Abstract: Antibiotically active compounds derived from rifamycin S or from the corresponding hydroquinone, rifamycin SV, or from derivatives at least partially hydrogenated in positions 16, 17; 18, 19; 28, 29, such as the 16, 17; 18, 19 - tetrahydro- or the 16, 17; 18, 19; 28, 29 - hexahydro derivatives, which contain in position 3 a free or an aliphatically substituted amino group. The hydrocarbon radicals of the aliphatically substituted amino group can also be interrupted in their carbon chain by heteroatoms and/or be substituted by functional groups.A special group of these new compounds is represented by 3-amino derivatives as defined above, in which the amino group is a particular type of N- aza - cyclo - aliphatic radical unsubstituted by functional groups, and which has, in addition to the antibiotic action against sensitive microorganisms also an antibacterial activity against certain types of resistant microorganisms.

Abstract: The invention concerns 7.beta.-amino-cepham-3-ol-4-carboxylic acid compounds, particularly esters thereof, and the N-substituted, especially N-acylated derivatives of such compounds, as well as the 3-O-esters of these compounds. They can be used as intermediates, for example, for the manufacture of the corresponding 3-unsubstituted 7.beta.-amino-3-cephem-4-carboxylic acid compounds, which show outstanding pharmacological effects.

Abstract: 6-Acylamino-penam-3-carboxylic acids and 7-acylamino-3-cephem-4-carboxylic acids in which the acyl group has the formula ##EQU1## in which R.sub.1 is hydrogen, R.sub.2 is optionally substituted phenyl, thienyl or furyl, or R.sub.1 and R.sub.2 together are optionally substituted cycloalkyl, and B is a radical which is bonded via a sulphur atom or is bonded to oxygen or sulphur with the interposition of an optionally substituted CH.sub.2 -group.

Abstract: 3-R-Methyl-7-amino-ceph-2-em-4.xi.-carboxylic acid compounds, in which R is the C-residue of a C-nucleophilic compound are valuable intermediates, for example, in the manufacture of the corresponding 3-R-methyl-7-amino-ceph-3-em-4-carboxylic acid compounds with antibiotic properties.

Abstract: 7-Aminopyridiniumacetylamino-cephalosporanic acids and derivatives thereof. The new compounds have antibacterial properties.