Pathophysiology
Gram-negative, motile, non-lactose fermenting bacilli. Type III secretion system delivers effector proteins into enterocytes -> invasion, IL-8 recruitment of neutrophils, inflammatory diarrhoea. Low infectious dose in immunocompromised, achlorhydria (PPI use), and haemoglobinopathies.
Sources: IDSA Infectious Diarrhoea Guideline (Clin Infect Dis 2017;65:e45); CDC Salmonella (2024 update); WHO Typhoid Position Paper (2018)
Clinical presentation
Non-typhoidal: 12-72 h incubation, non-bloody or bloody diarrhoea, cramps, fever, vomiting; 4-7 days duration. Complications: bacteraemia (esp. SCD, HIV, endovascular grafts), reactive arthritis, osteomyelitis (SCD -> Salmonella osteomyelitis).
Diagnosis
Stool culture or GI PCR panel. Blood cultures for high fever, immunocompromise, prolonged illness. Consider endovascular seeding (abscess, mycotic aneurysm) if persistent bacteraemia.
Management
Uncomplicated: oral rehydration, no antibiotics (prolong shedding). Antibiotics (azithromycin, ceftriaxone or fluoroquinolone) for age <3 mo, >50 y with atherosclerosis, immunocompromised, prosthetic vascular grafts, or severe bacteraemia. Anti-motility drugs (loperamide) generally avoided in inflammatory diarrhoea.
Prevention
Cook eggs and poultry to safe internal temperatures, avoid raw milk, hand hygiene after reptile/bird handling, safe water. Typhoid vaccination for travellers to endemic areas.
