Medication Summary
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
Rehydration solutions
Class Summary
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).
Lactated Ringer solution with NS
Both fluids are essentially isotonic and have equivalent volume-restorative properties. While some differences exist between metabolic changes observed with administration of large quantities of either fluid, for practical purposes and in most situations, differences are clinically irrelevant. No demonstrable difference exists in hemodynamic effect, morbidity, or mortality between resuscitation using either NS or LR.
Oral electrolyte mixtures (Rehydralyte, Pedialyte)
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.
Antidiarrheals
Class Summary
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.
Attapulgite (Kaopectate, Diasorb)
Adsorbent and protectant that controls diarrhea.
Aluminum hydroxide (Amphojel, Dialume, ALternaGEL)
Commonly used as an antacid. Adsorbent and protectant that controls diarrhea.
Bismuth subsalicylate (Pepto-Bismol)
Antisecretory agent that also may have antimicrobial and anti-inflammatory effects.
Diphenoxylate and atropine (Lomotil, Lonox)
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).
Loperamide (Imodium)
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).
Antibiotics
Class Summary
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.
Ciprofloxacin (Cipro)
First-line therapy. Fluoroquinolone with activity against pseudomonads, streptococci, MRSA, Staphylococcus epidermidis, and most gram-negative organisms, but no activity against anaerobes. Inhibits bacterial DNA synthesis, and, consequently, growth.
Norfloxacin (Noroxin)
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.
Trimethoprim/sulfamethoxazole (Bactrim DS, Septra DS)
Alternative therapy, but resistant organisms are common in the tropics. Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid.
Doxycycline (Doryx, Vibramycin, Vibra-Tabs)
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.
Rifaximin (Xifaxan, RedActiv, Flonorm)
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.
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| 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 |
| 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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