It's too late for penicillin at this point.
The penicillin itself would probably develop chancres.
What Kitty now has seems to be a particularly virulent and highly antibiotic-resistant strain of some variety of STD that in its later stages attacks the central nervous system.
Or at least that is what I think Ann may have been hinting at.
Ann can be so obscure at times, that occasionally I fear I may miss her most important points in her weekly addresses.