Enteric Fever (Typhoid Fever)

Key Features

Essentials of Diagnosis

• Gradual onset of headache, vomiting, abdominal pain

• Rose spots, relative bradycardia, splenomegaly, and abdominal distention and tenderness

• Slow (stepladder) rise of fever to maximum and then slow return to normal

• Leukopenia; blood, stool, and urine cultures positive for Salmonella

General Considerations

• Caused by typhoidal strains of Salmonella, S typhi (typhoid fever) and to a lesser extent S paratyphi (subtypes A, B and C)

• Unlike other strains of Salmonella, the S typhi and S paratyphi subtypes A and B are restricted to humans

• Infection begins when organisms breach the mucosal epithelium of the intestines

  • Having crossed the epithelial barrier, organisms invade and replicate in macrophages in Peyer patches, mesenteric lymph nodes, and the spleen

  • Serotypes other than typhi usually do not cause invasive disease, presumably because they lack the necessary human-specific virulence factors

  • Bacteremia occurs, and the infection then localizes principally in the lymphoid tissue of the small intestine

  • Peyer patches become inflamed and may ulcerate, with involvement greatest during the third week of disease

  • The organism may disseminate to the lungs, gallbladder, kidneys, or CNS

• May have a long incubation period (6–30 days)

Clinical Findings

Symptoms and Signs

Prodromal stage

• Increasing malaise, headache, cough, and sore throat

• Abdominal pain and constipation are often present while the fever ascends in a stepwise fashion

• During the early prodrome, physical findings are few

• There may be marked constipation

Later stage

• After about 7–10 days, the fever reaches a plateau and the patient is much more ill, appearing exhausted and often prostrated

• Marked constipation may develop into "pea soup" diarrhea

• Splenomegaly, abdominal distention and tenderness, relative bradycardia, and occasionally meningismus appear

• The rash (rose spots) commonly appears during the second week of disease

  • The individual spot, found principally on the trunk, is a pink papule 2–3 mm in diameter that fades on pressure

  • It disappears in 3–4 days

Differential Diagnosis

• Brucellosis

• Tuberculosis

• Infective endocarditis

• Q fever and other rickettsial infections

• Other causes of acute diarrhea

• Viral hepatitis

• Lymphoma

• Amebiasis

• Malaria

Diagnosis

Laboratory Tests

• Best diagnosed by isolation of the organism from blood culture, which is positive in the first week of illness in 80% of patients who have not taken antimicrobial agents

• Cultures of bone marrow occasionally are positive when blood cultures are not

• Leukopenia is observed

• Transaminitis is common

• Stool cultures are often negative by the time systemic symptoms develop

Treatment

Medications

• Agents of choice

  • Ciprofloxacin 750 mg orally twice daily

  • Levofloxacin 500 mg orally once ...