Final answer:
PCR for Rickettsia rickettsii is the test that can be used to confirm RMSF diagnosis, alongside clinical evaluation. ELISA may also be employed, but requires DNA testing or culture for confirmation. Blood culture and Western blot are other methods, but less commonly employed for RMSF.
Step-by-step explanation:
The diagnosis of Rocky Mountain spotted fever (RMSF) is primarily clinical, involving observation of symptoms and patient history. However, additional tests can be run to confirm the diagnosis. Among the options provided, PCR (Polymerase Chain Reaction) for Rickettsia rickettsii, the causative agent of RMSF, is a molecular test that can help identify the presence of the bacteria’s DNA. ELISA (enzyme-linked immunosorbent assay) can also be used for serological detection, but confirmation with DNA testing or culture is necessary. In contrast, a blood culture may be used, but the bacteria are not easily isolated, and serologic tests like Western blot may be considered after ELISA. PCR tends to be more rapid and can detect systemic infections efficiently.