DSA 3: Acute Infectious Diarrhea Flashcards by Cassie Dasmarinas

what are the signs of mild dehydration?

thirst, dry mouth, decreased axillary sweat, decreased urine output, slight weight loss

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what are the signs of moderate dehydration?

orthostatc fall in blood pressure, skin tenting, sunken eyes (infants: sunken fontanelle)

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what are the signs of severe dehydration?

lethargy, obtundation, feeble pulse, hypotension, frank shock

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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

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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

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what is the work-up for diarrhea?

CBC, electrolytes, BUN, Cr, blood culture

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what is the cornerstone of diagnosis for diarrhea?

microbiologic analysis of the stool

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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

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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)

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what may be indicated if stool studies are unrevealing?

endoscopy

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what can you identify on abdominal CT?

colitis

CT more sensitive than XR for free air

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what can you ID on plain abd XR?

ileus or toxic megacolon

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what are the common food poisoning pathogens found in chicken?

salmonella, campylobacter, shigella

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what are the common food poisoning pathogens found in undercooked hamburger?

enterohemorrhagic E.coli (0157:H7)

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what is the most common food poisoning pathogen found in fried rice?

bacillus cereus

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what are the common food poisoning pathogens found in potato salad, mayo or cream pastries?

staph aureus

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what is the common food poisoning pathogen found in eggs?

salmonella

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what is the common food poisoning pathogen found in uncooked foods, lunch meat or soft cheeses?

listeria

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what are the common food poisoning pathogens found in seafood?

Vibrio species (salmonella, acute HepA)
Norovirus
Campylobacter

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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

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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

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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

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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!

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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

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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

DSA 3: Acute Infectious Diarrhea Flashcards

(94 cards)