Abstract: Antibiotic compounds of the general formula ##STR1## [wherein R is a phenyl, thienyl or furyl group; R.sup.a and R.sup.b, which may be the same or different, are each selected from hydrogen, C.sub.1-4 alkyl, C.sub.2-4 alkenyl C.sub.3-7 cycloalkyl, phenyl, naphthyl, thienyl, furyl, carboxy, C.sub.2-5 alkoxycarbonyl and cyano, or R.sup.a and R.sup.b together with the carbon atom to which they are attached from a C.sub.3-7 cycloalkylidene or cycloalkenylidene group; R.sup.c is hydrogen or lower alkyl; R.sup.d is hydroxy, lower alkoxy, aralkoxy or aryloxy; m and n are each 0 or 1 such that the sum of m and n is 0 or 1; and P is selected from a hydrogen atom, a halogen atom and various organic groups] and non-toxic derivatives thereof.

Abstract: Cephalosporin antibiotics in which the 7.beta.-acylamido group has the formula ##STR1## (where R.sup.1 is furyl or thienyl and R.sup.2 is C.sub.1-4 alkyl, C.sub.3-7 cycloalkyl, furylmethyl or thienylmethyl) and in which the 3-position substituent is a pyridiniummethyl group wherein the pyridine ring is optionally substituted by carbamoyl, carboxy, carboxymethyl, sulpho or methyl exhibit high antibacterial activity against a broad range of gram-positive and gram-negative organisms, coupled with particularly high stability to .beta.-lactamases produced by various gram-negative organisms and good stability in vivo, particularly to esterases.

Abstract: Novel semisynthetic 4-thio-azetidin-2-one derivatives of use in the production of cephalosporins, penicillins and related .beta.-lactam antibiotic compounds are provided by cleavage reactions involving the corresponding 4-dithio-azetidin-2-one derivative or a suitable thiazoline derivative, which starting materials may be obtained from penicillins without changing the configuration of the .beta.-lactam structure desired in the final product.