Non-typhoidal Salmonella

Background

• Serotypes of Salmonella enterica that exclude Typhi and Paratyphi, which cause typhoid fever

Epidemiology

• Numerous animal reservoirs
• May be transmitted by animal products (especially eggs, poultry, undercooked ground meat, dairy, or contaminated fresh produce), contaminated water exposure, and contact with animals and their environment

Clinical Manifestations

Gastroenteritis

• One of the most common causes of foodborne illness
• Incubation period 6 to 48 hours (range up to 7 days)
• Diarrhea, abdominal pain, nausea and vomiting, fevers and chillds
  • Stools are usually loose but can be profuse and watery ("cholera-like") or small volume but with tenesmus ("dysentery-like")
• May have headaches and myalgias
• Can mimic appendicitis (from mesenteric adenitis) and inflammatory bowel disease
• Self-limited, lasting 3 to 7 days

Extraintestinal Manifestations

Bacteremia

• Most common extraintestinal site, in up to 8% of cases of NTS gastroenteritis
• More common in older patients >65 years, immunocompromised hosts, and patients with hemoglobinopathies (particularly sickle cell disease)

Endovascular Infection

• Can cause aortitis, vascular graft infection, and endocarditis
• Complicates up to 25% of bacteremia
• More common in people with atherosclerosis, aortic aneurysms, prosthetic vascular grafts, valvular heart disease, and prosthetic heart valves
• Endovascular infection can be predicted by a scoring system1
  • +1 point for each of: male gender, hypertension, coronary artery disease, and serogroup C1 infection
  • −1 point for each of: immunsuppression and malignancy
  • ≤1 is low-risk and ≥2 is high-risk, giving a sensitivity of 95% and specificity 45%

Bone and Joint Infection

• Can cause osteomyelitis, especially in sickle cell disease, as well as septic arthritis
• Can also cause a reactive arthritis characterized by lower-limb acute arthritis, urethritis, and conjunctivitis

Genitourinary Infection

• Can rarely cause urinary tract infection
• May be secondary to bacteremia

Meningitis

• More common in infants

Asymptomatic Carriage

• Asymptomatic shedding following treatment continues for a median of 5 weeks
  • Possibly longer in patients who have been treated with antibiotics
  • Some people chronically shed bacteria in stool for >1 year
• Occurs in less than 1% of cases

Management

Gastroenteritis

• Mild to moderate gastroenteritis: rehydration and supportive care
• Severe gastroenteritis: antibiotics
• Other indications for antibiotics include: older age >50 years, prosthetic joints, valvular heart disease, prosthetic heart vales, endovascular stents, severe atherosclerosis, active malignancy, uremia, sickle cell disease, severe joint disease, immunosuppression, advanced or untreated HIV, infants <3 months
• Options include:
  • Ceftriaxone 1-2 g IV q24h
  • Ciprofloxacin 500 mg PO bid
  • Azithromycin 1000 mg PO on day 1 followed by 500 mg PO on days 2 to 7
  • TMP-SMX SD 1 tablet PO bid
• Duration depends on immune status and bacteremia
  • Immunocompetent without bacteremia: 3 to 7 days
  • Immunocompetent with bacteremia alone: 7 to 14 days
  • Advanced HIV/AIDS: 2 to 6 weeks
  • Other immunosuppressed host: 14 or more days

Bacteremia

• Ceftriaxone 2 g IV q24h for 7 to 14 days

• Alternatives include cefotaxime or high-dose ciprofloxacin

Other Foci

• Vascular graft infection or vascular prosthesis infection: as for bacteremia, for 6 weeks; remove prosthesis or graft, or do lifelong suppressive therapy
• Osteomyelitis: as for bacteremia, for 4+ weeks
• Septic arthritis: as for bacteremia, for 4 to 6 weeks
• Endocarditis: as for bacteremia, for 6 weeks
• Urinary tract infection: intravenous therapy for 1 to 2 weeks followed by oral therapy to complete 6 weeks
  • IV: ceftriaxone, cefotaxime, ciprofloxacin IV/PO
  • PO: ciprofloxacin or TMP-SMX

Asymptomatic Carriage

• No treatment, since it does not eradicate carriage but does promote resistance
• Encourage hand hygiene