Combination of thienamycin-type antibiotics with dipeptidase inhibitors

An antibacterial composition comprising a combination of thienamycin-type compound of the formula ##STR73## wherein X is CH.sub.2 or S;

• R.sup.2 is H;
• --S--C.sub.1 --C.sub.6 alkyl;
• --S--(CH.sub.2).sub.2 --NHR.sup.3 wherein R.sup.3 is H, acetyl, formimidoyl, or acetimidoyl;
• --S(O)--CH.dbd.CHNHCOCH.sub.3 ;
• or --S--CH.dbd.CHNHCOCH.sub.3 and R.sup.6 is H or ##STR74## wherein R.sup.7 is H, OH or sulfonyloxy and a dipeptidase (3.C.3.413.11) inhibitor compound of the following formula ##STR75## wherein R.sup.2 and R.sup.3 are hydrocarbon radicals in the range respectively of 3-10 and 1-15 carbon atoms;
• in either one of these R.sup.2 or R.sup.3 hydrocarbon chains 1-6 hydrogens may be replaced by halogens or a nonterminal methylene may be replaced by oxygen or sulfur, including oxidized forms of the latter;
• additionally, a terminal hydrogen in R.sup.3 can also be replaced by hydroxyl or thiol, which may be acylated or carbamoylated;
• or the hydrogen can be replaced by amino, which may be derivatized as in an acylamino, ureido, amidino, guanidino, or alkyl or substituted alkyl amino group, including quaternary nitrogen groupings;
• or, there may be replacement by acid groups such as carboxylic, phosphonic or sulfonic acid groups or esters or amides thereof, or cyano;
• or combinations thereof, such as a terminal amino acid grouping;
• and R.sup.1 is hydrogen or lower alkyl (C.sub.1-6) or dialkylaminoalkyl, or a pharmaceutically acceptable cation, the ratio of the thienamycin-type compound to the dipeptidase inhibitor being within the range of about 1:3 to about 30:1.