A patient has a strong productive cough for 3 weeks. He comp…

A patient has a strong productive cough for 3 weeks. He complains of fever, chills, and night sweats. The radiograph is consistent with patchy infiltrates and blebs. In addition, the white blood cell count is found to be elevated. The sputum is described as hemoptysis. Which of the following laboratory tests would you recommend to render a diagnosis?