Rapid diagnostic tests exist for several patho- gens currently linked to acute bronchitis. However, not all the rapid tests are widely available, and their routine use is not cost-effective in an outpa- tient setting. Rapid tests should be used primarily when the suspected organism is treatable, the in- fection is known to be circulating in the commu- nity, and the patient has suggestive symptoms or signs (e.g., testing for inf luenza during inf luenza season in patients with cough and fever) (Table 1). Multiplex polymerase-chain-reaction (PCR) testing of nasopharyngeal swabs or aspirates is being developed to diagnose infections resulting from B. pertussis, M. pneumoniae, or C. pneumoniae with clinically useful sensitivity and specificity, as com- pared with culture or monoplex PCR.30