eMedicine Specialties > Gastroenterology > Colon

Gastroenteritis, Bacterial

Jennifer Lynn Bonheur, MD, Attending Physician, Division of Gastroenterology, Lenox Hill Hospital
Mukul Arya, MD, Associate Professor of Internal Medicine, Assistant Director of Therapeutic Endoscopy, Department of Gastroenterology and Internal Medicine, Wyckoff Heights Medical Center/Weill Medical College; Richard E Frye, MD, PhD, Assistant Professor, Departments of Pediatrics and Neurology, University of Texas Health Science Center at Houston; M Akram Tamer, MD, Program Director, Professor, Department of Pediatrics, University of Miami

Updated: Feb 19, 2009

Introduction

Background

Bacterial gastroenteritis is a very common disorder. It has many causes, can range from mild to severe, and usually manifests with symptoms of vomiting, diarrhea, and abdominal discomfort. Other causes of some of these symptoms include viral infections, improper diet, malabsorption syndromes, various enteropathies, and inflammatory bowel disease. Bacterial gastroenteritis is usually self-limited, but improper management of an acute infection can lead to a protracted course. By far, the most common complication is dehydration.^1,2,3,4

For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center and Public Health Center. Also, see eMedicine's patient education articles Gastroenteritis and Foreign Travel.

Pathophysiology

Bacteria employ several mechanisms to invoke a pathologic response. Invasive bacteria cause mucosal ulceration and abscess formation with a subsequent inflammatory cascade. Bacterial toxins control enteral and extraenteral cellular processes. For example, the heat-labile and heat-stable enterotoxins of Escherichia coli activate enteral adenylate cyclase and guanylate cyclase.
 
Verotoxin, which enterohemorrhagic E coli and Shigella species produce, causes systemic disorders such as seizures and hemolytic-uremic syndrome (HUS). Other noninvasive bacteria adhere to the gut wall, causing inflammation. Organisms such as E coli and Clostridium species are normal enteric flora, pathogenic strains of which can cause gastroenteritis.

Frequency

United States

Bacterial gastroenteritis is a very common problem in primary care and emergency department settings, especially for children younger than 5 years.^3,4 Diarrhea accounts for as many as 5% of pediatric office visits and 10% of hospitalizations in this age group. Very often, gastroenteritis is underreported in the adult population.

Each year, gastroenteritis affects adults and accounts for 8 million doctor visits and 250,000 hospitalizations. Episodes of gastroenteritis do not occur at random but usually occur in outbreaks. Traveler's diarrhea affects 20-50% of people traveling from industrialized to developing countries.^4,5,6

International

Worldwide, millions of children and adults are affected by diarrhea each year. In developing countries, where sanitation is suboptimal, epidemics of bacterial gastroenteritis can develop and cause significant mortality.^2,4,5,6,7

Mortality/Morbidity

Diarrhea and vomiting are so commonplace that nonphysicians usually underappreciate the potential mortality and morbidity of bacterial gastroenteritis. In the United States each year, several hundred people die from complications of bacterial gastroenteritis; the majority are elderly people.

Many developing countries do not have the resources to properly treat diarrhea and vomiting associated with bacterial gastroenteritis, leading to a disproportionately high mortality rate. Gastroenteritis-causing pathogens are the second leading cause of morbidity and mortality worldwide.

Race

It has been reported that the preparation and ingestion of chitterlings, common among some blacks, especially during the holiday season, may pose an increased risk of infection with Yersinia enterocolitica serotype O:3.^8,9

Sex

Most infectious diarrheas do not affect one sex more than the other; however, females have a higher incidence of Campylobacter infections and hemolytic-uremic syndrome (HUS).

Age

Yersinia species infect children younger than 1 year almost exclusively, and Aeromonas species are a significant cause of bacterial gastroenteritis in young children. Very young children are particularly susceptible to secondary dehydration and malabsorption.

Clinical

History

• Stool characteristics
  • Diarrhea is defined as daily stools with a mass greater than 15 g/kg for children younger than 2 years and greater than 200 g for children aged 2 years and older. Adult stool patterns vary from 1 stool every 3 days to 3 stools per day; therefore, consider individual stool patterns.
  • Consistency, color, volume, and frequency are very important in determining whether the stool source is from the small or large bowel. Below, Table 1 outlines these characteristics and demonstrates that an index of suspicion can be generated easily for a specific set of organisms.

Table 1. Stool Characteristics and Determining Their Source

HPF = high-power field; WBC = white blood cell.

• Associated systemic symptoms can guide empiric therapy. Some enteric infections have characteristic systemic symptoms, whereas the associated systemic features of others do not occur reliably. Below, Table 2 outlines the frequency of these symptoms with various organisms.
• Symptom onset and duration characteristics can narrow the differential diagnosis of the organism (see Differential Diagnoses). The onset of symptoms within 6 hours of exposure to the bacterial source indicates a preformed toxin, probably produced by Staphylococcus or Bacillus species. Table 2 outlines the incubation and duration characteristics of common bacteria.

Table 2. Organisms and Frequency of Symptoms

• Particular foods are associated with certain bacteria. Ingestion of raw or contaminated food, particularly raw milk and meat, is a common cause of bacterial gastroenteritis. The following list outlines organisms that cause food poisoning:
  • Dairy -Campylobacter, Salmonella, Listeria, and Staphylococcus species
  • Eggs -Salmonella species
  • Meats -C perfringens and Salmonella, Aeromonas, Campylobacter, and Staphylococcus species
  • Ground beef - Enterohemorrhagic E coli
  • Poultry -Campylobacter species
  • Pork -C perfringens and Y enterocolitica
  • Seafood -Aeromonas, Plesiomonas, and Vibrio species and astrovirus
  • Oysters -Plesiomonas and Vibrio species and calicivirus
  • Vegetables -Aeromonas species and C perfringens
  • Alfalfa sprouts - Enterohemorrhagic E coli and Salmonella species
  • Fried rice -Bacillus species
  • Custards, mayonnaise -Staphylococcus species
• Water is a major reservoir for many organisms that cause diarrhea. Swimming pools have been associated with outbreaks of Shigella organisms, and Aeromonas species are associated with exposure to the marine environment.
• Travel history is an important and useful clue in determining bacterial etiology. Enterotoxigenic E coli is the leading cause of traveler's diarrhea. Rotavirus and Shigella, Salmonella, and Campylobacter species are prevalent worldwide and need to be considered, regardless of specific travel history.Other organisms that are prevalent in particular parts of the world are listed below. The risk of contracting diarrhea while traveling is highest in travel to Africa. Travel to Portugal, Spain, and Eastern European countries is also associated with a relatively high risk. Organisms associated with travel to particular locations are as follows:
  • Nonspecific - Enterotoxigenic E coli and Aeromonas, Giardia, Plesiomonas, Salmonella, and Shigella species
  • Underdeveloped tropics -C perfringens
  • Africa -Entamoeba species and V cholerae
  • Americas (South and Central) -Entamoeba species and V cholerae
  • Asia -V cholerae
  • Australia -Yersinia species
  • Canada -Yersinia species
  • Europe -Yersinia species
  • India -Entamoeba species and V cholerae
  • Japan -Vibrio parahaemolyticus
  • Mexico -Aeromonas, Entamoeba, Plesiomonas, and Yersinia species
  • New Guinea -Clostridium species
• Animals can transmit particular bacteria. Exposure to young dogs or cats is associated with Campylobacter transmission. Exposure to turtles is associated with Salmonella transmission.
• Preexisting medical conditions can predispose for infections with particular organisms. The following list outlines such medical conditions and their associated organisms:
  • C difficile - Hospitalization with antibiotic administration
  • Plesiomonas species - Liver diseases or malignancy
  • Salmonella species - Intestinal dysmotility, malnutrition, achlorhydria, hemolytic anemia (especially sickle cell disease), immunosuppression, and malaria
  • Rotavirus - Hospitalization
  • Giardia species -Agammaglobulinemia, chronic pancreatitis, achlorhydria, and cystic fibrosis
  • Cryptosporidia - Immunocompromise and immunosuppression
• Outbreaks are caused by particular bacteria, including enterohemorrhagic E coli O157:H7, Listeria monocytogenes, C perfringens, and Salmonella species.

Physical

• Dehydration is the primary cause of morbidity and mortality in cases of gastroenteritis. Assess every patient for signs, symptoms, and severity of dehydration. Lethargy, depressed consciousness, dry mucous membranes, sunken eyes, poor skin turgor, and delayed capillary refill should raise the suspicion of dehydration.
• Malnutrition is typically a sign of a chronic process. Reduced muscle and fat mass is found. This is usually due to development of secondary carbohydrate intolerance.
• Abdominal pain is a common symptom in gastroenteritis. Nonspecific, nonfocal abdominal pain and cramping are common with some organisms. This pain usually does not increase with palpation. Focal abdominal pain worsened by palpation, rebound tenderness, or guarding should alert the clinician to possible complications or to another noninfectious gastrointestinal diagnosis.
• Borborygmi, defined as a significant increase in peristaltic activity with small bowel diarrhea, can cause an audible and/or palpable increase in bowel activity.
• Perianal erythema results from many stools causing a constantly wet area. Failure to properly dry the buttocks and perianal area results in erythema and skin breakdown.

Causes

• Salmonella, Shigella, and Campylobacter species are the top 3 leading causes of bacterial diarrhea worldwide, followed closely by Aeromonas species.
• Aeromonas and Shigella infection have a higher incidence in summer and fall, and Campylobacter infection usually occurs in summer months.
• Yersinia infection occurs most frequently in winter months and colder climates.

Differential Diagnoses

Workup

Laboratory Studies

• A stool pH of 5.5 or below or the presence of reducing substances indicates carbohydrate intolerance. This is usually transient in nature.
• Enteroinvasive infections of the large bowel cause leukocytes, predominantly neutrophils, to be shed into stool. Absence of fecal leukocytes does not eliminate the possibility of enteroinvasive organisms; however, the presence of fecal leukocytes eliminates consideration of enterotoxigenic E coli, Vibrio species, and viruses.
• Examine any exudate found in the stool for leukocytes. Such exudates highly suggest inflammatory bowel disease, which could be infectious or of another origin.
• Below, Table 3 lists common bacteria and the optimal culture media for their growth.

Table 3. Common Bacteria and Optimum Culture Media

CCFE = cycloserine-cefoxitin-fructose-egg; CIN = cefsulodin-irgasan-novobiocin; EIA= enzyme immunoassay; EMB = e-methylene blue; GNB = gram-negative bacillus; GNR = gram-negative rod; GPB = gram-positive bacillus; GPC = gram-positive cocci; GPR = gram-positive rod; H2S = hydrogen sulfide; HE = Hektoen enteric; LA = latex agglutination; SM = Sorbitol-MacConkey; TCBS = thiosulfate-citrate-bile-sucrose; XLD = xylose-lysine-deoxycholate.

• The following is a list of the different culture media used to isolate bacteria. A high index of suspicion is needed to choose the appropriate medium.
  • Blood agar - All aerobic bacteria and yeast; detects cytochrome oxidase production
  • MacConkey EMB agar - Inhibits gram-positive organisms; permits lactose fermentation
  • XLD agar and HE agar - Inhibit gram-positive organisms and nonpathogenic gram-negative bacilli; permit lactose fermentation and H2S production
  • Skirrow agar - Selective for Campylobacter species
  • SM agar - Selective for enterohemorrhagic E coli
  • CIN agar - Selective for Y enterocolitica
  • Thiosulfate-citrate-bile-sucrose agar - Selective for Vibrio species
  • CCFE agar - Selective for C difficile
• Stool cultures are useful when positive, but the yield is usually low.
  • Refrigerate stool that is not cultured within 2 hours of collection at 4°C, or place it in a transport medium.
  • Always culture stool for Campylobacter, Salmonella, and Shigella species, especially if stool leukocytes or gross blood is found in the stool.
• Serotype Salmonella for S typhimurium DT104, particularly if the gastroenteritis is associated with raw milk or cheese ingestion. S typhimurium DT104 is a multidrug-resistant organism, and antibiotic sensitivities are crucial to guide therapy.^10,11
• Preformed toxin from Bacillus or Staphylococcus species may cause rapid-onset gastroenteritis. In such cases, the bacteria may not exist in the gastrointestinal tract; therefore, culture the food ingested by the person.
• Bloody diarrhea with a history of ground beef ingestion should raise the suspicion for enterohemorrhagic E coli. If E coli is found in the stool, type it to determine if it is O157:H7. Report cases of E coli O157:E7 gastroenteritis (and other infectious problems) to the state health department.
• History of raw seafood ingestion or foreign travel should prompt additional screening for Vibrio and Plesiomonas species.
• The leukocyte count is usually not elevated in viral and toxin-mediated diarrhea. Leukocytosis is seen with enteroinvasive bacteria. Shigella characteristically causes marked bandemia with variable total WBC count.
• Antilisteriolysin O (ALLO) is positive during the convalescent phase of the illness and when invasive disease has occurred.

Procedures

• Identification of pseudomembranes in the colon by direct visualization is diagnostic for C difficile; however, the yield may be low.

Treatment

Medical Care

Because most infectious diarrhea is self-limited, medical care is primarily supportive in nature. Oral rehydration is the mainstay of treatment. Young infants and neonates are at high risk for secondary complications and require close monitoring, as do older individuals. Consider intravenous rehydration when oral rehydration is unsuccessful. Particular attention must be paid to repletion of potassium as needed.

• Oral rehydration therapy is the cornerstone of diarrhea treatment, especially for small bowel infections that produce a large volume of watery stool output. Studies confirm that early refeeding hastens recovery. Many commercial oral rehydration formulas are available and have been designed to promote optimal absorption of nutrients. Administer maintenance fluids plus replacement of losses to ill children. Administer small amounts of fluid at frequent intervals in order to minimize discomfort and vomiting. A 5- or 10-cc syringe without a needle is a very useful tool. The syringe can be used to place small amounts of fluid in the mouth quickly. Once the patient becomes better hydrated, cooperation improves enough for the patient to take small sips from a cup. This method is time intensive and requires dedication. Encouragement from the physician is necessary to promote compliance.
• Antimicrobial therapy is indicated for some bacterial gastroenteritis infections. However, many conditions are self-limited and do not require therapy. The following is a list of standard therapies:
  • Aeromonas species - Use cefixime and most third-generation and fourth-generation cephalosporins.
  • Bacillus species - No antibiotics are necessary for self-limited gastroenteritis, but vancomycin and clindamycin are first-line drugs for severe disease.
  • Campylobacter species - Erythromycin may shorten illness duration and shedding. Delaying therapy beyond 4 days from onset of symptoms appears to produce no clinical benefit.
  • C difficile - Discontinue potential causative antibiotics. If antibiotics cannot be stopped or this does not resolve diarrhea, use oral metronidazole or vancomycin. Vancomycin is reserved for seriously ill patients whose condition does not respond to metronidazole.
  • C perfringens - Do not treat with antibiotics.
  • E coli - Antibiotic treatment appears to increase the likelihood of HUS developing. Consider antibiotics if diarrhea is moderate or severe. Trimethoprim-sulfamethoxazole is a first-line drug, but use a parenteral second-generation or third-generation cephalosporin for systemic complications.
  • Listeria species - No antibiotics are needed unless invasive disease occurs. Ampicillin and Bactrim are first-line drugs for invasive disease.
  • Plesiomonas species - Use trimethoprim-sulfamethoxazole or any cephalosporin.
  • Salmonella species - Antibiotic treatment prolongs the carrier state and is associated with relapse; thus, treatment is not indicated for nontyphoid, uncomplicated diarrhea. Consider treatment for infants younger than 3 months and for high-risk patients, such as patients who are immunocompromised or who have sickle cell disease. Ampicillin is recommended for drug-sensitive strains. Trimethoprim-sulfamethoxazole, fluoroquinolones, or third-generation cephalosporins (fluoroquinolones are not recommended for use in children) are also acceptable alternatives. S typhimurium T104 is a multidrug-resistant organism. Sensitivities from the cultured specimens are important to guide therapy.
  • Shigella species - Antibiotic treatment may shorten illness duration and shedding but does not prevent complications. Most mild infections will recover without antibiotics. Moderate to severe cases should be treated with antibiotics. Ampicillin is preferred for drug-sensitive strains. For ampicillin resistant strains or in cases of penicillin allergy, trimethoprim-sulfamethoxazole is the drug of choice, although resistance does occur. Fluoroquinolones may be considered in patients with highly resistant organisms.
  • Vibrio cholerae - Tetracycline is the usual antibiotic of choice, but resistance to it is increasing. Other antibiotics that are effective when V cholerae are sensitive to them include cotrimoxazole, erythromycin, doxycycline, chloramphenicol, and furazolidone.
  • Yersinia species - Treatment (ie, trimethoprim-sulfamethoxazole, fluoroquinolones, aminoglycosides) does not shorten the disease duration and should be reserved for complicated cases.
• Antimotility agents are not indicated routinely for infectious diarrhea, (except for refractory cases of Cryptosporidium infection).
• Live Lactobacillus GG and heat-killed Lactobacillus LB reduce the duration of diarrhea in children when they are added to oral rehydration solution.^12,13

Consultations

• Certain organisms cause abdominal pain and bloody stools. Symptoms resembling appendicitis, hemorrhagic colitis, intussusception, or toxic megacolon may be appreciated. In such cases, obtain a consultation with a surgeon.
• Consider consultation with an infectious disease specialist, especially for any patient who is immunocompromised due to human immunodeficiency virus (HIV) infection, chemotherapy, or immunosuppressive drugs, because atypical organisms are more likely and complications can be more serious and can fulminate.

Diet

• The BRAT diet (ie, bananas, rice, applesauce, toast) has been recommended for years in cases of gastroenteritis. This diet is adequate during early convalescence, but, as the patient tolerates solid food, advance the diet to provide adequate protein and caloric intake.^14,15,16
• Introduce lean meats and clear fluids as soon as possible.¹⁴ Dairy products are said to be better absorbed when given with proteins or complex carbohydrates.
• When feeding lactose-containing dairy products, carefully monitor patient for signs of malabsorption.
• Breast milk contains many substances that promote bowel growth and antagonize bacteria; thus, continue breastfeeding throughout the illness for infants.

Medication

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

Antibiotics

Along with the immune system, antibiotics help destroy offending organisms.

Cefixime (Suprax)

Potent long-acting oral cephalosporin with increased gram-negative coverage.

Dosing

Adult

400 mg/d PO qd for 7-10 d

Pediatric

8 mg/kg/dose PO qd for 7-10 d

Interactions

Aminoglycosides increase nephrotoxic potential; probenecid may increase effects by decreasing clearance

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in patients with penicillin hypersensitivity; adjust dose in the presence of renal impairment; administer with food to minimize adverse GI effects (eg, nausea, diarrhea)

Ceftriaxone (Rocephin)

Third-generation parenteral antibiotic with wide coverage, including gram-negative bacilli. Arrests bacterial growth by binding to one or more penicillin-binding proteins.

Dosing

Adult

1-2 g IV/IM q24h for 7-10 d

Pediatric

50 mg/kg/dose IV/IM qd/bid for 7-10 d

Interactions

Probenecid may increase levels; coadministration with ethacrynic acid, furosemide, and aminoglycosides may increase nephrotoxicity.

Contraindications

Documented hypersensitivity; hyperbilirubinemic neonates

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in patients with penicillin hypersensitivity; common adverse drug reactions include skin rashes, diarrhea, and pain at the site of injection; adjust dose in the presence of renal impairment; caution in breastfeeding women

Cefotaxime (Claforan)

Third-generation parenteral antibiotic with wide coverage, including gram-negative bacilli. Arrests bacterial cell wall synthesis, which, in, turn inhibits bacterial growth.

Dosing

Adult

1-2 g IV/IM q6-8h for 7-10 d

Pediatric

50 mg/kg/d IV/IM tid for 7-10 d

Interactions

Probenecid may increase levels; coadministration with furosemide and aminoglycosides may increase nephrotoxicity.

Contraindications

Documented hypersensitivity to cefotaxime or cephalosporin antibiotics.

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in patients with penicillin hypersensitivity; skin rashes, thrombophlebitis, and GI upset (eg, nausea, vomiting, diarrhea) are the most common adverse drug reactions

Erythromycin (E.E.S., E-Mycin, Eryc, Ery-Tab)

Old bacteriostatic macrolide with activity against most gram-positive organisms and atypical respiratory organisms. Useful for Campylobacter and Vibrio enteritis. Nausea is a common adverse effect and may be tolerated poorly in some patients. Enteric-coated tablets reduce nausea.

Dosing

Adult

250-500 mg (base, stearate, estolate) PO qid

400-800 mg (ethylsuccinate) PO qid

Pediatric

50 mg/kg/d PO/IV qid for 7-10 d

Interactions

Coadministration may increase toxicity of theophylline, digoxin, carbamazepine, and cyclosporine; may potentiate anticoagulant effects of warfarin; coadministration with lovastatin and simvastatin increases risk of rhabdomyolysis

Contraindications

Documented hypersensitivity; hepatic impairment; concomitant administration of cisapride

Precautions

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

Nausea is a common adverse effect and may be tolerated poorly in some patients (enteric-coated tablets reduce nausea); caution in patients with liver disease; estolate formulation may cause cholestatic jaundice; adverse GI effects are common (give doses pc); discontinue use if nausea, vomiting, malaise, abdominal colic, or fever occur

Trimethoprim-sulfamethoxazole (Bactrim, Bactrim DS, Septra, Septra DS)

Folate synthesis blocker that has wide antibiotic coverage.

Dosing

Adult

160 mg, based on trimethoprim, PO bid for 7-10 d

Pediatric

10 mg/kg/d (trimethoprim) PO bid for 7-10 d

Interactions

May increase PT duration 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

Contraindications

Documented hypersensitivity; do not use in neonates, pregnant or lactating women, or persons with history of megaloblastic anemia; do not administer to infants <2 mo

Precautions

Pregnancy

X - Contraindicated; benefit does not outweigh risk

Precautions

Caution in the presence of renal or hepatic impairment; maintain adequate fluid intake to prevent crystalluria and stone formation; rash, sore throat, fever, arthralgia, cough, shortness of breath, pallor, purpura, or jaundice may be early indications of serious reactions; hemolysis occurs in individuals with G6PD deficiency

Vancomycin (Vancocin, Lyphocin)

Powerful treatment of antibiotic-associated colitis. Indicated for patients who cannot receive or whose conditions have not responded to penicillins and cephalosporins or have infections with resistant staphylococci.

To avoid toxicity, current recommendation is to assay trough levels after third dose drawn 0.5 h before next dosing. Use creatinine clearance to adjust the dose in patients diagnosed with renal impairment.

Used in conjunction with gentamicin for prophylaxis in patients allergic to penicillin who are undergoing GI or genitourinary procedures.

Dosing

Adult

500 mg PO qid for 10-14 d

Pediatric

25-50 mg/kg/d PO qid for 10-14 d

Interactions

Erythema, histaminelike flushing, and anaphylactic reactions may occur when administered with anesthetic agents; taken concurrently with aminoglycosides, risk of nephrotoxicity may increase above that with aminoglycoside monotherapy; effects in neuromuscular blockade may be enhanced when coadministered with nondepolarizing muscle relaxants

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

X - Contraindicated; benefit does not outweigh risk

Precautions

Caution in the presence of renal failure or neutropenia; red man syndrome is caused by IV infusion that is too rapid (dose given over a few min) but rarely happens when dose given as 2-h administration or PO or IP; red man syndrome is not an allergic reaction

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 analogue. 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.

Dosing

Adult

200 mg PO tid

Pediatric

<12 years: Not established

>12 years: Administer as in adults.

Interactions

Induces CYP450 3A4 in vitro; limited data exist; no significant interactions shown in single-dose studies with midazolam and oral contraceptives

Contraindications

Documented hypersensitivity to rifaximin or rifamycin antimicrobial agents (eg, rifampin)

Precautions

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

Further Inpatient Care

• Admit neonates or young infants with moderate dehydration, suspected infection with enterohemorrhagic E coli, or bloody diarrhea.
• Oral rehydration in cases of gastroenteritis is a time-consuming task that requires vigilance. Evaluate the caretaker of a child who requires oral rehydration for compliance. Consider admission if any doubt in potential compliance exists.
• Older patients, often with other illnesses, require careful observation and consideration for admission.

Further Outpatient Care

• Follow-up care in cases of bacterial gastroenteritis depends on the severity of the infection and the age of the patient.
  • Uncomplicated diarrhea may not require follow-up if the patient or caretaker is reliable and has adequate access to medical care if needed.
  • Monitor young children, elderly patients, and debilitated individuals closely to ensure complications do not occur.
  • Monitor patients requiring labor-intensive oral rehydration to ensure that the proper diet has been reintroduced.
  • Neonates require strict follow-up care within a few days of illness to ensure that malabsorption and dehydration do not occur.

Deterrence/Prevention

• Salmonella typhi vaccine is recommended for travelers to countries with a high incidence of this infection, persons with intimate exposure to a documented typhoid fever carrier, and workers with frequent exposure to these bacteria. Live attenuated, killed whole-cell, and capsular polysaccharide vaccines are available.
• Vibrio vaccine is available but only protects 50% of immunized persons for 3-6 months. It is not indicated for widespread use.
• In February 2006, the United States Food and Drug Administration (FDA) approved an oral vaccine for rotavirus (RotaTeq) for use in infants. It is currently the only vaccine approved in the United States for the prevention of rotavirus gastroenteritis as of the date of this publication. On February 21, 2006, the American Academy of Pediatrics (AAP) and the Advisory Committee on Immunization Practices (ACIP) recommended RotaTeq to be part of regularly scheduled childhood immunizations. RotaTeq is administered in a 3-dose series starting between age 6 to 12 weeks and completing before age 32 weeks.Clinical trials demonstrated prevention of 74% of all rotavirus gastroenteritis cases, of nearly all severe rotavirus gastroenteritis cases, and of nearly all hospitalizations. Previously marketed rotavirus vaccine (RotaShield) was associated with intussusception, but RotaTeq did not show an increased risk compared with placebo in clinical trials.
• In April 2008, the FDA approved Rotarix, another oral vaccine, for prevention of rotavirus gastroenteritis. Rotarix administration is currently recommended as 2 separate doses to patients between age 6 and 24 weeks. Rotarix was efficacious in a large study showing that it protected patients with severe rotavirus gastroenteritis as well as decreasing the rate of severe diarrhea or gastroenteritis of any cause.¹⁷
• Avoidance of undercooked meats and seafood, as well as contaminated water supplies, when traveling may help reduce the risk of transmission of food and water-borne infectious causes of gastroenteritis and associated symptoms.

Complications

• Common complications that can occur with various organisms in cases of bacterial gastroenteritis are as follows:
  • Aeromonas caviae - Intussusception, gram-negative sepsis, and HUS
  • Bacillus species - Fulminant liver failure (very rare) and rhabdomyolysis (very rare)
  • Campylobacter species - Bacteremia, meningitis, cholecystitis, urinary tract infection, pancreatitis, and Reiter syndrome
  • C difficile - Chronic diarrhea, toxic megacolon, and ileus
  • C perfringens serotype C - Enteritis necroticans
  • Enterohemorrhagic E coli - Hemorrhagic colitis
  • Enterohemorrhagic E coli O157:H7 - HUS
  • Listeria species - Bacteremia and meningitis
  • Plesiomonas species - Septicemia
  • Salmonella species - Enteric fever, bacteremia, meningitis, osteomyelitis, myocarditis, and Reiter syndrome
  • Shigella species - Seizures, HUS, perforation, and Reiter syndrome
  • Vibrio species - Rapid dehydration
  • Yersinia enterocolitica - Appendicitis, perforation, intussusception, peritonitis, toxic megacolon, cholangitis, bacteremia, and Reiter syndrome
• S typhi causes enteric fever. This syndrome has an insidious onset of malaise, fever, abdominal pain, and bradycardia. Diarrhea and rash (rose spots) appear after 1 week of symptoms. Bacteria may have disseminated at that time, and treatment is required to prevent systemic complications, such as hepatitis, myocarditis, cholecystitis, or gastrointestinal bleeding.
• Damage to vascular endothelial cells by verotoxin causes HUS. Thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure are characteristic of HUS. Symptoms usually develop 1 week after onset of diarrhea, when organisms may be absent.
• Reiter syndrome can complicate acute infections. Arthritis, urethritis, conjunctivitis, and mucocutaneous lesions are characteristic. Affected individuals usually do not demonstrate all features.
• Carrier states are observed after some bacterial gastroenteritis infections. After Salmonella diarrhea, 1-4% of individuals with nontyphoid and enteric fever infections become carriers. Carrier stage for Salmonella species is more likely to develop in females, infants, and individuals with biliary tract disease. Asymptomatic C difficile carriage may be seen in many hospitalized patients receiving antibiotics and in 50% of infants.
• Hyponatremic seizures can be avoided by rehydrating with oral rehydration solution instead of free water.
• A study suggested that infectious gastroenteritis may play a role in the initiation and/or exacerbation of inflammatory bowel disease.¹⁸ Similarly, irritable bowel syndrome may develop more often following bacterial gastroenteritis. This topic is highly controversial, and no conclusive evidence currently exists to support or refute this hypothesis.

Prognosis

• With proper management, prognosis is very good, especially in developed countries.
• Mortality predominantly is due to dehydration and secondary malnutrition from a protracted course. Treat severe dehydration with parenteral fluids.
• Once malnutrition from secondary malabsorption begins, prognosis becomes grim unless the patient is hospitalized and supplemental parenteral nutrition is started.
• Neonates and young infants are at particular risk for dehydration, malnutrition, and malabsorption syndromes.
• Even though the mortality rate is low in developed countries, people can, and do, die from complications. Prognosis in countries without modern medical care or for patients with serious preexisting medical conditions is more guarded.

Patient Education

• Education is most important for prevention and treatment of bacterial gastroenteritis.
• Proper oral rehydration therapy helps to prevent dehydration and speed recovery of the intestinal mucosa.
• Diet restrictions that prevent secondary malabsorption are extremely important; relapse typically occurs due to diet noncompliance.
• Emphasize proper hygiene and food preparation practices to caretakers in order to prevent future infections and spread of bacterial gastroenteritis.

Miscellaneous

Medicolegal Pitfalls

• Dehydration is the most common complication from gastroenteritis in the United States. Continuing losses without compensatory intake can result in severe dehydration. In high-risk populations, maintain close follow-up in order to ensure proper therapy is provided. For example, oral rehydration is a time-consuming task that requires vigilance. If the physician has any doubt concerning the compliance of the caretaker with proper rehydration therapy, consider admission to the hospital.
• Chronic diarrhea and carbohydrate malabsorption can develop with a prolonged bout of diarrhea, especially if dietary concerns are not sustained.
  • Although some claim that changes in dietary regimen are not necessary, improper diet can result in prolonged recovery or development of carbohydrate malabsorption, especially if the acute episode is overshadowed by an undiagnosed chronic bacterial or malabsorption syndrome.
  • Thus, a prolonged course of diarrhea should prompt investigation of complicating factors. Results from tests such as stool acidity and reducing substances can indicate carbohydrate malabsorption. Failure to recognize this complication can result in significant rapid weight loss with wasting of fat and muscle mass.

Special Concerns

• Studies have suggested that the use of acid-suppressing medications (proton pump inhibitors (PPIs) though not H2 receptor antagonists [H2RAs]) may increase the risk of developing gastroenteritis by reducing the acidic environment which serves as an initial defense against gastrointestinal infections. This effect has also been noted to be dose-dependent ( ie, increased dose of PPI therapy is associated with an increased risk of infection).
• PPI therapy has also been suggested to be an independent risk factor for the development and recurrence of C difficile colitis.¹⁹

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Keywords

bacterial gastroenteritis, gastroenteritis, diarrhea, traveler's diarrhea, acute gastroenteritis, viral infection, improper diet, malabsorption syndrome, enteropathy, inflammatory bowel disease, Salmonella, Shigella, Campylobacter, Aeromonas, Escherichia coli, E coli, vomiting

Contributor Information and Disclosures

Author

Jennifer Lynn Bonheur, MD, Attending Physician, Division of Gastroenterology, Lenox Hill Hospital
Jennifer Lynn Bonheur, MD is a member of the following medical societies: American Gastroenterological Association, American Society for Gastrointestinal Endoscopy, New York Academy of Sciences, New York Society for Gastrointestinal Endoscopy, and Sigma Xi
Disclosure: Nothing to disclose.

Coauthor(s)

Mukul Arya, MD, Associate Professor of Internal Medicine, Assistant Director of Therapeutic Endoscopy, Department of Gastroenterology and Internal Medicine, Wyckoff Heights Medical Center/Weill Medical College
Mukul Arya, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Medical Association, and American Society for Gastrointestinal Endoscopy
Disclosure: Nothing to disclose.

Richard E Frye, MD, PhD, Assistant Professor, Departments of Pediatrics and Neurology, University of Texas Health Science Center at Houston
Richard E Frye, MD, PhD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, Child Neurology Society, and International Neuropsychological Society
Disclosure: Nothing to disclose.

M Akram Tamer, MD, Program Director, Professor, Department of Pediatrics, University of Miami
M Akram Tamer, MD is a member of the following medical societies: American Medical Association and Florida Medical Association
Disclosure: Nothing to disclose.

Medical Editor

John Gunn Lee, MD, Director of Pancreaticobiliary Service, Associate Professor, Department of Internal Medicine, Division of Gastroenterology, University of California at Irvine School of Medicine
John Gunn Lee, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, and American Society for Gastrointestinal Endoscopy
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Simmy Bank, MD, Chair, Professor, Department of Internal Medicine, Division of Gastroenterology, Long Island Jewish Hospital, Albert Einstein College of Medicine
Disclosure: Nothing to disclose.

CME Editor

Alex J Mechaber, MD, FACP, Associate Dean for Undergraduate Medical Education, Associate Professor of Medicine, University of Miami Miller School of Medicine
Alex J Mechaber, MD, FACP is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians-American Society of Internal Medicine, and Society of General Internal Medicine
Disclosure: Nothing to disclose.

Chief Editor

Julian Katz, MD, Clinical Professor of Medicine, Drexel University College of Medicine; Consulting Staff, Department of Medicine, Section of Gastroenterology and Hepatology, Hospital of the Medical College of Pennsylvania
Julian Katz, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Geriatrics Society, American Medical Association, American Society for Gastrointestinal Endoscopy, American Society of Law Medicine and Ethics, American Trauma Society, Association of American Medical Colleges, and Physicians for Social Responsibility
Disclosure: Nothing to disclose.

Related eMedicine topics

• Campylobacter Infections
• Escherichia Coli Infections
• Gastroenteritis, Viral
• Pediatrics, Rotavirus
• Salmonella Infection
• Shigellosis
• Travel Medicine and Vaccination

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