Shigellosis

Non-typhoidal Salmonella infection (distinct from Salmonella Typhi/Paratyphi causing enteric fever, see the Typhoid entry) is typically acquired from contaminated poultry, eggs, meat, or dairy products, or from reptile/amphibian contact, causing a self-limiting gastroenteritis in the large majority of immunocompetent hosts, though invasive, bacteremic disease occurs more readily in specific at-risk groups.

Watery or, less commonly, bloody diarrhea, abdominal cramping, fever, nausea, and vomiting, typically beginning 6 to 72 hours after exposure and resolving within 4 to 7 days in most cases.

Invasive/bacteremic disease (more common in infants under 3 months, the elderly, immunocompromised patients including HIV, and those with sickle cell disease, hemolytic anemia, or a prosthetic vascular graft/joint) can seed distant sites, causing osteomyelitis (particularly in sickle cell disease, see that entry), endovascular infection (mycotic aneurysm, particularly in the elderly with atherosclerotic disease), or meningitis in infants.

Stool culture confirms diagnosis and allows susceptibility testing; stool multiplex PCR panels, where available, offer faster results.

Blood cultures should be sent in any patient with risk factors for invasive disease (age extremes, immunocompromise, sickle cell disease) or signs of systemic toxicity, given the risk of bacteremia even without an obvious focus.

• Uncomplicated gastroenteritis in an otherwise healthy host: supportive care only (rehydration, antiemetics), with antibiotics not recommended, since treatment does not shorten illness duration in this group and may prolong intestinal carriage and shedding
• Antibiotics are indicated for: infants under 3 months, age over 65 with comorbidity, immunocompromise (including HIV, malignancy, or immunosuppressive therapy), sickle cell disease, prosthetic vascular grafts or joints, severe illness with systemic toxicity, or confirmed/suspected bacteremia
• When indicated: ciprofloxacin 500 mg PO bd for 7 to 10 days (longer, 14 days or more, for bacteremic disease), or ceftriaxone 2 g IV od for severe illness or where fluoroquinolone resistance is a concern; azithromycin as an alternative
• Focal invasive infection (osteomyelitis, endovascular infection, meningitis) requires prolonged, source-specific antibiotic courses (often 4 to 6 weeks or more) guided by the specific site and specialist input, sometimes combined with surgical source control (e.g. vascular graft removal for mycotic aneurysm)
• Public health notification (notifiable disease in most jurisdictions) given outbreak potential from a common food source

Referral: infectious disease for any invasive disease or high-risk patient requiring antibiotics; vascular surgery for suspected mycotic aneurysm.