Acute Infectious Diarrhea Flashcards
In the US, what are five groups that are high risk for infectious diarrhea?
- travelers
- immunodeficient
- daycare employees, kids, and their family
- institutionalized
- consumers of certain foods
List some risk factors for acquiring infectious diarrhea.
- recent abx
- ill contacts
- exposure to unclean water
- animal exposure
- consuming raw/undercooked meat
What effects of dehydration would you see on temperature, blood pressure, and heart rate?
-fever, hypotension, and tachycardia
What are signs of mild, moderate, and severe diarrhea?
mild- thirst, decreased sweat and urine,
moderate - orthostatic fall in BP, tenting, sunken eyes
severe - lethargy, weak pulse, frank shock
What would you expect to hear when auscultating bowel sounds in a patient with diarrhea? In a patient with ileus or toxic megacolon?
- increased bowel sounds in diarrhea
- decreased/absent sounds in ileus or toxic megacolon
True or False: route of transmission for acute infectious diarrhea is typically fecal-oral
True
True or False: most cases of acute infectious diarrhea are mild and self-limited.
True
What are red flag indications of acute infectious diarrhea that would indicate that a work-up is necessary?
- 6+ diarrhea stools/day with dehydration
- mucoid, bloody diarrhea
- fever greater than 101F
- lasts 48+ hrs w/o improvement
- new community outbreaks
What blood work would you order for acute infectious diarrhea?
- CBC
- electrolytes
- BUN
- Cr
- Blood culture
What stool studies would you order for acute infectious diarrhea?
- fecal leukocytes
- fecal calprotein (checks for IBD)
- fecal lactoferrin (checks for IBD or inflammatory cause)
What pathogens are normally included in a routine bacterial stool culture?
- salmonella
- shigella
- E. coli
- Campylobacter (maybe)
How long does it take for stool cultures to return?
24-48 hrs
What are other stool tests besides a bacterial culture?
- stool immunoassay for C. diff PCR/toxin
- O and P
- stool protozoal Ag for parasites like giardia and crypto
- stool viral PCR/Ag for rotavirus and norovirus
What test (other than radiology) would you order if the stool studies didn’t reveal anything?
-endoscopy, upper or lower
- upper EGD w/ duodenal aspirates and biopsy
- lower flexible sigmoidoscopy w/ biopsy
What kinds of radiology might you order if stool studies didn’t reveal anything?
- plain abd xray
- -detects free intraperitoneal air
- -assess for ileus or toxic megacolon
- abd CT usually w/ PO/IV contrast
- -more sensitive for free air; identify colitis
What pathogens are normally associated with chicken?
- salmonella
- campylobacter
- shigella
What pathogen is normally associated with undercooked hamburger?
-E. coli O157:H7 (EHEC)
What pathogen is normally associated with fried rice?
B. cereus
What pathogen is normally associated with potato salad, mayonnaise, or cream pastries?
S. aureus
What pathogen is normally associated with eggs?
-salmonella
What pathogen is normally associated with deli meats or soft cheeses?
-L. monocytogenes
What pathogens are normally associated with seafood?
- vibrio
- salmonella
- Hep A
- norovirus
- campylobacter
What are the symptoms of Staphylococcus aureus (a gram-positive cocci, clustered like grapes)?
- N/V
- watery diarrhea
- rapid onset (within 6h due to preformed enterotoxin)
- rapid resolution (within 24-48h)
What are the symptoms of Bacillus cereus (a gram-positive rod)?
- vomiting (main symptom)
- watery diarrhea
- rapid onset (within 6h due to preformed enteroxin)
- rapid resolution (within 24-48h)
What are the symptoms of C. perfringens (a gram-positive, heat-resistant, spore-forming rod)?
- watery diarrhea w/abd cramping and pain
- NO fever, NO vomiting
- rapid onset (within 8-16h d/t preformed enterotoxin)
- rapid resolution (within 24-48h)
True or False: you need to consume large quantities of Clostridium perfringens to develop symptoms
True
What are the symptoms of Shigella (gram-negative rods)?
- fever for 3-4 days
- symptoms last 1-2 weeks
- bloody diarrhea (it’s the classic cause of dysentery)
- -begins watery, then progresses to blood and pus
- -small volume w/ cramping and intense colitis
What GI condition would also be in the differential for Shigella?
IBD
-need fecal leukocytes and culture to differentiate
What is a possible complication of Shigella, post-infection?
- reactive arthritis and HUS
- -conjunctivitis, urethritis, arthritis
- HLA-B27 genotype is involved
What are the symptoms, lasting 5-10 days, of Salmonella typhimurium (gram-negative motile rod)?
- watery to bloody diarrhea
- fever
- abd cramping
- N/V
- fecal leukocytes +
What group of immunocompromised individuals is at increased risk of S. typhimurium?
Sickle Cell pts
What are complications of S. typhimurium?
-septic arthritis, abscess, osteomyelitis
What are the symptoms of Salmonella typhi (gram-negative, anaerobic rod that causes typhoid fever)?
- 2 symptomatic phases, separated by no symptoms
- -sustained fever of 103-104F
- -rose spots
- -smelly, pea soup diarrhea, or bloody diarrhea
- -relative bradycardia w/ dicrotic pulse
What are the diagnostic tests used for S. typhi?
- stool cultures
- blood cultures (90% when febrile)
- fecal leukocytes
What is the mechanism behind how Salmonella organisms cause disease?
- penetration of small intestine mucus layer
- then, the organisms transverse the epithelium through M cells that overlay Peyer’s Patches
What is unique about how S. typhi interacts with the body vs. S. typhimurium?
-S. typhi can have “healthy carriers” when the organisms colonize the gallbladder (ex: Typhoid Mary)
What are the symptoms of Campylobacter jejuni (gram-negative curved/spiral rod)?
- watery to bloody diarrhea
- fever
- crampy abd pain
- erythema nodosum
- resolves in a week (maybe up to 3-4wks)
How do you diagnose C. jejuni?
- fecal leukocytes
- stool culture on Campy Blood Agar
What is a complication of C. jejuni?
- Guillian Barre Syndrome 1-8wks after diarrhea
- -ascending symmetrical muscle weakness/paralysis
What are the symptoms of Vibrio cholerae (gram-negative, comma-shaped anaerobic rod w/ flagellum)?
- N/V
- abd cramping
- profuse rice water diarrhea (1L/hr)
- dehydration d/t electrolyte imbalance
- -hypotension leads to renal failure and eventual death
What are the diagnostic tests for V. cholerae?
- stool microscopy to identify motile, darting rods
- gram stain of stool specimen
What are the treatment and prevention of cholera?
- rehydration and electrolyte replacement
- abx may shorten duration
- sanitation and vaccination to prevent
What are the symptoms of V. parahemolyticus (gram-negative cytotoxin-producing rod)?
- N/V
- abd cramps
- watery to bloody diarrhea
- resolves in 2-5 days
What are the symptoms of V. vulnificus (gram-negative rod)?
- -vomiting and diarrhea within 16 hrs
- -bullous skin lesions in open wounds
- -cirrhosis in pts w/ hemochromatosis
- -life-threatening for immunocompromised
- -coastal saltwater is a risk
What are the symptoms of Aeromonas hydrophila (gram-negative spore-forming facultative anaerobic rod?
- One type: watery rice stool diarrhea
- Second type: bloody mucoid stool
-rapidly progressing wound infection after freshwater exposure (necrotizing fasciitis)
What are the risk factors of Aeromonas hydrophila?
- freshwater or brackish water
- foot and ankle wounds in the water
What is the most common pathogen for Traveler’s Diarrhea?
-enterotoxigenic E. coli (ETEC)
What are the symptoms of ETEC (gram-negative rod)?
- N/V
- watery diarrhea
- occasional fever
- sudden onset
- resolves in 3-6 days
True or False: ETEC must be diagnosed clinically
True; stool cultures cannot differentiate between ETEC and other E. coli strains found in normal colonic microbiota; additionally fecal leukocytes are negative
What are the symptoms of E. coli O157:H7 (EHEC - a gram negative rod that produces shiga-like toxin)?
- watery to bloody diarrhea
- abd tenderness
- NO fever
- most common cause of acute hemorrhagic colitis
- most common cause of ARF in children
How is E. coli O157:H7 diagnosed?
- CBC peripheral leukocytes, anemia, thrombocytopenia
- fecal leukocytes +
- fecal lactoferrin +
–stool culture shows shiga-like toxin
What is the treatment of E. coli O157:H7?
- supportive
- rehydration
-abx use increases risk of HUS, so abx are only used in severe cases
What are complications of E. coli O157:H7?
- hemolytic uremic syndrome
- -5-10 days into illness
- -much more likely in children
- -more likely if treated w/ abx
What are other forms of E. coli and their characteristics?
- Enteroaggressive E. coli (EAEC)
- -persistent diarrhea in kids, non-bloody, afebrile
- Enteropathogenic E. coli (EPEC)
- -infantile watery/bloody diarrhea
- Enteroinvasive E. coli (EIEC)
- -fever, abd pain, water/bloody diarrhea w/leukocytes (dysentery)
What are the symptoms, lasting 10-20 days, of Yersinia enterocolitica (gram-negative coccobacilli)?
- diarrhea (may be bloody)
- fever
- N/V
- abd pain on R side + pharyngitis
- -d/t infection in the terminal ileum
-What other diseases are on the differential for Y. enterocolitica?
- appendicitis
- Crohn’s
- Salmonella, Shigella (clinically indistinguishable)
How is Y. enterocolitica diagnosed?
- blood or stool cultures (special media needed)
- fecal leukocytes +
Derangement of what element’s metabolism enhances the virulence of Y. enterocolitica?
–Iron: pts with iron-overload syndromes, cirrhosis, hemochromatosis, aplastic anemia, and thalassemia
–also increases in pts with diabetes and pre-existing GI disorders
What are complications of Y. enterocolitica?
- erythema nodosum (like Campylobacter)
- reactive arthritis (like Shigella)
- myocarditis
- kidney disease
What are the symptoms, lasting 2-3 days, of Listeria monocytogenes (gram-positive rod)?
- -non-bloody diarrhea
- -fever
- -headache
- -N/V
- -during pregnancy: mild fever and malaise
How is L. monocytogenes diagnosed?
- blood culture
- CSF
- cannot be cultured from stool samples
Who is at risk for L. monocytogenes?
- pregnant women
- age extremes
- immunosuppressed
- pts with hemochromatosis
What are complications of L. monocytogenes?
- meningoencephalitis
- Listeria placentitis
What are the symptoms of Tropheryma whipplei (gram-positive rod)?
- -low-grade intermittent fever
- -arthralgias
- -weight loss
- -malabsorption
- -chronic diarrhea
How is Tropheryma whipplei treated?
-abx results in dramatic improvement within several weeks, but prolonged Tx for at least a yr is required
- prefer to use drugs that cross the BBB
- duodenal biopsies needed q6 months for 1yr
True or False: Whipple Disease is fatal if left untreated.
True; some neurological signs (dementia, lethargy, coma, seizures, nystagmus) may be permanent.
Pts must be followed closely after Tx for signs of recurrence.
What are the symptoms of C. diff (gram-positive, spore-forming, anaerobic, cytotoxin-producing rod)?
- watery diarrhea
- abd pain
- fever
How is C. diff diagnosed?
- stool assay PCR for toxin (A and B)
- peripheral leukocytes +
- pseudomembranes on colonic mucosa
What are risk factors for C. diff?
- hospitalization within the past 2 months
- use of PPI
-abx use (esp. clindamycin, cephalosporins, and fluoroquinolones)
What are prevention and treatments for C. diff?
- wash hands with soap and water
- PO/IV metronidazole
- PO vanc
What is a complication of C. diff?
-toxic megacolon; needs aggressive Tx and surgery consult for a colectomy (50% mortality rate)
What is the most common cause of acute diarrhea in children under age 2?
- -rotavirus
- -more common in winter
- -fecal-oral spread
What type of virus is Rotavirus?
–double-stranded RNA (Reoviridae family)
What are symptoms of Rotavirus?
- vomiting
- watery diarrhea
- resolves after 2-5 days
- may result in death d/t dehydration
How is Rotavirus diagnosed?
- -detected by viral culture or PCR
- -has a “wagon-wheel appearance” on EM
What type of virus is Adenovirus?
–double-stranded DNA virus
What are the symptoms of Adenovirus?
- -fever of 103-104F and chills
- -myalgias
- -pharyngitis
- -watery diarrhea
- -vomiting
What is the most common cause of viral conjunctivitis in children?
Adenovirus
What type of virus is Norovirus?
–small, non-enveloped RNA virus
What are the symptoms of Norovirus?
- vomiting
- watery diarrhea (4-8 stools per day)
- resolves in 3 days
True or False: work-up is necessary in Norovirus cases
False; the resolution of symptoms is so fast, no work-up is needed
CMV rarely causes diarrhea except in what group of patients?
- primarily in AIDS patients and organ transplant patients with a CD4 count < 200
- or as a result of reactivation of a previous infection
What type of virus is CMV?
–double-stranded DNA (Herpesviridae)
What are symptoms of CMV (can last for several weeks)?
- fever
- abd pain
- bloody diarrhea
How is CMV diagnosed?
–endoscopy w/ biopsy of ulcerated lesions using CMV-specific stains
What is the most common cause of dysentery in the world?
E. histolytica
True or False: asymptomatic carriers of E. histolytica still need treatment
True
What are the symptoms of E. histolytica (can persist from a few days up to a few weeks)?
- fever
- abd pain and tenesmus
- bloody diarrhea
- liver abscesses
- -can penetrate bowel and enter portal circulation
How is E. histolytica diagnosed?
- -flask-shaped ulcer on histology
- -stool for Ova and Parasite
- -stool Ag (PCR for DNA)
- fecal leukocytes +
What are risk factors of E. histolytica?
- endemic areas: Asia, Africa, Central/South America
- crowded living conditions and poor sanitation
- mental health institutions
- ingestion of contaminated food/water
What are complications of E. histolytica?
- toxic megacolon
- pneumatosis coli (gas cysts in the bowel wall)
What does giardia look like?
–pear-shaped protozoan w/ flagella and 2 nuclei
What are the symptoms of Giardia, lasting 2-4 weeks?
- watery, malodorous, persistent diarrhea
- steatorrhea
- belching/flatulence
- abd pain and cramps
- nausea, anorexia, and weight loss
How is Giardia diagnosed?
- stool Ag test
- Ova and Parasites checked 3x sequentially
What are risk factors of Giardia?
- -lakes, streams, hiking, camping
- -beaver, cattle, dogs, rodents, bighorn sheep
- -person-person transmission in daycares
- -pts w/ IgA deficiency are more susceptible
- -contaminated water in Russia
What are the two different courses that Cryptosporidium can take for immunocompetent pts versus immunosuppressed pts?
–self-limited diarrhea (7-10 days) in immunocompetent pts
–life-threatening intractable diarrhea in immunosuppressed pts
What are the symptoms of Crypto?
- nausea
- malaise
- abd cramping
- large volumes of watery diarrhea (20L/day)
What are risk factors for Crypto?
- contaminated food/water
- swimming pools
- daycare
- unsanitary milk production
- municipal water supply
How is Crypto diagnosed?
- -stool Ag detection
- -direct microscopy
- -modified acid-fast staining, direct fluorescent Ab
What type of parasite is Strongyloides stercoralis?
- nematode:roundworm
- most common in tropics or subtropics
- enters body through bare feet on contaminated soil
- larva travel to lungs and grow
- -they are coughed up and swallowed
What are the symptoms of S. stercoralis?
- mostly asymptomatic
- -abd pain, bloating
- -vomiting
- -diarrhea
- -cough, SOB
What are risk factors for S. stercoralis?
- -rural areas, associated w/ agriculture activities
- -low socioeconomic status
- -institutionalized populations
- -hyperinfection in the immunocompromised
- -HTLV-1 pts
How is S. stercoralis diagnosed?
- rhabditiform larvae in stool
- eosinophils in stool
What are risk factors for Cyclospora cayetanensis?
- produce from endemic areas (Guatemala, Haiti, Peru)
- -chlorine or iodine does NOT kill
What are the symptoms of C. cayetanensis (lasts up to 21 days in immunocompetent, but can be indefinite in immunosuppressed) ?
- watery diarrhea
- malaise
- anorexia
- nausea
- fever
How is C. cayetanensis diagnosed?
detection of oocysts in stool sample
What are the symptoms of Cytoisospora belli?
- watery diarrhea
- abd pain and cramping
- malabsorption and weight loss
- can be severe in immunosuppressed pts
How is C. belli diagnosed?
- eosinophilia
- repeated stool samples and concentration procedures
- -b/c oocysts are passed in small amts intermittently
- duodenal specimens by biopsy
By what laboratory methods can C. belli be visualized?
- -wet mounts by microscopy w/ bright-field
- -stained by modified acid-fast
What are characteristics of Ascaris lumbricoides?
- -hookworm/whipworm
- -soil-transmitted helminths
- -fecal-oral transmission (ingest eggs from soil)
- -can get long and cause BOWEL OBSTRUCTION
What are characteristics of Diphyllobothrium latum?
- fish tapeworm
- can get up to 30ft long
- abd symptoms
- absorbs vit B12 and thus causes vit B12 deficiency
- -pernicious anemia and neuro symptoms
What are characteristics of Schistosoma mansoni?
- trematode in Africa
- 2nd common cause of African esophageal varices
- -most common cause of small portal v. obstruction
- contaminated freshwater snails
- bloody stools, bladder CA, liver cysts
What is the treatment for S. mansoni?
Praziquantel
What are some characteristics of Taenia solium?
- pork tapeworm (hooks)
- mostly asymptomatic
- -rare, serious cases of Cysticercosis (seizures) and muscle or eye disease
What are some characteristics of Taenia saginata?
- beef tapeworm (suckers)
- asymptomatic
What are some characteristics of Echinococcus granulosus?
- -tapeworm (DOGS are the main carriers)
- -unsanitary SHEEP slaughter
- -fecal-oral, poor sanitation
- -FORM CYSTS IN LIVER OR LUNGS
- -FREE-FLOWING “HYDATID SAND” on CT
What are some characteristics of Enterobius vermicularis (Pinworm)?
- -fecal-oral transmission
- -severe perianal itching
- -diagnosed by “Scotch Tape Test”
- -Tx: Mebendazole
When can anti-motility agents be used to treat acute infectious diarrhea?
- when there’s no fever
- when there’s no bloody stool
-do NOT use in C. diff or EHEC
Name two causes of acute infectious diarrhea that are not phased by alcohol hand sanitizers.
C. diff
Noro
Which causes of acute infectious diarrhea have vaccines?
- Rotavirus
- S. typhi
- V. cholera
- Hep A
While bismuth subsalicylate may reduce the frequency of traveler’s diarrhea (and is safe for up to 3wks), it has side effects, such as:
- darkening of the tongue and stools
- tinnitus
True or False: antibiotic prophylaxis is recommended for traveler’s diarrhea
False; it is only indicated for use in immunocompromised, IBD, hemochromatosis, gastric achlorhydria
Which causes of acute infectious diarrhea can be followed by reactive arthritis (Reiter’s Syndrome)?
- Salmonella
- Shigella
- Campylobacter
- Yersinia
What are characteristics of reactive arthritis?
- -conjunctivitis, urethritis, arthritis
- -HLA-B27
What are some complications that can occur as a result of Yersiniosis?
- -autoimmune-type thyroiditis
- -pericarditis
- -glomerulonephritis
What are some characteristics of when pathogens affect the small bowel?
- -large volume, WATERY stools
- -abd cramps
- -weight loss
- -dehydration/malabsorption
- -non-inflamatory
What are some examples of pathogens that affect the small bowel?
- S. aureus, B. cereus, C. perfringens
- Crypto and Giardia
- ETEC, EPEC
- Y. enterolitica
- Rotavirus, Norovirus, Adenovirus
What are some characteristics of when pathogens affect the large bowel?
- frequent, small volume BLOODY stools
- FEVER
- WBC in stool (inflammatory)
- fecal leukocytes +
What are some examples of pathogens that affect the large bowel?
- Cambylobacter
- Salmonella, Shigella
- EIEC, EHEC
- C. diff
- E. histolytica
Patients with lymphoma, HIV, or who have had bone marrow transplants are more susceptible to which causes of acute infectious diarrhea?
- Cyclospora and Cytoisospora
- Salmonella, Shigella
- Campylobacter
- CMV, Herpes, Adenovirus
- Crypto
Patients with IgA deficiency are more susceptible to what cause of acute infectious diarrhea?
Giardia
Patients with hemachromatosis are more susceptible to what causes of acute infectious diarrhea?
- Vibrio spp.
- Listeria
- Yersinia
In AIDS pts, which agents (transmitted venereally per rectum) may contribute to proctocolitis?
- N. gonorrhea
- T. pallidum
- Chlamydia
