Clinical Correlation: Enteric Infections Bacterial Diarrhea
description
Transcript of Clinical Correlation: Enteric Infections Bacterial Diarrhea
Clinical Correlation:Enteric InfectionsBacterial Diarrhea
Chris E. Forsmark, M.D.Division of Gastroenterology, Hepatology,
and Nutrition
Infectious Diarrhea
• 3-5 billion episodes yearly• Major cause of worldwide morbidity and
mortality• 5 million deaths yearly, 80% < 1 year of age• Major cause of work/school absenteeism• Major economic burden, especially in
developing countries• Bacteria cause 5.2 million cases of diarrhea
in US yearly (80% foodborne)
Organisms
• Bacteria– E. Coli, Salmonella, Shigella, Campylobacter,
Vibrio, Yersinia, Clostridium difficle, S. aureus, B. cereus, C. botulinum
• Viruses– Norovirus, Rotavirus, CMV
• Parasites– Giardia, Amoeba, Ascaris, etc
These organisms cause diarrhea through a wide variety of mechanisms
Pathophysiology– Osmotic– Secretory– Exudation– Abnormal motility
Osmotic Diarrhea
• Interferes with absorption of water• Solutes are ingested (fasting stops diarrhea)– Magnesium sulfate or citrate or magnesium
containing antacids– Sorbitol– Malabsorption of food
• Lactase deficiency• Celiac sprue• Variety of infectious organisms (particularly viruses)
Definition: Increased amounts of poorly absorbed, osmotically active solutes in gut lumen
Secretory Diarrhea
• Excess secretion of electrolytes and water across mucosal surface
• Usually coupled with inhibition of absorption• Clinical features– stools very watery– stool volume large– fasting does not stop diarrhea
Secretory Diarrhea
Bacterial or viral enterotoxins• Vibrio cholerae• Noncholeraic vibrios• Enterotoxigenic E. coli• B. cereus• S. aureus• Others: Rotavirus, Norovirus
Non-infectious causes
Exudative Diarrhea• Intestinal or colonic mucosa inflamed and
ulcerated– Leakage of fluid, blood, pus– Impairment of absorption– Increased secretion (prostaglandins)
• The extent and location of bowel involved determines– Severity of diarrhea– Systemic signs and symptoms (abdominal pain,
fever, leukocytosis, etc)– Tenesmus, urgency
Exudative Diarrhea
• Infectious, invasive organisms– Shigella, Campylobacter, Yersinia, E.
histolytica, EIEC, C diff– CMV
• Idiopathic inflammatory bowel disease– Crohns disease– Ulcerative Colitis
• Ischemia
Invasive organisms produce leukocytes and blood in stool
A laboratory equivalent of this is the presence of lactoferrin in a sample of stool
Abnormal Motility
• Increased colonic motility– Irritable bowel syndrome
• Increased small bowel motility– Hyperthyroidism, post-operative dumping
• Decreased small bowel motility– Scleroderma, with bacterial overgrowth
• Anal sphincter dysfunction– Incontinence
Diarrhea• Non-inflammatory– Watery diarrhea, no blood or mucus or pus in stool, no
fever or systemic signs– Secretory or osmotic mechanism– Dehydration may occur– Generally self-limited and more benign– Therapy generally supportive
• Inflammatory– Frequent lower volume stool, mucoid, bloody, or
purulent. Often with fever or systemic signs, tenesmus, urgency
– Exudative mechanism– Dehydration rare– Less benign
Common syndromes of infectious diarrhea
• Food poisoning• Acute watery diarrhea– Travelers diarrhea– Epidemics
• Acute bloody diarrhea– Dysentery
Special circumstances
• Outbreaks/food poisoning• Overseas travel• Immunocompromised host• Raw seafood ingestion• Antibiotic usage
History
• Onset and duration of diarrhea• Timing of exposure to potential pathogens– Travel, ingestion history, environment, recent
medications (antibiotics), age
• Character of stool– Volume, presence of blood, mucus, or pus
• Associated symptoms and signs– Abdominal pain, fever, vomiting, dehydration
Physical examination
• Vital signs: Fever, tachycardia• Abdominal tenderness or pain• Signs of dehydration• Blood, mucus, or pus in stool
E. coliType Clinical Features Complications
ETEC Watery diarrhea, travelers diarrhea
rare
EHEC
(Shiga toxin 1 and 2)
Bloody diarrhea Hemolytic uremic syndrome, TTP (mostly 0157:H7)
EIEC bloody diarrhea, dysentery rare
EAEC Watery diarrhea or bloody diarrhea, mainly in children
May be protracted
Nontyphoidal Salmonella
• Salmonella typhimurium and enteritidis• Clinical syndromes– Gastroenteritis (non-inflammatory) and colitis
(inflammatory)– Bacteremia and endocarditis– Enteric fever (typhi and paratyphi)– Localized tissue infection– Carrier state (> 1 year)
• Food-borne illness (poultry, meat, eggs)
Shigella
• dysenteriae, flexneri, boydii, sonnei• Usually bloody diarrhea• May be complicated by reactive arthritis and
rarely HUS• Very infectious ( ~100 organisms cause
disease)
Campylobacter
• Mainly C. jejuni• Transmission from infected animals or food
products, fresh or salt water• Usually bloody diarrhea or dysentery• May be complicated by Guillain-Barré and
IPSID
Vibrio
• Cholera• Non choleriac• Enterotoxin elaborated causes severe watery
diarrhea• Complications common due to dehydration
Classic Syndromes: Acute food poisoning
• Similar illness in 2 or more persons• Epidemiologic evidence of common food source• Onset of symptoms typically within 6 hours of
ingestion• Nausea and vomiting prominent• Preformed toxin of S. aureus or B. cereus • Longer incubation periods for C. perfringens
Classic Syndromes: Travelers Diarrhea
• Attack rates of as high as 25%
• 90% brief and self-limited
• Persistent diarrhea in 1-2%
• Depends on destination, eating habits, length of stay
Pathogen %
ETEC 40
EAEC 15
C. jejuni 10
Shigella 10
EHEC or EIEC
<5
Salmonella < 5
Vibrio < 5
Food-borne illness
Agent %
Norovirus 45
C. perfringens 12
Salmonella 11
S. aureus 4
EHEC (0157) 4
C. jejuni 4
B. cereus 2
Shellfish-borne
%
Norovirus 52
Vibrio 37
Salmonella <1
Other 10
Nosocomial diarrhea
• Clostridium difficle• Increasing worldwide due
to hypervirulent strain (North American Pulsefield type 1)
• High fluoroquinolone resistance
• Less responsive to usual therapy (metronidazole)
• Higher complication rate
Evaluation of diarrhea• How long has the diarrhea been present?• Was it acquired in a particular environment?– Hospital– Recent antibiotic use– While traveling– Day care, cruise ship, picnic, etc– Exposure to sick persons
• What are the characteristics of the diarrhea– Is there blood, mucus, or pus in the stool– Is it high volume or low volume– Is there associated tenesmus or urgency
• What are the associated symptoms?– Fever, abdominal pain, vomiting, dehydration
Is evaluation required in every patient?
• No• Evaluate those with high fever, systemic
illness, tenesmus, blood/pus in stool, dehydration, immunocompromised, prolonged course
• Remainder can often be managed without specific diagnosis with rehydration and anti-peristaltic agents
Evaluation of Infectious Diarrhea
• Stool studies– fecal leukocytes or lactoferrin, RBC/blood– Bacterial culture• Include C. difficle toxin assay• May need to request EHEC screen
• Endoscopic evaluation may be useful in some– especially for bloody diarrhea or chronic
diarrhea
Fecal PMNs
• Common in Shigella, Campylobacter, EIEC, C. diff
• Less common in Salmonella, Yersinia, ETEC, EAEC
• Now largely replaced with fecal lactoferrin
Treatment of Diarrhea
• Treatment of specific etiology• Non-specific treatment– hydration– Absorptions (Kaopectate®)– Bismuth – Antiperistaltics/opiate derivatives– Fiber supplementation
Oral rehydration solutions
Components WHO Ricelyte Pedialyte
Na (mEq/L) 90 50 45
K (mEq/L) 20 25 20
Cl (mEq/L) 80 45 35
Citrate (mEq/L) 30 34 30
Glucose (g/L) 20 30 25
Why not treat everyone with bacterial diarrhea?
• Some have no effective specific treatment• Treatment may not change disease duration
or severity• Treatment may predispose to carrier state• Treatment may produce complications (HUS,
antibiotic resistance, C. difficle, toxic megacolon)
Who should be treated?Antibiotics indicated Antibiotics indicated if
•Severely ill
•immunocompromised
Antibiotics not indicated
Shigella Campylobacter EHEC
ETEC Yersinia viruses
V. cholera EAEC Food poisoning
C. diff Salmonella
Antibiotic choice• E. coli– Quinolone
• Shigella– Quinolone or TMP-SMX
• Vibrio cholera– Tetracycline or quinolone
• Salmonella– Quinolone or TMP-SMX
• Campylobacter– Erythromycin or quinolone
• Yersinia– tetracycline, TMP-SMX, or quinolone