Are there any non-beta-lactam antibiotic options for treatment of neurosyphilis in non-pregnant adults?  

Doxycycline is a consideration. There are no conclusive data, but a few anecdotal reports are supportive -- the most recent (in a brief PubMed search) cited below. On the other hand, there is at least one case report (also cited) of a patient treated with doxycycline who subsequently re-presented wi...