Diarrhea Flashcards
Definition of diarrhea
- stool volume >200 g/d
- loose to watery
- abnormally frequent diarrhea (hard to measure)
Types of diarrhea to r/o
- IBS: sensation of incomplete evacuation
- Fecal incontinence
- Overflow diarrhea
Daily fluids
- 2 L ingested
- 7 L digestive secretions
- 8 L absorbed in small intestine
- 500 mL absorbed in colon (can do slightly more if needed)
Osmotic gap in stool
- if there is a gap, indicates presence of abnormal solute in stool
- Osmotic diarrhea has gap >100 (lots of solute)
- Secretory diarrhea has gap <50: no abnormal solute in stool
Types of diarrhea
- Inflammatory or non-inflammatory
Non-inflammatory
- Secretory
- persistent
Inflammatory
- dt invasion
- hemorrhagic dt cytotoxin
Clinical features of osmotic diarrhea
- > 100 osmotic gap: lots of solute
- contains water and mal absorbed solutes (lactose, fat, etc.)
- resolves with fasting or cessation of offending agent
- Ex. lactose intolerance, miralax, etc.
Clinical features of secretory diarrhea
- <100 osmotic gap (no abnl solutes)
- lots of water, lots of electrolytes
- large volume of watery stool
- ex. cholera
Red flags for infectious diarrhea
- high fever (>39C/102.2F)
- systemic illness
- Hematochezia
- > 2 weeks
- volume depletion
- weight loss
What percent of acute diarrhea is infectious?
90%
Three important topics to cover during history
- Is IV fluid replacement needed: volume depletion, vitals
- Is it osmotic or secretory
- Is it inflammatory or non-inflammatory: is there hematochezia (inflammatory)
what is the best way to determine if viral, bacterial, parasite?
good history
Complications of infectious diarrhea
- dehydration, hypovolemia
- electrolyte loss (Na, K, Mg, Cl)
Hypokalemia: dysrrhythmias
Hypomg: tetany, tremor
Metabolic acidosis: bicarb loss - vascular collapse: severe diarrhea, extremes of age
- Acute tubular necrosis: renal failure
Infectious Diarrhea
- worldwide epidemiology
- leading cause of childhood mortality
- 5 million deaths a year
- 2,195 deaths a day
Infectious Diarrhea
- US epidemiology
- 99 million acute cases a year
- 5,000 deaths annually dt food borne illness
- 95% of diarrhea deaths are people >65 yo
Infectious Diarrhea
- US risk factors
- Immunocompromised
- Institutionalized: SNF, prison
- Social/occupational: day care
- Travel: underdeveloped tropical regions (40%)
- Food/Diet: raw meat, raw egg, shellfish, unpasteurized milk, buffets, picnic, poor food hygiene
- *poop sprouts and poop spinach
what is the pathway for infectious diarrhea?
fecal to oral, always. And yes that is disgusting
Risk factors of fecal-oral transmission (6)
- improper disposal of feces, poor sanitation
- drinking contaminated water
- poor hand hygiene (esp. food handlers)
- improper food hygiene
- inadequate food refrigeration
- food exposure to flies
Three common viral pathogens
- Virus MC cause in US
- rotavirus
- norovirus
- adenovirus
7 common bacterial pathogens
- E. coli
- Salmonella
- Shigella
- Vibrio cholera
- Yersinia
- Campylobacter
- C. difficile
3 common parasitic pathogens
- giardia
- cryptosporidium
- entamoeba hystolytica
Two main ways pathogens cause diarrhea
- inflammation
- active secretion (creates osmotic difference)
Inflammatory diarrhea
- pathophys overview: list the two mechanisms
- Direct invasion
2. Cytotoxin release
Inflammatory diarrhea
- pathophys of direct invasion
- common pathogens
- invade gut lining, destroy macrophages as they try to engulf the pathogen
- Salmonella typhi, Yersinia, Campylobacter, Norovirus, Rotavirus, Entamoeba histolytica
Inflammatory diarrhea
- pathophys cytotoxin release
- common pathogens
- directly cause cell death
- C. diff
- Shiga toxin producing orgs: shigella, STEC E. coli (STEC = shiga toxin producing e. coli)
What is special about Shigella’s MOA
invasive AND produces cytotoxins
Two main ways pathogens cause active secretion
- Enterotoxin production
2. Preformed toxins
Secretory Diarrhea
- Enterotoxin production: pathophys
- example of pathogen
- cause cells to secrete chloride into the lumen
- Na and water follow
- ex cholera
Secretory Diarrhea
- preformed toxins: pathophys
- example of 2 pathogens
- neurotoxins cause the secretin of water and electrolytes
- C. pefringes and staph aureus
Three types of toxins that make pathogens pathogenic
- Enterotoxins
- Cytotoxins
- Neurotoxins
Enterotoxins
- how produced
- effect
- example
- produced by pathogen inside the body
- Act direction on mucosa to alter secretory mechanisms
- Increase Cl secretion and inhibit Na resorption
ex. cholera
Cytotoxins
- production
- effect
- examples
- Produced by bacteria in body
- destroy mucosal sells (direct destruction)
- cause inflammation and dysentery
- ex. shigella, STEC, c. diff
Neurotoxins
- production
- effect
- preformed toxins
- produced outside the body
- act directly on nervous system to alter secretion of electrolytes
Preformed toxins
- vomiting
- pain
- fever
- diarrhea
- ex
- common
- 1-2+
- rare
- 3-4+ watery
- staph, B. cereus, C. perfrigens
Enterotoxin
- vomiting
- pain
- fever
- diarrhea
- ex
- common
- ?
- rare
- 3-4+ watery
- vibrio cholerae
C. diff cytotoxin
- vomiting
- pain
- fever
- diarrhea
- ex
- rare
- 3-4+
- rare
- 2-3+ watery
- C. diff
Shiga-toxins
- vomiting
- pain
- fever
- diarrhea
- ex
- rare
- 3-4+
- common
- 1-2+ bloody
- Shigella, E. coli (STEC)
Direct invasion: bacteria
- vomiting
- pain
- fever
- diarrhea
- ex
- rare
- 2-4+
- common
- 1-4+ can be bloody
- salmonella, Campylobacter, yersinia
Direct invasion: virus
- vomiting
- pain
- fever
- diarrhea
- ex
- maybe
- 2-3+
- common
- 1-3+ watery
- norovirus, rotavirus
Types of non-inflammatory diarrhea
- pathogen attaches superficially, produces enterotoxin
- Gastroenteritis:
- Viral: norovirus, rotavirus, adenovirus
- Bacterial: Staph. aureus (MC), clostridium perfringens, Bacillus cereus
Gastroenteritis
- overview
- sx
- affects stomach and small bowel
- Caused by virus or preformed bacterial toxins
- Nausea and vomitting
- abd pain common
How to differentiate viral vs. bacterial gastroenteritis
- Bacterial: <10 hr incubation, no fever, 24 hour duration
- Viral: >14 hr incubation, mild fever, 72 hour duration
Viral gastroenteritis
- overview
- 3 main types
- “stomach flu”
- Think daycare, school, cruise ship, sports teams
- Norovirus (60-80%), all year, all ages
- Rotavirus: <2 YO
- Adenovirus: assoc. URI sx
Norovirus
- overview
- sx
- timing
- transmission
- MC cause GE
- winter
- very contagious
- can survive for a long time on surfaces!!
- Self limiting
- n/v/d, crampy pain, low grade fever, +/- HA
- lasts 1-4 days
- transmission: fecal-oral via fomites, food, water (possible person to person or airborne droplets)
Bacterial GE
- cause of sx
- sx
- “food poisoning”
- cause: preformed toxins (neuro toxins act on CNS)
- rapid onset, short duration
- vomiting
Bacterial GE
- three orgs
- S. aureus: MC
- Clostridium perfringens: meat, gravy, buffet
- Bacillus cereus: “fried rice syndrome” from re-heating fried rice
Bacterial GE caused by S. aureus
- Very common
- milk, meat, custard
- preformed neurotoxin > CNS > vomiting
- onset 2-8 hrs
- lasts 3-6 hrs
- 24 hour “stomach bug”
Secretory Diarrhea
- overview
- non-inflammatory
- voluminous emts watery diarrhea
- NO blood
- NO high fever (usu)
- active electrolyte secretion, no excess solute: low osmotic gap
- diarrhea despite fasting
- dehydration is worry
Secretory diarrhea
- examples
- Travelers diarrhea
- Vibrio cholerae
Traveler’s Diarrhea
- 3 MC orgs
- usually e. coli of some type
- Enterotoxigenic E. coli
- Enteroaggregative E. coli
- Campylobacter jejuni
Traveler’s Diarrhea
- sx
- pathogenesis
- transmission
aka Montezuma’s revenge
- self limited, watery diarrhea, starts ~3 days after exposure, lasts 3-4 days
- causes secretion of Cl
- contaminated food/water in underdeveloped countries in tropical climates
Travelers Diarrhea
- tx
- oral fluids and electrolytes
- pepto-bismol: sx control (black stool)
- Imodium: sx control
- Abx unnecessary!!!
Travelers Diarrhea
- prevention
- wash hands
- bottled water
- be a boring eater :)
- ice/raw foods
Vibrio Cholerae
- overview
- rare in US, common in world
- rapid spread, outbreaks
- HIGHLY contagious
- contaminated food or water*
- poor sanitation
- rainy season
- 10% develop severe dz
- death dt hypovolemic shock
Vibrio Cholerae
- pathophys
- Secretogogue: directly activates adenylate cyclase which opens Cl channels and causes massive secretion of Cl ion into gut lumen
- Also increase cAMP in cells which stimulates water and Na secretion
Vibrio Cholerae
- trasmission
contaminated water MC
Vibrio Cholerae
- sx
- *Secretory diarrhea
- large volume, watery (up to 1 L / hour)
- “rice water stool”
- vomiting common
- reduced urine
- rapid dehydration
- muscle cramps
- thirst
- fever rare
Vibrio Cholerae
- Tx
- Oral rehydration #1
- Glucose containing solutions (ORS) given orally is best option
- Forces sodium-glucose cotransporter in small intestine to transport glucose and sodium into enterocytes, Cl and water follow
- IV fluids if severe: Ringers lactate
- Abx if hospitalized
- Zinc has been shown to shorten illness in children
Vibrio Cholerae
- vaccine
- 10 days prior to travel
- 18-64 yo
- 1 dose
- Vaxchora or PaxVax
- Risk of getting dz is higher if visit friends/relatives
Inflammatory Diarrhea
- aka
- basic pathophys
- basic sx
- dysentery, infectious colitis
- invades colon wall
- bloody diarrhea, fever >101F, abd pain
Inflammatory Diarrhea
- pathogens
Many, she said to focus on:
- Shigella
- E. coli (STECs)
- Salmonella (incld. tyhoid fever)
- Campylobacter jejuni
- C. diff
Shigella
- describe org
- MC species
- overview
- gram neg bacillus
- Four species cause diarrhea dz, Shigella sonnei is MC in US
- not seasonal
- VERY contagious, small infective dose
- daycare breakouts
- MC in children, families vulnerable
Shigella
- Sx
- 1-2 days after exposure
- watery and/or bloody diarrhea
- small volume of stool
- tenesmus
- abd pain
- fever
- 5-7 day course
Shigella
- Dx
stool tests:
- WBC +
- guiac +
- culture +
Shigella
- Tx
- severe dehydration rare, supportive care only
- fluid replacement, rest, bland diet
- pepto-bismol
- Abx only in severe cases
Escherichia coli
- org description
- org habitat
- gram negative motile bacillus
- some produce shiga toxins = inflammation
- part of normal flora in people and animals, few strains are pathogenic
E. coli
- transmission
- what do stool cultures detect?
- contaminated food/water
- person to person
- contact with animals
- cultures only detect pathogenic strains
Two pathogenic strains of E. coli
- Enteroinvasic E. coli: invasive, causes dysentery similar to shigellosis
- Enterohemorrhagic E. coli: produces shiga toxin which causes colitis
Enterohemorrhagic E. Coli
- aka
- sx
- how common
- reservoirs and vectors
- E. coli 0157:H7
- “hemorrhagic” bloody diarrhea
- can cause hemolytic-uremic syndrome **
- most common STEC in US
- reservoirs: cattle, sheep, goats
- vectors: birds, flies
Enterohemorrhagic E. Coli
- Transmission
- outbreaks
- contaminated food/water, contact with animals/feces/soil
- food outbreaks: undercooked meat, vegetables irrigated with contaminated water (sprouts, spinach, lettuce)
- can survive >9 mo in ground beef stored -20C
Enterohemorrhagic E. Coli
- Sx
- 3-4 days after exposure
- starts watery, then bloody diarrhea
- hemorrhagic colitis: severe abd pain, bloody stool, might present like UC
Hemolytic-uremic syndrome
- HUS
- acute renal failure
- hemolytic anemia
- thrombocytopenia
- 1 week after diarrhea stops, when pt is improving
- 50% will require dialysis
Enterohemorrhagic E. Coli
- lab testing
- stool culture for STECs: detects shiga toxins or genes that encode them
- report to state health dept
Enterohemorrhagic E. Coli
- tx
- supportive, fluid rehydration, bland diet
- NO ABX (and stop them if they have been started): do not prevent complications/shedding DO increase risk of HUS and toxin release!
- avoid anti-diarrheal like Lomotil
Salmonella
- org
- epidemiology and risks
- gram neg motile bacillus
- 1.2M US annual cases
- MC in summer
- Children <5 highest risk
- acid-lowering meds increase risk
- handling of ducklings, reptiles, chicks, hedgehogs
Salmonella
- sx
- 12-72 hrs after exposure
- diarrhea +/- blood, cramping, fever
- children highest risk for dehydration
Salmonella
- tx
- supportive: rest, fluids and electrolytes
- abx only if severe
- bacteria shed in stool 4-5 weeks after illness!!
Typhoid fever
- sx
- severe illness caused by salmonella typhi
- sustained fever (103-104), chills, diarrhea (constipation too), cramping, HA, anorexia, cough, myalgia
Typhoid fever
- transmission
- incubation
- US pts usually get during travel outside the country
- chronic carrier state can occur
- incubation: 6-30 days
Typhoid fever
- tx
- abx
- no tx: 30% die
- vaccination avail if plan to travel to SE Asia
Campylobacter jejuni
- gram neg motile rod
- flagellated
- illness similar to salmonellosis
- Foodborne and travel
- undercooked poultry, meats, dairy, water
- causes dysentery, also mild travelers diarrhea
- late complication: Guillain-Barre syndrome (rare)
C. Diff
- org
-
- gram positive bacillus
- spore-forming
- normal inhabitant of colon
- Secretes enterotoxin (A) and cytotoxin (B)
- Abx associated colitis
C. diff
- sx
- 5-10 days after abx
- diarrhea +/- blood
- cramping pain
- pseudomembranous colitis
C. diff
- lab test
stool assay for c. diff toxin
C. diff
- tx
- oral or enema vanc
- fecal transplant
Listeria
- organism
- transmission
- listeria moncytogenes
- gram positive bacillus
- food borne, can cause outbreaks
- unpasteurized dairy products and lunch meat
Listeria
- who is at high risk
- immunocompromised
- pregnant women (13X risk)
Listeria
- sx
- fever and flu like sx
- diarrhea less common
- can cause sepsis
- encephalitis/meningitis
Listeria
- Dx
- Tx
- blood culture
- abx
Yersinia
- org
- transmission
- Yersinia enterocolitica
- gram neg bacillus
- raw, undercooked, contaminated pork
- Children>adults
- MC in winter
Yersinia
- sx
- fever
- diarrhea +/- blood
- severe abd pain, common in RLQ
- mimics appendicitis!
- arthritis and erythema nodosum
Yersinia
- Dx
- Tx
- special culture to isolate (add request to lab order)
- Abx
Invasive amebiasis
- org
- transmission
- entamoeba histolytica
- food or water, in US usually institutionalized, migrant laborers, Indian reservations
- only 10-20% symptomatic
Invasive amebiasis
- sx
- Mild, intermittent diarrhea
- urgency
- +/- generalized pain/cramping
- liver abscess (rare)
Amebic dysentery
- severe form of invasive amebiasis
- pain, bloody stool, fever
Persistent Diarrhea
- define
- common causes
- > 14 days
- Protozoa: guardia, cryptosporidium
- insidious onset, intermittent sx
- non-invasive (no inflammation or cell death), attach superficially to lining
- common signs: weight loss, malabsorption
Persistent diarrhea
- w/u
- full GI w/u
- test for IBD, celiac, IBS, etc
Giardiasis
- org
- describe org
- transmission
- Giardia lamblia
- lives in intestines, passes in feces
- Cysts can survive for months in cold water
- transmission: contaminated water (mountain stream, camping)
- MC intestinal parasite in US
Giardiasis
- Sx
- diarrhea
- gas/bloat
- greasy, foul smelling stools
- cramps
- upset stomach
- n/v
- intermittent, can be chronic
- weight loss, malabsorption, lactose intolerance, vitamin A, B12 can occur
Giardiasis
- dx
- Microscopic stool examination (stool for O and P)
- stool antigen test
Giardiasis
- tx
Flagyl
Cryptosporidium
- pathogen
- epidemiology
- cryptosporidium parvum and C. hominis
- protozoa
- large waterborne outbreaks
- contaminated water, resistant to chlorine
- only small # oocysts needed for infection
Cryptosporidium
- sx
- abrupt, profuse, watery diarrhea
- abd cramp
- +/- nausea and anorexia
- persists 1-2 weeks, then abates
- asx shedding of oocysts continues for weeks
Cryptosporidium
- dx
- stool antigen test
- microscopic examination of stool (stool for O&P)
Cryptosporidium
- Tx
- abx
- usually self-limited in immunocompetent people
- can be severe in AIDS
Blastocystis hominis
- organism
- unclear classification historically
- genus: Stramenopiles (protists)
- common, found throughout world
Blastocystis hominis
- transmission
- sx
- contaminated water
- diarrhea
- gas
- abd cramps
- anal itching **
- weight loss
- poss constipation
- many people asx
Blastocystis hominis
- tx
abx
Clinical skills
see presentation for all the details
Diarrhea
- how to differentiate small colon from large
- Small: watery, high volume stool, signs of malabsorption, dehydration
- Large: frequent, small volume stool, blood, urgency, tenesmus
Signs infection due to S. aureus or B. cereus
“food poisoning”
- vomiting
- 6 hrs after food
- no/low fever
Signs infection viral
- incubation >14 hours
- HA
Signs invasive or toxin producing
- severe abd pain
- high fever
- peritoneal signs
Mild dehydration
- alterness
- vitals
- s/sx
- weight loss
- normal
- no change
- thirst
- <5%
moderate dehydration
- alterness
- vitals
- s/sx
- weight loss
- restless, irritable, weak
- tachycardia, postural hypotension
- thirsty, dry membranes, poor skin turgor, dark urine
- 5-10%
Severe dehydration
- alterness
- vitals
- s/sx
- weight loss
- unconscious, lethargy, floppy, unable to drink
- weak/absent pulse, low blood pressure
- sunken eyes, depressed fontanels, wrinkled skin, minima/no urine
- > 10%
S/sx indicate need to start a w/u
- high fever >101 or toxic appearing
- severe sx, >6 diarrheas a day
- severe dehydration
- Evidence of colitis: bloody stool, severe abd pain
- empiric tx failed
- duration >2 weeks
Lab w/u for diarrhea
- fecal leukocytes: positive is inflammatory
- Stool for ova and parasites: multiple samples best dt intermittent shedding
- Stool culture: good for acute sx, helps narrow differential
- CBC: anemia, leukocytosis, thrombocytopenia (HUS)
- BMP: electrolytes, hyponatremia, metabolic acidosis (secretory diarrhea)
What orgs are on stool culture
- Salmonella
- Shigella
- Campylobacter
- C. diff
- E. coli (STEC)
- +/- vibrio
- +/- Yersinia
Diarrhea supportive care
- oral rehydration: pedialyte, sports drinks, make your own
- IV fluids if can’t quit vomiting or VERY volume depleted
- anti-diarrheal: imodium, pepto-bismol
- anti-emetics
- BRAT diet, avoid dairy
When to use Abx
only when needed!!
- severe
- hospitalized
- infants
- elderly
Late complications of diarrhea
- Reiter’s syndrome: reactive arthritis, urethritis, conjunctivitis
- HUS (shigella, EHEC)
- Autoimmune type sequelae: pericarditis, thyroiditis, glomerulonephritis
- Post-infectious IBS
Exposure/condition vs. pathogen
great chart at end of lecture
