▁could ▁not ▁be ▁used ▁system ically ▁because ▁of ▁to x icity . ▁Ty roc id ine ▁also ▁proved ▁too ▁to xic ▁for ▁system ic ▁usage . ▁Research ▁results ▁obtained ▁during ▁that ▁period ▁were ▁not ▁shared ▁between ▁the ▁A xis ▁and ▁the ▁Al lied ▁powers ▁during ▁World ▁War ▁II ▁and ▁limited ▁access ▁during ▁the ▁Cold ▁War . ▁ ▁Late ▁ 2 0 th ▁century ▁During ▁the ▁mid - 2 0 th ▁century , ▁the ▁number ▁of ▁new ▁ant ib i otic ▁subst ances ▁introduced ▁for ▁medical ▁use ▁increased ▁significantly . ▁From ▁ 1 9 3 5 ▁to ▁ 1 9 6 8 , ▁ 1 2 ▁new ▁classes ▁were ▁launched . ▁However , ▁after ▁this , ▁the ▁number ▁of ▁new ▁classes ▁dropped ▁marked ly , ▁with ▁only ▁two ▁new ▁classes ▁introduced ▁between ▁ 1 9 6 9 ▁and ▁ 2 0 0 3 . ▁ ▁Et ym ology ▁ ▁The ▁term ▁' ant ib ios is ', ▁meaning ▁" ag ain st ▁life ", ▁was ▁introduced ▁by ▁the ▁French ▁b acter i ologist ▁Jean ▁Paul ▁V u ille min ▁as ▁a ▁descript ive ▁name ▁of ▁the ▁phenomen on ▁exhib ited ▁by ▁these ▁early ▁ant ib acter ial ▁dru gs . ▁Ant ib ios is ▁was ▁first ▁described ▁in ▁ 1 8 7 7 ▁in ▁b acter ia ▁when ▁Louis ▁P aste ur ▁and ▁Robert ▁Koch ▁observed ▁that ▁an ▁air bor ne ▁b ac ill us ▁could ▁in hib it ▁the ▁growth ▁of ▁Bac ill us ▁anth rac is . ▁These ▁dru gs ▁were ▁later