able to count all of the cations?
Under 50 mOsm/kg
26
What kind of osmotic gap will be present in osmotic diarrhea?
Over 100 mOsm/kg
27
What causes a negative osmotic gap?
Poorly absorbed multivalent anion like phosphate or sulfate
28
Why is measured stool osmolality of little value?
Tends to rise once the stool has been collected due to continuing bacterial fermentation in vivo
29
What kind of laxitive can cause a large osmotic gaP?
Magnesium
30
What is useful to look at to see if stool samples have been diluted with urine in the case of laxitive injestion?
Stool osmolarity (very high if stool is diluted with urine)
31
What is the #1 foodbourne illness in the US?
Salmonella typhi
32
What is salmonella typhi infection assoc with?
Poultry, milk, eggs
| Pet turtles
33
People with salmonella typhi infection have increased risk for:
Gallbladder colonization and gallstones
34
Patients with sickle cell disease have an increased risk for:
Salmonella osteomylitis
35
Sx of acute salmonella typhi GI infection:
Anorexia, ab pain, bloating, N/V, bloody diarrhea
| **Colonic/dysenteric like illness despite small bowel disease
36
What area of the GI does shigella most commonly infect/
Left colon, ileum might also be involved
37
What is shigella rarely assoicated with? (3)
HUS
Seizures
Reactive arthritis
38
What is the leading cause of acute bacterial diarrhea worldwide?
Campylobacter jejuni
39
What are three things that can result from Campylobacter jejuni infection?
Reactive arthritis or erythema nodosum
Guillian Barre syndrome
Pseduoappendicitis (bad abdominal pain)
40
What is the most common pathogenic parasitic infection in humans?
Giardia lamblia
41
How is giardia lamblia acquired? Presentation?
Drinking unfiltered/rural water
| Acute/chronic diarrhea with upper abdominal pain
42
What are the 4 kinds of E. coli infections?
Enterotoxigenic (ETEC)
Enteroinvasive (EIEC)
Enteroaggregative (EAEC)
Enterohemorrhagic (EHEC) 0157:H7
43
What type of E. coli resembles shigella and produces blood diarrhea?
Enteroinvasive (EIEC)
44
What type of E. coli attaches to enterocytes via adherence fimbriae
Enteroaggregative (EAEC)
45
What type of E coli is associated with HUS?
Enterohemorrhagic (EHEC)
46
What are the two toxins that Enterotoxigenic E coli has?
Heat-labile: like cholera toxin
| Heat-stabile: increased IC cGMP with effects similar to cAMP electations by LT
47
How does the cholera enterotoxin cause disease?
- Increase in IC cAMP
- Opens CFTR
- Releases Cl- into lumen and water follows
48
What causes about half of all gastroenteritis outbreaks worldwide
Norovirus
49
What is the principal cause of traveller's diarrhea?
Enterotoxigenic E coli
50
Who is most susceptible to rotavirus infection?
Children between 6 and 24 months
51
What is an extra-GI sx that ascaris (nematode) can cause?
Ascaris pneumonitis (cough)
52
What causes stronyloides infections to persist?
Autoinfection: Adult worms in the intestines lay eggs that hatch and release larvae that penetrate the mucosa
53
What is the leading cause of IDA in the developing world?
Hookworms like Necator americanus and Ancylostoma duodenale
54
What are some parasites that are more likely to infect patients with lymphoma, BMT, HIV?
Cryptosporidium parvum
Isospora belli
Cyclospora
Microsporia
55
What are some bacteria that are more likely to infect patients with lymphoma, BMT, HIV?
Salmonella
Campylobacter
Shigella
MAC (myobacterium avium complex)
56
What are some viruses that are more likely to infect patients with lymphoma, BMT, HIV?
CMV
HSV
Adenovirus
57
What defines nosocomial diarrhea?
New diarrhea at least 72 hours after admission
| **increases the length of stay, severity depends on age
58
What is the most common cause of nosicomial diarrhea?
Clostridium difficile
| **also tube feeds, meds, fecal impaction, ischemic colitis, and CMV/HSV/GVHD in BMT transplants
59
What does diarrhea within 6 hours of eating suggest?
Ingestion of a toxin--S.aureus in potato salad or Bacillus cereus in Chinese food/rice
60
What does diarrhea at 8-14 hr after eating suggest?
Clostridium perfringens
61
What is needed for diagnosis of the etiology of infectious colitis?
CULTURE
| **endoscopy not indicated
62
What is a stool culture indicated?
- Severely ill
- Outbreaks
- Hospitalization requirement
- IC patients
- Comorbidities
- IBD
- some employees
63
Why are there many false negatives for ova and parasites? What must be done because of this?
```
Ova shed intermittantly
Repeated 3x (3 consecutive days, 24 hr apart)
```
64
When should stool for O and P be ordered?
```
Persistent diarrhea >14 days
Travel to mountainous regions
Exposure to infants in daycare
Immune-compromised
Community waterborne outbreak
```
65
What are ELISAs or DFA good at identifying in the school?
Giardiasis
| Cryptosporidium
66
What is the key aspect of treatment for diarrhea?
HYDRATION
67
What are the important factors for oral rehydration in diarrhea tx?
Intestinal glucose absorption via sodium-glucose cotransport remains intact
Intestine able to absorb water if glucose and salt are present
68
What is the Na/glucose cotransporter on the apical surface?
SGLT-1
69
How does EHEC presentation differ from the other E coli infections?
Bloody stool
NO fever
WBC >10,000
Abdominal tenderness
70
Why is it important to distinguish between EHEC and the other E. colis?
Don't want to give EHEC antibiotics--precipitates HUS
71
Presentation and Tx for traveller's diarrhea (enterotoxic E.coli)
>4 stools daily with fever, blood/pus/mucus in stool
| Prompt tx with fluoroquinolone or TMP-SMX (reduces duration from 3-5 to 1-2 days)
72
What are the indications for empiric antibiotics for diarrhea? What antibiotic?
Fever, bloody diarrhea, and the presence of occult blood or fecal leukocytes in the stool
**except for C. diff and EHEC
Fluoroquinolone for 3-5 days (azithromycin and erythromycin if there is resistance)
73
What are two antimotility agents?
Loperamide
| Diphenoxylate
74
When is the only time that antimotility agents should be used?
If fever is absent and stools are NOT bloody
75
What happens if you use antimotility agents for EHEC?
Facilitates the development of HUS
76
Classification of C. diff
Gram + spore forming anaerobic bacteria
77
Transmission of C. diff?
Fecal oral
78
What % of inpatients have asymptomatic colonization with C diff? Outpatients?
7-26%
| 2%
79
Why do newborns have a high carrier rate but don't get infected?
Don't have the receptors that the toxins bind to, don't get sick
80
How many days from exposure to sx with c diff?
2-3 days
81
Of the C. diff spores and vegetative cells ingested, which one makes it to the small bowel?
Spores can survive the stomach acidity and germinate in the small bowel upon exposure to bile acids
82
Where does C. diff colonize?
Colonic mucosa
83
What happens after antibiotics destroy normal bacterial flora?
C. difficile grows and secretes toxins
Toxins inflame and ulcerate the mucosa
Damaged mucosa secretes fluid that causes the diarrhea
84
What are the toxins produced by C. difficile?
Toxin A: potent enterotoxin
Toxin B: cytotoxin in vitro
Binary
85
What C diff toxin is typically tested for?
Toxin B
86
What are characteristics of the hypervirulent C. diff strain
BI/NAP1/027 strains have 16x more toxin A and 23x more toxin B
tcdC gene mutation may have increased toxin levels
Increased fluoroquinolone resistance
87
What are the typical clinical feautures of C. diff colitis?
```
Bloody, watery diarrhea
Fever
Ab pain
Leukocytosis (VERY HIGH)
Pseudomembrinous colitis
```
88
What are the features of severe forms of C. diff infections ?
Toxic megacolon
Sepsis
Colonic perforation
Death
89
Important modes of prevention of C. diff?
Gloves
HAND WASHING (alcohol based gels don't work)
Minimize antibiotic exposure (esp quinolones)
90
What are the mainstay therapies for primary C. diff?
Vancomycin
Metronidazole
**similar efficacy, but vanco is slightly more effective for severe cases
91
Severe C diff disease is defined as any one of the following:
1. Age over 65
2. Creatinine over 1.5 times baseline
3. WBC > 15K
92
What percent of patients with C. diff will have recurrence of sx after intial infection?
10-35%
93
What are risk factors for recurrence of C diff infection?
```
COntinued antibiotics (prevent reest of normal flora)
Age and comorbidities
Antacid medication
Immunosuppression
Immunodeficiency
```
94
What are the options for tx of recurrence of C diff
Repeat initial therapy
Switch to vanco
Vanco taper (allow good bacteria to return)
Rifaximin chaser (follows vanco)
95
What is an alternative to vanco for C diff that inhibits RNA pol, but lacks activity vs gram negative bacteria, preserving some natural flora?
Fidaxomicin (low serum conc, high fecal concentration)
* *has better protection against recurrence than vanco
* *too expensive
96
What are the risks of using probiotics for protecting against C diff recurrence?
Fungemia from sacchromyces
Endocartitis from lactobaccilus and bifidobacteria
**in IC and critically ill patients
97
What is the probiotic that is MC used following C diff tx?
Sacchromyces boulardii
98
What antibodies increase following C diff infection?
Anti-toxin A and B antibody levels
| **High IgA anti-toxin A is 48x more protective than low levels
99
What is the MOA of IVIG for C diff?
Neutralization of toxin A thorugh IgG anti-toxin A antibodies
**good choice for patients that are immunosuppressed
100
What is IBS?
Recurrent and relapsing abdominal pain, bloating, and change in bowel habits including diarrhea and constipation
101
Causes of IBS
Psychologic stressors
Diet
Abnormal GI motility
Visceral hypersentitivity
102
When does IBS manifest? Labs?
20-40 yo in females
| Labs all normal, normal endoscopy
103
What is the Rome III criteria for IBS?
Recurrent abdominal pain or discomfort 3 days/month in the last 3 months along with 2 or more of the following:
1. Improvement with defecation
2. Onset assoc with change in BM frequency
3. Onset assoc with change in appearance of stool
104
What happens in diverticular disease?
Pseudodiverticular outpouching of the colonic mucosa and submucosa
Nerves and arterial vasa recta penetrate the inner circular muscle coat to create discontinuities in the muscle wall
105
Who gets diverticular disease? Under what conditions? Exacerbated by:
```
Older people (505 in Western adult populations over 60)
Conditions of elevated intraluminal pressure in the sigmoid colon, exacerbated by diets low in fiber which reduces stool bulk
```
106
What region of the colon is MC affected by diverticular disease?
Obstruction of diverticula leads to:
Sigmoid colon
| Diverticulitis
107
What can happen with perforation in diverticulitis?
Pericolonic abscesses
Sinus tracts
Peritonitis
108
Sx of diverticular disease?
Usually asymptomatic
| 20%: cramping, lower abdominal discomfort, constipation, diarrhea
109
What might prevent development of diverticulitis from diverticular disease? Tx if diverticulitis develops?
High fiber diet
| Resolves spontaneously or after antibiotic tx
110
What causes appendicitis in 50-80% of cases?
Overt lumenal obstruction like a stonelike mass of stool (fecolith)
111
What is the name for the point where abdominal pain focuses in appendicitis?
McBurney's point: right lower quadrant
112
What is McBurney's sign?
Deep tenderness noted at 2/3 the distance from the umbilicus to the right anterior iliac spine
113
What causes mucosal infartion ischemic colitis? Transmural infarction?
Hypoperfusion: hypotension or arterial spasm
| Arterial occlusion: thrombosis or embolis
114
What are the two watershed regions that are particularly susceptible to ischemic colitis?
1. Splenic flexure (SMA to IMA)
| 2. Sigmoid colon and rectum (IMA to pudendal)
115
What will be seen on endoscopy with ischemic colitis?
Segmental and patchy hemorrhage/ulceration of the mucosa
| Linear ulcerations
116
Who gets ischemic colitis?
Older people with coexisting cardiac or vascular disease
117
How does acute transmural infarction causing ischemic colitis manifest?
Sudden, severe abdominal pain and tenderness
| Sometimes accompanied by nausea, vomiting, bloody diarrhea, or grossly melanotic stool
