DSA 3: Acute Infectious Diarrhea Flashcards
what are the signs of mild dehydration?
thirst, dry mouth, decreased axillary sweat, decreased urine output, slight weight loss
what are the signs of moderate dehydration?
orthostatc fall in blood pressure, skin tenting, sunken eyes (infants: sunken fontanelle)
what are the signs of severe dehydration?
lethargy, obtundation, feeble pulse, hypotension, frank shock
if pt presents with fever >38.5 degrees, bloody stools, increased fecal WBC’s, immunocomprimised or is an elderly host, should you order stool microbiology studies?
yes
- if no pathogen is found, empirical treatment and further evaluation
- if pathogen found, select specific treatment
what are the indications for further evaluation?
- profuse diarrhea (6+ stools/day)
- hypotension and tachycardia
- dysentery (bloody diarrhea with leukocytes)
- fever >38.5
- last longer than 48 hrs, no improvement
- recent antibiotic use (check for C.Diff)
- severe abdominal pain in pt >50
- elderly pt >70 or immunocomp
what is the work-up for diarrhea?
CBC, electrolytes, BUN, Cr, blood culture
what is the cornerstone of diagnosis for diarrhea?
microbiologic analysis of the stool
what does a routine stool culture include?
- salmonella
- shigella
- E. Coli
- most detect campylobacter (but may need to request)
takes 24-48 hours for results
what stool bacterial cultures need to be asked for specifically?
- Shiga-like toxin detection for 0157:H7 EHEC
- Vibrio species
- Yersinia
- C. Diff
- stool protozoal antigen (Giardia, Cryptosporidium, E. histolytica)
- stool viral PCR antigen (rotovirus, norovirus)
what may be indicated if stool studies are unrevealing?
endoscopy
what can you identify on abdominal CT?
colitis
CT more sensitive than XR for free air
what can you ID on plain abd XR?
ileus or toxic megacolon
what are the common food poisoning pathogens found in chicken?
salmonella, campylobacter, shigella
what are the common food poisoning pathogens found in undercooked hamburger?
enterohemorrhagic E.coli (0157:H7)
what is the most common food poisoning pathogen found in fried rice?
bacillus cereus
what are the common food poisoning pathogens found in potato salad, mayo or cream pastries?
staph aureus
what is the common food poisoning pathogen found in eggs?
salmonella
what is the common food poisoning pathogen found in uncooked foods, lunch meat or soft cheeses?
listeria
what are the common food poisoning pathogens found in seafood?
- Vibrio species (salmonella, acute HepA)
- Norovirus
- Campylobacter
gram positive cocci (grape clusters), preformed enterotoxins
- N/V
- **watery diarrhea
- rapid onset w/in 6hrs of ingestion
- rapid resolution w/in 24-48 hrs
risk factors: potato salad, mayo
Staph aureus
gram positive rod, preformed enterotoxins
- watery diarrhea
- rapid onset w/in 6 hrs
- rapid resolution w/in 24-48 hrs
risk factors: fried rice!
Bacillus cereus
heat resistant gram positive, spore-forming rod
- preformed enterotoxin
- watery diarrhea (**NO fever or vomiting)
- crampy abd pain
- onset w/in 8-16 hrs of ingestion, need to ingest large quantities of org
- rapid resolution w/in 24-48 hrs
risk factors: beef, ham, poultry, legumes, gravy
Clostridium perfringens
gram NEG rod, non-motile
- enterotoxin shiga toxin
- DYSENTERY begins as watery diarrhea -> intense colitis with fever and frequent small-volume stools w/blood and pus
- fever for 3-4 days, typically lasts 7 days
risk factors: potato salad, lettuce, raw veggies
Shigella
GIVE ABX!
what are the dx and tx of shigella?
- dx: (+) fecal leukocytes, (-) lactose on stool culture difficult to distinguish from IBD
- tx: Bismuth, ampicillin, fluoroquinolone, or trimethoprim/sulfamethoxazole
what are the post-infectious complications of Shigella?
reactive arthritis, HUS
gram neg, NON-lactose fermenting, MOTILE, rod-shaped
- orgs traverse intestinal epithelium through M cells overlying Peyer’s Patches
- non-typhoidal
- watery -> blood diarrhea
- fever, abd camping, N/V
- lasts 5-10 days, self limiting
risk factors: eggs, poultry, milk, exposure to reptiles (turtles)
- increased risk with immunocompromised/HIV, leukemia and Sickle Cell
Salmonella typhimurium
what is the dx needed for salmonella typhimurium?
stool culture
what are the complications of salmonella typhimurium infection?
septic arthritis, abscess, osteomyelitis
gram NEG rod, anaerobic
- org’s penetrate thru Peyer’s Patches
- can be asymptomatic carriers
- Rose spots rash with fever
- 7-14 days AFTER ingestion
- 2 symptomatic phases separated by asymptomatic phase: febrile (103-104!)
- **pea-soup green-yellow fowl smelling diarrhea -> bloody diarrhea
risk factors: poor sanitation, travel
Salmonella typhi
TYPHOID FEVER
what is the dx and tx of Salmonella typhi?
- dx: stool culture, blood culture, fecal leukocyte (+)
- tx: hand-washing, vaccine, fluoroquinolones (becoming resistant)
gram NEG curved/spiral-shaped rod
- oxidase (+), motile flagellum with “cork-screw” motion
- watery -> bloody diarrhea
- fever, malaise
- crampy abd pain
- erythema nodosum
risk factors: undercooked poultry, dairy, contaminated water
Campylobacter jejuni
what is the dx and tx of campylobacter jejuni?
- dx: fecal leukocyte (+)
- stool culture need Campy blood agar
- tx: supportive, NO abx
what are the complications of campylobacter jejuni infection?
reactive arthritis, Guillan-Barre syndrome
gram NEG bacilli, anaerobic, curved-shaped with flagellum
- toxin production
- N/V/abd cramping
- PROFUSE (1L/hr) watery diarrhea
- mucous with epithelial cells = “rice water”
- lasts 7 days
risk factors: waterborne illness (saltwater), raw seafood (oysters), poor sanitation in underdeveloped nations
Vibrio cholerae
what is the dx and tx of Vibrio cholerae?
- dx: stool microscopy (motile, darting short curved gram neg rods), gram stain of stool specimen
- tx: rehydration/electrolyte replacement
prevention: sanitation, vaccination
gram NEG bacilli, cytotoxin production
- N/V/abd cramps
- watery -> bloody diarrhea (colonic)
- lasts 2-5 days
risk factors: seafood (shellfish, oysters, shrimp)
Vibrio parahemolyticus
what is the dx and tx of Vibrio parahemolyticus?
- dx: fecal leukocyte (+), stool culture (special media needed)
- tx: self-limited
gram NEG bacillus
- vomiting. diarrhea, abd pain w/in 16 hrs of ingestion
- open wound in the water: bullous skin lesions
- can be life threatening in immunocompromised (esp cirrhosis and hemochromatosis pts)
risk factors: war, shallow, coastal salt water, oysters
Vibrio vulnificus
gram NEG, non-spore forming, rod-shaped, facultative anaerobic bacteria, motile with flagellum
- two types of sx: cholera-like (watery diarhea), OR bloody mucoid stools
risk factors: fresh water environments, open wounds in water (foot and ankle most common), suspect in early necrotizing fasciitis
Aeromonas hydrophila
GIVE ABX
what is the tx of Aeromonas hydrophila?
ampicillin
what are risk factors for travelers diarrhea?
- travel to developing countries
- H2 blocker/PPI use (decrease acid production, increasing pH)
what is the most common pathogen for traveler’s diarrhea?
EnteroToxigenic E. coli (ETEC)
gram NEG rod
- N/V, occasional fever
- watery diarrhea
- sudden onset, 3-6 days duration
risk factors: children, elderly, travelers, ingesting contaminated food or water
ETEC
what is the dx and tx of E. coli
- dx: fecal leukocyte (-), must be dx clinically because stool cultures can’t differentiate between ETEC and commensal gut E.coli
- tx: abx may reduce infection by 1-2 days (trimethoprim/sulfamethoxazole, doxycycline, ciprofloxacin)
- bismuth may help
gram NEG rod, produces shiga-like toxin
- watery -> bloody diarrhea -> ischemic colitis
- NO fever
risk factors: food-borne (undercooked hamburger), raw veggies, raw milk
EnteroHemorrhagic E. coli (EHEC)
what is the dx and tx of EHEC?
- dx: CBC- peripheral leukocytes (+), anemia, thrombocytopenia, fecal leukocytes (+), fecal lactoferrin (+), stool culture w/ shiga-like toxin
- tx: supportive, rehydration, abx only in extreme cases
what are complications of EHEC?
hemolytic uremic syndrome (kidney insuff, hemolytic anemia, thrombocytopenia
- occurs 5-10 days into course
- much more likely to happen in children OR if EHEC treated with abx
what is another E. coli, that causes fever, abd pain, watery -> bloody diarrhea with leukocytes
EnteroInvasive E. coli (EIEC)
gram NEG coccobacilli
- bloody diarrhea
- fever
- N/V, abd pain w/ PHARYNGITIS
- infection located in terminal ileum (R side abd pain), can mimic appendicitis or CroHn’s disease
risk factors: virulence affects iron metabolism -> iron-overload syndromes, cirrhosis, hemochromatosis
Yersinia enterocolitica
tx: supportive
what are the dx and complications of Yersinia enterocolitica
- dx: stool/blood cultures (special media), fecal leukocytes (+)
- clinically indistinguishable from salmonella or shigella
- complications: erythema nodosum, reactive arthritis, myocarditis, kidney dz
gram + rod, can grow in cold
- fever, **NON-bloody diarrhea
- headache, N/V, non-specific malaise in pregnant women**
- 2-3 days duration
risk factors: pregnancy, extremes of age, immunocomp, eating unpasteurized dairy or deli meats
Listeria monocytogenes
GIVE ABX
what is the dx and tx of listeria?
- dx: blood culture (doesn’t grow on stool culture)
- tx: ampicillin and trimethoprim/sulfamethoxazole
gram + bacillus, not acid fast, typically affects white men in their 40-60’s
- arthralgia
- wt loss
- malabsorption
- chronic diarrhea
Whipple disease (Tropheryma whipplei)
what is the dx, tx and prognosis of Whipple disease?
- dx: endoscopy with duodenal biopsy, PAS-positive macrophages with characteristic bacillus
- tx: Abx therapy that cross BBB to help w/CNS symptoms
- if untreated, disease is FATAL
anaerobic, gram + spore forming bacillus, cytotoxin producing
- watery, fowl smelling diarrhea
- abd pain
- fever
risk factors: hospitalization or ill contact w/in past 2 months, ABX USE (esp clindamycin, cephalosporin, fluoroquinolones), PPI also risk factor
Clostridium difficile
what are the dx, tx and complications of C. diff?
- dx: STOOL ASSAY - PCR for toxin A and B, peripheral leukocyte (+), pseudomembranes on colonic mucosa (green or yellow color)
- tx: wash hands with soap and water, metronidazole, vancomycin
- comp: TOXIC MEGACOLON (50% mortality rate, needs aggressive tx
what is the most common cause of acute diarrhea in children <2 years old?
Rotavirus, especially in the winter months
- double stranded RNA virus
- vomiting and watery diarrhea
- sx begin w/in 72 hours, last 2-3 days but up to 5
- fecal leukocyte (-), detected by viral culture or PCR
- wagon-wheel appearance on electron microsopy
Rotavirus
double stranded DNA virus
- **FEVER (103-104), chills, myalgia, sore throat
- watery diarrhea and vomiting
- conjunctivits, pharyngitis (may see exudates)
- prolonged course (10 days)
- dx: viral culture
Adenovirus (serotypes 40 /41)
small non-enveloped RNA virus
- fecal-oral transmission, outbreaks via contaminated food, water in nursing homes, child care centers, CRUISE SHIPS
- vomiting, watery diarrhea
- sx w/in 24-48 hrs
- last 3 days
- fecal leukocyte (-), viral cultures unrevealing, NO workup necessary d/t rapid resolution
Norwalk virus
double stranded linear DNA (Herpesvirus family)
- primarily affects the immunocompromised with CD4 <200
- fever, abd pain, bloody diarrhea
- persists for several weeks
- dx: endoscopy with biopsy of ulcerated lesions using specific stains
Cytomegalovirus
need CMV-specific stain
what is the most common cause of dysentery in the world?
Entamoeba histolytica
trophozoite
- fever, bloody diarrhea, abd pain
- can penetrate bowel into portal circulation -> liver abscesses
- persists for days/weeks
- dx: FLASK-SHAPED ULCER on histology, stool for ova & parasite, or stool antigen (PCR for DNA)
- fecal leukocytes (+)
risk factors: crowded living conditions (fecal-oral)
Entamoeba histolytica
what are the tx and complications of Entamoeba histolytica?
- tx: eliminate the trophozoite
- comp: TOXIC MEGACOLON or PNEUMATOSIS COLI (air in bowel wall)
PEAR/KITE-SHAPED protozoa, 4 flagella, 2 nuclei
- interferes with fat absorption -> steatorrhea, flatulence, abd pain
- watery malodorous diarrhea (steatorrhea)
- lasts 14-28 days, common cause of persistent diarrhea
- STOOL AG DETECTION: check stool for ova/parasites
risk factors: water (streams/lakes-camping!), cattle, dogs, rodents
- those with IgA def more susceptible
Giardia lamblia
tx: supportive, tinidazole or metronidazole
oocyst with 4 motile sporozoites
- nausea, malaise, abd cramping
- watery diarrhea (large vol >20L/day)
- self-limiting, resolved in 7-14 days
- immunocompromised pt: can be life-threatening
- dx: stool antigen detection or direct microscopy, modified acid-fast staining, direct fluorescent antibody (have to ask for it!)
risk factors: SWIMMING POOLS
Cryptosporidium parvum
NOTE: resistant to chlorine tx, give ANTIVIRALS to immunocompromised patients to increase CD4 count and boost immune system
roundworm (nematode)
- enter the body via BARE FEET
- larvae travel to lungs -> cough -> then swallowed and pooped out
- often asymptomatic, or can cause abd pain, vomiting, bloating, diarrhea, cough, SOB
- dx: rhabditiform larvae and esosinophils in stool
risk of HYPERINFETION in immunocompromised pts
Strongyloides stercoralis
tx: anti-helmintic
malaise, anorexia, nausea, low-grade fever
- watery diarrhea
- can last up to 21 days in immunocompetent
- indefinite in immunosuppressed :(
- dx: oocysts in stool sample
risk factors: FRUITS/VEGS imported from endemic areas, TRAVEL to endemic areas
Cyclospora cayetanensis
tx: trimethoprim/sulfamethoxazole (TMP/SMX)
acute, NON-bloody/watery diarrhea
- crampy abd pain
- can last for weeks -> malabsorption and wt loss
- severe diarrhea in immunosuppressed
- dx: repeated stool examinations, duodenal biopsy, oocysts visualized wet mounts by microscopy, or acid-fast stain
Cystoisospora belli
tx: Bactrim DS (trimethoprim/sulfamethoxazole)
hookworm/whipworm
- soil-transmitted helminth
- can get very long, causing bowel obstruction
Ascaris lumbricoides
fish tapeworm (from raw/undercooked fish)
- can grow to 30 feet!
- abd symptoms
- worm absorbs Vit B12, causing B12 deficiency -> pernicious anemia and neurological symptoms
Diphyllobothrium latum
what is the 2nd most common cause of esophageal varices behind alcohol in Africa?
- also most common cause of small portal vein branch obstructions
Schistosoma mansoni
tx: praziquantel
trematode, from contaminated FRESHWATER SNAILS
- bloody stools
- bladder cancer
- liver cysts
Schistosoma mansoni
tx: praziquantel
pork tapeworm, from ingesting undercooked pork
- mostly asymptomatic -> rare serious cases cause SEIZURES (cysticercosis)
- muscle or eye disease
Taenia solium
beef tapeworm (suckers), from ingesting undercooked beef - mostly asymptomatic
Taenia saginata
tapeworm, from unsanitary sheep slaughter that dogs eat
- fecal-oral transmission, poor sanitation
- form CYSTS IN LIVER/LUNGS
- looks like free-flowing “hydatid sand” on CT
Echinococcus granulosus
pinworm that causes severe perianal itching
- dx: transparent tape test
- tx: mebemdazole
Enterobius vermicularis
prevent infection by washing hands thoroughly and frequently, cut fingernails, disinfecting doorknobs, toilet seats, furniture, etc
what is the tx for NON-bloody stools?
- hydration (PO or IV) 8-10 glasses clear fluids/day
- maintain electrolyte balance
- anti-motility agents may be used, but **NOT in pt with C. diff or EHEC
what foods should pt with diarrhea avoid?
lactose and high fiber foods, fats, caffeine, and alcohol
what two pathogens mentioned are NOT killed by alcohol hand sanitizer?
Norovirus and C. diff
- must wash hands with soap and water
what vaccines exist for diarrhea-causing pathogens?
- Rotavirus
- S. typhi
- V. cholera
- Hep A
when is antibiotic prophylaxis indicated for travelers?
- if immunocomprimised, IBD, hemochromatosis, or gastric achlorhydra
- or if traveling to high risk areas
- probiotics may be helpful, but in general prophylactic antibiotics not usually recommended
formerly known as Reiter’s syndrome
- arthritis, urethritis, and conjunctivitis
Reactive arthritis
Reactive arthritis may accompany or follow infections by which 4 pathogens?
- salmonella
- campylobacter
- shigella
- yersinia
autoimmune-type thyroiditis
- pericarditis
- glomerulonephritis
Yersiniosis
what is the major complication of campylobacter jejuni infection?
Guillian-Barre syndrome
- inflammatory demyelinating polyneuropathy, paresthesias in hands/feet
- severe respiratory muscle weakness
- absent or depressed DTR’s
EHEC (shiga-like toxin) can lead to what?
HUS
- most common cause of acute renal failure in children
- microangiopathic hemolytic anemia, thrombocytopenia
what is recognized as a complication of infectious diarrhea?
post-infectious IBS
acute diarrhea can also be a major symptom of which systemic infections?
viral hepatitis, listeriosis, legionellosis, toxic shock syndrome
which pathogens typically affect the small bowel?
vibrio chilerae, ETEC, Rotavirus, Norovirus, CMV, Adenovirus, Giardia, Cyclospora, Staph aureus, Bacilis cereus
= watery stools
which pathogens typically affect the large bowel?
campylobacter, shigella, EHEC, C. diff, Vibrio parahaemolyticus, E. histolytica, Herpes
= bloody stools
what is a common pathogen that affects those with IgA deficiency?
Giardia
Pt with hemochromatosis are prone to which pathogens?
- Vibrio species
- Listeria
- Yersinia
should avoid raw fish
AIDs pt are prone to which opportunistic infections?
- Mycobacterium species
- CMV, Adenovirus, Herpes
- Cryptosporidium, Cystiosospora belli, Microsporidia, Blastocystic hominis
- Neisseria gonorrhea, Trep pallidum, Chlamydia
