A 57-year-old woman returns to the physician because of a worsening, productive cough and generalized weakness. She was healthy until approximately 3 months ago when she was diagnosed with her first episode of pneumonia and treated with antibiotics. She felt better but had a lingering cough. Three weeks ago, she was admitted to the hospital for another episode of pneumonia and was treated with 10 days of antibiotics. She has lost approximately 10 pounds (4.5 kg) in these 3 months. One expectorated sputum culture from the last admission grew Mycobacterium avium-intracellulare complex (MAC) at 20 days incubation. Testing for HIV infection was negative.
Her other medical problems include type 2 diabetes mellitus, allergic rhinitis, and chronic hypertension. She gets sinus infections once every 2 to 3 years requiring antibiotics. Four months ago, she was diagnosed with Bell's palsy and was treated with a course of prednisone and acyclovir, with complete recovery. Her medications include lisinopril, hydrochlorothiazide, metformin, nasal fluticasone, and loratadine. She has never smoked.
Her temperature is 37.8 C (100.1 F), blood pressure is 112/78 mm Hg, and pulse is 98/min. Examination reveals patchy crackles in both lungs. Heart sounds are normal. There are no skin rashes or swollen joints.
Her chest-x ray and CT scan show multiple nodular opacities with some cavities. Some bronchiectatic changes are noted in the right middle lobe and left lingula. Serum chemistries are within normal limits.
Which of the following is the most appropriate next step in management?

Question

A 57-year-old woman returns to the physician because of a worsening, productive cough and generalized weakness.  She was healthy until approximately 3 months ago when she was diagnosed with her first episode of pneumonia and treated with antibiotics.  She felt better but had a lingering cough.  Three weeks ago, she was admitted to the hospital for another episode of pneumonia and was treated with 10 days of antibiotics.  She has lost approximately 10 pounds (4.5 kg) in these 3 months.  One expectorated sputum culture from the last admission grew Mycobacterium avium-intracellulare complex (MAC) at 20 days incubation.  Testing for HIV infection was negative.
Her other medical problems include type 2 diabetes mellitus, allergic rhinitis, and chronic hypertension.  She gets sinus infections once every 2 to 3 years requiring antibiotics.  Four months ago, she was diagnosed with Bell's palsy and was treated with a course of prednisone and acyclovir, with complete recovery.  Her medications include lisinopril, hydrochlorothiazide, metformin, nasal fluticasone, and loratadine.  She has never smoked.
Her temperature is 37.8 C (100.1 F), blood pressure is 112/78 mm Hg, and pulse is 98/min.  Examination reveals patchy crackles in both lungs.  Heart sounds are normal.  There are no skin rashes or swollen joints.
Her chest-x ray and CT scan show multiple nodular opacities with some cavities.  Some bronchiectatic changes are noted in the right middle lobe and left lingula.  Serum chemistries are within normal limits.
Which of the following is the most appropriate next step in management?

Quizplus · Accepted Answer

11ec193a_984d_dda7_853d_e57bfc9e7b86_MD0002_00 This patient's clinical history and presentation is consistent with non-tuberculosis mycobacterial (NTM) lung disease. These infections are most frequently caused by Mycobacterium avium or Mycobacterium intracellulare, which are generally grouped together as Mycobacterium avium-intracellulare complex (MAC). Pulmonary MAC infection frequently occurs in non-HIV patients with underlying lung disease (e.g., cystic fibrosis, COPD, or alpha-1 antitrypsin deficiency), but it can also occur in the absence of prior lung disease (e.g., hot tub lung). MAC is commonly found in the environment (even in the tap water of some US areas), and can present with symptoms similar to tuberculosis (e.g., fever, cough, weight loss). Current guidelines recommend the presence of clinical criteria in addition to microbiological confirmation to diagnose pulmonary MAC disease. Since MAC can contaminate or colonize sputum, confirmation of pulmonary MAC disease requires at least 2 positive sputum cultures. However, M. tuberculosis positive sputum is always pathologic and should be treated. This patient meets the clinical criteria for pulmonary MAC, but has only one positive sputum culture. A repeat sputum sample is needed to establish the diagnosis, and if the repeat sputum is negative, a positive culture from a BAL specimen would then be required. Treatment involves a combination of clarithromycin, ethambutol, and rifampin for nodular/bronchiectatic MAC. (Choice A) CT-guided biopsy of the pulmonary nodules is invasive, but may be required if the repeat sputum sample is negative in order to establish a diagnosis. (Choice B) Cyclic antineutrophil cytoplasmic antibodies are usually positive in granulomatosis with polyangiitis (Wegener's), but this patient's lack of renal disease makes this unlikely. (Choice C) Isoniazid, rifampin, ethambutol, and pyrazinamide are used for Mycobacterium tuberculosis, which can present similarly to this patient's presentation. However, her sputum did not grow M. tuberculosis. (Choice E) Serum angiotensin converting enzyme may be elevated in sarcoidosis, which can be associated with cranial nerve VII palsy. However, this patient's abnormal sputum culture makes this diagnosis less likely. Educational objective: Mycobacterium avium-intracellulare complex (MAC) is commonly found in the environment and can contaminate or colonize sputum. The diagnosis of pulmonary MAC infection requires the presence of clinical criteria in addition to microbiological confirmation, with at least 2 positive sputum cultures. Once diagnosis is confirmed, patients are treated with combination therapy of clarithromycin, ethambutol, and rifampin. __________ References: Pulmonary nontuberculous mycobacterial disease prevalence and clinical features: an emerging public health disease (http://www.ncbi.nlm.nih.gov/pubmed/20508209) Nontuberculosis mycobacterial lung diseases (http://www.ncbi.nlm.nih.gov/pubmed/20674803)

A 57-Year-Old Woman Returns to the Physician Because of a Worsening