@ShinGetsu
Penicillin is the first known antibacterial, but unfortunately it can do very little against plague bacteria. . . other antibiotic strains suitable for the family Enterobacteriaceae would be needed. The best cure would be to synthesize streptomycin from actinobacterial cultures, followed by a narrow turn of the wheel by a restoration of bacteria for intestinal flora. . .
I mean, it's not that much of a health walk without the right tools and knowledge.
For the medical knowledge and the means they have (since despite the nineteenth-century clothes seem to have a medieval culture) the only salvation is "escapes from haunted places, washes and disinfects everything, does not eat anything raw and hopes to God not to be infected. And if you're infected, hope to be one of the very few lucky ones who can fight the bacteria naturally. Otherwise we'll see you at the next reincarnation, if you believe (lol)"