ium ▁not atum ▁( since ▁renamed ▁Pen ic ill ium ▁ch rys ogen um ). ▁ ▁B acter ia ▁often ▁develop ▁resistance ▁to ▁ β - la ct am ▁ant ib iot ics ▁by ▁synth es izing ▁a ▁ β - la ct am ase , ▁an ▁en zym e ▁that ▁attacks ▁the ▁ β - la ct am ▁ring . ▁To ▁overcome ▁this ▁resistance , ▁ β - la ct am ▁ant ib iot ics ▁are ▁often ▁given ▁with ▁ β - la ct am ase ▁in hib itors ▁such ▁as ▁cla v ul an ic ▁acid . ▁ ▁Medical ▁use ▁ β - la ct am ▁ant ib iot ics ▁are ▁indicated ▁for ▁the ▁prevent ion ▁and ▁treatment ▁of ▁b acter ial ▁in fe ctions ▁caused ▁by ▁sus cept ible ▁organ isms . ▁At ▁first , ▁ β - la ct am ▁ant ib iot ics ▁were ▁mainly ▁active ▁only ▁against ▁Gram - pos itive ▁b acter ia , ▁yet ▁the ▁recent ▁development ▁of ▁broad - spect rum ▁ β - la ct am ▁ant ib iot ics ▁active ▁against ▁various ▁Gram - negative ▁organ isms ▁has ▁increased ▁their ▁useful ness . ▁ ▁Ad verse ▁effects ▁ ▁Ad verse ▁drug ▁re actions ▁Common ▁ad verse ▁drug ▁re actions ▁for ▁the ▁ β - la ct am ▁ant ib iot ics ▁include ▁di arr he a , ▁n ause a , ▁r ash , ▁u rt ic aria , ▁super in fection ▁( including ▁candid ias is ). ▁ ▁Inf re quent