Acute diarrheal diseases
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Transcript of Acute diarrheal diseases
ACUTE DIARRHEAL DISEASES
INTRO
• leading cause of illness globally
• 4.6 billion episodes worldwide per year
• ranks second to LRI as the most common infectious cause of death worldwide
• contributes to malnutrition and thereby reduces resistance to other infectious agents - indirect factor in a far greater burden of disease
• wide variety of infectious agents involved, including viruses, bacteria, and parasitic pathogens
PATHOGENIC MECHANISMS
TOXIN PRODUCTION
• Enterotoxins - cause watery diarrhea by acting directly on secretory mechanisms in the intestinal mucosa. cholera toxin, heat-labile enterotoxin, heat-stable enterotoxin
• Cytotoxins - cause destruction of mucosal cells and associated inflammatory diarrhea
• Neurotoxins - act directly on the central or peripheral nervous system - produced by bacteria outside the host and therefore cause symptoms soon after ingestion - staphylococcal and Bacillus cereus toxins
INVASION
• Dysentery - from bacterial invasion and destruction of intestinal mucosal cells
• Shigella and enteroinvasive E. coli - invasion of mucosal epithelial cells, intraepithelial multiplication, and subsequent spread to adjacent cells
• Salmonella - inflammatory diarrhea by invasion of the bowel mucosa but generally is not associated with the destruction of enterocytes
• Salmonella typhi and Yersinia enterocolitica - penetrate intact intestinal mucosa, multiply intracellularly in peyer's patches and intestinal lymph nodes, and then disseminate through the bloodstream to cause enteric fever
GASTROINTESTINAL PATHOGENS CAUSING ACUTE DIARRHEA
NONINFLAMMATORY (ENTEROTOXIN)
• Vibrio Cholerae, ETE.Coli, EAE. Coli, Clostridium Perfringens, Bacillus Cereus, Staphylococcus Aureus
• Rotavirus, Norovirus, Enteric Adenoviruses
• Giardia Lamblia, Cryptosporidium Spp
• Proximal small bowel
• Watery diarrhea
• Stool - no fecal leukocytes; mild or no increase in fecal lactoferrin
INFLAMMATORY (INVASION OR CYTOTOXIN)
• Shigella Spp., Salmonella Spp., Campylobacter Jejuni, Enterohemorrhagic E. Coli, Enteroinvasive E. Coli, Yersinia Enterocolitica, Listeria Monocytogenes, Vibrio Parahaemolyticus, Clostridium Difficile
• Entamoeba Histolytica
• Colon or distal small bowel
• Dysentery or inflammatory diarrhea
• Stool - Fecal polymorphonuclear leukocytes; substantial increase in fecal lactoferrin
PENETRATING
• Salmonella Typhi, Y. Enterocolitica
• Enteric fever
• Stool - Fecal mononuclear leukocytes
TRAVELER'S DIARRHEA
• Most common travel-related infectious illness
• time of onset is usually 3 days to 2 weeks after the traveler's arrival in a resource-poor area
• most cases begin within the first 3–5 days
• generally self-limited, lasting 1–5 days
• related to the ingestion of contaminated food or water
• enterotoxigenic and enteroaggregative strains of E. coli are the most common
BACTERIAL FOOD POISONING
• Bacterial disease caused by an enterotoxin elaborated outside the host - staphylococcus aureus or b. cereus, has the shortest incubation period (1–6 h) and generally lasts <12h
• staphylococcal food poisoning - caused by contamination from infected human carriers
• B. cereus - syndrome with a short incubation period—the emetic form, mediated by a staphylococcal type of enterotoxin—or one with a longer incubation period (8–16 h)—the diarrheal form, caused by an enterotoxin resembling E. coli LT
• emetic form - contaminated fried rice
• Clostridium perfringens - slightly longer incubation period (8–14 h) , results from the survival of heat-resistant spores in inadequately cooked meat, poultry, or legumes
APPROACH TO THE PATIENT: INFECTIOUS DIARRHEA OR BACTERIAL
FOOD POISONING
PHYSICAL EXAMINATION
• Signs of dehydration - provides essential information about the severity of the diarrheal illness and the need for rapid therapy
• Mild dehydration - by thirst, dry mouth, decreased axillary sweat, decreased urine output, and slight weight loss
• Moderate dehydration - orthostatic fall in blood pressure, skin tenting, and sunken eyes
• Severe dehydration - lethargy, obtundation, feeble pulse, hypotension, and frank shock
LABORATORY EVALUATION
• Noninflammatory diarrhea - self-limited or can be treated empirically, no need to determine a specific etiology
• Cholera - stool should be cultured on selective media such as thiosulfate–citrate–bile salts–sucrose (TCBS) or tellurite-taurocholate-gelatin (TTG) agar
• rotavirus - latex agglutination test
• patients with fever and evidence of inflammatory disease - stool cultured for Salmonella, Shigella, and Campylobacter
DIAGNOSTIC APPROACH
TREATMENT
• Mainstay of treatment is adequate rehydration - oral rehydration solution
• glucose-facilitated absorption of sodium and water in the small intestine remains intact in the presence of toxin
• World Health Organization recommended a "reduced-osmolarity/reduced-salt" ORS that is better tolerated and more effective
• 2.6 g of sodium chloride, 2.9 g of trisodium citrate, 1.5 g of potassium chloride, and 13.5 g of glucose (or 27 g of sucrose) per liter of water
• severely dehydrated or in whom vomiting precludes the use of oral therapy - IV solutions such as Ringer's lactate
PROPHYLAXIS
• IMPROVEMENTS IN HYGIENE TO LIMIT FECAL-ORAL SPREAD OF ENTERIC PATHOGENS
• ROTAVIRUS VACCINE
• VACCINES AGAINST S. TYPHI AND V. CHOLERAE ARE ALSO AVAILABLE
TREATMENT OF TRAVELER'S DIARRHEA
• loperamide: 4 mg initially followed by 2 mg after passage of each unformed stool, not to exceed 8 tablets (16 mg) per day
• Loperamide should not be used by patients with fever or dysentery; its use may prolong diarrhea in patients with infection due to Shigella or other invasive organisms
• fluoroquinolone such as ciprofloxacin, 750 mg as a single dose or 500 mg bid for 3 days; levofloxacin, 500 mg as a single dose or 500 mg qd for 3 days; or norfloxacin, 800 mg as a single dose or 400 mg bid for 3 days
• Azithromycin, 1000 mg as a single dose or 500 mg qd for 3 days
• Rifaximin, 200 mg tid or 400 mg bid for 3 days