Shabnam Tehrani M.D., MPH Assistant Professor of Infectious Diseasese &Tropical Medicine Research Center, Shahid Beheshti University of Medical

Transcription

1 Shabnam Tehrani M.D., MPH Assistant Professor of Infectious Diseasese &Tropical Medicine Research Center, Shahid Beheshti University of Medical Sciences

2 Introduction Pathophysiology Clinical Presentation Clinical Evaluation and Diagnostic Approach Treatment Specific Pathogens

3 Watery Diarrhea: 3 or more liquid or watery stools in 24 h Dysentery: Presence of blood and/or mucus in stools Persistent Diarrhea: Diarrhea lasting for 14 days or more

4 Developing Countries % mortality in children <5 yo -Leads to cognitive and physical developmental delay United States each year million episodes -73 million MD visits -1.8 million hospitalizations -Foodborne diarrheal illness is increasing

5 Major Mechanisms of Diarrhea: -Decreased absorption -Increased secretion -Increased luminal osmolality -Changes in gut motility

6 Mechanisms of Enteropathogens: -Enterotoxin production (V. cholera, ETEC) -Cytotoxin production (C. difficile, STEC, Shigella) -Preformed toxin (S. aureus, B. cereus) -Enteroadherence(EAEC, EPEC) -Mucosal invasion (Shigella, Salmonella, Campy, EIEC) -Penetration and proliferation in the submucosa(salmonella, Yersinia) -Others intestinal secretogogues, neuronal pathways

7 Most infectious diarrhea is brief (24-48h), selflimited, and managed by patients alone. Small Intestinal Disease Diffuse periumbilical pain Large volume stools Watery stools Malabsorption & dehydration Ileocolonic Disease Lower abdominal pain Small volume stools May be bloody Tenesmus

8 watery diarrhea Large volume Abdominal cramping Bloating, gas Weight loss Fever is rarely a significant symptom Stool does not contain occult blood or inflammatory cells

9 Frequent Regular Small volume Often painful bowel movements. Fever Bloody or mucoid stools are common, Red blood cells and inflammatory cells may be seen routinely on the stool smear.

10 Volume status Severity of illness Epidemiologic clues Is diagnostic evaluation appropriate?

11 Confusion Dry Axillae Extremity weakness Severe postural dizziness Sunken Eyes Tachycardia Dry Mucous membranes

12 Prolonged illness Illness not improving after 48 hrs >6 stools per day Volume depletion Bloody or dysenteric stools Severe abd pain in pts >50 yo

13 Travel History Recent Hospitalizations Underlying Medical Illnesses Sexual History Exposure to daycare Ingestion of unsafe foods

14 Ingestion of untreated fresh water Exposure to animals Recent antibiotics

15 Individuals Severe disease Systemic symptoms Illness lasting >1 week Elderly and immunocompromised Public Health Infection Control -Suspected Outbreak Persons with high risk to transmit infections

16 Selective testing based on epidemiologic clues (i.e. Giardia Ag) Fecal Leukocytes Stool Culture C. difficile toxin assays Stool for Ova and Parasites

17 Sending stool samples for ova and parasites is not cost effective for the majority of patients with acute diarrhea

18 Persistent diarrhea ( Giardia, Cryptosporidium& Entamoeba histolytica) Persistent diarrhea following travel to special region ( Giardia, Cryptosporidium& Cyclospora) Persistent diarrhea with exposure to infants in daycare centers ( Giardia & Cryptosporidium) Diarrha community waterborne outbreak (Giardia and Cryptosporidium) Bloody diarrhea with few or no fecal leukocytes (associated with intestinal amebiasis)

19 Rehydration -Oral Rehydration Solutions -Intravenous fluids Electrolyte Repletion and Nutrition -Monitor and replete electrolytes Continue diet (breastfeeding/formula)

20 Antidiarrheals -bismuth subsalicylate and loperamide - Generally safe in combination with antimicrobials (Adults) AVOID IN: - children, adults with severe bloody or inflammatory diarrhea, - severe colitis or C. difficile infection

21 Antimicrobials Due to risks of Abx therapy, awaiting culture results is best Empiric Treatment: Severe illness requiring hospitalization (esp. ICU) Moderate-severe traveler s diarrhea Elderly or immunocompromised hosts Suspected C. difficile colitis with severe disease Suspected shigellosis Persistent diarrhea with suspected Giardia

22 Small Intestinal: Viral: Calciviruses Rotavirus Enteric adenovirus

23 -Bacterial: ETEC, EPEC, EAEC Vibrio Cholera Listeria monocytogenes C. perfringens S. aureus

24 Parasites: Giardia lamblia Cryptosporidium Microsporidium Cyclospora Isospora

25 Viral: CMV Adenovirus

26 Bacterial: Salmonella Shigella Campylobacter EHEC, EIEC C. difficile

27 Bacterial Yersinia Non-cholera vibrios C. perfringens

28 Parasites: E. histolytica Balantidium coli Blastocystis hominis

29 65yo M admitted with 5 days of diarrhea, bloody the last 2 days. He is stable overnight with IVF, and is afebrile.

30 A)Yersinia B)Toxigenic E. coli C)Norwalk-like virus (Norovirus) D)C. difficile E)E. coli O157:H7 (STEC)

31 E)E. coli O157:H7 (STEC)

32 Over 400 serotypes, only 10 cause disease. Majority is O157 strains. STEC produces Stx1 and Stx2 Sx: * Biphasic diarrhea : watery then bloody absent or low-grade fever

33 Complications: TTP/HUS (5-10%) Dx: Stool Cx Stool may lack fecal leukocytes Tx: Supportive.

34 Four species: S. dysenteriae most common worldwide Humans are only natural host Highly contagious <100 organisms Sx: Biphasic 2 day prodrome of constitutional sx sand secretory(watery) diarrhea Dysentery, fever, abd cramps, tenesmus

35 Complications intestinal perforation, toxic megacolon, dehydration and metabolic derangements, sepsis, HUS/TTP, Reactive arthritis Dx: Stool Cx Tx: - ORT/IVF -cipro 500 mg BD 3d / Azithro 500 daily 3d

36 1)GE (NTS): Transmission: Contaminated foods (raw meat, eggs, fresh produce, milk) Sx: N/V then cramps & diarrhea Complications (5-10%) Bacteremia, meningitis, endovascular lesions Risk Factors: Hemoglobinopathies, corticosteroids, IBD, immunosuppression, achlorhydria and extremes of age

37 Dx: stool cx, get sensitivities! Tx: Supportive care ABx: age <3 mo, older than 50 years, IC, cardiac valvular or endovascular abnormality, significant joint dis. Ciprofloxacin, TMP-SMX, amoxicillin

38 2)Enteric fever ( Typhoid ): Fever, abd pain, constipation DX: isolation of salmonella from blood, BM, & another site TX: -Azithromycin (1 g once, then 500 mg daily) 7 d -IV: third generation cephalosporin or FQ 10 d or 5 d after resolution of fever

39 Chronic carrier state persistance of salmonella in stool or urine for more than 12 months after acute infection TX: -High dose ampicillin/amoxicillin 4 to 6 g daily with probenecid 2 g daily for 3 mo -TMP-SMX 800/160 mg twice daily for 3 mo -Ciprofloxacin 750 mg twice daily for 28 days

40 Most common cause of diarrhea worldwide. U.S. C. jejuni most common Transmission: contaminated food (poultry, eggs, milk), water or fecal-oral spread Sx: cramping, nausea, anorexia and watery or bloody diarrhea. Resolves within a week. Mimics appendicitis

41 Complications Post-infectious IBS, reactive arthritis, Guillain-Barré syndrome Dx: Stool Cx Tx: Mild-moderate: Supportive Severe or >1 week: Macrolides (FQs can be used, but increasing resistant strains)

42 74yo F w/ DM2 presents w/ 2 weeks of watery diarrhea; passing 6-8 stools/day and occasional nocturnal diarrhea. +Nausea. No vomiting, bloody stools or fever. Recently switched from metformin to insulin. 6 weeks ago completed a course of ciprofloxacin for UTI. On exam, VSS, abd with mild nonspecific tenderness. Studies notable for + fecal leukocytes and negative C. difficiletoxin by ELISA.

43 A)Initiate treatment with loperamide to symptom control B)Prescribe prednisone 40mg daily C)Prescribe metronidazole 500mg TID for 10 days D)Prescribe vancomycin 125mg QID for 10 days E)Send 2 additional stool samples for C. difficile toxin testing

44 Send 2 additional stool samples for C. difficiletoxin testing

45 Both Nosocomi & Community-acquired Pathogenesis: enterotoxina and cytotoxin B Sx: watery (rarely bloody) diarrhea, lower abd cramping, fever Severe Disease: severe pain, abd distension, hypovolemia, lactic acidosis, and marked leukocytosis(wbc>15) Predictors of Mortality: WBC >35 or <4, bandemia(>10%), age>70, immunosuppressionand cardiorespiratory failure

46 Dx: Who? Hospitalized, institutionalized, recent ABx, and now community-acquired. Depends on your facility: C.diff Ag with confirmatory toxin A and/or B by EIA or PCR If clinical suspicion is high, treat anyway

47 Treatment: Discontinuation of offending antibiotic (if possible) AVOID antidiarrheals Mild-Moderate: Metronidazole 500mg PO TID x days Severe: Vancomycin 125mg PO QID x days

48 Rice-watery stool(up to 20L of fluids lost per day) High infectious dose Marked dehydration Projectile vomiting No fever or abdominal pain Muscle cramps Hypovolemic shock

49 Treatment: -Azithromycin 1 g SD -Ciprofloxacin 500 mg BD 3 days -Doxycycline 300 mg SD

50 Most common cause of infectious diarrhea in the U.S. Sx: Dehydrating diarrhea, vomiting, +/-fever Typically resolves within a few days Etiology: Pediatrics: Rotavirus and Noroviruses Adults: Noroviruses

51 Dx: Based on symptoms Tx: Supportive

52 General suggestions on how to reduce the risk of gastroenteritis include: Wash hands thoroughly with soap and water after going to the toilet or changing nappies, after smoking, after using a handkerchief or tissue, or after handling animals Wash your hands thoroughly with soap and water before preparing food or eating

53 Use disposable paper towels to dry your hands rather than cloth towels, since the bacteria can survive for some time on objects. Keep cold food cold (below 5 C) Make sure foods are thoroughly cooked

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55 Infectious diarrhea is a major cause of morbidity and mortality worldwide. Not everyone needs a workup. Viral gastroenteritis is the most common cause of infectious diarrhea in the U.S.

56 When in doubt, it is best to wait for stool cultures before treatment Avoid ABx therapy in STEC and Salmonella Check frequently updated sources for antimicrobial sensitivities

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