Synthesis and biological properties of a series of optically active 2-oxaisocephems

Synthesis and activity of 2-(sulfonamido)methyl-carbapenems: discovery of a novel, anti-MRSA 1,8-naphthosultam pharmacophore

A series of 1beta-methyl carbapenems substituted at the 2-position with lipophilic, acyclic and cyclic (sulfonamido)methyl groups was prepared and evaluated for activity against resistant gram-positive bacteria. From these studies, the 1,8-naphthosultamyl group emerged as a novel, PBP2a-binding, anti-MRSA pharmacophore worthy of further exploration.

Therapeutic efficacy of BO-3482, a novel dithiocarbamate carbapenem, in mice infected with methicillin-resistant Staphylococcus aureus

The in vivo activity of BO-3482, which has a dithiocarbamate chain at the C-2 position of 1beta-methyl-carbapenem, was compared with those of vancomycin and imipenem in murine models of septicemia and thigh infection with methicillin-resistant Staphylococcus aureus (MRSA). Because BO-3482 was more susceptible than imipenem to renal dehydropeptidase I in a kinetic study of hydrolysis by this renal enzyme, the therapeutic efficacy of BO-3482 was determined during coadministration with cilastatin. In the septicemia models, which involved two homogeneous MRSA strains and one heterogeneous MRSA strain, the 50% effective doses were, respectively, 4.80, 6.06, and 0.46 mg/kg of body weight for BO-3482; 5.56, 2.15, and 1.79 mg/kg for vancomycin; and >200, >200, and 15.9 mg/kg for imipenem. BO-3482 was also as effective as vancomycin in an MRSA septicemia model with mice with cyclophosphamide-induced immunosuppression. In the thigh infection model with a homogeneous MRSA strain, the bacterial counts in tissues treated with BO-3482-cilastatin were significantly reduced in a dose-dependent manner compared with the counts in those treated with vancomycin and imipenem-cilastatin (P < 0.001). These results indicate that BO-3482-cilastatin is as effective as vancomycin in murine systemic infections and is more bactericidal than vancomycin in local-tissue infections. The potent in vivo activity of BO-3482-cilastatin against such MRSA infections can be ascribed to the good in vitro anti-MRSA activity and improved pharmacokinetics in mice when BO-3482 is combined with cilastatin and to the bactericidal nature of the carbapenem.

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.