Enteric fever

Background

Microbiology

• Caused by Salmonella enterica subsp. typii and paratyphii
• Virulence is related to Vi antigen and invasin protein

Epidemiology

• Fecal-oral transmission acquired from contraminated food, milk, or water
• Less than 5% of infected people become chronic carriers, with bacteria remaining in the gallbladder despite adequate antibiotic treatment

Pathophysiology

• Induction of pH-shock proteins and other adaptions allow ingested bacteria to pass through the stomch and into the small intestine
• There, they penetrate the intestinal mucosa followed by mononuclear cells, which transport them to lypmh nodes
• They multiple within the reticuloendothelial system during the incubation period
• After a threshold is reached, they disseminate to blood

Clinical Presentation

• Most commonly presents as fever in a returned traveller
• Incubation period 5 to 21 days
• Prominent symptoms include high fever, headache, diarrhea or constipation, relative bradycardia, splenomegaly, and leukopenia
• If untreated for several weeks, a blanchable papular rash ("rose spots") may appear
• Extraintestinal manifestations are myriad
  • Meningoencephalopathy, abscess or empyema, and others
  • Endocarditis, myocarditis, and pericarditis
  • Pneumonia
  • Hepatitis, cholestasis, hepatic abscesses
  • Osteomyelitis, rarely

Diagnosis

• Blood cultures (large volume, like x4), stool cultures, bone marrow
• Biopsy (most sensitive)

Management

• Treatment with third-generation cephalosporins like ceftriaxone
• Avoid fluoroquinolones due to high resistance rate