Transcript E coli O157:H7 - MCE Conferences

“Don’t Drink the Water”:
A Primer on Infectious Diarrhea
Patty W. Wright, MD
with appreciation to Ban Allos, MD
March 2011
Objectives
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To familiarize participants with the
causes, diagnostic work-up, and
treatment of the most common
etiologies of infectious diarrhea.
Foodborne-related Illness and Death
in the U.S.
Events per year
Number
Illnesses
>76 million
Hospitalizations
>325,000
Deaths
>5,000
Common Food- and Water-borne
Pathogens Causing Diarrhea in the US
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Salmonella
Campylobacter
Shigella
Listeria
Vibrio
E. coli O:157
Bacillus
Clostridium
S. aureus
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Rotaviruses
Norwalk-like viruses
Cyclospora
Isospora
Cryptosporidium
Giardia
Case 1
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A 19 year old female college student
presents to the ED at 5 pm c/o the
acute onset of N/V with abdominal
cramps and mild diarrhea. She denies
associated fevers. She ate at a local
restaurant today at noon. She reports
that several of her classmates have
been ill over the past week with the
“stomach flu”.
Case 1
What pathogens are on your
differential?
 What diagnostic work-up would you
perform?
 How would you treat the patient?
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Acute N/V +/- Diarrhea:
Pathogens
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Pathogens that have preformed toxins
– Cause onset of symptoms within 1-6 hours
of ingestion
– S. aureus
– Bacillus cereus (short-incubation)
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“Winter Vomiting Disease”
– Norwalk-like viruses
– Rotavirus
Acute N/V +/- Diarrhea:
Dx and Rx
Typically resolves within 12-24 hrs,
without specific therapy
 No diagnostic work-up required
 Treat with anti-emetics and hydration,
if needed
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Classic Association/Outbreak
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Staphylococcus aureus – ham,
cream-filled pastries
Classic Association/Outbreak
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Norwalk-like viruses – cruise ships,
raw seafood
Case 2
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A 45 year old male develops nausea,
diarrhea, and abd cramps at bedtime.
He denies any associated vomiting,
fever, or blood in his stool. He reports
that a friend from work, who at lunch
with him at a local Chinese restaurant,
is also ill with similar symptoms.
Case 2
What pathogens are on your
differential?
 What diagnostic work-up would you
perform?
 How would you treat the patient?
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Acute Diarrhea w/o
Vomiting/Fever
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Pathogens that produce toxins in vivo
– Bacillus cereus (long-incubation)
– Clostridium perfringens
Typically resolves within 24 – 48 hrs,
without specific therapy
 No diagnostic work-up required
 Treat symptomatically
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Classic Association/Outbreak
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Bacillus cereus – fried rice
Case 3
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A 56 year old male with HTN presents
to the clinic with a 2 day h/o diarrhea,
abd cramps, and fever to 101. He
denies blood in his stool or N/V. His wife
also reports diarrhea over the past 24
hours. He denies any recent
hospitalizations or antibiotic usage.
Case 3
What pathogens are on your
differential?
 What diagnostic work-up would you
perform?
 How would you treat the patient?
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Acute Diarrhea and Fever w/o
Bloody Stool
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Pathogens that cause tissue invasion
– Salmonella
– Shigella
– Campylobacter
– Vibrio
– Invasive E coli
– Listeria
Acute Diarrhea and Fever w/o
Bloody Stool
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For diarrhea > 1 day in duration or
severe (dehydration, fever, blood)
– Obtain additional exposure history
– Check fecal WBC
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If + fecal WBC
– Stool culture for pathogens
– Consider testing for C diff toxin
– Consider empiric abx (adults only)
Acute Diarrhea and Fever w/o
Bloody Stool
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Treatment:
– Hydration
– Quinolones typically empiric treatment of
choice for food-borne diarrhea
– Azithromycin is alternative if cannot take
quinolones or risk of resistant
Campylobacter
Classic Association/Outbreak
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Salmonella – peanut butter
Classic Association/Outbreak
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Salmonella and Campylobacter –
poultry and poultry products
Classic Association/Outbreak
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Vibrio – raw oysters (or wading in the
Gulf of Mexico), especially in patients
with hepatic dysfxn
Classic Association/Outbreak
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Listeria – refrigerated food items (cold
cuts, prepared salads), soft cheeses
Classic Association/Outbreak
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Shigella – low infectious dose (10-100
organisms), “cool, moist foods that
require much handling after cooking”,
Classic Association/Outbreak
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Yersinia – pork, chitterlings
Case 4
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A 23 year old female presents to the
ED with 3 days of diarrhea. She reports
that she initially had watery diarrhea,
but that it has now turned grossly
bloody. She reports severe abd
cramps. She denies fever or N/V.
Case 4
What pathogens are on your
differential?
 What diagnostic work-up would you
perform?
 How would you treat the patient?
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Acute Bloody Diarrhea
+/- Fever
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Pathogens that produce shiga toxin
– Shigella dysenteriae
– E coli O157:H7
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Evaluation:
– Fecal WBC
– Stool culture for pathogens (including
E coli O157:H7)
– Consider testing for C diff toxin
– CBC with diff, BMP
Acute Bloody Diarrhea
+/- Fever
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Treatment
– NaCl hydration and supportive care
– AVOID antibiotics (especially trim-sulfa)
– AVOID antimotility agents in all patients
with diarrhea and
• High fever or
• Bloody diarrhea or
• Fecal WBC’s
Hemolytic Uremic
Syndrome (HUS)
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Occurs in about 10% of pts with E coli
O157:H7
Begins ~ 5-10 days after symptom onset
Triad of microangiopathic hemolytic anemia,
thrombocytopenia, and acute renal failure
Most common in kids < 4 yrs old
Mortality rate 5-15%
Older children and adults have poorer
prognoses
Na load most protective factor in the
prevention of HUS in pts with E coli O157:H7
Classic Association/Outbreak:
E. coli O157:H7
1. Food
-Foods of bovine origin (hamburger, milk, etc.)
-Fruits (apple cider) and vegetables
contaminated with manure
Classic Association/Outbreak:
E. coli O157:H7
2. Water
-Contaminated drinking water
-Swimming in contaminated pools and lakes
3. Direct person-to-person or animal-to-person
spread
-Daycare centers
-Long-term care facilities
-Petting zoos
Case 5
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A 37 year old male presents to the clinic
c/o 4 weeks of daily diarrhea with
associated anorexia, fatigue, bloating,
and nausea. He denies fevers, vomiting,
or blood in his stool. He has lost about 7
pounds over the past month. He denies
recent travel.
Case 5
What pathogens are on your
differential?
 What diagnostic work-up would you
perform?
 How would you treat the patient?
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Chronic Diarrhea (Non-bloody)
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Etiologies
– Parasites
– Tropical Sprue
– Bacterial overgrowth syndromes
– Non-infectious causes
• Food allergies
• Neoplasm and endocrine processes
• Functional disorders
Chronic Diarrhea (Non-bloody)
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Most common parasitic causes in US
– Giardia
– Cryptosporidium
– Cyclospora
– Isospora
Giardia photos: http://phil.cdc.gov/phil/details.asp
Chronic Diarrhea (Non-bloody)
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Diagnosis:
– Fecal WBC
– Wet mount for ova and parasites
– Modified acid-fast stain to detect
• Cyclospora
• Isospora
• Cryptosporidium
– Giardia antigen testing (stool)
– HIV antibody testing
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Treatment specific for pathogen isolated
Classic Association/Outbreak
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Cryptosporidium –
drinking water
contaminated with
manure after
flooding
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Cyclospora –
raspberries
contaminated with
bird feces
Chronic Bloody Diarrhea
Inflammatory Bowel Disease
(ulcerative colitis or Crohn's disease)
most common cause
 Differential includes bowel ischemia,
colon cancer, or polyps
 Infectious causes possible, but much
less likely
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Case 6
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A 68 year old female with chronic
sinusitis presents with fever to 100.7,
malaise, abdominal pain, and severe
diarrhea which started yesterday. She
reports having 20 watery, non-bloody
stools since her diarrhea began. Her
current medications include a steroid
nasal spray, loratidine, and omeprazole.
Case 6:
What pathogens are on your
differential?
 What diagnostic work-up would you
perform?
 How would you treat the patient?
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Clostridium difficileAssociated Disease
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Risk Factors for CDAD:
– Antibiotic exposure
• Any abx within the prior 2 months
– Prolonged hospitalization
– Severity of underlying disease
– Age > 65 years
– GI surgery
– PPI
Clostridium difficileAssociated Disease
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Spectrum of Disease
– Asymptomatic carrier
– Diarrhea without colitis
– Colitis without pseudomembranes
– Pseudomembranous colitis
– Fulminant colitis
Clostridium difficileAssociated Disease
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www.faculty.plattsburgh.edu
Pseudomembranous
Colitis
Clostridium difficileAssociated Disease
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Fulminant colitis
– About 3% of cases
– Signs and Symptoms
• Diffuse abd tenderness/distention,
diarrhea, low BP, high fever,
leukocytosis
– Complications
• Ileus, toxic megacolon, bowel
perforation, death
Clostridium difficileAssociated Disease
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Diagnosis
– ELISA testing for toxins A and B
• May need to repeat to improve sensitivity
– Cytotoxicity assays
• “Gold Standard”, but expensive & requires 48 hrs
– Culture for C. diff
• Does not distinguish disease from colonization
– Colonoscopy
• Risk for perforation
Clostridium difficileAssociated Disease
Treatment of mild disease
– Metronidazole po 500mg Q8hrs x
10-14 days
 Treatment of moderate to severe
disease (WBC > 15k or increasing cr)
– Vancomycin po 125mg Q6hrs x 1014 days
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Clostridium difficileAssociated Disease
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Treatment of severe disease
(hypotension, obstruction, ileus, or
perforation)
– Metronidazole iv 500mg Q8hrs and
vancomycin via NGT 500mg Q6hrs
and/or vancomycin enema
– Surgical consult
• Consider colectomy if rising WBC and
lactate
Clostridium difficileAssociated Disease
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Recurrence
– Occurs in 5-30% of patients
– Rate does not vary with initial agent used
– Can consider re-treatment with same agent
– Consider vancomycin po pulse dosed
(125-500mg Q 3days x 3 wks) or tapered
– ? Role of cholestyramine and probiotics
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ELISA not recommended as a test of
cure in asymptomatic pts
Clostridium difficileAssociated Disease
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Prevention and Control
– Avoid unnecessary antibiotic use
– Hand washing with soap and water
• Avoid alcohol-based hand sanitizers
for hand hygiene after seeing patients
with known or suspected C. diff
– Contact precautions for hospitalized pts
– Clean pt environment with 1:10 dilution
of bleach
Summary- Diarrhea
Acute diarrhea with N/V will typically
resolve within 24-48 hrs without rx
 If diarrhea persists or is severe,
evaluate with fecal WBC, cx, +/- C. diff
 Hydration and supportive care +/- abx
for treatment
 Evaluate for parasites and HIV if chronic
diarrhea
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Summary- CDAD
Wide spectrum of disease states
 Dx with ELISA testing for toxins A and B
 Rx mild disease w/ po metronidazole;
Rx severe disease w/ po vancomycin;
Rx w/ iv metro and NGT/pr vanc, if ileus
 Recurrence is common
 Use hand washing and contact
precautions to prevent spread
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