Infectious Disease · Gastrointestinal Infections
The facts most likely to be tested
Salmonella enterica serotype Typhi causes typhoid fever, characterized by a step-ladder fever pattern, abdominal pain, and hepatosplenomegaly.
Patients with typhoid fever often present with rose spots, which are faint, salmon-colored maculopapular lesions on the trunk.
Salmonella species are motile, Gram-negative rods that produce hydrogen sulfide (H2S) on Hektoen enteric agar.
Transmission of non-typhoidal Salmonella typically occurs via ingestion of contaminated poultry, eggs, or contact with reptiles.
Patients with sickle cell disease or other hemoglobinopathies have an increased risk of Salmonella osteomyelitis.
Antibiotic treatment for non-typhoidal Salmonella is generally reserved for immunocompromised patients, infants, or those with severe systemic disease.
The chronic carrier state of Salmonella Typhi is associated with colonization of the gallbladder, often requiring cholecystectomy for eradication.
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A 24-year-old male presents with a 10-day history of progressive high-grade fever, malaise, and constipation. Physical examination reveals hepatosplenomegaly and a few faint, salmon-colored macules on his abdomen. He recently returned from a trip to Southeast Asia where he consumed street food. Laboratory studies show leukopenia and elevated transaminases. His blood cultures are currently pending.
What is the most likely diagnosis?
Typhoid fever (Enteric fever)
The patient's presentation of a step-ladder fever, rose spots, and hepatosplenomegaly following travel to an endemic area is classic for typhoid fever, which is tested via the clinical features described in Bet 1 and Bet 2.
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Etiology / Epidemiology
Caused by Salmonella enterica; associated with poultry, eggs, and reptiles. High risk in immunocompromised and sickle cell patients.
Clinical Manifestations
Presents as pea-soup diarrhea and rose spots. Look for fever and abdominal pain.
Diagnosis
Stool culture is the gold standard. Blood cultures are required for systemic enteric fever.
Treatment
Ciprofloxacin is first-line for severe cases. Avoid antibiotics in mild, uncomplicated gastroenteritis.
Prognosis
Most recover in 5-7 days. Osteomyelitis is a major risk in sickle cell disease.
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Epidemiology & Etiology
Transmission occurs via the fecal-oral route through contaminated food or water. Outbreaks are frequently linked to undercooked poultry or contact with pet turtles. Patients with achlorhydria or those on PPIs have lower infectious dose thresholds.
Pertinent Anatomy
The bacteria primarily colonize the distal ileum and colon. Systemic spread involves the reticuloendothelial system, specifically the liver, spleen, and bone marrow.
Pathophysiology
Ingested bacteria invade the intestinal mucosa, triggering an inflammatory response and neutrophil recruitment. In Typhoid fever, the organism survives within macrophages, allowing for hematogenous dissemination. This intracellular survival explains the risk of chronic gallbladder carriage.
Clinical Manifestations
Gastroenteritis presents with fever, abdominal cramps, and bloody diarrhea. Rose spots (faint salmon-colored macules on the trunk) are pathognomonic for Typhoid fever. Red flags include high-grade fever, severe dehydration, and signs of intestinal perforation.
Diagnosis
Stool culture is the diagnostic test of choice for gastroenteritis. For systemic enteric fever, blood cultures are more sensitive than stool. PCR testing is increasingly used for rapid identification of specific serotypes.
Treatment
Supportive care with fluid resuscitation is the mainstay for mild cases. Ciprofloxacin is the first-line agent for severe or systemic disease. Avoid antibiotics in uncomplicated cases as they may prolong the carrier state.
Prognosis
Most patients recover spontaneously within one week. Osteomyelitis is a classic complication in patients with sickle cell disease due to functional asplenia. Chronic carriers require cholecystectomy if the gallbladder is the reservoir.
Differential Diagnosis
Shigellosis: high fever and frequent, small-volume bloody stools
Campylobacter: associated with raw poultry and post-infectious Guillain-Barré
Yersinia enterocolitica: mimics acute appendicitis
E. coli (EHEC): associated with HUS and lack of fever
Viral gastroenteritis: typically afebrile and watery diarrhea