fe ctions . ▁They ▁may ▁either ▁kill ▁or ▁in hib it ▁the ▁growth ▁of ▁b acter ia . ▁A ▁limited ▁number ▁of ▁ant ib iot ics ▁also ▁possess ▁ant ip ro to zo al ▁activity . ▁Ant ib iot ics ▁are ▁not ▁effective ▁against ▁vir uses ▁such ▁as ▁the ▁common ▁cold ▁or ▁influen za ▁; ▁dru gs ▁which ▁in hib it ▁vir uses ▁are ▁term ed ▁ant iv iral ▁dru gs ▁or ▁ant iv ir als ▁rather ▁than ▁ant ib iot ics . ▁ ▁Sometimes , ▁the ▁term ▁ant ib i otic — liter ally ▁" opp osing ▁life ", ▁from ▁the ▁Greek ▁roots ▁ ἀ ν τ ι ▁anti , ▁" ag ain st " ▁and ▁ β ί ος ▁b ios , ▁" life " — is ▁broad ly ▁used ▁to ▁refer ▁to ▁any ▁subst ance ▁used ▁against ▁micro bes , ▁but ▁in ▁the ▁usual ▁medical ▁usage , ▁ant ib iot ics ▁( such ▁as ▁pen ic ill in ) ▁are ▁those ▁produced ▁naturally ▁( by ▁one ▁micro organ ism ▁fighting ▁another ), ▁whereas ▁non ant ib i otic ▁ant ib acter ial s ▁( such ▁as ▁sul fon am ides ▁and ▁ant ise pt ics ) ▁are ▁fully ▁synth etic . ▁However , ▁both ▁classes ▁have ▁the ▁same ▁goal ▁of ▁killing ▁or ▁prevent ing ▁the ▁growth ▁of ▁micro organ isms , ▁and ▁both ▁are ▁included ▁in ▁ant im icro b ial ▁chem other apy . ▁" Ant ib acter ial s " ▁include ▁ant ise ptic ▁dru gs , ▁ant