Described herein are methods for the manufacture of ceftolozane and related compounds, as well as compositions comprising the same.

Cephem compounds, pharmaceutically acceptable salts thereof, and methods of using same, wherein the compound has a bicyclic nitrogen-containing aromatic heterocyclic ring as the quaternary ammoniomethyl group at the 3-position and one or both of a terminal amidine residue (substituted or unsubstituted) attached to an aryl or a 5- or 6-membered heteroaryl group (substituted or unsubstituted) which is further attached through a spacer to the free N-atom of the quaternary nitrogen-containing bicyclic ring at the 3-side chain, or a terminal guanidine residue attached to an aryl or a 5- or 6-membered heteroaryl group (substituted or unsubstituted) which is further attached through a spacer to the free N-atom of the quaternary nitrogen-containing bicyclic ring at the 3-side chain.

Cephem compounds, pharmaceutically acceptable salts thereof, and methods of using same, wherein the compound has a bicyclic nitrogen-containing aromatic heterocyclic ring as the quaternary ammoniomethyl group at the 3-position and one or both of a terminal amidine residue (substituted or unsubstituted) attached to an aryl or a 5- or 6-membered heteroaryl group (substituted or unsubstituted) which is further attached through a spacer to the free N-atom of the quaternary nitrogen-containing bicyclic ring at the 3-side chain, or a terminal guanidine residue attached to an aryl or a 5- or 6-membered heteroaryl group (substituted or unsubstituted) which is further attached through a spacer to the free N-atom of the quaternary nitrogen-containing bicyclic ring at the 3-side chain.

Cephem compounds, pharmaceutically acceptable salts thereof, and methods of using same, wherein the compound has a bicyclic nitrogen-containing aromatic heterocyclic ring as the quaternary ammoniomethyl group at the 3-position and one or both of a terminal amidine residue (substituted or unsubstituted) attached to an aryl or a 5- or 6-membered heteroaryl group (substituted or unsubstituted) which is further attached through a spacer to the free N-atom of the quaternary nitrogen-containing bicyclic ring at the 3-side chain, or a terminal guanidine residue attached to an aryl or a 5- or 6-membered heteroaryl group (substituted or unsubstituted) which is further attached through a spacer to the free N-atom of the quaternary nitrogen-containing bicyclic ring at the 3-side chain.

Cephem compounds, pharmaceutically acceptable salts thereof, and methods of using same, wherein the compound has a bicyclic nitrogen-containing aromatic heterocyclic ring as the quaternary ammoniomethyl group at the 3-position and one or both of a terminal amidine residue (substituted or unsubstituted) attached to an aryl or a 5- or 6-membered heteroaryl group (substituted or unsubstituted) which is further attached through a spacer to the free N-atom of the quaternary nitrogen-containing bicyclic ring at the 3-side chain, or a terminal guanidine residue attached to an aryl or a 5- or 6-membered heteroaryl group (substituted or unsubstituted) which is further attached through a spacer to the free N-atom of the quaternary nitrogen-containing bicyclic ring at the 3-side chain.