▁from ▁Mexico , ▁( 1 9 9 2 - 1 9 9 6 ), ▁and ▁Gonz alo ▁Me j ía , ▁from ▁the ▁Domin ican ▁Republic , ▁( 1 9 9 6 - 2 0 0 0 ). ▁ ▁Aff ili ated ▁M embers ▁ ▁These ▁are ▁the ▁members ▁of ▁C OT E CC : ▁ ▁References ▁▁▁ ▁Category : T ennis ▁organizations <0x0A> </s> ▁ β - la ct am ▁ant ib iot ics ▁( beta - la ct am ▁ant ib iot ics ) ▁are ▁the ▁ant ib i otic ▁agents ▁that ▁contain ▁a ▁beta - la ct am ▁ring ▁in ▁their ▁mole cular ▁structure . ▁This ▁includes ▁pen ic ill in ▁derivatives ▁( pen ams ), ▁ce phal os por ins ▁( ce ph ems ), ▁mon ob act ams , ▁car b ap en ems ▁and ▁car b ace ph ems . ▁Most ▁ β - la ct am ▁ant ib iot ics ▁work ▁by ▁in hib iting ▁cell ▁wall ▁b ios yn thesis ▁in ▁the ▁b acter ial ▁organ ism ▁and ▁are ▁the ▁most ▁widely ▁used ▁group ▁of ▁ant ib iot ics . ▁Until ▁ 2 0 0 3 , ▁when ▁measured ▁by ▁sales , ▁more ▁than ▁half ▁of ▁all ▁commer cially ▁available ▁ant ib iot ics ▁in ▁use ▁were ▁ β - la ct am ▁comp ounds . ▁The ▁first ▁ β - la ct am ▁ant ib i otic ▁discovered , ▁pen ic ill in , ▁was ▁isolated ▁from ▁a ▁rare ▁variant ▁of ▁Pen ic ill