Convergent routes to various classes of lactams exploiting the unique radical chemistry xanthates are described. Emphasis is placed on reactions leading by direct cyclization, intermolecular additions alkenes followed ring closure, and furnishing amino esters acids precursors that can be converted into ionic condensations. The possibility modifying existing lactam structures briefly discussed. ...

Several,3-lactams were investigated on the affinity for the penicillin-binding proteins (PBPss) and the antibacterial activity in Bacillus subtilis. The 19-lactams uch as ampicillin, PS-5, methicillin and SCE-963, which had high affinities for PBP-2 showed strong antibacterial activities and the 3-lactams such as cephamycin C, Y-G19Z-GG and Y-G19Z-G, which had high affinities for PBP-1 but low ...

Several mutants isolated after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis of Streptomyces cacaoi strain KCCS-0352, were resistant to benzylpenicillin ranging in concentration from 1,000 to 5,000 micrograms/ml (4- to 20-fold more resistant than the parent). These mutants also acquired resistance to mecillinam, cephamycin C and methicillin. The affinity for beta-lactams of penicillin-bindin...

We assessed the in vitro susceptibility of Streptococcus pneumoniae isolates from patients with confirmed community-acquired pneumonia (CAP) to β-lactams, macrolides and fluoroquinolones and the association of non-susceptibility and resistance with serotypes/serogroups (STs/SGs), patient's risk factors and vaccination status. Samples (blood or lower respiratory tract) were obtained in 2007-2009...

Total serum IgE result from the combination of specific and non-specific pools. High specific/total IgE ratio may reflect high level of allergen-specific IgE on mast cells. No data regarding its applications to drug allergies is available. One hundred seventy-one patients with a history of immediate reactions to β-lactams, confirmed by positive skin testing, and 122 control subjects tolerant to...

The discovery of natural and synthetic antibiotics is one of the most important medical breakthroughs in human history. Many diseases, such as bacterial meningitis, pneumonia, and septicemia, are now curable with the use of antibiotics. Antibiotics are efficacious, generally well tolerated in patients, and have a low toxicity level. It is for these reasons antibiotics remain an attractive targe...

The four-membered cyclic amides commonly known as 2-azetidinones or β-lactams occupy a prominent place in the realm of organic and medicinal chemistry since the structure elucidation of penicillin showed the presence of β-lactam ring in it and the antibacterial activity of penicillin was attributed to the presence of β-lactam ring. The early investigations in organic chemistry were focused on d...

BACKGROUND The emergence of multi-drug resistant Gram-negatives (MDRGNs) coupled with an alarming scarcity of new antibiotics has forced the optimization of the therapeutic potential of available antibiotics. To exploit the time above the minimum inhibitory concentration mechanism of β-lactams, prolonging their infusion may improve outcomes. The primary objective of this meta-analysis was to de...

There is a critical need to better use existing antibiotics due to the urgent threat of antibiotic resistant bacteria coupled with the reduced effort in developing new antibiotics. β-lactam antibiotics represent one of the most commonly used classes of antibiotics to treat a broad spectrum of Gram-positive and -negative bacterial pathogens. However, the rise of extended spectrum β-lactamase (ES...

We found ampicillin- and imipenem-resistant isolates of vanA-possessing Enterococcus faecalis with MICs of 8 to 16 microg/ml and 4 to 32 microg/ml, respectively. There have been few reports about penicillin- and imipenem-resistant E. faecalis. Two mechanisms of beta-lactam resistance in E. faecalis, the production of beta-lactamase and the overproduction of penicillin-binding proteins (PBPs), h...