Diarrhea & GI pathogens Flashcards
Diarrhea that lasts less than _ weeks is considered acute diarrhea
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
Diarrhea that lasts longer than _ weeks is considered chronic diarrhea
Diarrhea that lasts longer than 4 weeks is considered chronic diarrhea
* Often due to a chronic condition and might require more extensive management
Diarrhea that lasts between 2-4 weeks could be _ or _
Diarrhea that lasts between 2-4 weeks could be lingering infection or early presentation of chronic disease
* Gray zone; this is indeterminate diarrhea
The number one cause of acute diarrhea is _ ; other causes include _
The number one cause of acute diarrhea is infection ; other causes include medications, ischemia
Develop a ddx for chronic diarrhea:
Develop a ddx for chronic diarrhea:
* IBD
* Celiac
* Pancreatic disease
* Medications
* Malabsorption
* Cancer
Acute infectious diarrhea is most often caused by (viruses/ bacteria/ protazoa/ parasites)
Acute infectious diarrhea is most often caused by viruses
* “stomach bug,” “stomach flu” = viral gastroenteritis
Two big categories of diarrhea are _ (non-invasive) and _ (invasive)
Two big categories of diarrhea are watery diarrhea (non-invasive) and inflammatory diarrhea (invasive)
Watery diarrhea is most often caused by _
Watery diarrhea is most often caused by an enterotoxin
* Recall that watery diarrhea is non-invasive and non-inflammatory
Watery diarrhea often involves an enterotoxin targeting the _ (location)
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
Pathogens that cause watery diarrhea include:
Pathogens that cause watery diarrhea include:
* Vibrio cholera
* E.coli (enterotoxigenic, enteroaggregative)
* Bacillus cereus
* Staphylococcus aureus
* Norovirus
* Adenovirus
* Giardia
* Cryptosporidium
What are some signs that diarrhea may be inflammatory?
Inflammatory diarrhea may have:
* Mucus, pus, blood
* Fever, Systemic symptoms
Inflammatory/ invasive diarrhea often involves _ (location)
Inflammatory/ invasive diarrhea often involves the colon +/- small bowel
Inflammatory/ invasive diarrhea may be caused by _ or _
Inflammatory/ invasive diarrhea may be caused by cytotoxin or invasive damage to mucosa
Pathogens that cause inflammatory/invasive diarrhea include:
Pathogens that cause inflammatory/invasive diarrhea include:
* Shigella
* Salmonella
* Campylobacter jejuni
* E.coli (enterohemorrhagic, enteroinvasive)
* Clostridium difficile
* Entamoeba histolytica
* Yersinia enterocolitica
* Salmonella typhi
We usually treat non-invasive, non-inflammatory diarrhea with _
We usually treat non-invasive, non-inflammatory diarrhea with supportive care
Vibrio cholera exposure in the US is most often from _
Vibrio cholera exposure in the US is most often from oysters (shellfish)
* Cholera likes salt water conditions
The watery diarrhea in vibrio cholera infection is caused by (toxin/ bacteria)
The watery diarrhea in vibrio cholera infection is caused by enterotoxin
Cholera enterotoxin causes _ secretion in the small bowel
Cholera enterotoxin causes Na/Cl secretion in the small bowel
Cholera treatment involves _
Cholera treatment involves supportive care, rehydration solution
* Damage/ sx caused by the toxin so care is supportive
_ is a corkscrew organism which is a common cause of “food poisoning” from undercooked chicken, beef, etc
Campylobacter jejuni is a corkscrew organism which is a common cause of “food poisoning” from undercooked chicken, beef, etc
Campylobacter jejuni sx are caused by (toxin/ organism)
Campylobacter jejuni sx are caused by the organism itself
* The organism directly invades intestinal/ colonic epithelial cells
* Causes intense bloody diarrhea
Yersinia entercolitica is a fairly common pathogen that gets transmitted from _
Yersinia entercolitica is a fairly common pathogen that gets transmitted from undercooked pork, milk, water
Yersinia enterocolitica is able to survive the low pH of the stomach by producing _
Yersinia enterocolitica is able to survive the low pH of the stomach by producing urease
“Dysentery” is diarrhea with _
“Dysentery” is diarrhea with crampy pain (tenesmus) and mucoid stools
* The most common cause is shigella dysenteriae
Shigella dysenteriae produces shiga toxin which is a _
Shigella dysenteriae produces shiga toxin which is an enterotoxin, cytotoxin, and neurotoxin
(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
Shigella treatment involves _
Shigella treatment involves antibiotics
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
Patients with typhoid fever get _ (skin lesion)
Patients with typhoid fever get an erythematous maculopapular rash (rose spots)
Typhoid fever is spread via _
Typhoid fever is spread via fecal-oral
* It sheds in the stool for weeks
* Antibiotics recommended
Typhoid fever is caused by _
Typhoid fever is caused by salmonella typhi
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
_ creates a shiga-like toxin that causes endothelial damage
Enterohemorrhagic E.coli (EHEC) creates a shiga-like toxin that causes endothelial damage
* O157: H7
Sources of EHEC include _
Sources of EHEC include undercooked beef, unpasteurized milk, contaminated water
A patient with low platelets following an EHEC infection may have _
A patient with low platelets following an EHEC infection may have HUS-TTP
The most common cause of traveler’s diarrhea is _
The most common cause of traveler’s diarrhea is ETEC
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
Enteropathic E.coli is (non-invasive/ invasive)
Enteropathic E.coli is non-invasive
Enteropathogenic E.coli works by _
Enteropathogenic E.coli works by flattening the microvilli and reducing absorption –> diarrhea
_ 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
Watery diarrhea includes two subcategories: _ and _
Watery diarrhea includes two subcategories: osmotic diarrhea and secretory diarrhea
* Both of these include the frequent, watery stools
“Fatty diarrhea” is a sign of _
“Fatty diarrhea” is a sign of malabsorption
* Greasy or oily
* Malodorous stools
* May float
* Hard to flush
_ 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
Name some causes of chronic watery diarrhea
Name some causes of chronic secretory diarrhea
Name some causes of chronic fatty diarrhea
Name some causes of chronic inflammatory diarrhea
Name some causes of mixed diarrhea/ motility issues
_ 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
Enteroinvasive pathogens are all _ intracellular
Enteroinvasive pathogens are all facultative intracelluar
* Invasion of the host cells is key to pathogenesis
All clostridia are gram (positive/negative), spore-forming, (anaerobes/ aerobes)
All clostridia are gram positive, spore-forming, anaerobes
C. tetani causes _
C. tetani causes tetanus (spastic paralysis, lockjaw)
C. tetani produces a heat-labile neurotoxin called _
C. tetani produces a heat-labile neurotoxin called tetanospasmin
C. botulinum produces a toxin that inhibits the release of _
C. botulinum produces a toxin that inhibits the release of Ach –> flaccid paralysis
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
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
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
E.coli is gram (neg/pos), (anaerobe/aerobe), _ shape
E.coli is gram negative, facultative anaerobe, rod
E.coli will turn MacConkey pink because it is a _
E.coli will turn MacConkey pink because it is a lactose fermenter
ETEC is _
ETEC is enterotoxigenic E.coli
ETEC causes _ type illness
ETEC causes watery diarrhea that is similar to cholera
_ is the most common cause of traveler’s diarrhea
ETEC is the most common cause of traveler’s diarrhea
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
* eL Agua
* San Gabriel
EHEC stands for _ ; it has a specific subtype called _
EHEC stands for enterohemorrhagic E.coli ; it has a specific subtype called O157:H7
Manifestations of EHEC include:
Manifestations of EHEC include:
* Bloody diarrhea
* Dysentery-like disease
* Can lead to HUS-TTP
EHEC secretes a _ toxin that works by _
EHEC secretes a shiga-like toxin that works by binding ribosomes & inhibiting host cell protein synthesis
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
Is EHEC invasive and/or inflammatory?
EHEC is not invasive but is inflammatory
How do we treat EHEC?
Supportive care! do not treat with antibiotics; may increase risk of HUS
Describe the infective mechanism of shigella
Shigella invades M cells –> lyses phagosome –> replicates in cytosol –> spreads cell to cell via actin tail
Shigella manifests with _ sx
Shigella manifests with bloody diarrhea due to extensive colonic epithelial damage
Shiga toxin works by _
Shiga toxin works by inhibiting host cell protein synthesis
Shigella is (inflammatory/ invasive/ both/ neither)
Shigella is invasive and inflammatory
_ 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
Shigella can cause renal damage due to _
Shigella can cause renal damage due to shistocytes –> HUS
Explain the infective mechanism of salmonella
Salmonella invades M cells –> invades macrophages –> inhibits phagosome-lysosome fusion –> replicates within vacuole
Salmonella is gram (pos/neg), (aerobe/anaerobe), (motile/ non motile)
Salmonella is gram negative rod, facultative anaerobe, motile
Salmonella is a _ producer
Salmonella is a H2S producer (TSI)
Salmonella is (inflammatory/invasive/ both/ neither)
Salmonella is invasive, inflammatory
Typhoid fever is only caused by _
Typhoid fever is only caused by salmonella typhi (subspecies of salmonella enterica)
Typhoid fever is acquired via _
Typhoid fever is acquired via contaminated food/ water
Typhoid fever manifests as _ initially, followed by _
Typhoid fever manifests as constipation –> fever –> diarrhea –> rash
Typhoid fever is associated with _ skin manifestation
Typhoid fever is associated with rose-colored, flat rash
We have a _ vaccine against salmonella typhi
We have a oral live attenuated vaccine against salmonella typhi
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)
Yersenia enterocolitica is psychrotrophic meaning _
Yersenia enterocolitica is psychrotrophic meaning it can grow at lower temperatures (refrigeration)
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
Yersinia entercolitica is transmitted via _
Yersinia entercolitica is transmitted via contaminated food (pork) and raw milk
Yersinia entercolitica is (inflam/ invasive)
Yersinia entercolitica is invasive & inflammatory
_ 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
C. jejuni is a gram (pos/neg), _ shape
C. jejuni is a gram-negative spiral, motile; corkscrew motility allows propulsion through mucus
C. jejuni is transmitted via _
C. jejuni is transmitted via contaminated food (poultry) and raw milk
The most common bacterial foodborne diarrheal disease in the US is _
The most common bacterial foodborne diarrheal disease in the US is C. jejuni
C. jejuni is (invasive/ inflam)
C. jejuni is invasive and inflammatory
* Infection can lead to autoimmune neuropathy (Guillain-Barre)
Helicobacter pylori is a gram (pos/neg), _ shape
Helicobacter pylori is a gram-negative spiral, motile, facultative anaerobe
Helicobacter pylori survives the acidic GIT by _
Helicobacter pylori survives the acidic GIT by ammonia buffering (urease positive)
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
H. pylori is associated with _
H. pylori is associated with gastritis, peptic ulcers, gastric cancer risk
H. pylori is (invasive/ inflammatory)
H. pylori is inflammatory; not invasive
Vibrio cholerae is gram (pos/neg), _ , _
Vibrio cholerae is gram-negative, comma-shaped, motile, facultative anaerobe
* It is also oxidase positive
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
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
V. cholerae manifests as _
V. cholerae manifests as watery diarrhea; rice water stools
* Requires rehydration with water, salt, sugar mix
* Not invasive, secretory
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)
Listeria binds via _
Listeria binds via interalins
_ 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
_ 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
Listeria may present with _
Listeria may present with watery diarrhea
* Complications in pregnant or elderly
* Can cause meningitis or miscarraige
Listeria is transmitted via _
Listeria is transmitted via contaminated foods (soft cheeses and processed meats)
