Long story short: since medkits no longer cure infection and antibiotics no longer cure infection instantly, “infected” scenario got MUCH more difficult.
And the real problem is, quite likely you only have 8 hours to get antibiotics because at that point penalties effectively disable most characters. Which is very steep now that you will likely have to search for much longer to get them.
I would suggest that the player should be given more time to find them to compensate. I. e. add a couple of WEAK antibiotics pills to starting inventory to slow down the onset of symptoms without actually changing the overall situation too much. As a nice bonus we can add some story fluff that the characters was, in fact, trying to prevent the wound from getting infected, but just got too weak antibiotics.
Well, character can cure an infection without any drugs, too. (It’s just very unlikely.)
But if that’s somehow an issue, I see no reason not to instance a unique drug for this scenario that simply slows the infection without helping you cure it.
Heck, this drug can be made to both slow the infection and LOWER you chances to cure naturally while it’s in effect.