Question | Discussion | References | CME Credit  Case 5: A
32-Year-Old with Chronic Cough  You answered:  E The patient’s
CD4 cell count is almost certainly less than 100 cells/mm3.
This answer is incorrect. Tuberculosis can occur at any CD4
count in an HIV-infected patient. This patient’s ability to
mount a reaction to the tuberculin skin test indicates some
degree of cell-mediated immunity, but cannot be reliably used to
estimate his CD4 count.  Choose another answer:  A If a nucleic
acid amplification test on sputum is positive for Mycobacterium
tuberculosis, sputum culture is not required. B If the pleural
effusion is tapped, there is greater than 80% likelihood that a
Ziehl-Neelsen stain of pleural fluid will show AFB. C The
patient’s small tuberculin skin test reaction is probably due to
prior BCG vaccination, and an alternative diagnosis should be
sought. D Therapy for TB should be initiated while the
diagnostic work-up continues.  [Back to Case 5 Question | Go to
Correct Answer]