A 35-year-old woman comes to the office due to 2 months of productive cough, fever, and weight loss. The patient has no chronic medical conditions and takes no medications. She works as a janitor at a prison in Baltimore. The patient has never traveled outside of Baltimore. She does not use tobacco or illicit drugs but drinks 1 or 2 beers each evening. Temperature is 38.3 C (100.9 F), blood pressure is 120/78 mm Hg, pulse is 84/min, and respirations are 15/min. Examination shows cervical lymphadenopathy and fine crackles at the left upper posterior thorax. Chest x-ray reveals an infiltrate with a small cavity in the left upper lobe. Sputum Gram stain and acid-fast staining show no organisms. Sputum culture is pending. What is the most appropriate next step in management?

Question

A 35-year-old woman comes to the office due to 2 months of productive cough, fever, and weight loss.  The patient has no chronic medical conditions and takes no medications.  She works as a janitor at a prison in Baltimore.  The patient has never traveled outside of Baltimore.  She does not use tobacco or illicit drugs but drinks 1 or 2 beers each evening.  Temperature is 38.3 C (100.9 F), blood pressure is 120/78 mm Hg, pulse is 84/min, and respirations are 15/min.  Examination shows cervical lymphadenopathy and fine crackles at the left upper posterior thorax.  Chest x-ray reveals an infiltrate with a small cavity in the left upper lobe.  Sputum Gram stain and acid-fast staining show no organisms.  Sputum culture is pending.  What is the most appropriate next step in management?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d475_5a2e_bc81_a14580a04ede_MD0003_00 This patient's chronic cough, fever, weight loss, cavitary upper lobe lesion, lymphadenopathy, and employment history (prison setting) raise strong suspicion for active pulmonary tuberculosis (TB). Although culturing Mycobacterium tuberculosis from sputum is the gold standard for diagnosis, culture results are often unavailable for >4 weeks due to the slow replication rate of the organism. Therefore, a tentative diagnosis is often established with rapid testing: Direct microscopy with acid-fast bacillus (AFB) stain: Because this technique requires a high burden of organisms (>10,000/mL) for a positive result, the sensitivity of a single sample is low (~50%). TB cannot be ruled out with one negative AFB sputum stain. However, sensitivity is increased to ~85% by taking 3 samples 8-24 hours apart. AFB stain cannot differentiate tuberculous from nontuberculous mycobacteria. Nucleic acid amplification testing (NAAT): Fewer bacilli (~10/mL) are required for positive testing, so sensitivity is higher than with AFB stain. NAAT also specifically identifies M tuberculosis. However, results take 24-48 hours. Patients with a high pretest probability of pulmonary TB (as in this case), require airborne isolation, a series of sputum tests/cultures, and initiation of empiric therapy while awaiting test results to reduce transmission and progression. Treatment involves 2 months of 4-drug therapy with isoniazid, rifampin, pyrazinamide, and ethambutol followed by 4 months of 2-drug therapy with isoniazid and rifampin; initial 2-drug therapy is ineffective and increases the risk of resistance (Choice B). Directly observed or video-observed therapy is recommended to ensure compliance. (Choices A and D) Aspiration pneumonia can cause cavitary lung lesions and can sometimes be treated empirically with amoxicillin-clavulanate (anaerobic organisms are also slow-growing); however, aspiration is most common in those with dysphagia or periods of reduced consciousness (eg, alcoholism, drug abuse, seizure) and generally causes symptoms over a few days/weeks (not months). Community-acquired pneumonia can be treated with high-dose levofloxacin. However, most patients develop symptoms within hours/days (not months), and most cases are marked by lobar, not cavitary, infiltrates. The combination of amoxicillin-clavulanate and levofloxacin is not commonly used; and because fluoroquinolones partially treat TB, levofloxacin monotherapy is not appropriate in patients in whom TB is suspected (increased risk of resistance). (Choice E) Delaying therapy in a patient with a high-pretest probability of pulmonary TB increases the risk of progression and spread. Patients with a high pre-test probability of disease should be given empiric therapy while awaiting test results. Educational objective: Mycobacterium tuberculosis takes several weeks to grow in culture. In order to reduce the risk of transmission and progression, patients with a high pretest probability of pulmonary tuberculosis require empiric 4-drug treatment with isoniazid, rifampin, pyrazinamide, and ethambutol while awaiting culture results. Although rapid testing (eg, acid fast bacilli stain) supports the diagnosis, several samples are required to achieve adequate sensitivity.

A 35-Year-Old Woman Comes to the Office Due to 2