What test should be performed next if a 12-year-old girl has a positive RPR and a positive spot test for infectious mononucleosis?

In this scenario, the girl presents with a positive RPR (Rapid Plasma Reagin) test and a positive spot test for infectious mononucleosis. The RPR test is a non-treponemal test that can indicate syphilis but may also yield false-positive results when certain conditions are present, including viral infections such as infectious mononucleosis caused by the Epstein-Barr virus (EBV).

To clarify the situation regarding the RPR result, the next logical step is to confirm whether the positive RPR is indeed indicative of syphilis or if it is a false positive due to the concurrent infectious mononucleosis. The Treponema pallidum particle agglutination (TP-PA) test is a treponemal test that specifically detects antibodies against the Treponema pallidum organism, which causes syphilis. A positive TP-PA would confirm a diagnosis of syphilis and provide clarity regarding the girl's RPR result.

Performing an EBV-specific antigen test could help confirm infectious mononucleosis but would not address the uncertainty around the RPR test. An HIV test by ELISA is also relevant for overall screening; however, it would not specifically clarify the relationship between the