Clinical Correlation: Enteric Infections Bacterial Diarrhea

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Clinical Correlation: Enteric Infections Bacterial Diarrhea

  1. 1. Clinical Correlation: Enteric Infections Bacterial Diarrhea Chris E. Forsmark, M.D. Division of Gastroenterology, Hepatology, and Nutrition
  2. 2. Infectious Diarrhea <ul><li>3-5 billion episodes yearly </li></ul><ul><li>Major cause of worldwide morbidity and mortality </li></ul><ul><li>5 million deaths yearly, 80% < 1 year of age </li></ul><ul><li>Major cause of work/school absenteeism </li></ul><ul><li>Major economic burden, especially in developing countries </li></ul><ul><li>Bacteria cause 5.2 million cases of diarrhea in US yearly (80% foodborne) </li></ul>
  3. 3. Organisms <ul><li>Bacteria </li></ul><ul><ul><li>E. Coli, Salmonella, Shigella, Campylobacter, Vibrio, Yersinia, Clostridium difficle, S. aureus, B. cereus, C. botulinum </li></ul></ul><ul><li>Viruses </li></ul><ul><ul><li>Norovirus, Rotavirus, CMV </li></ul></ul><ul><li>Parasites </li></ul><ul><ul><li>Giardia, Amoeba, Ascaris, etc </li></ul></ul>
  4. 4. These organisms cause diarrhea through a wide variety of mechanisms <ul><li>Pathophysiology </li></ul><ul><ul><li>Osmotic </li></ul></ul><ul><ul><li>Secretory </li></ul></ul><ul><ul><li>Exudation </li></ul></ul><ul><ul><li>Abnormal motility </li></ul></ul>
  5. 6. Osmotic Diarrhea <ul><li>Interferes with absorption of water </li></ul><ul><li>Solutes are ingested (fasting stops diarrhea) </li></ul><ul><ul><li>Magnesium sulfate or citrate or magnesium containing antacids </li></ul></ul><ul><ul><li>Sorbitol </li></ul></ul><ul><ul><li>Malabsorption of food </li></ul></ul><ul><ul><ul><li>Lactase deficiency </li></ul></ul></ul><ul><ul><ul><li>Celiac sprue </li></ul></ul></ul><ul><ul><ul><li>Variety of infectious organisms (particularly viruses) </li></ul></ul></ul>Definition: Increased amounts of poorly absorbed, osmotically active solutes in gut lumen
  6. 7. Secretory Diarrhea <ul><li>Excess secretion of electrolytes and water across mucosal surface </li></ul><ul><li>Usually coupled with inhibition of absorption </li></ul><ul><li>Clinical features </li></ul><ul><ul><li>stools very watery </li></ul></ul><ul><ul><li>stool volume large </li></ul></ul><ul><ul><li>fasting does not stop diarrhea </li></ul></ul>
  7. 9. Secretory Diarrhea <ul><li>Bacterial or viral enterotoxins </li></ul><ul><li>Vibrio cholerae </li></ul><ul><li>Noncholeraic vibrios </li></ul><ul><li>Enterotoxigenic E. coli </li></ul><ul><li>B. cereus </li></ul><ul><li>S. aureus </li></ul><ul><li>Others: Rotavirus, Norovirus </li></ul><ul><li>Non-infectious causes </li></ul>
  8. 10. Exudative Diarrhea <ul><li>Intestinal or colonic mucosa inflamed and ulcerated </li></ul><ul><ul><li>Leakage of fluid, blood, pus </li></ul></ul><ul><ul><li>Impairment of absorption </li></ul></ul><ul><ul><li>Increased secretion (prostaglandins) </li></ul></ul><ul><li>The extent and location of bowel involved determines </li></ul><ul><ul><li>Severity of diarrhea </li></ul></ul><ul><ul><li>Systemic signs and symptoms (abdominal pain, fever, leukocytosis, etc) </li></ul></ul><ul><ul><li>Tenesmus, urgency </li></ul></ul>
  9. 11. Exudative Diarrhea <ul><li>Infectious, invasive organisms </li></ul><ul><ul><li>Shigella, Campylobacter, Yersinia, E. histolytica, EIEC, C diff </li></ul></ul><ul><ul><li>CMV </li></ul></ul><ul><li>Idiopathic inflammatory bowel disease </li></ul><ul><ul><li>Crohns disease </li></ul></ul><ul><ul><li>Ulcerative Colitis </li></ul></ul><ul><li>Ischemia </li></ul>
  10. 12. Invasive organisms produce leukocytes and blood in stool A laboratory equivalent of this is the presence of lactoferrin in a sample of stool
  11. 13. Abnormal Motility <ul><li>Increased colonic motility </li></ul><ul><ul><li>Irritable bowel syndrome </li></ul></ul><ul><li>Increased small bowel motility </li></ul><ul><ul><li>Hyperthyroidism, post-operative dumping </li></ul></ul><ul><li>Decreased small bowel motility </li></ul><ul><ul><li>Scleroderma, with bacterial overgrowth </li></ul></ul><ul><li>Anal sphincter dysfunction </li></ul><ul><ul><li>Incontinence </li></ul></ul>
  12. 15. Diarrhea <ul><li>Non-inflammatory </li></ul><ul><ul><li>Watery diarrhea, no blood or mucus or pus in stool, no fever or systemic signs </li></ul></ul><ul><ul><li>Secretory or osmotic mechanism </li></ul></ul><ul><ul><li>Dehydration may occur </li></ul></ul><ul><ul><li>Generally self-limited and more benign </li></ul></ul><ul><ul><li>Therapy generally supportive </li></ul></ul><ul><li>Inflammatory </li></ul><ul><ul><li>Frequent lower volume stool, mucoid, bloody, or purulent. Often with fever or systemic signs, tenesmus, urgency </li></ul></ul><ul><ul><li>Exudative mechanism </li></ul></ul><ul><ul><li>Dehydration rare </li></ul></ul><ul><ul><li>Less benign </li></ul></ul>
  13. 16. Common syndromes of infectious diarrhea <ul><li>Food poisoning </li></ul><ul><li>Acute watery diarrhea </li></ul><ul><ul><li>Travelers diarrhea </li></ul></ul><ul><ul><li>Epidemics </li></ul></ul><ul><li>Acute bloody diarrhea </li></ul><ul><ul><li>Dysentery </li></ul></ul>
  14. 17. Special circumstances <ul><li>Outbreaks/food poisoning </li></ul><ul><li>Overseas travel </li></ul><ul><li>Immunocompromised host </li></ul><ul><li>Raw seafood ingestion </li></ul><ul><li>Antibiotic usage </li></ul>
  15. 18. History <ul><li>Onset and duration of diarrhea </li></ul><ul><li>Timing of exposure to potential pathogens </li></ul><ul><ul><li>Travel, ingestion history, environment, recent medications (antibiotics), age </li></ul></ul><ul><li>Character of stool </li></ul><ul><ul><li>Volume, presence of blood, mucus, or pus </li></ul></ul><ul><li>Associated symptoms and signs </li></ul><ul><ul><li>Abdominal pain, fever, vomiting, dehydration </li></ul></ul>
  16. 19. Physical examination <ul><li>Vital signs: Fever, tachycardia </li></ul><ul><li>Abdominal tenderness or pain </li></ul><ul><li>Signs of dehydration </li></ul><ul><li>Blood, mucus, or pus in stool </li></ul>
  17. 20. E. coli Type 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
  18. 22. Nontyphoidal Salmonella <ul><li>Salmonella typhimurium and enteritidis </li></ul><ul><li>Clinical syndromes </li></ul><ul><ul><li>Gastroenteritis (non-inflammatory) and colitis (inflammatory) </li></ul></ul><ul><ul><li>Bacteremia and endocarditis </li></ul></ul><ul><ul><li>Enteric fever ( typhi and paratyphi ) </li></ul></ul><ul><ul><li>Localized tissue infection </li></ul></ul><ul><ul><li>Carrier state (> 1 year) </li></ul></ul><ul><li>Food-borne illness (poultry, meat, eggs) </li></ul>
  19. 23. Shigella <ul><li>dysenteriae, flexneri, boydii, sonnei </li></ul><ul><li>Usually bloody diarrhea </li></ul><ul><li>May be complicated by reactive arthritis and rarely HUS </li></ul><ul><li>Very infectious ( ~ 100 organisms cause disease) </li></ul>
  20. 24. Campylobacter <ul><li>Mainly C. jejuni </li></ul><ul><li>Transmission from infected animals or food products, fresh or salt water </li></ul><ul><li>Usually bloody diarrhea or dysentery </li></ul><ul><li>May be complicated by Guillain-Barr é and IPSID </li></ul>
  21. 25. Vibrio <ul><li>Cholera </li></ul><ul><li>Non choleriac </li></ul><ul><li>Enterotoxin elaborated causes severe watery diarrhea </li></ul><ul><li>Complications common due to dehydration </li></ul>
  22. 28. Classic Syndromes: Acute food poisoning <ul><li>Similar illness in 2 or more persons </li></ul><ul><li>Epidemiologic evidence of common food source </li></ul><ul><li>Onset of symptoms typically within 6 hours of ingestion </li></ul><ul><li>Nausea and vomiting prominent </li></ul><ul><li>Preformed toxin of S. aureus or B. cereus </li></ul><ul><li>Longer incubation periods for C. perfringens </li></ul>
  23. 29. Classic Syndromes: Travelers Diarrhea <ul><li>Attack rates of as high as 25% </li></ul><ul><li>90% brief and self-limited </li></ul><ul><li>Persistent diarrhea in 1-2% </li></ul><ul><li>Depends on destination, eating habits, length of stay </li></ul>Pathogen % ETEC 40 EAEC 15 C. jejuni 10 Shigella 10 EHEC or EIEC <5 Salmonella < 5 Vibrio < 5
  24. 30. 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
  25. 31. Nosocomial diarrhea <ul><li>Clostridium difficle </li></ul><ul><li>Increasing worldwide due to hypervirulent strain (North American Pulsefield type 1) </li></ul><ul><li>High fluoroquinolone resistance </li></ul><ul><li>Less responsive to usual therapy (metronidazole) </li></ul><ul><li>Higher complication rate </li></ul>
  26. 32. Evaluation of diarrhea <ul><li>How long has the diarrhea been present? </li></ul><ul><li>Was it acquired in a particular environment? </li></ul><ul><ul><li>Hospital </li></ul></ul><ul><ul><li>Recent antibiotic use </li></ul></ul><ul><ul><li>While traveling </li></ul></ul><ul><ul><li>Day care, cruise ship, picnic, etc </li></ul></ul><ul><ul><li>Exposure to sick persons </li></ul></ul><ul><li>What are the characteristics of the diarrhea </li></ul><ul><ul><li>Is there blood, mucus, or pus in the stool </li></ul></ul><ul><ul><li>Is it high volume or low volume </li></ul></ul><ul><ul><li>Is there associated tenesmus or urgency </li></ul></ul><ul><li>What are the associated symptoms? </li></ul><ul><ul><li>Fever, abdominal pain, vomiting, dehydration </li></ul></ul>
  27. 33. Is evaluation required in every patient? <ul><li>No </li></ul><ul><li>Evaluate those with high fever, systemic illness, tenesmus, blood/pus in stool, dehydration, immunocompromised, prolonged course </li></ul><ul><li>Remainder can often be managed without specific diagnosis with rehydration and anti-peristaltic agents </li></ul>
  28. 34. Evaluation of Infectious Diarrhea <ul><li>Stool studies </li></ul><ul><ul><li>fecal leukocytes or lactoferrin, RBC/blood </li></ul></ul><ul><ul><li>Bacterial culture </li></ul></ul><ul><ul><ul><li>Include C. difficle toxin assay </li></ul></ul></ul><ul><ul><ul><li>May need to request EHEC screen </li></ul></ul></ul><ul><li>Endoscopic evaluation may be useful in some </li></ul><ul><ul><li>especially for bloody diarrhea or chronic diarrhea </li></ul></ul>
  29. 35. Fecal PMNs <ul><li>Common in Shigella, Campylobacter , EIEC, C. diff </li></ul><ul><li>Less common in Salmonella, Yersinia, ETEC, EAEC </li></ul><ul><li>Now largely replaced with fecal lactoferrin </li></ul>
  30. 36. Treatment of Diarrhea <ul><li>Treatment of specific etiology </li></ul><ul><li>Non-specific treatment </li></ul><ul><ul><li>hydration </li></ul></ul><ul><ul><li>Absorptions (Kaopectate®) </li></ul></ul><ul><ul><li>Bismuth </li></ul></ul><ul><ul><li>Antiperistaltics/opiate derivatives </li></ul></ul><ul><ul><li>Fiber supplementation </li></ul></ul>
  31. 37. Oral rehydration solutions
  32. 39. Why not treat everyone with bacterial diarrhea? <ul><li>Some have no effective specific treatment </li></ul><ul><li>Treatment may not change disease duration or severity </li></ul><ul><li>Treatment may predispose to carrier state </li></ul><ul><li>Treatment may produce complications (HUS, antibiotic resistance, C. difficle, toxic megacolon) </li></ul>
  33. 40. Who should be treated? Antibiotics indicated <ul><li>Antibiotics indicated if </li></ul><ul><li>Severely ill </li></ul><ul><li>immunocompromised </li></ul>Antibiotics not indicated Shigella Campylobacter EHEC ETEC Yersinia viruses V. cholera EAEC Food poisoning C. diff Salmonella
  34. 41. Antibiotic choice <ul><li>E. coli </li></ul><ul><ul><li>Quinolone </li></ul></ul><ul><li>Shigella </li></ul><ul><ul><li>Quinolone or TMP-SMX </li></ul></ul><ul><li>Vibrio cholera </li></ul><ul><ul><li>Tetracycline or quinolone </li></ul></ul><ul><li>Salmonella </li></ul><ul><ul><li>Quinolone or TMP-SMX </li></ul></ul><ul><li>Campylobacter </li></ul><ul><ul><li>Erythromycin or quinolone </li></ul></ul><ul><li>Yersinia </li></ul><ul><ul><li>tetracycline, TMP-SMX, or quinolone </li></ul></ul>

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