A 2-year-old child was recently adopted from India. She appears to be healthy, and there are no abnormal symptoms. Her weight and height are at 25th percentile for age. Her examination is normal. On screening, you find a positive TB skin test using purified protein derivative (PPD) with 20 mm induration. She has a history of receiving a BCG vaccination at birth. Your management plan is to do which of the following?
- Obtain a chest x-ray and treat only if this is abnormal.
- Obtain a chest x-ray and initiate prophylactic treatment with isoniazid (INH).
- Repeat the test in 36 months.
- Attribute the positive PPD to the BCG vaccination and do serial yearly x-rays.
- Obtain sputum cultures.
Answer(s): B
Explanation:
Generally, the interpretation of tuberculin skin test (TST) is the same regardless of BCG status. Induration >5 mm is considered positive in children in close contact with known or suspected cases of tuberculosis disease or children suspected to have tuberculosis disease. Induration >10 mm is considered positive in children at greater risk of disseminated disease (age <4 years; other medical conditions such as lymphoma, diabetes, chronic renal failure, or malnutrition) or children at greater risk of exposure to tuberculosis disease (born in, or parents born in high-prevalence regions, travel to these regions, exposure to adults at high risk, such as HIV infected, homeless, or drug abusers). Induration >15 mm is positive in children >4 years without any risk factors. Radiographic evaluation of all children with positive TST is recommended. Latent tuberculosis infection is defined as an infection in a person with a positive TST, no physical findings of the disease, and a chest radiograph that is either normal or reveals only granulomas or calcifications in the lungs or regional lymph nodes. Children with latent tuberculosis infection should receive prophylaxis, usually 9 months of INH. Those with symptoms, signs, and/or radiographic manifestations are said to have tuberculosis dsease. There is no benefit to repeating the test in 36 months, and it will delay treatment. Sputum cultures are difficult to obtain in younger children. Gastric aspirate specimens obtained with a nasogastric tube are preferred. Culture material should be obtained in children with evidence of the disease in order to obtain information on drug susceptibility and resistance patterns.