A 22-year-old male patient, recently incarcerated and now homeless, has received 1 week of clarithromycin for low-grade fever and left upper-lobe pneumonia. He has not improved on antibiotics, with persistent cough productive of purulent sputum and flecks of blood. Repeat chest x-ray suggests a small cavity in the left upper lobe. Which of the following statements is correct?A) The patient has anaerobic infection and needs outpatient clindamycin therapy
The patient is high risk for tuberculosis due to his history of incarceration and homelessness. The location of the infiltrate in the upper lobe, as well as the formation of a cavity, further suggests reactivation tuberculosis. Sputum smear and culture for AFB are mandatory. The patient requires respiratory isolation precautions in a negative pressure room, not contact precautions. Anaerobic infection would be in the differential diagnosis of upper lobe infiltrate with cavity formation, but evaluation for tuberculosis is critical because of the risk of person-to-person spread. Single-drug therapy with INH is a good prophylactic regimen but is inappropriate until active TB is excluded. Monotherapy for active TB leads to the rapid development of drug resistance. The pneumococcus rarely causes cavitary pneumonia. Interferon-gamma release assay and tuberculin skin testing with purified protein derivative are used to diagnose latent TB infection, not active TB disease like the patient presented in the vignette.