Antibacterial agents and potentiators of carbapenem antibiotics

A pharmaceutical composition useful in the treatment of antibacterial infections which comprises a pharmaceutically acceptable carrier and a pharmaceutically effective amount to treat bacterial infections of an antibacterial compound of formula I:

• ##STR53## wherein R.sub.1 is
• H, or
• CH.sub.3 ;
• R.sub.2 is
• (a) hydrogen;
• (b) C.sub.1 -C.sub.12 linear or branched alkyl;
• (c) C.sub.1 -C.sub.12 linear or branched monoalkenyl;
• (d) C.sub.7 -C.sub.20 aralkyl, wherein the alkyl chain is linear or branched C.sub.1 -C.sub.8 and wherein said above values from R.sub.2 can be substituted by one halo, hydroxy, carboxy, C.sub.1 -C.sub.4 alkoxycarbonyl, C.sub.7 -C.sub.16 arylalkoxycarbonyl, C.sub.3 -C.sub.7 cycloalkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.6 -C.sub.12 aryloxy, amino, mono- or di-C.sub.1 -C.sub.8 alkylamino, thio, C.sub.1 -C.sub.4 alkylthio, C.sub.6 -C.sub.12 arylthio, C.sub.7 -C.sub.16 aralkylthio, or the radical --S--(CH.sub.2).sub.n --CH--(NH.sub.2)COOH, where n=1-2;
• with the proviso that R.sub.2 is at least C.sub.2 alkyl if substituted by one of the above-defined thio groups, and wherein the aryl ring can be further substituted by one C.sub.1 -C.sub.4 linear or branched alkyl, trihalomethyl, nitro, halo, cyano or sulfonamido;
• R.sub.3 and R.sub.4 are
• hydrogen,
• C.sub.1 -C.sub.4 alkyl;
• wherein the carbon atoms attached to R.sub.1 are D(S) or DL(SR) and R.sub.2 are D(R) or DL(RS) stereoconfiguration.