A nurse is caring for an 11-year-old child who presents to the emergency department with a mild cough and malaise that have been present for 1 week and an oral temperature of 38.1° C (100.6° F). After gathering a history, the nurse suspects pertussis. Which of the following should the nurse anticipate the healthcare provider to prescribe to aid in the rapid diagnosis of pertussis?

A. Polymerase chain reaction test: PCR testing is the preferred method for rapidly detecting Bordetella pertussis DNA. It is highly sensitive and can confirm the diagnosis early in the course of illness, allowing prompt initiation of appropriate antibiotic therapy. B. Pulmonary function testing (PFT): PFTs assess lung function and are used for chronic respiratory conditions such as asthma, not for diagnosing acute infections like pertussis. C. CT scan: Computed tomography is not indicated for routine diagnosis of pertussis. It is reserved for evaluating complex or severe pulmonary conditions and provides more detail than necessary for bacterial infection identification. D. Chest x-ray: A chest x-ray may help rule out pneumonia or other complications but cannot confirm pertussis. Imaging is supportive, not diagnostic, for pertussis.