Typhoid Fever

 

Thank you Emma for presenting a fascinating case of a man in his 30s who presented with persistent fevers, malaise, and self-resolved diarrhea, after returning from a 1-month trip to India. He was found to have 2/2 blood cultures positive for Salmonella, and was diagnosed with Typhoid Fever!

Typhoid Fever

  • Epidemiology
    • Most prevalent impoverished areas with poor access to sanitation
    • South-central Asia, Southeast Asia, southern Africa are regions with highest incidence of Typhoid Fever.
  • Microbiology
    • Salmonella enterica serotype Typhi (formerly Salmonella typhi) is the classic organism!
    • Other Salmonellae that cause similar clinical syndrome: Salmonella paratyphi A, B,C, and Salmonella choleraesuis
  • Clinical Features
    • Febrile illness with onset of symptoms 5-21 days after ingestion of bacteria in contaminated food or water
    • 1st week of illness: rising fever and bacteremia
    • 2nd week of illness: abdominal pain, and “rose spots” (salmon colored macules on trunk and abdomen) may be seen
    • 3rd week of illness: hepatosplenomegaly, intestinal bleeding, perforation due to ileocecal lymphatic hyperplasia of Peyer’s patches, peritonitis
    • Weeks to months: symptoms gradually resolve
    • Neurologic manifestations? As in the case of our morning report patient, headache is a frequent symptoms reported in 44-94% of cases! Other neurologic manifestations include: disordered sleep patterns, acute psychosis, myelitis, rigidity
  • Diagnostic tests
    • Blood Cultures are positive in 40-80% of patients
    • Other cultures: stool, urine, rose spots, duodenal contents, or bone marrow culture (Wow!) à Stool culture is positive in up to 30-40% of cases à Bone marrow culture is the most sensitive routinely available diagnostic tool. This may be useful in cases where antimicrobial therapy has already been initiated, and the diagnosis remains uncertain. Bone marrow cultures may be positive in up to 50% of patients after as many as 5 days of antibiotics.
    • Serology: The Widal test detects anti-S. typhi antibodies, but this is of limited clinical utility in endemic areas because positive results may represent previous infection.
  • Treatment
    • Multidrug resistant (MDR) strains have caused numerous outbreaks in parts of Asia and Africa (especially to ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol)
    • While awaiting sensitivities, treat with third-generation cephalosporins, azithromycin, and fluoroquinolones as empiric therapy.

Indications for Diagnostic Evaluation in Acute Diarrhea

Not every patient with acute diarrhea needs stool culture, O&P, and fecal leukocytes! Reserve diagnostic evaluations for patients with relatively severe disease, as suggested by one or more of the following:

  • Profuse diarrhea with signs of hypovolemia
  • Small volume stools with blood and mucus
  • Bloody diarrhea
  • Temperature > 38.5
  • Passage of 6 or more stools per 24 hours
  • Severe abdominal pain
  • Hospitalized patients or recent use of antibiotics
  • Diarrhea in the elderly or the immunocompromised

A Special Plug for “Fever in a Returned Traveler”

  • Always ask about location of exposure and incubation time to limit your differential diagnosis (each infection has a characteristic incubation period that is helpful in differential building).
  • Check out the chapter on “Fever in Returned Travelers” published by the CDC. It has wonderful charts on common causes of fever (by geographic area) as well as common infections organized by incubation period! http://wwwnc.cdc.gov/travel/yellowbook/2016/post-travel-evaluation/fever-in-returned-travelers

 

Evernote Link: https://www.evernote.com/shard/s338/sh/2c8440c6-912f-448f-81ea-98467ea2521f/6d3bdf8b3ed8685f10565a66f4bc5a5c

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