I'm not that old, mate :) Sure, it was the previous millenium, but the late 90s - not the stone age...
Funny thing is, it was actually in the USA. Russian docs never write scripts for long- or even mid-term Antibiotics w/o nystatin. It's standard procedure here and has been for the last 30 years or so.
...also, Russian docs, for all their faults, will certainly at least question how the hell a sheltered upper-middle-class little kid from the suburbs got a disease that's an issue exclusive to the country's high-security prison population. Anyone with half a brain would figure it to be about as likely as catching the bubonic plague :)
Mum's script-stamper, on the other hand, probably remembered some article about TB being an issue there and figured "sounds right", cuz it's a well-known fact that everyone in the rest of the world - and, hell, in the rest of his own star-spangled country bar his little multi-million-dollar gated community - lives in a horrific morass of mud huts, drinks from ditches that double as open sewers, and shares needles with toddlers for kicks'n'giggles.