PPD is an appropriate part of chronic cough evaluation. Mycoplasma pneumoniae . Cough is quite troublesome and persistent. Chest x-ray typically shows lower lobe infiltrate. Cold agglutinins are not positive until the second week of illness.
Specific serology is available.
Cough may be prolonged. Serology is available. Erythromycin vs. clarithromycin. Environmental tobacco smoke. Usually follows a typical URI with cough.