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 (including pet hedgehogs)

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

• More common in people with atherosclerosis, aortic aneurysms, prosthetic vascular grafts, valvular heart disease, and prosthetic heart valves
  • Most common include aortitis (particularly infrarenal abdominal aorta), vascular graft infection, and endocarditis
  • Other endovascular sources are possible; pathophysiology appears to involve infection of atherosclerosis
• Complicates up to 25% of bacteremia
• Endovascular infection can be predicted by the NTSVI score1
  • +1 point for each of: male sex, hypertension, coronary artery disease, and serogroup C1 infection
  • −1 point for each of: immunosuppression and malignancy
  • ≤1 is low-risk and effectively rules out endovascular infection

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 DS 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
• Aortitis: 2
• 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