Background
Microbiology
- Caused by Salmonella enterica subspecies enterica serotypes Typhi and Paratyphi
- Virulence is related to Vi antigen and invasin protein
Epidemiology
- Fecal-oral transmission acquired from contaminated 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 stomach and into the small intestine
- There, they penetrate the intestinal mucosa followed by mononuclear cells, which transport them to lymph nodes
- They multiple within the reticuloendothelial system during the incubation period
- After a threshold is reached, they disseminate to blood
Clinical Manifestations
- Most commonly presents as fever in the returned traveller
- Incubation period 5 to 21 days
- Symptoms progress over weeks
- First week: fever, chills, bacteremia, relative bradycardia, headache
- Second week: abdominal pain, and a blanchable papular rash ("rose spots") may appear
- Third week: can progress to gastrointestinal perforation, hepatosplenomegaly, GI bleed, secondary bacteremia
- Constipation is more common in adults, while diarrhea is more common in children and people with HIV
- CBC shows leukopenia and anemia
- Extraintestinal manifestations are myriad
Diagnosis
- Blood cultures (large volume, like x4), stool cultures, bone marrow biopsy (most sensitive)
Management
- Treatment with third-generation cephalosporins like ceftriaxone, stepped down to oral when improving and susceptibility data are available
- Alternatives are azithromycin, followed by ampicillin, TMP-SMX, chloramphenicol
- Avoid fluoroquinolones due to high resistance rate
- Duration 10 to 14 days
- Can take 4 to 6 days to defervesce, even with treatment
- Monitor for relapse 2 to 3 weeks after treatment ends
| Antibiotic | Dose | Duration |
|---|---|---|
| azithromycin | 1 g p.o. once followed by 500 mg p.o. daily, or
1 g p.o. daily |
5 to 7 days |
| ciprofloxacin | 500 mg p.o. twice daily | 7 to 10 days |
| ofloxacin | 400 mg p.o. twice daily | |
| ceftriaxone | 2 g IV daily | 10 to 14 days |
| cefotaxime | 1 to 2 g IV every 6 to 8 hours | |
| cefixime | 200 mg p.o. twice daily | |
| meropenem | 1 to 2 IV every 8 hours | |
| TMP-SMX | 1 DS tablet p.o. twice daily | |
| amoxicillin | 1 g p.o. three times daily | |
| chlormaphenicol | 500 tp 750 mg p.o. four times daily | 14 to 21 days |
