Salmonella Infections
Salmonella Infections: Excerpt from The 5-Minute Pediatric Consult
Suzanne Dawid, MD, PhD
Salmonella Infections - BASICS
Salmonella Infections - description
Salmonella is responsible for a broad spectrum of pathologic states ranging from asymptomatic infection to acute gastroenteritis to enteric fever.
Salmonella Infections - general prevention
Personal hygiene and sanitation measures are the primary means by which to prevent Salmonella infections.
- Carriers of Salmonella are a public health concern:
- Hospitalized patients: Enteric precautions for length of illness
- Outpatients: Should be restricted from preparing food for others
- 2 vaccines against Salmonella typhi are licensed for use in persons living in high-risk environments, including those residing with a chronic carrier or living in an endemic area:
- The Ty21a vaccine is a live attenuated strain that is given orally in 4 doses on alternating days. It is approved only for children older than 6 years.
- The Vi capsular polysaccharide vaccine is a parenteral vaccine that is licensed for children older than 2 years.
- Both vaccines require frequent booster doses.
Salmonella Infections - epidemiology
- Reservoirs:
- Salmonella species other than S. typhi: Animals and animal products (mammals, birds, reptiles, and insects); contaminated food and water; infected humans (fecal excretion may persist for several months)
- Humans are the only natural reservoir for S. typhi: Most commonly transmitted via fecally contaminated food and water; may be transmitted congenitally; chronic carriers may excrete S. typhi in stool for years.
- Incubation period:
- Salmonella species other than S. typhi: 6–72 hours; symptoms typically begin within 24 hours.
- Incubation period of invasive Salmonella strains and S. typhi is 1–3 weeks.
- Age distribution: Children younger than 5 years and the geriatric population are most commonly infected with nontyphoidal Salmonella; S. typhi is most common in 5–25-year-olds.
Salmonella Infections - etiology
3 species are responsible for most human salmonellosis: Salmonella enteritidis (>2,000 serotypes exist), Salmonella choleraesuis, and S. typhi.
Salmonella Infections - associated conditions
- Acute asymptomatic infection:
- No clinical signs or symptoms become apparent.
- Probably most common Salmonella syndrome
- Patients can be identified only by recovery of organisms in stool.
- Acute gastroenteritis:
- Salmonella is the most common type of infectious food poisoning in the US.
- Symptoms begin 6–48 hours after Salmonella ingestion.
- Predominant manifestations are nausea, vomiting, cramps (often severe) abdominal pain, and diarrhea (rarely, gross blood may be found).
- Other common features are malaise, myalgia, headache, and fever.
- Symptoms usually resolve spontaneously in 2–7 days.
- Bacteremia:
- Salmonella organisms may produce acute or intermittent bacteremia.
- Symptoms: Fever/chills, diaphoresis, myalgia, anorexia
- Bacteremia may occur before clinical gastroenteritis or, in infants, present as a persistent bacteremic state with failure to thrive.
- Up to 1/20 patients with Salmonella gastroenteritis may develop bacteremia (perhaps as high as 1/4 in infants).
- Enteric fever (typhoid fever, paratyphoid fever):
- Caused by S. typhi and several other Salmonella serotypes
- Incubation period is 1–3 weeks.
- Insidious onset of symptoms over 2–7 days: Fever as high as 41°C, malaise, anorexia, abdominal pain, constipation
- Additional symptoms and signs: Lethargy, myalgia, headache, cough, either diarrhea or constipation, rigors, delirium, lymphadenopathy, organomegaly, rose spots
- Progression of illness: When untreated, illness with high fevers may last weeks; severe morbidity or death may result from especially virulent Salmonella strains.
- Asymptomatic chronic carriage: ~1% of patients infected with Salmonella gastroenteritis or enteric fever will continue to shed Salmonella in the stool for >1 year.
Salmonella Infections - DIAGNOSIS
Salmonella Infections - signs & symptoms
Salmonella Infections - history
- Exposure:
- History of eating raw or undercooked meat or eggs
- Exposure to pet lizard, turtle, or snake. Recent outbreaks have been tied to exposure to infected pet rodents (hamsters, mice, and rats)
- Common historical features of Salmonella gastroenteritis:
- Nausea and vomiting begin 6–48 hours after ingestion.
- Diarrhea and abdominal pain with tenesmus follow; pain is typically periumbilical and in the right lower quadrant.
- Diarrhea lasts 2–4 days.
- Fever seldom exceeds 39°C; occurs in 50% of affected patients.
- Common historical features of enteric fever:
- Symptoms begin 3–60 days after exposure.
- Commonly acquired during foreign travel
- Diarrhea uncommon early in course
- Fever ensues, which gradually increases in magnitude.
- Malaise, anorexia, myalgia, headache, abdominal pain, and vomiting may occur.
Salmonella Infections - physical exam
- Salmonella GI disease may display certain features:
- Dehydration may be evident.
- Abdominal pain may closely mimic appendicitis and/or cholecystitis.
- Stools may be bloody, watery, or contains mucus.
- Important signs of enteric fever:
- Enlarged liver and spleen
- Relative bradycardia for height of fever: A frequently distinguishing finding
- Rose spots: 2–4 mm in diameter; blanching pink papules; most commonly found on anterior thorax; 5–20 are generally apparent at a time; fade in 3–4 days after appearance; characteristic of enteric fever, but not specific
Salmonella Infections - tests
Salmonella Infections - lab
- There are several nonspecific laboratory aids to diagnosis:
- Stool examination: May have hemoccult-positive stools; stool may be positive for fecal leukocytes in enterocolitis.
- CBC with differential: Normal in simple gastroenteritis; neutropenia, thrombocytopenia, and mild anemia are common in enteric fever.
- Serum chemistries: Metabolic acidosis and electrolyte abnormalities may occur with severe enteritis; a mild hepatitis is frequently found in enteric fever.
- Stool and blood culture and identification of Salmonella organisms: The gold standard method for laboratory confirmation of infection
- Bone marrow aspirate: The most sensitive source for isolation of Salmonella in patients with enteric fever; early in the course of invasive illness, bone marrow culture may be positive, even when stool samples fail to grow the bacteria; may provide positive cultures, even after initial antibiotic pretreatment.
- Urine culture: May be a source of Salmonella organisms in the young or geriatric population and in those with enteric fever
- Biopsy: Needle aspiration of purulent material may yield positive cultures; punch biopsy and culture of rose spots may confirm diagnosis of S. typhi.
- False-positives: Leukocytes in the stool are suggestive of colitis, but are more typical of Campylobacter, Shigella, or milk allergy.
- Pitfall: Enteric fever may precede enteritis symptoms and fecal shedding of bacteria.
Salmonella Infections - differencial diagnosis
- The following illnesses may mimic Salmonella gastroenteritis and/or enterocolitis:
- Shigellosis: Severe abdominal pains often are present; associated with high fevers; ulcers of the GI lining are common; stools are often grossly bloody, with sheets of fecal leukocytes.
- Staphylococcal food poisoning
- Other bacterial infections of the gastrointestinal tract
- Viral enteritis: Rotavirus, Norwalk virus, and other viruses
- Parasitic infections
- Toxic ingestion
- Noninfectious systemic illnesses marked by inflammatory colitis
- Enteric fever from Salmonella infection may be confused with:
- Invasive bacterial disease
- Spirochetal infection
Salmonella Infections - TREATMENT
Salmonella Infections - initial stabilization
- Acute asymptomatic infection: Should not be treated with antibiotics. Antibiotics do not have an impact on duration of diarrhea and may lengthen duration of carrier state.
- Acute gastroenteritis (see “FAQ”):
- Supportive care: Maintain intravascular volume; correct electrolyte abnormalities.
- Do not administer antidiarrheal agents; they prolong GI transit time.
- Consider antibiotics in individuals at high risk of subsequent systemic invasive illness: Children younger than 3 months, immunocompromised hosts, patients with hemoglobinopathies or chronic GI tract disease.
- Bacteremia, enteric fever, and/or chronic carrier state:
- Supportive care
- Antibiotics are indicated; initial therapy usually to be administered intravenously
- Surgical drainage of local suppuration is indicated as in most other infections.
- Corticosteroids (3 mg/kg load, 1 mg/kg q6h) may be beneficial to critically ill patients with enteric fever exhibiting neurologic complications.
- Antipyretics are controversial in enteric fever syndromes because they may cause precipitous declines in temperature and shock.
Salmonella Infections - medication
Various antibiotics may be used to treat Salmonella infection:
- Salmonella gastroenteritis at high risk of invasive disease: Increasing resistance to amoxicillin, ampicillin, and trimethoprim/sulfamethoxazole; parenteral 3rd-generation cephalosporins or fluoroquinolones are preferred.
- Invasive Salmonella disease: IV ampicillin for 2 weeks has been first-line therapy; chloramphenicol, a 3rd-generation cephalosporin, or a quinolone may be used for resistant organisms; cefotaxime for treatment of meningitis; meningitis or osteomyelitis may require 4–6 weeks of parenteral antibiotic therapy.
- Some authorities treat chronic carriers of Salmonella typhi who shed for >1 year with high-dose parenteral ampicillin; high-dose oral amoxicillin (with or without probenecid), or ciprofloxacin; consider cholecystectomy for recalcitrant cases.
Salmonella Infections - FOLLOW UP
- Acute GI illness:
- Symptoms usually resolve spontaneously within 7 days.
- Supportive care to prevent or treat dehydration may be required.
- Young children and those with underlying disease processes may be at higher risk of complications.
- Enteric fever:
- Untreated, this illness will have a prolonged course over weeks.
- Life-threatening complications are most common during the 2nd or 3rd week of illness, often after a period of apparent clinical improvement.
- Even with appropriate treatment, up to 20% of patients may suffer relapse.
- Chronic carriage:
- 1–3% of patients with Salmonella infection will shed bacteria in the stool for >1 year.
- Chronic carriers should be identified because they represent a public health threat.
- More people with Salmonella infestation are asymptomatic than are symptomatic.
- Antibiotic resistance is a growing problem.
- Even with appropriate therapy, patients may shed bacteria on a persistent basis or may suffer relapse.
Salmonella Infections - prognosis
- Most normal hosts with Salmonella gastroenteritis will recover spontaneously.
- Some individuals will develop a chronic carrier state, persistently shedding bacteria in the stool.
- The relapse rate of enteric fever may approach 20% of patients, even when adequately treated.
Salmonella Infections - complications
- Dehydration and/or electrolyte imbalance is the most common complication arising from acute gastroenteritis.
- Invasive Salmonella may lead to complications of bacteremia:
- Sepsis: Most common in neonates and immunosuppressed individuals
- Meningitis: Vast majority of cases occur in 1st month of life.
- Osteomyelitis: Most common in patients with sickle cell anemia
- Other local infections: Pneumonia, pericarditis
- Complications of enteric fever include intestinal or splenic rupture (at areas of lymphoid hypertrophy), hepatitis, pancreatitis, parotitis, orchitis, arthritis, and myocarditis.
- A postinfectious form of hemolytic uremic syndrome may occur following Salmonella infection.
Salmonella Infections - bibliography
American Academy of Pediatrics. Salmonella. In: Pickering LK, ed. 2006 Red Book: Report of the Committee on Infectious Diseases. 27th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2006.- Fierer J, Swancutt M. Non-typhoid salmonella: A review. Curr Clin Top Infect Dis. 2000;20:134–157.
- Nataro JP. Treatment of bacterial enteritis. Pediatr Infect Dis J. 1998;17:420–421.
- St. Geme JW, Hodes HL, Marcy M, et al. Consensus: Management of salmonella infection in the first year of life. Pediatr Infect Dis J. 1988;7:615–621.
- Sirinavin S, Garner P. Antibiotics for treating salmonella gut infections. Cochrane Database Syst Rev. 2000;CD001167.
- Stephens I, Levine MM. Management of typhoid fever in children. Pediatr Infect Dis J. 2002;21:157–158.
- Swanson SJ, Snider C, Braden CR, et al. Multidrug-resistant Salmonella enterica serotype Typhimurium associated with pet rodents. N Engl J Med. 2007;356:21–28.
Salmonella Infections - CODES
Salmonella Infections - icd9
- 003.0 Salmonella dysentery
- 003.0 Salmonella enteritis infection
- 003.9 Salmonella infection, unspecified
Salmonella Infections - FAQ
- Q: Should all infants with Salmonella gastroenteritis be treated with antibiotics?
- A: Clinicians caring for children younger than 1 year with proven, or suspected, Salmonella infection face many treatment dilemmas. Any toxic-appearing infant and any infant with proven Salmonella bacteremia should be admitted to the hospital for parenteral antibiotics. High-risk infants (those younger than 3 months of age) with positive stool cultures should be treated with antibiotics after blood cultures are obtained. Well-appearing infants older than 3 months of age with Salmonella enterocolitis and fever can be observed off antibiotics after surveillance blood cultures are obtained.
Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
More About Salmonella enteritidis
More Medical Textbooks Online about Salmonella enteritidis
Review other book chapters online related to Salmonella enteritidis:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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