Acute diarrhea--bacterial causes Flashcards
diarrhea- definition
- adult- >200 g/day
- child- >20 g/kg/day
- clinically- 3 or more loose/watery stools/day OR dec in consistency and inc in frequency of BM of individual
- lose HCO3 and K!!
noninfectious causes
- medications
- food sweeteners (sorbitol)
- food allergies
- tube feeding
- acute diverticulitis
- Graft vs Host dz
- ingestion of toxins
- chronic illness!- IBD, endocrine dz, tumors
- ischemic colitis!!
epidemiology
- 2nd most common infectious cause of death worldwide
- 90% of acute diarrhea is infectious- 75% is viral
- 10%- caused by medications, toxic ingestions, ischemia, etc
- dehydration = major cause of death!
most frequent causes of infection
Salmonella and Campylobacter
Acute infectious diarrhea- transmission
- fecal-oral- ingestion of contaminated food/water
- most mild, self-limited
- endoscopy rarely needed- check for C diff, distinguish if infection vs IBD or ischemia
bacterial toxins, enterotoxin-producing bacteria
small-bowel hyper-secretion
- water diarrhea
- vomiting
- minimal or no fever
- after a few hrs after ingestion
entero-adherent pathogens
small-bowel hyper-secretion
- less vomiting
- greater abd cramping/bloating
- higher fever
cytotoxin-producing and invasive microorganisms
- high fever
- abd pain
5 high risk groups in US
- travelers
- immunodef
- daycare workers/kids/their family members (shigella, giardia, cryptosporidium, rotavirus)
- nursing homes, assisted living, hospitals
- consumers of certain foods
discriminations from true diarrhea
- pseudo-diarrhea- freq passage of small volumes of stool- accompanies IBS or proctitis
- fecal incontinence- neuromuscular disorders
- overflow diarrhea- elderly/nursing home pts
diarrhea- indications for evaluation
- profuse diarrhea with dehydration
- hypotension and tachycardia not responsive to volume repletion
- dysentery
- fever >101 (38.5)
- duration >48 h
- recent abx use
- new community outbreaks
- severe abd pain
- elderly
- immunocompromised
- creatinine >1.5x
- peripheral leukocytes > 15,000
work-up cornerstone of diagnosis
- microbiologic analysis of stool
- if stool studies unrevealing- endoscopy may be indicated
routine stool culture includes?
- Salmonella
- Shigella
- E coli- ask for Shiga toxin detection for 0157:H7 eHEC
- campylobacter
- takes 24-48 hrs for results
stool culture- need to ask specifically for?
- C diff PCR/toxin
- ova parasites
- stool ag (parasites- giardia, cryptosporidium)
labs
- stool culture
- viral stool culture
- fecal leukocytes
- lactoferrin (enzyme found in leukocytes)
- CBC/renal fxn (BMP)- hemolytic uremic syndrome
- may need blood cultures
radiology
- plain abd xray- detect intraperitoneal air, assess for ileus or toxic megacolon
- abd CT- free air, colitis
- endoscopy- C diff pseudomembranes
food poisoning- chicken
salmonella, campylobacter, shigella
food poisoning- undercooked hamburfer
-EHEC (O157:H7)
food poisoning- fried rice or other reheated food
-Bacillus cereus
Food poisoning- potato salad, mayonnaise, cream pastries
-Staph aureus
food poisoning- eggs
-Salmonella
food poisoning- Lunch meat, soft cheeses
-Listeria
food poisoning- seafood
- Vibrio species, Salmonella, acute hep A
- Norwalk, campylobacter
Staphylococcus Aureus
- preformed enterotoxins!!
- N/V
- watery diarrhea!
- rapid onset- within 6 hrs
- rapid resolution- 24/48 hrs
- eggs, potato salad, mayonnaise, cream pastries!!!
Bacillus Cereus
- preformed enterotoxins!!!
- vomiting- main symptom
- rapid onset- within 6 hrs
- rapid resolution- 24-48 hrs
- fried rice!!!
- watery diarrhea
Clostridium Perfringens
- preformed enterotoxins!!
- watery diarrhea
- crampy abd pain
- rapid onset- 8-16 hrs- need to ingest large quantity of organisms!!
- rapid resolution
- beef, ham, poultry, legumes, gravy- heat resistant spores inadequately cooked
Shigella
- toxin mediated- enterotoxin shiga toxin!!
- only need to ingest 100 organisms
- children!
- potato or egg salad, lettuce, raw veggies
- BLOODY diarrhea
- fever- 3-4 days
- fecal leukocytes +
- stool culture- diff to distinguish from IBD; lactose neg
- 1-2 wks duration
Shigella- tx, complications
- Bismuth, ampicillin, fluoroquinolone, or TMP/SMX
- resp complaints and seizures
- reactive arthritis!
Salmonella typhimurium
- gram-neg, non-lactose fermenting, motile, rod-shaped bacteria
- most cases in US- non-typhoidal!!
- BLOODY diarrhea
- fever
- self-limited- 5-10 days
- eggs, poultry; exposure to reptiles (turtles)
- inc risk with Sickle cell pts!
- stool culture- lactose -, motile
Salmonella typhimurium- complications, tx
- abx usually not indicated
- septic arthritis, osteomyelitis!
Salmonella typhi- sx, dx, tx
- international travel; poor sanitation
- feca-oral
- lives only in humans- there can be “healthy” carriers
- prevention- good food prep, hand washing, vaccine
- Typhoid fever!- sustained febrile illness (103-104)- rash of flat rose-colored spots
- stool/blood samples- test for Salmonella typhi, fecal leukocyte +
- fluoroquinolones, ceftriaxone, azithromycin
Campylobacter jejuni
- BLOODY diarrhea
- fecal leukocytes +
- self limited- 7 days
- stool culture- need Campy blood agar- spiral, oxidase +, motile with flagellum
- poultry
- wild birds
Campylobacter jejuni- complications, Tx
- Guillian-Barre syndrome!!
- supportive
Vibrio cholerae
- toxin production!
- O1 and O139 variants
- rice water diarrhea- profuse
- gram stain- curved/comma shaped, anaerobic gram-neg bacilli with flagellum
- waterborne illness (saltwater)!!
- raw oysters (seafood)!!
- undeveloped nations- poor sanitation
Vibrio cholerae- dx, tx
- stool- motile, darting short curved gram neg rods
- tx- rehydration/electrolyte replacement
- prevention- sanitation, vaccination
Vibrio parahemolyticus
- non-O1 and non-0139 variants
- cytotoxin production!
- bloody diarrhea!
- fecal leukocyte +
- lasts 2-5 days
- seafood!!
Vibrio Vulnificus
- gram neg bacillus
- coastal salt water!!
- eating raw shellfish/oysters
- open wound in water- bullous skin lesions!!
- life threatening in immunocompromised- esp cirrhosis pts!!
Aeromonas Hydrophila- sx, tx
- gram neg, non-spore forming, rod-shaped, facultatively anaerobic bacteria, flagellum
- fresh water!!
- eating fish/shellfish!!
- open wounds in water- necrotizing fasciitis aka flesh eating bacteria!!
- 2 types- Cholera-like- rice water stools; Bloody
- scuba divers that swallow fresh water then have gastroenteritis!
- Tx- ampicillin
Traveler’s Diarrhea- sx
- 50% of travelers to developing countries
- contaminated food/water
- watery diarrhea
- bloody diarrhea and fever UNCOMMON
- self-limited
- H2blocker/PPI- risk factors- lower pH
Traveler’s Diarrhea- causes
- ETEC- most common pathogen for TD!
- campylobacter jejuni- asia
- Salmonella, Shigella, Aeromonas, EAEC, norovirus, coronavirus
- Giardia- Russia; campers!!
- Cyclospora- Nepal
- Norovirus- cruise ships
E coli
-children, elderly, travelers ETEC- travelers!!- most common cause for TD -watery diarrhea -fecal leukocyte - -diagnose clinically -contaminated food/water
E coli- O157:H7
EHEC- O157:H7- aka Shiga-toxin producing E coli (STEC)
- bloody diarrhea
- no fever
- fecal leukocytes +
- stool culture- shiga-like toxin
- undercooked hamburger!!
- HUS!!- children and if treated with abx!!
- Tx- supportive, rehydration
Yersinia enterocolitica- sx, complications, tx
- higher risk in iron-overload syndromes!!!
- bloody diarrhea!
- abd pain + pharyngitis- suggests diagnosis
- can mimic appendicitis!!!
- clinically indistinguishable from salmonella or shigella!!
- complications- hemochromatosis!
- tx- supportive care
Listeria monocytogenes
- in pregnant women!!
- non-bloody diarrhea!
- Dx- blood culture!!!
- stool cultures- select media!!
- unpasteurized dairy and deli meats!!!
Clostridium difficile
- cytotoxin production
- watery diarrhea
- pseudomembranes!! on colonic mucosa
- PCR for toxin (A and B)!!
- abx especially- clindamycin, cephalosporins, fluoroquinolones!
- wash hands with soap and water!!
clostridium difficile- tx, complication
- PO/IV metronidazole, oral vancomycin
- toxic megacolon
Nosocomial infections
- C difficile most common!!
- Norovirus- nursing homes
