AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

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

INTRODUCTION

Section 2 of 10  

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

Background

Salmonella, Shigella, Yersinia, and Campylobacter species and pathogenic Escherichia coli account for about 10-15% of the diarrheal illnesses of children presenting to the emergency department. In the United States, Salmonella is the most common cause of bacterial gastroenteritis. In most cases, Salmonella is a self-limiting disease causing mild gastroenteritis; however, it can lead to a wide spectrum of complications including bacteremia, severe local infections, enterocolitis, and enteric fever.

Pathophysiology

Salmonella organisms are gram-negative bacilli in the family Enterobacteriaceae. Differences in lipopolysaccharide (LPS) and flagellar structure generate the antigenic variation that is reflected in the more than 2,000 known serotypes. The principal reservoirs for nontyphoidal Salmonella organisms are poultry, livestock, reptiles, and pets. The mode of transmission is ingestion of foods of animal origin, including poultry, red meats, unpasteurized milk, and eggs that have been contaminated by infected animals or an infected human. Contact with infected reptiles, such as iguanas, pet turtles, and tortoises, and ingestion of contaminated water are other modes of transmission.

Salmonella typhi is the species known to cause enteric fever (typhoid fever). S typhi is found only in humans. In the United States, typhoid fever is usually caused by foreign travel to countries with contaminated food and drinking water or by ingestion of food contaminated by a chronic carrier.

Once ingested, Salmonella can gain access to the small intestine. If large enough numbers of bacteria are ingested, they can survive in the normally lethal acidic pH of the stomach. Salmonella enterica typhimurium interacts with the physiologic receptor for epidermal growth factor to co-opt the receptor's signal transduction mechanisms and penetrate the mucosal barrier.

Frequency

United States

More than 50,000 culture-confirmed cases of Salmonella gastroenteritis occur per year. Approximately 400 cases of typhoid fever are reported per year. More than two thirds of cases are acquired from foreign travel. From 1985-1994, travel to Mexico and India accounted for most cases of typhoid fever.

International

Typhoid fever is endemic in many developing areas of the world.

Mortality/Morbidity

Morbidity and mortality rates are highest in infants (most dangerous in infants <3 mo with bacteremia), elderly patients, and patients with sickle cell disease, AIDS, neoplasms, or other causes of immunocompromise.

Age

Attack rates are highest in persons younger than 5 years or older than 70 years.

CLINICAL

Section 3 of 10  

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

History

Carefully obtain the patient's history to determine any potential sources of Salmonella and to help determine if the correct diagnosis has been made.

• General history
• • Inquire about any recent travel abroad.
  • Inquire about possible animal exposures, including contact with pet iguanas, turtles, tortoises, or other reptiles.
  • Inquire whether any family members have current or recent gastroenteritis.
  • Inquire whether any recent outbreaks have occurred in the community.
• Salmonella gastroenteritis
• • The incubation period of Salmonella gastroenteritis is 6-72 hours.
  • In most cases, children have cramping abdominal pain, nausea, vomiting, and loose watery stools.
  • Stools may be bloody; however, this is not as common as in infection with Shigella.
  • Fever, which rarely exceeds 39°C, occurs in approximately one half of infected patients.
  • Symptoms usually resolve spontaneously in 2-7 days.
• Enteric fever (typhoid fever)
• • Enteric fever is caused by S typhi and several other Salmonella serotypes.
  • The incubation period for enteric fever is 3-60 days, but symptoms typically occur in 1-2 weeks.
  • Patients may present with high fever, which rises in a steplike fashion.
  • Other symptoms include anorexia, abdominal pain, malaise, myalgias, headache, cough, diarrhea or constipation, and delirium.

Physical

• Salmonella gastroenteritis
• • On physical examination, patients may have signs of dehydration, such as delayed capillary refill, sunken eyes, dry mucous membranes, or tachycardia.
  • Patients may have tenderness to palpation on abdominal examination, which sometimes can be difficult to differentiate from appendicitis.
  • Rectal examination may reveal heme-positive stools, gross blood, or mucoid stools.
• Enteric fever (typhoid fever)
• • A typical finding of enteric fever is relative bradycardia for the height of the fever.
  • Hepatosplenomegaly may be found on examination.
  • Patients with enteric fever may develop rose spots; these spots are blanching pink papules most commonly found on the anterior thorax. They usually fade about 3-4 days after appearance, are 2-4 mm in diameter, and occur in groups of 5-20.

Causes

• Numerous serotypes of Salmonella exist. Serogroups A through E are the main ones causing disease in humans. In the United States, serogroups B, C, and D are responsible for most infections.
• Salmonella enteritidis (serogroup D) is the most common cause of gastroenteritis.
• S typhi (serogroup D) and other serotypes are responsible for typhoid fever (enteric fever).

DIFFERENTIALS

Section 4 of 10  

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

Other Problems to be Considered

Viral enteritis
Toxic ingestions
Gastroenteritis, Bacterial
Parasitic infections

WORKUP

Section 5 of 10  

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

Lab Studies

• Complete blood cell count with differential
• • CBC count is often 10,000-15,000 in simple gastroenteritis.
  • Patients with enteric fever commonly have anemia, thrombocytopenia, or neutropenia, although a shift to more immature forms can be seen on the differential count.
• Cultures
• • Isolation of Salmonella from cultures of stool, blood, urine, or bone marrow is diagnostic.
  • Cultures of rose spots and/or bone marrow aspirate may be positive in enteric fever even when stool cultures are negative for Salmonella.
• Stool examination: Stool may be hemoccult positive and may be positive for fecal polymorphonuclear cells.
• Chemistry
• • Electrolyte tests may reveal metabolic acidosis or other abnormalities consistent with dehydration.
  • Patients with enteric fever may have mild hepatitis.
• Serologic tests: Tests for Salmonella agglutinins (febrile agglutinins, Widal test) may suggest infection with S typhi; however, they are not recommended because of the number of false-positive and false-negative results.

Imaging Studies

• Imaging studies are not necessary for most patients with simple gastroenteritis and enteric fever without any severe complications.
• Consider chest radiography if pneumonia is suggested as the result of bacteremia.
• Perform abdominal radiography if the patient presents with peritoneal signs on physical examination. Consider intestinal perforation as a complication of enteric fever.
• Perform a bone scan if osteomyelitis is considered as a complication of bacteremia. MRI, which is more sensitive, can be done to evaluate osteomyelitis.

TREATMENT

Section 6 of 10  

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

Medical Care

• Salmonella gastroenteritis
• • For uncomplicated gastroenteritis caused by nontyphoidal Salmonella species, antimicrobial therapy is not indicated because it does not shorten the duration of illness.
  • Treatment involves monitoring hydration status and IV therapy to correct electrolyte imbalance or restore intravascular volume.
  • Antidiarrheal agents may actually prolong GI transit time and the illness.
  • Antimicrobial agents and hospital admission may be recommended in Salmonella gastroenteritis in infants younger than 3 months, infants younger than 12 months with temperatures higher than 39°C and unknown blood culture results, and patients with hemoglobinopathies, HIV infection or other causes of immunosuppression, neoplasms, or chronic GI illnesses.
  • The recommended antibiotics for individuals at high risk of invasive disease include ampicillin, amoxicillin, trimethoprim-sulfamethoxazole (TMP-SMZ), cefotaxime, and ceftriaxone.
• Treatment of invasive Salmonella disease (bacteremia, extraintestinal manifestations)
• • Antibiotic treatment includes ampicillin, amoxicillin, cefotaxime, ceftriaxone, chloramphenicol, TMP-SMZ, or a fluoroquinolone, if susceptible.
  • A 14-day course of antibiotics is recommended for patients with bacteremia.
  • Patients with localized infection, such as osteomyelitis or abscess, or patients with bacteremia and HIV infections should receive 4-6 weeks of therapy.
  • For Salmonella meningitis, ceftriaxone or cefotaxime is recommended for 4 weeks or longer.
• Enteric fever caused by S typhi infection
• • For S typhi infection, a 14-day course of chloramphenicol, ampicillin, or TMP-SMZ is indicated.
  • In severe infection, parenteral therapy is indicated.
  • Use antipyretics with caution or not at all because they may cause precipitous drops in temperature and shock.
  • Relapse is common, and patients must be re-treated.
  • Corticosteroids may be involved in treatment of patients with neurologic complications of enteric fever.
  • In particular parts of the world, namely India, Pakistan, and Egypt, multiply antibiotic-resistant strains of S typhi are found. Travelers from these regions should be treated with a 7- to 10-day course of ceftriaxone or 5- to 7-day course of ciprofloxacin or ofloxacin.
  • High-dose ampicillin or high-dose amoxicillin plus probenecid for 4-6 weeks has cured many chronic carriers.

Surgical Care

Cholecystectomy may be curative in carriers with chronic gallbladder disease.

Consultations

• Consider consultation with a pediatric infectious disease specialist if questions exist about the appropriate antibiotic for treatment or questions exist about the length of treatment of patients with documented Salmonella infection.
• Consider surgical consultation for patients with enteric fever who appear to have complications such as intestinal perforation, splenic rupture, or pancreatitis.

Diet

• Restrict initial oral intake to electrolyte solutions, such as Pedialyte or clear liquids.
• Add solid foods only when the diarrhea appears to be improving and dehydration is not present.
• Initially, children can be started on a BRAT diet (ie, bananas, rice, applesauce, toast) and then slowly advanced to a regular diet as tolerated.

MEDICATION

Section 7 of 10  

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

In most simple gastroenteritis, antibiotics are not necessary and, in fact, can prolong the duration of illness.

Drug Category: Antibiotics

Patients who are susceptible to invasive disease, those with invasive Salmonella, and those with enteric fever require treatment with antimicrobials.

Drug Category: Glucocorticoids

Glucocorticoids have been demonstrated to have some benefit in patients with severe neurologic complications of enteric fever.

FOLLOW-UP

Section 8 of 10  

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

Further Inpatient Care

• If admission is necessary, monitor the patient's hydration and electrolyte levels, continue IV or PO antibiotics as needed, and observe for and appropriately treat complications of Salmonella.

Further Outpatient Care

• Monitor patient's hydration status as an outpatient. Admission is warranted if the patient has signs and/or symptoms of dehydration.
• Monitor patients treated for enteric fever for possibility of relapse.
• Follow up on all blood cultures if the patient is being treated as an outpatient.

Deterrence/Prevention

• Good personal hygiene, hand washing, and appropriate sanitary practices deter spread of the disease.
• Standard precautions and contact precautions must be used during the entire hospitalization of patients, especially for children who are in diapers or are incontinent.
• For patients hospitalized with S typhi infection, precautions must be continued until results of 3 stool cultures are negative 48 hours after stopping antibiotic therapy.
• Typhoid vaccination can help deter typhoid fever.
• • Although vaccinations enhance resistance to infection with S typhi, immunity is overcome by a large bacterial inoculum.
  • Immunization is recommended for the following individuals: (1) those who travel to an endemic area, (2) those with intimate exposure to an individual known to be a carrier of typhoid fever, (3) laboratory workers with frequent contact with S typhi, and (4) individuals living in typhoid-endemic areas outside the United States.
  • Three vaccinations are available in the United States.
    • Oral Ty21a vaccine is a live attenuated vaccination that can be given to children aged 6 years or older.
    • Vi capsular polysaccharide vaccine can be given to patients aged 2 years or older and consists of one intramuscular injection.
    • Parenteral inactivated vaccine is indicated for children younger than 2 years and consists of 2 subcutaneous injections.

Complications

• Nontyphoidal salmonellosis
• • Bacteremia
  • Meningitis
  • Pneumonia
  • Endocarditis/pericarditis
  • Osteomyelitis (most common in patients with sickle cell anemia)
  • Hepatic/splenic abscess
• Typhoid fever (enteric fever)
• • Intestinal perforation and severe hemorrhage (occurs in 1-10% of children)
  • Toxic encephalopathy and cerebral thrombosis
  • Hepatitis, pancreatitis, arthritis, and myocarditis

Prognosis

• Nontyphoidal salmonellosis
• • Prognosis of patients with simple gastroenteritis is excellent except for very young infants or patients with debilitating diseases.
  • The prognosis for Salmonella meningitis or endocarditis is poor.
• Typhoid fever (enteric fever)
• • Therapy with antibiotics has decreased the mortality rate to 1%; however, prognosis depends on the extent of complications from the disease.
  • Relapse is common after therapy for enteric fever.
• Chronic carrier state: Patients who continue to shed bacteria for more than 1 year (approximately 1% of patients) are considered chronic carriers.

Patient Education

• Good personal hygiene and hand washing are essential for all people involved in food handling.
• All medical personnel must also use standard precautions when treating patients with Salmonella to avoid patient-to-patient transmission.
• For excellent patient education resources, visit eMedicine's Public Health Center. Also, see eMedicine's patient education article Foreign Travel.

MISCELLANEOUS

Section 9 of 10  

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

Medical/Legal Pitfalls

• Failure to consider S typhi as a differential diagnosis because the patient does not initially present with diarrhea and may have constipation
• Failure to ask about foreign travel and, therefore, not considering S typhi as a differential diagnosis
• Failure to aggressively treat infants younger than 3 months, patients with sickle cell disease, and patients who are immunocompromised and thus avoid potentially serious complications and poor outcome

Special Concerns

• Salmonella infections in day care
• • When a child or a staff member in a daycare setting has been diagnosed with S typhi infection, stool specimens from all children and staff members of the daycare should be obtained. All infected individuals should be excluded from the center until results from 3 consecutive stool cultures are negative for children younger than 5 years. Children older than 5 years can return to group care, if diarrhea has resolved for 24 hours.
  • When a child or adult contracts a case of Salmonella gastroenteritis (species other than S typhi), children or staff members should not be allowed to return to the day care center until they are asymptomatic. Asymptomatic individuals do not need to give stool specimens.

REFERENCES

Section 10 of 10

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

• Amieva MR. Important bacterial gastrointestinal pathogens in children: a pathogenesis perspective. Pediatr Clin North Am. 2005;52:749-77. [Medline].
• Behrman, RE, Kliegman, RM, Jenson, HB. Salmonella. In: Textbook of Pediatrics. 17th ed. 2003;912-919.
• Davis MA, Hancock DD, Besser TE. Multiresistant clones of Salmonella enterica: The importance of dissemination. J Lab Clin Med. 2002;140:135-41. [Medline].
• Fierer J, Guiney DG. Diverse virulence traits underlying different clinical outcomes of Salmonella infection. J Clin Invest. 2001;107:775-80. [Medline].
• Fleisher, GR, Ludwig, SL, Henretig FM. Infectious Disease Emergencies. In: Textbook of Pediatric Emergency Medicine. 5th ed. Baltimore, Md:. 2005;783-851.
• Khan GQ, Kadri SM, Hassan G, et al. Salmonella typhi endocarditis: a case report. J Clin Pathol. 2003;56:801-2. [Medline]. [Full Text].
• Leonard MK, Murrow JR, Jurado R, Gaynes R. Salmonella meningitis in adults infected with HIV: case report and review of the literature. Am J Med Sci. 2002;323:266-8. [Medline].
• Lu L, Walker WA. Pathologic and physiologic interactions of bacteria with the gastrointestinal epithelium. Am J Clin Nutr. 2001;73:1124S-1130S. [Medline].
• Mermin JH, Townes JM, Gerber M, et al. Typhoid fever in the United States, 1985-1994: changing risks of international travel and increasing antimicrobial resistance. Arch Intern Med. Mar 23 1998;158(6):633-8. [Medline].
• Misra S, Diaz PS, Rowley AH. Characteristics of typhoid fever in children and adolescents in a major metropolitan area in the United States. Clin Infect Dis. May 1997;24(5):998-1000. [Medline].
• Parry CM, Hien TT, Dougan G, et al. Typhoid fever. N Engl J Med. 2002;347:1770-82. [Medline].
• Pickering LK. Salmonella infections. Red Book 2003 Report of the Committee on Infectious Diseases, AAP. 2003;541-547. [Full Text].
• Rooney RM, Cramer EH, Mantha S, et al. A review of outbreaks of foodborne disease associated with passenger ships: evidence for risk management. Public Health Rep. 2004;119:427-34. [Medline].
• Rooney RM, Bartram JK, Cramer EH, et al. A review of outbreaks of waterborne disease associated with ships: evidence for risk management. Public Health Rep. 2004;119:435-42. [Medline].
• Torrey S, Fleisher G, Jaffe D. Incidence of Salmonella bacteremia in infants with Salmonella gastroenteritis. J Pediatr. May 1986;108(5 Pt 1):718-21. [Medline].
• Yates J. Traveler's diarrhea. Am Fam Physician. 2005;71:2095-100. [Medline].

Article Last Updated: Jul 26, 2006