Cefozopran hydrochloride is a third-generation cephalosporin that was launched for the treatment of severe infections in immunocompromised patients caused by staphylococci and enterococci. While it shows a very broad antibacterial spectrum against Gram-positive and Gram-negative organisms, it is particularly potent against S. aureus, Enterococcus faecalis, P. aeruginosa, and Citrobacter freundii. It is resistant to hydrolysis by most chromosomal and plasmid mediated β-lactamases and is reported to be active against respiratory, urinary tract, obstetrical, gynecological, soft tissue, and surgical infections. Similar to β-lactams, cephalosporins interfere with PBP (penicillin binding protein) activity involved in the final phase of peptidoglycan synthesis. PBP’s are enzymes which catalyze a pentaglycine crosslink between alanine and lysine residues providing additional strength to the cell wall. Without a pentaglycine crosslink, the integrity of the cell wall is severely compromised and ultimately leads to cell lysis and death. Resistance to cephalosporins is commonly due to cells containing plasmid encoded β-lactamases.

Cefalonium is a 1st generation cephalosporin with a broad spectrum of actvity against Gram-positive and Gram-negative bacterias. The drug inhibits the bacterial cell wall synthesis by binding to penicillin binding proteins. Cefalonium is approved for routine dry cow therapy to treat existing sub-clinical infections and to prevent new infections which occur during the dry period.

Cefetamet pivoxil is an oral third-generation cephalosporin which is hydrolysed to form the active agent, cefetamet. Cefetamet has excellent in vitro activity against the major respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Moraxella (Branhamella) catarrhalis and group A beta-haemolytic streptococci; it is active against beta-lactamase-producing strains of H. influenzae and M. catarrhalis, but has poor activity against penicillin-resistant S. pneumoniae. Cefetamet has marked activity against Neisseria gonorrhoeae and possesses a broad spectrum of activity against Enterobacteriaceae. Both staphylococci and Pseudomonas spp. are resistant to cefetamet. Cefetamet pivoxil has been investigated in the treatment of both upper and lower community-acquired respiratory tract infections and has demonstrated equivalent efficacy to a number of more established agents, namely cefaclor, amoxicillin and cefixime. In complicated urinary tract infections, cefetamet pivoxil showed similar efficacy to cefadroxil, cefaclor and cefuroxime axetil. Cefetamet pivoxil was effective in the treatment of otitis media, pneumonia, pharyngotonsillitis and urinary tract infections in children. Cefetamet is not extensively bound to plasma proteins. Cefetamet has a relatively small apparent volume of distribution consistent with that of other beta-lactam antibiotics. The absorption and disposition of cefetamet in human subpopulations [i.e. children, elderly (< 75 years of age), renal impairment, liver disease and patients taking concomitant drugs] have been studied extensively. Only impaired renal function appears to significantly alter the elimination of this drug. Cefetamet pivoxil exerts its bactericidal action by inhibition the final transpeptidation step of peptidoglycan synthesis in the bacterial cell wall by binding to one or more of the Penicillin-binding Proteins (PBPs).

Cefathiamidine is a beta-lactam antibiotic that exhibits a broad spectrum of bactericidal activity against gram-positive bacteria. By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, it inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins.

Sultamicillin is the mutual prodrug of sulbactam and ampicillin. It is the tosylate salt of the double ester of sulbactam plus ampicillin. Sulbactam is a semisynthetic ß-lactamase inhibitor which, in combination with ampicillin, extends the antibacterial activity of the latter to include some ß-lactamase-producing strains of bacteria that would otherwise be resistant. The combination of sulbactam plus ampicillin for parenteral use has previously been shown to be clinically and bacteriologically effective in a variety of infections. Sultamicillin is marketed under a trade name Unasyn among others.

Lenapenem is an anti-bacterial agent that was tested in late 90's in phase II clinical trials against bacterial infections. Lenapenem was shown to be active against both Gram-positive and Gram-negative bacteria and exerted its therapeutic effect by inhibiting penicillin binding proteins. The development of the drug was terminated due to the safety reason.

Cefluprenam is an anti-bacterial agent of broad spectrum. It was active in vitro against different bacteria strains with MIC values from 0.78 ug/ml to 3.13 ug/ml. The drug exerts its bactericidal activity through inhibition of penicillin-binding proteins, showing high affinity to all four subtypes. Cefluprenam was tested for the treatment of respiratory tract infections in phase III study, however the drug development was stopped.

Cefmatilen (codenamed S-1090) is an orally-active cephalosporin antibiotic, that shows high activity against a variety of Gram-positive and Gram-negative bacteria, including Streptococcus pyogenes and Neisseria gonorrhoeae.

The phthalidyl thiazolidine carboxylic ester of ampicillin, talampicillin (Talpen, Beecham), has been introduced recently to improve absorption and to reduce these side effects. After oral administration talampicillin is rapidly absorbed and hydrolysed by tissue esterases in the intestinal wall to release into the circulation ampicillin and the ester moiety, mainly 2-hydroxymethyl-benzoic acid. No unchanged talampicillin is detectable in the peripheral blood. It is not approved by the FDA for use in the United States

Carumonam is a monobactam antibacterial agent. It was highly active in vitro against members of the family Enterobacteriaceae, Pseudomonas aeruginosa, and Haemophilus influenzae and weakly active against Streptococcus pneumoniae, but it was not active against Staphylococcus aureus. The excellent activity of carumonam against Gram-negative bacteria is related to its high affinity for their penicillin-binding proteins. It is indicated for the treatment of urinary tract infections, chronic respiratory infections, biliary tract infections, peritonitis, sepsis. Another factor that contributes to the excellent activity of carumonam against Gram-negative bacteria is its resistance to beta-lactamases. Adverse effects of the carumonam were limited to phlebitis at the intravenous infusion site; bloody diarrhea.