Novelties in the field of parenteral cephem antibacterials since 1993

There is still considerable interest in cephem antibacterial agents. In fact, there are a significant number of patents submitted for this antibacterial class. All the new cephem derivatives, independent of which group they belong to (III to V), possess a 2-amino-5-thiazolyl or a 5-amino-2-thiadiazolyl ring with an oxime group (at position 7 of the cephem nucleus). At position 3, they have a C-3' quaternary ammonium moiety. Research has focused on the following structural modifications: the nature of the oxime residues and the charged azolium heterocycle, and the addition of the vinylogous chain. The aim of researchers is to increase the overall activity of these compounds against Gram-negative bacilli, including against isolates producing type 1 beta-lactamases or extended spectrum beta-lactamases (Enterobacteriaceae). Non-fermentative Gram-negative bacilli are now included in the first screening process, in addition to Pseudomonas aeruginosa. Extensive research is ongoing with the aim of solving the MRSA problem. New promising entities have been reported.