Serum cross-reactivity with Aspergillus galactomannan and cryptococcal antigen during fatal disseminated Trichosporon dermatis infection.

To the Editor—We thank Dr. Dylewski [1] for the feedback on our article [2]. It is understood that the usefulness of nucleic acid amplification (NAA) tests varies with the prevalence of the disease among the population being tested. In our article, we do not advocate NAA testing for all specimens submitted for culture. For patients whose specimens have negative acid–fast bacilli (AFB) smear results, our recommendation is to order NAA testing for those patients for whom there is a high suspicion of tuberculosis (TB) disease. The recommendation of the Centers for Disease Control and Prevention (CDC) is “that NAA testing be performed on at least one respiratory specimen from each patient with signs and symptoms of pulmonary TB for whom a diagnosis of TB is being considered” [3, pp. 7–8]. In addition, CDC guidelines state that “NAA tests should not be ordered routinely when the clinical suspicion of TB is low” [3, p. 9]. Furthermore, we do not recommend that laboratories assess which specimens should receive NAA testing. Clinical judgment is essential to optimize the use of these tests. In New York City, we ask that health care providers request NAA testing for patients who have specimens that have negative AFB smear results and in whom there is a high suspicion of TB.