“Don’t Drink the Water”: A Primer on Infectious Diarrhea

“Don’t Drink the Water”: A Primer on Infectious Diarrhea

Patty W. Wright, MDwith appreciation to Ban Allos, MD

March 2011

Objectives

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

Salmonella Campylobacter Shigella Listeria Vibrio E. coli O:157 Bacillus Clostridium S. aureus

Rotaviruses Norwalk-like viruses Cyclospora Isospora Cryptosporidium Giardia

Case 1

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?

Acute N/V +/- Diarrhea: Pathogens

Pathogens that have preformed toxins – Cause onset of symptoms within 1-6 hours

of ingestion– S. aureus – Bacillus cereus (short-incubation)

“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

Classic Association/Outbreak

Staphylococcus aureus – ham, cream-filled pastries


Norwalk-like viruses – cruise ships, raw seafood

Case 2

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




Acute Diarrhea w/o Vomiting/Fever 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


Bacillus cereus – fried rice

Case 3

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




Acute Diarrhea and Fever w/o Bloody Stool Pathogens that cause tissue invasion

– Salmonella– Shigella– Campylobacter– Vibrio– Invasive E coli– Listeria

Acute Diarrhea and Fever w/o Bloody Stool For diarrhea > 1 day in duration or

severe (dehydration, fever, blood)– Obtain additional exposure history– Check fecal WBC

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 Treatment:

– Hydration– Quinolones typically empiric treatment of

choice for food-borne diarrhea– Azithromycin is alternative if cannot take

quinolones or risk of resistant Campylobacter


Salmonella – peanut butter


Salmonella and Campylobacter – poultry and poultry products


Vibrio – raw oysters (or wading in the Gulf of Mexico), especially in patients with hepatic dysfxn


Listeria – refrigerated food items (cold cuts, prepared salads), soft cheeses


Shigella – low infectious dose (10-100 organisms), “cool, moist foods that require much handling after cooking”,


Yersinia – pork, chitterlings

Case 4

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




Acute Bloody Diarrhea +/- Fever

Pathogens that produce shiga toxin– Shigella dysenteriae– E coli O157:H7

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 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)

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

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




Chronic Diarrhea (Non-bloody)

Etiologies– Parasites– Tropical Sprue– Bacterial overgrowth syndromes– Non-infectious causes

• Food allergies• Neoplasm and endocrine processes• Functional disorders

Chronic Diarrhea (Non-bloody)

Most common parasitic causes in US– Giardia– Cryptosporidium– Cyclospora– Isospora

Giardia photos: http://phil.cdc.gov/phil/details.asp

Chronic Diarrhea (Non-bloody) 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

Treatment specific for pathogen isolated


Cryptosporidium – drinking water contaminated with manure after flooding

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

Case 6

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:




Clostridium difficile- Associated Disease

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 difficile- Associated Disease Spectrum of Disease

– Asymptomatic carrier– Diarrhea without colitis– Colitis without pseudomembranes– Pseudomembranous colitis– Fulminant colitis


Pseudomembranous Colitis

www.faculty.plattsburgh.edu

Clostridium difficile- Associated Disease 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


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 difficile- Associated 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 10-14 days

Clostridium difficile- Associated Disease 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 difficile- Associated Disease 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

ELISA not recommended as a test of cure in asymptomatic pts

Clostridium difficile- Associated Disease 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

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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“Don’t Drink the Water”: A Primer on Infectious Diarrhea

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