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Diarrhea & GI pathogens Flashcards

1
Q

Diarrhea that lasts less than _ weeks is considered acute diarrhea

A

Diarrhea that lasts less than 2 weeks is considered acute diarrhea
* This clues us in that it is probably an infectious cause and often self-limiting

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2
Q

Diarrhea that lasts longer than _ weeks is considered chronic diarrhea

A

Diarrhea that lasts longer than 4 weeks is considered chronic diarrhea
* Often due to a chronic condition and might require more extensive management

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3
Q

Diarrhea that lasts between 2-4 weeks could be _ or _

A

Diarrhea that lasts between 2-4 weeks could be lingering infection or early presentation of chronic disease
* Gray zone; this is indeterminate diarrhea

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4
Q

The number one cause of acute diarrhea is _ ; other causes include _

A

The number one cause of acute diarrhea is infection ; other causes include medications, ischemia

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5
Q

Develop a ddx for chronic diarrhea:

A

Develop a ddx for chronic diarrhea:
* IBD
* Celiac
* Pancreatic disease
* Medications
* Malabsorption
* Cancer

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6
Q

Acute infectious diarrhea is most often caused by (viruses/ bacteria/ protazoa/ parasites)

A

Acute infectious diarrhea is most often caused by viruses
* “stomach bug,” “stomach flu” = viral gastroenteritis

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7
Q

Two big categories of diarrhea are _ (non-invasive) and _ (invasive)

A

Two big categories of diarrhea are watery diarrhea (non-invasive) and inflammatory diarrhea (invasive)

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8
Q

Watery diarrhea is most often caused by _

A

Watery diarrhea is most often caused by an enterotoxin
* Recall that watery diarrhea is non-invasive and non-inflammatory

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9
Q

Watery diarrhea often involves an enterotoxin targeting the _ (location)

A

Watery diarrhea often involves an enterotoxin targeting the small bowel
* The small bowel is responsible for absorbing about 7/9 L of water that moves through the GIT

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10
Q

Pathogens that cause watery diarrhea include:

A

Pathogens that cause watery diarrhea include:
* Vibrio cholera
* E.coli (enterotoxigenic, enteroaggregative)
* Bacillus cereus
* Staphylococcus aureus
* Norovirus
* Adenovirus
* Giardia
* Cryptosporidium

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11
Q

What are some signs that diarrhea may be inflammatory?

A

Inflammatory diarrhea may have:
* Mucus, pus, blood
* Fever, Systemic symptoms

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12
Q

Inflammatory/ invasive diarrhea often involves _ (location)

A

Inflammatory/ invasive diarrhea often involves the colon +/- small bowel

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13
Q

Inflammatory/ invasive diarrhea may be caused by _ or _

A

Inflammatory/ invasive diarrhea may be caused by cytotoxin or invasive damage to mucosa

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14
Q

Pathogens that cause inflammatory/invasive diarrhea include:

A

Pathogens that cause inflammatory/invasive diarrhea include:
* Shigella
* Salmonella
* Campylobacter jejuni
* E.coli (enterohemorrhagic, enteroinvasive)
* Clostridium difficile
* Entamoeba histolytica
* Yersinia enterocolitica
* Salmonella typhi

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15
Q

We usually treat non-invasive, non-inflammatory diarrhea with _

A

We usually treat non-invasive, non-inflammatory diarrhea with supportive care

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16
Q

Vibrio cholera exposure in the US is most often from _

A

Vibrio cholera exposure in the US is most often from oysters (shellfish)
* Cholera likes salt water conditions

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17
Q

The watery diarrhea in vibrio cholera infection is caused by (toxin/ bacteria)

A

The watery diarrhea in vibrio cholera infection is caused by enterotoxin

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18
Q

Cholera enterotoxin causes _ secretion in the small bowel

A

Cholera enterotoxin causes Na/Cl secretion in the small bowel

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19
Q

Cholera treatment involves _

A

Cholera treatment involves supportive care, rehydration solution
* Damage/ sx caused by the toxin so care is supportive

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20
Q

_ is a corkscrew organism which is a common cause of “food poisoning” from undercooked chicken, beef, etc

A

Campylobacter jejuni is a corkscrew organism which is a common cause of “food poisoning” from undercooked chicken, beef, etc

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21
Q

Campylobacter jejuni sx are caused by (toxin/ organism)

A

Campylobacter jejuni sx are caused by the organism itself
* The organism directly invades intestinal/ colonic epithelial cells
* Causes intense bloody diarrhea

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22
Q

Yersinia entercolitica is a fairly common pathogen that gets transmitted from _

A

Yersinia entercolitica is a fairly common pathogen that gets transmitted from undercooked pork, milk, water

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23
Q

Yersinia enterocolitica is able to survive the low pH of the stomach by producing _

A

Yersinia enterocolitica is able to survive the low pH of the stomach by producing urease

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24
Q

“Dysentery” is diarrhea with _

A

“Dysentery” is diarrhea with crampy pain (tenesmus) and mucoid stools
* The most common cause is shigella dysenteriae

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25
Shigella dysenteriae produces shiga toxin which is a _
Shigella dysenteriae produces shiga toxin which is an **enterotoxin, cytotoxin, and neurotoxin**
26
(Numerous/ few) bacteria are needed for shigella infection
**Few bacteria** are needed for shigella infection because it is **resistant to stomach acid** * Fecal oral: feces, food, fingers, flies
27
Shigella treatment involves _
Shigella treatment involves **antibiotics**
28
The progression of "typhoid fever" first involves _ followed by _ weeks later
The progression of "typhoid fever" first involves **fever, constipation, abdominal pain** followed by **diarrhea** weeks later
29
Patients with typhoid fever get _ (skin lesion)
Patients with typhoid fever get an **erythematous maculopapular rash** (rose spots)
30
Typhoid fever is spread via _
Typhoid fever is spread via **fecal-oral** * It sheds in the stool for weeks * Antibiotics recommended
31
Typhoid fever is caused by _
Typhoid fever is caused by **salmonella typhi**
32
Salmonella (not typhi) is a common infection in the US and is caused by _
Salmonella (not typhi) is a common infection in the US and is caused by **eggs, poultry, dairy, contact with reptiles**
33
_ creates a shiga-like toxin that causes endothelial damage
**Enterohemorrhagic E.coli (EHEC)** creates a shiga-like toxin that causes endothelial damage * O157: H7
34
Sources of EHEC include _
Sources of EHEC include **undercooked beef, unpasteurized milk, contaminated water**
35
A patient with low platelets following an EHEC infection may have _
A patient with low platelets following an EHEC infection may have **HUS-TTP**
36
The most common cause of traveler's diarrhea is _
The most common cause of traveler's diarrhea is **ETEC**
37
ETEC sx are caused by (toxin/ organism)
ETEC sx are caused by **enterotoxin** * The bacteria attaches to the intestinal brush border via fimbria and releases enterotoxins * Does not invade cells --> no blood, no systemic sx
38
Enteropathic E.coli is (non-invasive/ invasive)
Enteropathic E.coli is **non-invasive**
39
Enteropathogenic E.coli works by _
Enteropathogenic E.coli works by **flattening the microvilli and reducing absorption** --> diarrhea
40
_ is a gram positive anaerobe that creates a toxin that damages enterocytes and colonocytes and causes pseudomembranes
**Clostridium difficile** is a gram positive anaerobe that creates a toxin that damages enterocytes and colonocytes and causes *pseudomembranes* * Hard to kill because it forms spores
41
Watery diarrhea includes two subcategories: _ and _
Watery diarrhea includes two subcategories: **osmotic diarrhea** and **secretory diarrhea** * Both of these include the frequent, watery stools
42
"Fatty diarrhea" is a sign of _
"Fatty diarrhea" is a sign of **malabsorption** * Greasy or oily * Malodorous stools * May float * Hard to flush
43
_ diarrhea may involve systemic symptoms like fever and mucoid (pus) in the stool
**Inflammatory** diarrhea may involve systemic symptoms like fever and mucoid (pus) in the stool
44
Name some causes of chronic watery diarrhea
45
Name some causes of chronic secretory diarrhea
46
Name some causes of chronic fatty diarrhea
47
Name some causes of chronic inflammatory diarrhea
48
Name some causes of mixed diarrhea/ motility issues
49
_ testing is a good way to differentiate between secretory vs. osmotic watery diarrhea
**Stool electrolyte** testing is a good way to differentiate between secretory vs. osmotic watery diarrhea
50
Enteroinvasive pathogens are all _ intracellular
Enteroinvasive pathogens are all **facultative intracelluar** * Invasion of the host cells is key to pathogenesis
51
Enteroinvasive pathogens usually cause sx like:
Enteroinvasive pathogens usually cause sx like: **bloody diarrhea with pus, severe cramping** * Includes EIEC, shigella, yersinia entercolitica, salmonella enterica, campylobacter jejuni, listeria
52
_ is enteroinvasive but it is *not inflammatory*
**Listeria** is enteroinvasive but it is *not inflammatory*
53
Vibrio cholerae is enterotoxic and (inflammatory/ non-inflammatory)
Vibrio cholerae is enterotoxic and **non-inflammatory**
54
C. diff is enterotoxic and (inflammatory/ non-inflammatory)
C. diff is enterotoxic and **inflammatory** (it is non-invasive)
55
Enteropathic bacteria are bacteria that _ ; examples include _ and _
Enteropathic bacteria are bacteria that **adhere and perturb epithelium** ; examples include **EPEC** and **H. pylori** * No bacterial invasion or exotoxins involved
56
All clostridia are gram (positive/negative), spore-forming, (anaerobes/ aerobes)
All clostridia are **gram positive**, spore-forming, **anaerobes**
57
C. tetani causes _
C. tetani causes **tetanus** (spastic paralysis, lockjaw)
58
C. tetani produces a heat-labile neurotoxin called _
C. tetani produces a heat-labile neurotoxin called **tetanospasmin**
59
C. botulinum produces a toxin that inhibits the release of _
C. botulinum produces a toxin that inhibits the release of **Ach** --> **flaccid paralysis**
60
C. diff infection is associated with _
C. diff infection is associated with **antibiotic use, nosocomial infection** * Clindamycin use is a common culprit * Poor hand hygiene by health care workers
61
The two major virulence factors of C. diff include _ and _
The two major virulence factors of C. diff include **Toxin A** and **Toxin B**
62
Both of C. diff's toxins (toxin A and toxin B) are _
Both of C. diff's toxins (toxin A and toxin B) are **Rho GTPases** * Cause the release of proinflammatory cytokines * Cause disruption of host actin cytoskeleton; increased permeability; PMN infiltration
63
C. diff may cause severe inflammation of the inner lining of the colon called _
C. diff may cause severe inflammation of the inner lining of the colon called **pseudomembranous colitis**
64
C. perfringens can cause 2 distinct diseases; the gas gangrene version is caused by _ virulence factor
C. perfringens can cause 2 distinct diseases; the gas gangrene version is caused by **alpha toxin** * Pore-forming phospholipase in wounds that degrades the membranes and releases gas
65
C. perfringens can cause 2 distinct diseases; the food poisoning version is caused by _
C. perfringens can cause 2 distinct diseases; the food poisoning version is caused by **heat-labile enterotoxin** * Ingestion of undercooked meat --> profuse, watery diarrhea
66
E.coli is gram (neg/pos), (anaerobe/aerobe), _ shape
E.coli is **gram negative, facultative anaerobe, rod**
67
E.coli will turn MacConkey pink because it is a _
E.coli will turn MacConkey pink because it is a **lactose fermenter**
68
EAEC is _ ; it causes _
EAEC is **enteroaggregative E.coli** ; it causes **watery diarrhea** (with or without blood) * Produces a biofilm and cytotoxin * Not invasive or inflammatory
69
ETEC is _
ETEC is **enterotoxigenic E.coli**
70
ETEC causes _ type illness
ETEC causes **watery diarrhea** that is similar to cholera
71
_ is the most common cause of traveler's diarrhea
**ETEC** is the most common cause of traveler's diarrhea
72
ETEC produces a heat-labile enterotoxin which increases _ and a heat-stable enterotoxin which increases _
ETEC produces a heat-labile enterotoxin which increases **cAMP** and a heat-stable enterotoxin which increases **cGMP** * e**L** **A**gua * **S**an **G**abriel
73
EPEC is _
EPEC is **enteropathogenic E.coli** * Causes a non invasive, non inflammatory, watery diarrhea
74
EPEC involves _ formation; that causes host cell cytoskeletal rearrangements
EPEC involves **pedestal formation**; that causes host cell cytoskeletal rearrangements
75
EIEC is _
EIEC is **enteroinvasive E.coli** * Invasive & inflammatory * Causes bloody diarrhea
76
EIEC causes necrosis and inflammation via _
EIEC causes necrosis and inflammation via **lysing phagosome, replicating in cytosol, spreading cell to cell**
77
EHEC stands for _ ; it has a specific subtype called _
EHEC stands for **enterohemorrhagic E.coli** ; it has a specific subtype called **O157:H7**
78
Manifestations of EHEC include:
Manifestations of EHEC include: * **Bloody diarrhea** * **Dysentery-like disease** * Can lead to HUS-TTP
79
EHEC secretes a _ toxin that works by _
EHEC secretes a **shiga-like toxin** that works by **binding ribosomes & inhibiting host cell protein synthesis**
80
EHEC is commonly transmitted via _
EHEC is commonly transmitted via **undercooked ground beef** * Recall the classic "child eats undercooked burger and gets HUS" * Higher risk in elderly and young
81
Is EHEC invasive and/or inflammatory?
EHEC is *not invasive* but is **inflammatory**
82
How do we treat EHEC?
Supportive care! **do not treat with antibiotics**; may increase risk of HUS
83
Shigella is gram (pos/neg), (aerobe/anaerobe), (motile/ non-motile)
Shigella is a **gram-negative rod**, **facultative anaerobe**, **non-motile**
84
Shigella has a (high/low) ID50
Shigella has a **low ID50** * It is resistant to gastric acids, so we only need a few bacteria
85
Salmonella has a (high/low) ID50
Salmonella has a **high ID50** * Requires lots of bacteria
86
Describe the infective mechanism of shigella
Shigella invades M cells --> lyses phagosome --> replicates in cytosol --> spreads cell to cell via actin tail
87
Shigella manifests with _ sx
Shigella manifests with **bloody diarrhea** due to extensive colonic epithelial damage
88
Shiga toxin works by _
Shiga toxin works by **inhibiting host cell protein synthesis**
89
Shigella is (inflammatory/ invasive/ both/ neither)
Shigella is **invasive and inflammatory**
90
_ uses host cells actin cytoskeleton to create a tail to propel itself from one cell to another
**Shigella** uses host cells actin cytoskeleton to create a tail to propel itself from one cell to another
91
Shigella can cause renal damage due to _
Shigella can cause renal damage due to **shistocytes** --> **HUS**
92
Explain the infective mechanism of salmonella
Salmonella invades M cells --> invades macrophages --> inhibits phagosome-lysosome fusion --> replicates within vacuole
93
Salmonella is gram (pos/neg), (aerobe/anaerobe), (motile/ non motile)
Salmonella is **gram negative rod, facultative anaerobe, motile**
94
Salmonella is a _ producer
Salmonella is a **H2S producer** (TSI)
95
Salmonella is (inflammatory/invasive/ both/ neither)
Salmonella is **invasive, inflammatory**
96
Typhoid fever is only caused by _
Typhoid fever is only caused by ***salmonella typhi*** (subspecies of salmonella enterica)
97
Typhoid fever is acquired via _
Typhoid fever is acquired via **contaminated food/ water**
98
Typhoid fever manifests as _ initially, followed by _
Typhoid fever manifests as **constipation** --> **fever** --> **diarrhea** --> **rash**
99
Typhoid fever is associated with _ skin manifestation
Typhoid fever is associated with **rose-colored, flat rash**
100
We have a _ vaccine against salmonella typhi
We have a **oral live attenuated** vaccine against salmonella typhi
101
Yersinia enterocolitica is gram (pos/neg), (aerobe/anaerobe), (motile/ non motile)
Yersinia enterocolitica is **gram negative rod, facultative anaerobe, motile at less than RT** (non-motile above room temp)
102
Yersenia enterocolitica is psychrotrophic meaning _
Yersenia enterocolitica is psychrotrophic meaning **it can grow at lower temperatures (refrigeration)**
103
Yersinia entercolitica uses _ to survive the gastric acid in the GIT
Yersinia entercolitica uses **ammonia (urease-positive)** to survive the gastric acid in the GIT
104
Yersinia entercolitica is transmitted via _
Yersinia entercolitica is transmitted via **contaminated food (pork) and raw milk**
105
Yersinia entercolitica is (inflam/ invasive)
Yersinia entercolitica is **invasive & inflammatory**
106
_ is a fastidious microaerophilic bacteria that infects the GIT
**Campylobacter jejuni, helicobacter pylori** are two *fastidious* (hard to grow) microaerophilic (likes low oxygen levels) bacteria that infect the GIT
107
C. jejuni is a gram (pos/neg), _ shape
C. jejuni is a **gram-negative spiral**, **motile**; corkscrew motility allows propulsion through mucus
108
C. jejuni is transmitted via _
C. jejuni is transmitted via **contaminated food (poultry) and raw milk**
109
The most common bacterial foodborne diarrheal disease in the US is _
The most common bacterial foodborne diarrheal disease in the US is **C. jejuni**
110
C. jejuni is (invasive/ inflam)
C. jejuni is **invasive and inflammatory** * Infection can lead to autoimmune neuropathy (Guillain-Barre)
111
Helicobacter pylori is a gram (pos/neg), _ shape
Helicobacter pylori is a **gram-negative spiral, motile, facultative anaerobe**
112
Helicobacter pylori survives the acidic GIT by _
Helicobacter pylori survives the acidic GIT by **ammonia buffering (urease positive)**
113
Helicobacter pylori has two exotoxins _ and _
Helicobacter pylori has two exotoxins **VacA** and **CagA** that cause tissue damage * *Mucinases* also degrade mucins and damage epithelium
114
H. pylori is associated with _
H. pylori is associated with **gastritis, peptic ulcers, gastric cancer risk**
115
H. pylori is (invasive/ inflammatory)
H. pylori is **inflammatory; not invasive**
116
Vibrio cholerae is gram (pos/neg), _ , _
Vibrio cholerae is **gram-negative, comma-shaped, motile, facultative anaerobe** * It is also oxidase positive
117
Vibrio cholerae lives in _ and is transmitted via _
Vibrio cholerae lives in **brackish/ saltwater** and is transmitted via **shellfish or contaminated water** * Endemic in countries with poor water filtration
118
Explain the pathogenesis of V. cholerae
**CT AB-subunit** ADP-ribosylates GTP-binding protein --> increase cAMP --> increase Cl- --> decrease NaCl absorption --> profuse fluid and electrolyte loss
119
V. cholerae manifests as _
V. cholerae manifests as **watery diarrhea; rice water stools** * Requires rehydration with water, salt, sugar mix * Not invasive, secretory
120
Listeria is a gram (pos/neg) rod, facultative anaerobe
Listeria is a **gram positive** rod, facultative anaerobe * Has motility at lower temperatures (below RT) * Psychotrophic (grows at low temps)
121
Listeria binds via _
Listeria binds via **interalins**
122
_ is an exotoxin that listeria uses to lyse phagosomes
**Listeriolysin O (LLO)** is an exotoxin that listeria uses to lyse phagosomes * Listeria is invasive but not inflammatory
123
_ is an exotoxin that listeria uses to polymerize host actin and move from cell to cell
**ActA** is an exotoxin that listeria uses to polymerize host actin and move from cell to cell
124
Listeria may present with _
Listeria may present with **watery diarrhea** * Complications in pregnant or elderly * Can cause meningitis or miscarraige
125
Listeria is transmitted via _
Listeria is transmitted via **contaminated foods (soft cheeses and processed meats)**

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