Updated: Mar 19, 2012
Laboratory Studies
- Gram staining and Loeffler methylene blue staining of the stool for WBCs help to differentiate invasive disease from noninvasive disease.
- Perform microscopic examination of the stool for ova and parasites.
- Bacterial culture for enteric pathogens, such as Salmonella, Shigella, and Campylobacter organisms, becomes mandatory if a stool sample shows positive results for WBCs or blood or if patients have fever or symptoms persisting for longer than 3-4 days.
- Perform blood culture if the patient is notably febrile.
- CBC with differential, serum electrolyte assessment, and BUN and creatinine levels help to assess the inflammatory response and the degree of dehydration.
- Assay for C difficile to help rule out antibiotic-associated diarrhea in patients receiving antibiotics or in those with a history of recent antibiotic use.
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Imaging Studies
- Flat and upright abdominal radiographs should be obtained if the patient experiences bloating, severe pain, or obstructive symptoms or if perforation is suggested.
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Other Tests
- When a stool examination is nondiagnostic, performing sigmoidoscopy/colonoscopy with biopsy and esophagogastroduodenoscopy (EGD) with duodenal aspirate and biopsy may be beneficial. This is especially important in patients who are immunocompromised.
- Consider sigmoidoscopy in patients with bloody diarrhea. It can be useful in diagnosing inflammatory bowel disease, antibiotic-associated diarrhea, shigellosis, and amebic dysentery.
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Proceed to Treatment & Management
References
Logan NA. Summer Meeting 2011: Bacillus and relatives in food-borne illness. J Appl Microbiol. Nov 28 2011;[Medline].
Lee JH, Shin H, Son B, Ryu S. Complete Genome Sequence of Bacillus cereus Bacteriophage BCP78. J Virol. Jan 2012;86(1):637-8. [Medline].
Hughes JM, Angulo FJ. Food borne diseases. In: Hurst JW, ed. Medicine for the Practicing Physician. 4th ed. Appleton & Lange: Stamford, Conn; 1996:344-7.
Smith JL. Foodborne illness in the elderly. J Food Prot. Sep 1998;61(9):1229-39. [Medline].
Goulet V, Hebert M, Hedberg C, Laurent E, Vaillant V, De Valk H, et al. Incidence of Listeriosis and Related Mortality Among Groups at Risk of Acquiring Listeriosis. Clin Infect Dis. Dec 14 2011;[Medline].
Preliminary FoodNet Data on the incidence of infection with pathogens transmitted commonly through food--10 States, 2008. MMWR Morb Mortal Wkly Rep. Apr 10 2009;58(13):333-7. [Medline]. [Full Text].
Surveillance for foodborne disease outbreaks - United States, 2006. MMWR Morb Mortal Wkly Rep. Jun 12 2009;58(22):609-15. [Medline]. [Full Text].
CDC research shows outbreaks linked to imported foods increasing. Available at http://www.cdc.gov/media/releases/2012/p0314_foodborne.html. Accessed March 14, 2012.
Jacobs RA. General problems in infectious diseases: acute infectious diarrhea. In: Tierney LM Jr, McPhee SJ, Papadakis MA, eds. Current Medical Diagnosis and Treatment 2001. 40th ed. New York, NY: McGraw-Hill; 2000:1215-6.
Xerry J, Gallimore CI, Iturriza-Gómara M, Gray JJ. Tracking the transmission routes of genogroup II noroviruses in suspected food-borne or environmental outbreaks of gastroenteritis through sequence analysis of the P2 domain. J Med Virol. Jul 2009;81(7):1298-304. [Medline].
Malek M, Barzilay E, Kramer A, Camp B, Jaykus LA, Escudero-Abarca B, et al. Outbreak of norovirus infection among river rafters associated with packaged delicatessen meat, Grand Canyon, 2005. Clin Infect Dis. Jan 1 2009;48(1):31-7. [Medline].
Atmar RL, Bernstein DI, Harro CD, Al-Ibrahim MS, Chen WH, Ferreira J, et al. Norovirus vaccine against experimental human Norwalk Virus illness. N Engl J Med. Dec 8 2011;365(23):2178-87. [Medline].
Archer DL. Incidence and cost of foodborne diarrheal disease in the United States. J Food Prot. 1985;48:887-94.
Butterton JR, Calderwood SB. Acute infectious diarrheal diseases and bacterial food poisoning. In: Braunwald E, Fauci AS, Kasper DL, Hauser SL, Longo DL, Jameson JL, eds. Harrison's Principles of Internal Medicine. 15th ed. New York, NY: McGraw-Hill; 2001:834-9.
Gianella RA. Infectious enteritis and proctocolitis and bacterial food poisoning. In: Sleisenger and Fordtran's Gastrointestinal and Liver Disease. Vol 2. 2006:2333-91.
Sherman PM, Wine E. Emerging intestinal infections. Gastroenterology & Hepatology Annual Review. 2006;1:50-54. [Full Text].
Table 1. Examples of Large Food-Borne Disease Outbreaks[9]
| Country | Year | Disease | Number of Cases |
| United Kingdom | 1985 | Salmonellosis | 1000 |
| United States | 1985 | Salmonellosis | >168,000 |
| United States | 1993 | Salmonellosis | 224,000 |
| China | 1988 | Hepatitis A | >310,000 |
| Germany | 1993 | Salmonellosis | 1000 |
| Australia | 1991 | Norwalk-like agent | >3050 |
| United States | 1992-1993 | E coli O157 infection | >500 |
| Japan | 1996 | E coli O157 infection | >6000 |
Table 2. Causes of Food Poisoning
| Causative Agents | Source and Clinical Features | Pathogenesis | Diagnosis and Treatment |
| Staphylococci | Improperly stored foods with high salt or sugar content favor growth of staphylococci Intense vomiting and watery diarrhea start 1-4 hours after ingestion and last as long as 24-48 hours. | Enterotoxin acts on receptors in gut that transmit impulses to medullary centers. | Symptomatic treatment |
| B cereus | Contaminated fried rice (emetic) Meatballs (diarrheal) Emetic: Duration is 9 hours, vomiting and cramps Diarrheal: Lasts for 24 h Mainly vomiting after 1-6 hours and mainly diarrhea after 8-16 hours after ingestion; lasts as long as 1 day | Emetic enterotoxin (short incubation and duration) - Poorly understood Diarrheal enterotoxin (long incubation and duration) - Increasing intestinal secretion by activation of adenylate cyclase in intestinal epithelium | Symptomatic treatment |
| C perfringens | Inadequately cooked meat, poultry, or legumes Acute onset of abdominal cramps with diarrhea starts 8-24 hours after ingestion. Vomiting is rare. It lasts less than 1 day. Enteritis necroticans associated with C perfringens type C in improperly cooked pork (40% mortality) | Enterotoxin produced in the gut, and food causes hypersecretion in the small intestine. | Culture of clostridia in food and stool Symptomatic treatment |
| C botulinum | Canned foods (eg, smoked fish, mushrooms, vegetables, honey) Descending weakness and paralysis start 1-4 days after ingestion, followed by constipation. Mortality is very high. | Toxin absorbed from the gut blocks the release of acetylcholine in the neuromuscular junction. | Toxin present in food, serum, and stool. Respiratory support Intravenous trivalent antitoxin from CDC |
| Listeria monocytogenes | Raw and pasteurized milk, soft cheeses, raw vegetables, shrimp Systemic disease associated with bacteremia Intestinal symptoms precede systemic disease Can seed meninges, heart valves, and other organs Highest mortality among bacterial food poisonings | Highly motile, heat-resistant, gram-positive organism | CSF or blood culture Must treat with antibiotics if bacteremic |
| Enterotoxic E coli (eg, traveler's diarrhea) | Contaminated water and food (eg, salad, cheese, meat) Acute-onset watery diarrhea starts 24-48 hours after ingestion. Concomitant vomiting and abdominal cramps may be present. It lasts for 1-2 days | Enterotoxin causes hypersecretion in small and large intestine via guanylate cyclase activation. | Supportive treatment No antibiotics |
| Enterohemorrhagic E coli (eg, E coli O157:H7) | Improperly cooked hamburger meat and previously spinach Most common isolate pathogen in bloody diarrhea starts 3-4 days after ingestion. Usually progresses from watery to bloody diarrhea. It lasts for 3-8 days May be complicated by HUS or TTP | Cytotoxin results in endothelial damage and leads to platelet aggregation and microvascular fibrin thrombi | Diagnosis with stool culture Supportive treatment No antibiotics |
| Enteroinvasive E coli | Contaminated imported cheese Usually watery diarrhea (some may present with dysentery) | Enterotoxin produces secretion Shiga-like toxin facilitates invasion. | Supportive treatment No antibiotics |
| Enteroaggregative E coli | Implicated in traveler's diarrhea in developing countries Can cause bloody diarrhea | Bacteria clump on the cell surfaces | Ciprofloxacin may shorten duration and eradicate the organism |
| V cholera | Contaminated water and food Large amount of nonbloody diarrhea starts 8-24 hours after ingestion. It lasts for 3-5 days. | Enterotoxin causes hypersecretion in small intestine. Infective dose usually is 107 -109 organisms. | Positive stool culture Prompt replacement of fluids and electrolytes (oral rehydration solution) Tetracycline (or fluoroquinolones) shortens the duration of symptoms and excretion of Vibrio. |
| V parahaemolyticus | Raw and improperly cooked seafood (ie, mollusks and crustaceans) Explosive watery diarrhea starts 8-24 hours after ingestion. It lasts for 3-5 days. | Enterotoxin causes hypersecretion in small intestine. Hemolytic toxin is lethal. Infective dose usually is 107 -109 organisms. | Positive stool culture Prompt replacement of fluids and electrolytes Sensitive to tetracycline, but unclear role for antibiotics |
| V vulnificus | Wound infection in salt water or consumption of raw oysters Can be lethal in patients with liver disease (50% mortality) | Polysaccharide capsule Growth correlates with availability of iron (esp. transferrin saturation >70%) | Culture of characteristic bullous lesions or blood Immediate antibiotics if suspected (eg, doxycycline and ceftriaxone) |
| C jejuni | Domestic animals, cattle, chickens Fecal-oral transmission in humans Foul-smelling watery diarrhea followed by bloody diarrhea Abdominal pain and fever also may be present. It starts 1-3 days after exposure and recovery is in 5-8 days. | Uncertain about endotoxin production and invasion | Culture in special media at 42°C Erythromycin for invasive disease (fever) |
| Shigella | Potato, egg salad, lettuce, vegetables, milk, ice cream, and water Abrupt onset of bloody diarrhea, cramps, tenesmus, and fever starts 12-30 hours after ingestion. Usually self-limited in 3-7 days | Organisms invade epithelial cells and produce toxins. Infective dose is 102 -103 organisms. Enterotoxin-mediated diarrhea followed by invasion (dysentery/colitis) | Polymorphonuclear leukocytes (PMNs), blood, and mucus in stool Positive stool culture Oral rehydration is mainstay. Trimethoprim-sulfamethoxazole (TMP-SMX) or ampicillin for severe cases No opiates |
| Salmonella | Beef, poultry, eggs, and diary products Abrupt onset of moderate-to-large amount of diarrhea with low-grade fever; in some cases, bloody diarrhea Abdominal pain and vomiting also present, beginning 6-48 hours after exposure and lasts 7-12 days | Invasion but no toxin production | Positive stool culture Antibiotic for systemic infection |
| Yersinia | Pets; transmission in humans by fecal-oral route or contaminated milk or ice cream Acute abdominal pain, diarrhea, and fever (enterocolitis) Incubation period not known Polyarthritis and erythema nodosum in children May mimic appendicitis | Gastroenteritis and mesenteric adenitis Direct invasion and enterotoxin | PMNs and blood in stool Positive stool culture No evidence that antibiotics alter the course but may be used in severe infections |
| Aeromonas | Untreated well or spring water Diarrhea may be bloody. May be chronic up to 42 days in the United States | Enterotoxin, hemolysin, and cytotoxin | Positive stool culture Fluoroquinolones or TMP/SMX for chronic diarrhea |
| Parasitic Food Poisoning | Source and Clinical Features | Pathogenesis | Diagnosis and Treatment |
| E histolytica | Contaminated food and water 90% asymptomatic 10% dysentery Minority may develop liver abscesses | Invasion of the mucosa by the parasites | Criterion standard is colonoscopy with biopsy Ova and parasites may be seen in the stool but has low sensitivity Luminal amebicides (eg, paromomycin) Tissue amebicides (eg, metronidazole) |
| G lamblia | Contaminated ground water Fecal-oral transmission in humans Mild bloody diarrhea with nausea and abdominal cramps starts 2-3 days after ingestion; lasts for 1 week May become chronic | Unknown Highest concentration in the distal duodenum and proximal jejunum | Initial diagnostic test is stool ELISA Duodenal aspiration or small bowel biopsy Cyst in the stool Metronidazole |
| Seafood/Shellfish Poisoning | Source and Clinical Features | Pathogenesis | Diagnosis and Treatment |
| Paralytic shellfish poisoning | Temperate costal areas Source - Bivalve mollusks Onset usually is 30-60 minutes. Initial symptoms include perioral and intraoral paresthesia. Other symptoms include paresthesia of the extremities, headache, ataxia, vertigo, cranial nerve palsies, and paralysis of respiratory muscles, resulting in respiratory arrest. | Fish acquires toxin-producing dinoflagellates | General observation for 4-6 hours Maintain patent airway. Administer oxygen, and assist ventilation if necessary. For recent ingestion, charcoal 50-60 g may be helpful. |
| Neurotoxic shellfish poisoning | Coastal Florida Source - Mollusks Illness is milder than in paralytic shellfish poisoning. | Fish acquires toxin-producing dinoflagellates | Symptomatic |
| Ciguatera | Hawaii, Florida, and Caribbean Source - Carnivorous reef fish Vomiting, diarrhea, and cramps start 1-6 hours after ingestion and last from days to months. Diarrhea may be accompanied by a variety of neurologic symptoms including paresthesia, reversal of hot and cold sensation, vertigo, headache, and autonomic disturbances such as hypotension and bradycardia. Chronic symptoms (eg, fatigue, headache) may be aggravated by caffeine or alcohol | Fish acquires toxin-producing dinoflagellates Toxin increases intestinal secretion by changing intracellular calcium concentration | Symptomatic Anecdotal reports of successful treatment of neurologic symptoms with mannitol 1 g/kg IV |
| Tetrodotoxin poisoning | Japan Source - Puffer fish Onset of symptoms usually is 30-40 minutes but may be as short as 10 minutes. It includes lethargy, paresthesia, emesis, ataxia, weakness, and dysphagia. Ascending paralysis occurs in severe cases. Mortality is high. | Neurotoxin is concentrated in the skin and viscera of puffer fish. | Symptomatic |
| Scombroid | Source - Tuna, mahi-mahi, kingfish Allergic symptoms such as skin flush, urticaria, bronchospasm, and hypotension usually start within 15-90 minutes. | Improper preservation of large fish results in bacterial degradation of histidine to histamine. | Antihistamines (diphenhydramine 25-50 mg IV) H2 blockers (cimetidine 300 mg IV) Severe reactions may require subcutaneous epinephrine (0.3-0.5 mL of 1:1000 solution). |
| Heavy Metal Poisoning | Source | Symptoms | Treatment |
| Mercury | Ingestion of inorganic mercuric salts | Causes metallic taste, salivation, thirst, discoloration and edema of oral mucous membranes, abdominal pain, vomiting, bloody diarrhea, and acute renal failure | Consult a toxicologist. Remove ingested salts by emesis and lavage, and administer activated charcoal and a cathartic. Dimercaprol is useful in acute ingestion. |
| Lead | Toxicity results from chronic repeated exposure. It is rare after single ingestion. | Common symptoms include colicky abdominal pain, constipation, headache, and irritability. Diagnosis is based on lead level (>10 mcg/dL) | Other than activated charcoal and cathartic, severe toxicity should be treated with antidotes (edetate calcium disodium [EDTA] and dimercaprol). |
| Arsenic | Ingestion of pesticide and industrial chemicals | Symptoms usually appear within 1 hour after ingestion but may be delayed as long as 12 hours. Abdominal pain, watery diarrhea, vomiting, skeletal muscle cramps, profound dehydration, and shock may occur. | Gastric lavage and activated charcoal Dimercaprol injection 10% solution in oil (3-5 mg/kg IM q4-6h for 2 d) and oral penicillamine (100 mg/kg/d divided qid for 1 wk) |
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