s nr a c and ch u2550 ch q is str2 l represents a c 1 8 alkylene group straight or branched and unsubstituted or substituted with 1 3 r c groups and b represents str3 the carbapenems of the present invention are useful against gram positive microorganisms especially methicillin resistant staphylococci application_number US 16841998 A description the invention is described herein in detail using the terms below unless otherwise specified the term 34 alkyl 34 refers to a monovalent alkane hydrocarbon derived radical containing from 1 to 15 carbon atoms unless otherwise defined it may be straight branched or cyclic preferred alkyl groups include methyl ethyl propyl isopropyl butyl t butyl cyclopentyl and cyclohexyl when substituted alkyl groups may be substituted with up to four substituent at any available point of attachment cycloalkyl is a specie of alkyl containing from 3 to 15 carbon atoms without alternating or resonating double bonds between carbon atoms it may contain from 1 to 4 rings which are fused the term 34 alkenyl 34 refers to a hydrocarbon radical straight branched or cyclic containing from 2 to 10 carbon atoms and at least one carbon to carbon double bond preferred alkenyl groups include ethenyl propenyl butenyl and cyclohexenyl the term 34 alkynyl 34 refers to a hydrocarbon radical straight or branched containing from 2 to 10 carbon atoms.