INTRODUCTION

Section 2 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

Background

Food poisoning is defined as an illness caused by the consumption of food or water contaminated with bacteria and/or their toxins, parasites, viruses, or chemicals. The symptoms, varying in degree and combination, include abdominal pain, vomiting, diarrhea, and headache; more serious cases can result in life-threatening neurologic, hepatic, and renal syndromes leading to permanent disability or death.

Most of the illnesses are mild and improve without any specific treatment. Some patients have severe disease and require hospitalization, aggressive hydration, and antibiotic treatment.

A food-borne disease outbreak is defined by the following 2 criteria:

1. Similar illness, often gastrointestinal, in a minimum of 2 people
2. Evidence of food as the source

Pathophysiology

The pathogenesis of diarrhea in food poisoning is classified broadly into either noninflammatory or inflammatory types.

Noninflammatory diarrhea is caused by the action of enterotoxins on the secretory mechanisms of the mucosa of the small intestine, without invasion. This leads to large volume watery stools in the absence of blood, pus, or severe abdominal pain. Occasionally, profound dehydration may result. The enterotoxins may be either preformed before ingestion or produced in the gut after ingestion. Examples include Vibrio cholerae, enterotoxic Escherichia coli, Clostridium perfringens, Bacillus cereus, Staphylococcus organisms, Giardia lamblia, Cryptosporidium, rotavirus, Norwalk virus, and adenovirus.

Inflammatory diarrhea is caused by the action of cytotoxin on the mucosa, leading to invasion and destruction. The colon or the distal small bowel commonly is involved. The diarrhea usually is bloody; mucoid and leukocytes are present. Patients are usually febrile and may appear toxic. Dehydration is less likely than with noninflammatory diarrhea because of smaller stool volumes. Fecal leukocytes or a positive stool lactoferrin test indicates an inflammatory process, and sheets of leukocytes indicate colitis. Sometimes, the organisms penetrate the mucosa and proliferate in the local lymphatic tissue, followed by systemic dissemination. Examples include Campylobacter jejuni, Vibrio parahaemolyticus, enterohemorrhagic and enteroinvasive E coli, Yersinia enterocolitica, Clostridium difficile, Entamoeba histolytica, and Salmonella and Shigella species.

In some types of food poisoning (eg, staphylococci, B cereus), vomiting is caused by a toxin acting on the central nervous system. The clinical syndrome of botulism results from the inhibition of acetylcholine release in nerve endings by the botulinum.

The pathophysiological mechanisms that result in acute gastrointestinal symptoms produced by some of the noninfectious causes of food poisoning (naturally occurring substances [eg, mushrooms, toadstools] and heavy metals [eg, arsenic, mercury, lead]) are not well known.

Frequency

United States

Initially, food-borne diseases were estimated to be responsible for 6-8 million illnesses and as many as 9000 deaths each year.^{1, 2} However, the change in food supply, the identification of new food-borne diseases, and the availability of new surveillance data have changed the morbidity and mortality figures. A study from the US Centers for Disease Control and Prevention (CDC) reports that food-borne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5000 deaths in the United States each year. Identified pathogens account for an estimated 14 million illnesses, 60,000 hospitalizations, and 1800 deaths. Salmonella, Listeria, and Toxoplasma organisms are responsible for 1500 deaths. Unidentified pathogens account for the remaining 62 million illnesses, 265,000 hospitalizations, and 3200 deaths. Overall, food-borne diseases appear to cause more illnesses but fewer deaths than previously estimated.

International

Transnational trade; travel; and migration and globalization of food production, manufacturing, and marketing pose greater risk of cross-border transmission of infectious diseases and food-borne illness.³ A travel history should be obtained because traveler's diarrhea is the leading cause of travel-related illness. Onset occurs 3 days to 2 weeks after arrival. Illness is self-limiting within 5 days. Enterotoxigenic E coli is the most common isolate.

Table 1. Examples of Large Food-Borne Disease Outbreaks³

Mortality/Morbidity

Symptoms vary in degree and combination. They may include abdominal pain, vomiting, diarrhea, headache, and prostration. More serious cases can result in life-threatening neurologic, hepatic, and renal syndromes leading to permanent disability or death.

In children younger than 5 years, attacks range from 2-3 illnesses per child per year in developed countries; attacks are at least 5 times more common in developing countries. In underdeveloped countries, acute diarrheal diseases are responsible for 1 billion cases per year and 4-6 million deaths per year.

Age

Morbidity and mortality are higher in elderly individuals. The reasons for this increased susceptibility in elderly populations include age-associated decrease in immunity, decreased production of gastric acid and intestinal motility, malnutrition, lack of exercise, habitation in a nursing home, and excessive use of antibiotics. Elderly persons are more likely to die from infection with C perfringens; E coli O157; and Salmonella, Campylobacter, and Staphylococcus organisms.

CLINICAL

Section 3 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

History

A detailed history, including the duration of the disease, characteristics and frequency of bowel movements, and associated abdominal and systemic symptoms, may provide a clue to the underlying cause. The presence of a common source, types of specific food, travel history, and use of antibiotics always should be investigated.

The presenting complaints, typical features and pathogenesis of various causative agents, and diagnosis and treatment information can be found in Table 2 in the Causes section.

The following are some of the salient features of food poisoning:

• Acute diarrhea in food poisoning usually lasts less than 2 weeks. Diarrhea lasting 2-4 weeks is classified as persistent. Chronic diarrhea is defined by duration of more than 4 weeks.
• The presence of fever suggests an invasive disease. However, sometimes fever and diarrhea may result from infection outside the gastrointestinal tract, as in malaria.
• A stool with blood or mucus indicates invasion of the intestinal or colonic mucosa.
• When vomiting is the major presenting symptom, suspect Staphylococcus aureus, B cereus, or Norovirus.
• Reactive arthritis can be seen with Salmonella, Shigella, Campylobacter, and Yersinia infections.
• A profuse rice-water stool suggests cholera or a similar process.
• Abdominal pain is most severe in inflammatory processes. Painful abdominal muscle cramps suggest underlying electrolyte loss, as in severe cholera.
• A history of bloating should raise the suspicion of giardiasis.
• Yersinia enterocolitis may mimic the symptoms of appendicitis.
• Proctitis syndrome, seen with shigellosis, is characterized by frequent painful bowel movement containing blood, pus, and mucus. Tenesmus and rectal discomfort are prominent features.
• Consumption of undercooked meat/poultry is suspicious for Salmonella, Campylobacter, Shiga toxin E coli, and C perfringens.
• Consumption of raw seafood is suspicious for Norwalk-like virus, Vibrio organism, or hepatitis A.
• Consumption of homemade canned foods is associated with Clostridium botulinum.
• Consumption of unpasteurized soft cheeses is associated with Listeria, Salmonella, Campylobacter, Shiga toxin E coli, and Yersinia.
• Consumption of deli meats notoriously is responsible for listeriosis.
• Consumption of unpasteurized milk or juice is suspicious for Campylobacter, Salmonella, Shiga toxin E coli, and Yersinia.
• Salmonella has been associated with consumption of raw eggs.

Physical

The physical examination should focus on assessing the severity of dehydration.

• A dry mouth, decreased axillary sweat, and decreased urine output indicate mild dehydration, whereas orthostasis, tachycardia, and hypotension indicate more severe volume depletion.
• A rectal examination always should be performed to directly visualize the stool, to test occult blood, and to palpate the rectal mucosa for any lesions.
• Rose spot macules on the upper abdomen and hepatosplenomegaly may be seen in Salmonella typhi infection.
• Erythema nodosum and exudative pharyngitis are suggestive of Yersinia infection.
• Patients with Vibrio vulnificus or Vibrio alginolyticus may present with cellulitis and otitis media.

Causes

The CDC estimates that 97% of all cases of food poisoning result from improper food handling; 79% of cases result from food prepared in commercial or institutional establishments and 21% of cases result from food prepared at home.

The most common causes are as follows: (1) leaving prepared food at temperatures that allow bacterial growth, (2) inadequate cooking or reheating, (3) cross-contamination, and (4) infection in food handlers. Cross-contamination may occur when raw contaminated food comes in contact with other foods, especially cooked foods, through direct contact or indirect contact on food preparation surfaces.

Bacteria are responsible for approximately 75% of the outbreaks of food poisoning and for 80% of the cases with a known cause in the United States.¹ As many as 1 in 10 Americans has diarrhea due to food-borne infection each year.

Table 2. Causes of Food Poisoning

WORKUP

Section 4 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

Lab 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.

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.

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.

TREATMENT

Section 5 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

Medical Care

Because most cases of acute gastroenteritis are self-limited, specific treatment is not necessary. Some studies have quantified that only 10% of cases require antibiotic therapy.

• The main objective is adequate rehydration and electrolyte supplementation. This can be achieved with either an oral rehydration solution (ORS) or intravenous solutions (eg, isotonic sodium chloride solution, lactated Ringer solution). Strict personal hygiene should be practiced during the illness.  
• • Oral rehydration is achieved by administering clear liquids and sodium-containing and glucose-containing solutions. A simple ORS may be composed of 1 level teaspoon of salt and 4 heaping teaspoons of sugar added to 1 liter of water.
  • The use of ORS has reduced the mortality rate associated with cholera from higher than 50% to less than 1%.
  • ORS also is indicated in other dehydrating diarrheal diseases.
  • ORS promotes cotransport of glucose, sodium, and water across the gut epithelium, a mechanism unaffected in cholera.
  • The World Health Organization (WHO) recommends a solution containing 3.5 g of sodium chloride, 2.5 g of sodium bicarbonate, 1.5 g of potassium chloride, and 20 g of glucose per liter of water.
• Intravenous solutions are indicated in patients who are severely dehydrated or who have intractable vomiting.
• Absorbents (eg, Kaopectate, aluminum hydroxide) help patients have more control over the timing of defecation. However, they do not alter the course of the disease or reduce fluid loss.  
• • An interval of at least 1-2 hours should elapse when using other medications with absorbents.
  • Antisecretory agents, such as bismuth subsalicylate (Pepto-Bismol), may be useful. The dose is 30 mL every 30 minutes, not to exceed 8-10 doses.
  • Antiperistaltics (opiate derivatives) should not be used in patients with fever, systemic toxicity, or bloody diarrhea or in patients whose condition either shows no improvement or deteriorates.
  • Diphenoxylate with atropine (Lomotil) is available in tablets (2.5 mg of diphenoxylate) and liquid (2.5 mg of diphenoxylate/5 mL). The initial dose for adults is 2 tablets 4 times a day (ie, 20 mg/d). The dose is tapered as diarrhea improves.
  • Loperamide (Imodium) is available over the counter as 2-mg capsules and as a liquid (1 mg/5 mL). It increases the intestinal absorption of electrolytes and water and decreases intestinal motility and secretion. The dose in adults is 4 mg initially, followed by 2 mg after each diarrhea stool, not to exceed 16 mg in a 24-hour period.
• If symptoms persist beyond 3-4 days, the specific etiology should be determined by performing stool cultures.
• If symptoms persist and the pathogen is isolated, specific treatment should be initiated.
• Empiric treatment should be initiated in patients with suspected traveler's diarrhea or dysenteric or systemic symptoms. Treatment with an agent that covers Shigella and Campylobacter organisms is reasonable in patients with diarrhea (>4 stools/d) for more than 3 days and with fever, abdominal pain, vomiting, headache, or myalgias. A 5-day course of a fluoroquinolone (eg, ciprofloxacin 500 mg PO bid, norfloxacin 400 mg PO bid) is the first-line therapy.
• TMP/SMX (Bactrim DS 1 tab qd) is an alternative therapy, but resistant organisms are common in the tropics. Infection with either V cholerae or V parahaemolyticus can be treated either with a fluoroquinolone or with doxycycline (100 mg PO bid).
• In the absence of dysentery, do not administer antibiotics until a microbiologic diagnosis is confirmed and E coli O157:H7 is ruled out.

Diet

During episodes of acute diarrhea, patients often develop an acquired disaccharidase deficiency due to washout of the brush-border enzymes. For this reason, avoiding milk, dairy products, and other lactose-containing foods is advisable.

MEDICATION

Section 6 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Drug Category: Rehydration solutions

The main objective is adequate rehydration and electrolyte supplementation. This can be achieved with ORS or intravenous solutions (eg, isotonic sodium chloride solution, lactated Ringer solution).

Drug Name	Oral electrolyte mixtures (Rehydralyte, Pedialyte)
Description	Acts by glucose-facilitated absorption of sodium and water, which is unaffected in diseases such as cholera. Oral rehydration is achieved using clear liquids and sodium-containing and glucose-containing solutions. WHO recommends a solution containing 3.5 g of sodium chloride, 2.5 g sodium bicarbonate, 1.5 g potassium chloride, and 20 g glucose per liter of water. A simple solution may be made using 1 level tsp salt and 4 heaping tsp sugar added to 1 L water.
Adult Dose	Depends on severity of dehydration; should be given until adequately resuscitated and able to take PO fluids
Pediatric Dose	Administer as in adults
Contraindications	Intractable vomiting or diarrhea; prolonged shock; anuria; oliguria
Interactions	None reported
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Critical fluid losses require IV therapy

Drug Category: Antidiarrheals

Adsorbents (eg, attapulgite, aluminum hydroxide) help patients have more control over the timing of defecation but do not alter the course of the disease or reduce fluid loss. Antisecretory agents (eg, bismuth subsalicylate) may be useful. Antiperistaltics (opiate derivatives) should not be used in patients with fever, systemic toxicity, bloody diarrhea, or in patients whose condition either shows no improvement or deteriorates.

Drug Name	Aluminum hydroxide (Amphojel, Dialume, ALternaGEL)
Description	Commonly used as an antacid. Adsorbent and protectant that controls diarrhea.
Adult Dose	15-45 mL/dose PO q3-6h or 1 and 3 h pc and hs
Pediatric Dose	5-15 mL/dose PO q3-6h or 1 and 3 h pc and hs
Contraindications	Documented hypersensitivity
Interactions	Decreases effects of tetracyclines, ranitidine, ketoconazole, benzodiazepines, penicillamine, phenothiazines, digoxin, indomethacin, and isoniazid; corticosteroids decrease effects of aluminum in hyperphosphatemia
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Caution in patients with recent massive upper GI hemorrhage; renal failure may cause aluminum toxicity; should be interval of at least 1-2 h when using other medications with adsorbents

Drug Name	Bismuth subsalicylate (Pepto-Bismol)
Description	Antisecretory agent that also may have antimicrobial and anti-inflammatory effects.
Adult Dose	2 tab or 30 mL PO q30min; not to exceed 8 doses/24 h
Pediatric Dose	3-6 years: One third of tab or 5 mL PO q30min to 1 h prn 6-9 years: Two thirds of tab or 10 mL PO q30min to 1 h prn 9-12 years: 1 tab or 15 mL PO q30min to 1 h prn Not to exceed 8 doses/24 h
Contraindications	Documented hypersensitivity
Interactions	Coadministration with anticoagulants may increase risk of bleeding; may increase toxicity of aspirin and hypoglycemics; decreases effects of tetracyclines and uricosurics
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	May cause temporary and harmless darkening of tongue and/or black stool; alcohol consumption may cause abdominal cramps, nausea, and vomiting

Drug Name	Diphenoxylate and atropine (Lomotil, Lonox)
Description	Drug combination that consists of diphenoxylate, which is a constipating meperidine congener, and atropine to discourage abuse. Inhibits excessive GI propulsion and motility. Available in tabs (2.5 mg diphenoxylate) and liquid (2.5 mg diphenoxylate/5 mL).
Adult Dose	5-20 mg/d of diphenoxylate PO tid/qid Maintenance dose: 5-15 PO mg/d
Pediatric Dose	<2 years: Not recommended 2-5 years: 2 mg of diphenoxylate PO tid 5-8 years: 2 mg of diphenoxylate PO qid 8-12 years: 2 mg of diphenoxylate PO 5 times/d >12 years: Administer as in adults
Contraindications	Documented hypersensitivity; narrow-angle glaucoma; hepatic insufficiency
Interactions	May delay metabolism of drugs in liver; CNS depressants, MAOIs, and antimuscarinic agents may increase toxicity
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	In young children, dehydration may influence variability of response and predispose patients to delayed diphenoxylate intoxication; caution in patients with ulcerative colitis; decrease in intestinal motility may be detrimental to patients with diarrhea resulting from Shigella or Salmonella organisms and toxigenic strains of E coli

Drug Name	Loperamide (Imodium)
Description	Acts on intestinal muscles to inhibit peristalsis and slow intestinal motility. Prolongs movement of electrolytes and fluid through bowel and increases viscosity and loss of fluids and electrolytes. Available over the counter in 2-mg capsules and liquid (1 mg/5 mL).
Adult Dose	4 mg PO initially, then 2 mg after each loose stool; not to exceed 16 mg/d
Pediatric Dose	Initial doses 2-6 years: 1 mg PO tid 6-8 years: 2 mg PO bid 8-12 years: 2 mg PO tid Maintenance 0.1 mg/kg PO after each loose stool, not to exceed initial dose Chronic diarrhea 0.08-0.24 mg/kg/d PO divided bid/tid; not to exceed 2 mg/dose
Contraindications	Documented hypersensitivity; diarrhea resulting from infections; pseudomembranous colitis
Interactions	Phenothiazines, tricyclic antidepressants, and CNS depressants may increase toxicity
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Discontinue if no clinical improvement in 48 h; because loperamide primarily is metabolized in the liver, monitor for CNS toxicity in patients with hepatic insufficiency; do not use if high fever or blood in stool coincides with diarrhea

Drug Category: Antibiotics

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting. Antibiotic selection should be guided by blood culture sensitivity.

Drug Name	Norfloxacin (Noroxin)
Description	Fluoroquinolone with activity against pseudomonads, streptococci, MRSA, S epidermidis, and most gram-negative organisms, but no activity against anaerobes. Inhibits bacterial DNA synthesis, and, consequently, growth.
Adult Dose	400 mg PO bid for 3 d; not to exceed 800 mg/d
Pediatric Dose	<18 years: Not recommended >18 years: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after taking fluoroquinolones; cimetidine may interfere with metabolism of fluoroquinolones; reduces therapeutic effects of phenytoin; probenecid may increase serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, and digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	In prolonged therapy, perform periodic evaluations of organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in patients with renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy

Drug Name	Trimethoprim and sulfamethoxazole (Bactrim DS, Septra DS)
Description	Alternative therapy, but resistant organisms are common in the tropics. Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid.
Adult Dose	160 mg TMP/800 mg SMX PO qd for 3 d
Pediatric Dose	<2 months: Do not administer >2 months: 6-10 mg TMP/kg/d PO divided q12h
Contraindications	Documented hypersensitivity; megaloblastic anemia due to folate deficiency
Interactions	May increase PT when used with warfarin (perform coagulation tests and adjust dose accordingly); coadministration with dapsone may increase blood levels of both drugs; coadministration of diuretics increases incidence of thrombocytopenia purpura in elderly persons; phenytoin levels may increase with coadministration; may potentiate effects of methotrexate in bone marrow depression; hypoglycemic response to sulfonylureas may increase with coadministration; may increase levels of zidovudine
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Discontinue at first appearance of skin rash or sign of adverse reaction; obtain CBC counts frequently; discontinue therapy if significant hematologic changes occur; goiter, diuresis, and hypoglycemia may occur with sulfonamides; prolonged IV infusions or high doses may cause bone marrow depression (if signs occur, give 5-15 mg/d leucovorin); caution in folate deficiency (eg, persons with long-term alcoholism, elderly persons, those receiving anticonvulsant therapy, or those with malabsorption syndrome); hemolysis may occur in individuals who are G-6-PD deficient; patients with AIDS may not tolerate or respond to TMP/SMZ; caution in patients with renal or hepatic impairment (perform urinalyses and renal function tests during therapy); give fluids to prevent crystalluria and stone formation

Drug Name	Doxycycline (Doryx, Vibramycin, Vibra-Tabs)
Description	For V cholerae or V parahaemolyticus infections. Inhibits protein synthesis and thus bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria.
Adult Dose	200 mg PO/IV immediately and 100 mg hs, followed by 100 mg bid for 3 d Alternatively, 100-200 mg PO bid for 14 d
Pediatric Dose	<8 years: Not recommended >8 years: 2-5 mg/kg/d PO/IV qd or divided bid; not to exceed 200 mg/d
Contraindications	Documented hypersensitivity; severe hepatic dysfunction
Interactions	Bioavailability decreases with antacids containing aluminum, calcium, magnesium, iron, or bismuth subsalicylate; tetracyclines can increase hypoprothrombinemic effects of anticoagulants; tetracyclines can decrease effects of oral contraceptives, causing breakthrough bleeding and increased risk of pregnancy
Pregnancy	D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions	Photosensitivity may occur with prolonged exposure to sunlight or tanning equipment; reduce dose in patients with renal impairment; consider drug serum level determinations in prolonged therapy; tetracycline use during tooth development (last half of pregnancy through 8 y) can cause permanent discoloration of teeth; Fanconilike syndrome may occur with outdated tetracyclines

Drug Name	Rifaximin (Xifaxan, RedActiv, Flonorm)
Description	Nonabsorbed (<0.4%), broad-spectrum antibiotic specific for enteric pathogens of the gastrointestinal tract (ie, gram-positive, gram-negative, aerobic, anaerobic). Rifampin structural analog. Binds to beta-subunit of bacterial DNA-dependent RNA polymerase, thereby inhibiting RNA synthesis. Indicated for E coli (enterotoxigenic and enteroaggregative strains) associated with travelers' diarrhea.
Adult Dose	200 mg PO tid
Pediatric Dose	<12 years: Not established >12 years: Administer as in adults
Contraindications	Documented hypersensitivity to rifaximin or rifamycin antimicrobial agents (eg, rifampin)
Interactions	Induces CYP450 3A4 in vitro; limited data exist; no significant interactions shown in single-dose studies with midazolam and oral contraceptives
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	May promote intestinal bacterial overgrowth and cause superinfection; discontinue if diarrhea persists >24-48 h or worsens; seek immediate medical care if fever and/or bloody stools emerge (tablets not effective); not effective for travelers' diarrhea due to suspected pathogens other than E coli; postmarketing reports include allergic dermatitis, rash, angioneurotic edema, urticaria, and pruritus

FOLLOW-UP

Section 7 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

Further Outpatient Care

• Because most cases of food poisoning are self-limited, prolonged follow-up care is not required.
• Stool cultures should be monitored in individuals working in hospitals, food establishments, and daycare centers and who are infected with E coli O157:H7 or Salmonella or Shigella organisms until they become culture-negative without antibiotics. These people should not return to work until that time.

Deterrence/Prevention

• Food poisoning caused by infectious agents is prevented by the following:  
• • Strict personal hygiene
  • Adequate cooking
  • Avoidance of cross-contamination of raw and cooked foods
  • Keeping food at appropriate temperatures (ie, <40°F for refrigerated items and >140°F for hot items)
• Proper maintenance of vending machines and avoidance of acidic beverages in metallic containers prevent heavy metal poisoning.
• Avoiding eating wild mushrooms prevents mushroom poisoning.
• Prevention of fish poisoning requires avoidance of large tropical fish (ciguatera poisoning) and compliance with seasonal or emergency quarantines of shellfish harvesting areas (shellfish poisoning).
• Raw or undercooked milk, poultry, eggs, meat, and seafood are best avoided.
• Local health authorities should be notified if an outbreak of food poisoning occurs. This leads to appropriate actions to prevent further spread of food poisoning.
• Irradiation of food (ie, the use of ionizing radiation or ionizing energy to treat foods, either packaged or in bulk form) can eliminate food-borne pathogens.  
• • Annually, more than half a million tons of food is now irradiated worldwide.
  • Treating raw meat and poultry with irradiation at the slaughter plant could eliminate bacteria, such as E coli O157:H7 and Salmonella