A 3-month-old boy is brought to the emergency department due to fever and respiratory distress. The patient's parents report that he has had a cough and labored breathing over the past 2 weeks. He was born at term and lives at home in North Carolina with his parents, 2 older siblings, and grandmother. The family has 2 dogs and a cat. The grandmother has a chronic cough, but there are no other sick contacts or recent travel. Temperature is 39.1 C (102.4 F). The patient is pale and lethargic. The liver and spleen are palpable 4 cm below the costal margin. CT scan reveals diffuse micronodular lesions in the lungs, liver, and spleen. The boy is intubated and admitted to the intensive care unit. Which of the following is the most likely cause of this patient's findings?
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This infant with fever, cough, lethargy, and respiratory failure has numerous micronodular lesions in the liver, lungs, and spleen, a presentation highly concerning for miliary tuberculosis (TB).
Miliary TB is caused by the lymphohematogenous spread of Mycobacterium tuberculosis. It is a rare but serious complication of primary TB infection in hosts with poor T-cell function, such as infants and immunocompromised persons. The lack of a robust T-cell/macrophage response allows the organism to disseminate throughout the body, including to the lymph nodes, liver, spleen, bones and marrow, and CNS. Hematogenous delivery of M tuberculosis back to the lungs results in the development of pulmonary micronodules that have the classic millet-seed appearance from which the term miliary TB is derived.
Miliary TB presents with chronic and often nonspecific symptoms (eg, fever, failure to thrive), so making the diagnosis requires a high degree of suspicion based on exposures (eg, chronic cough in the grandmother, a household contact). The ineffective T-cell response in these patients means that interferon-based testing, such as interferon-gamma release assays and tuberculin skin testing, is often falsely negative. Definitive diagnosis requires culture of M tuberculosis from lungs, blood, or tissue biopsy.
(Choice A) Bartonella henselae infection can present with prolonged fever, lymphadenopathy, and lesions in the liver and spleen. However, this infection does not cause lung disease and cough.
(Choice B) Chlamydia trachomatis can cause chronic cough in young infants following infection from the maternal genital tract at delivery. However, the liver and spleen are not affected.
(Choice C) Coccidioidomycosis can present with disseminated disease affecting the lungs, liver, and spleen. However, Coccidioides immitis is endemic in the southwestern United States and northern Mexico; coccidioidomycosis is not seen in North Carolina.
(Choice D) Neonatal listeriosis typically presents in the first few days of life with fever, rash, and respiratory distress (early-onset sepsis) or in the first few weeks of life with meningitis (late-onset sepsis). Granulomatosis infantiseptica is a rare, often fatal form of infection in which disseminated abscesses or granulomas are present at birth. Manifestations develop relatively acutely (eg, days). This patient's age and 2-week symptom course make Listeria monocytogenes infection unlikely.
(Choice F) Young infants are at risk for sepsis due to Neisseria meningitidis infection. However, symptom onset is sudden, and micronodular lesions are not present.
Educational objective:
Miliary tuberculosis is caused by lymphohematogenous dissemination of Mycobacterium tuberculosis from the lungs to other organs, resulting in micronodular lesions in the lungs, liver, and spleen. It is most common among infants and immunocompromised hosts with poor T-cell function and is often associated with false-negative tuberculosis test results.