Antibiotic selection is challenging in patients with severe β-lactam allergy due to declining reliability of alternate antibiotics. Organisms isolated from these patients may exhibit unique resistance phenotypes. The objective of this study was to determine which alternate antibiotics or combinations provide adequate empirical therapy for patients with β-lactam allergy who develop Gram-negative...

This study aimed to characterize the role of Pseudomonas aeruginosa low-molecular-mass penicillin-binding proteins (LMM PBPs), namely, PBP4 (DacB), PBP5 (DacC), and PBP7 (PbpG), in peptidoglycan composition, β-lactam resistance, and ampC regulation. For this purpose, we constructed all single and multiple mutants of dacB, dacC, pbpG, and ampC from the wild-type P. aeruginosa PAO1 strain. Peptid...

The 2-azetidinone ring of the Class A and D β-lactamase inhibitor clavulanic acid (1) is synthesized by the ATP-utilizing enzyme β-lactam synthetase (βLS). A hydroxyethyl group attached to C-6 of 1 in the (S) configuration markedly enhances the efficacy of this compound against Class C β-lactamases. Guided by a series of X-ray structures of βLS, we have engineered this enzyme to act upon a meth...

The biosynthetic pathways of penicillins, cephalosporins and cephamycins are well known and most of the enzymes for the biosynthesis of these three classes of β-lactams have been now purified and characterized biochemically. However, the biosynthetic pathways for the more complex β-lactam (clavulanic acid, clavams and carbapenems) are still poorly known. Most of the genes for penicillins, cepha...

Nylon-3 polymers contain β-amino-acid-derived subunits and can be viewed as higher homologues of poly(α-amino acids). This structural relationship raises the possibility that nylon-3 polymers offer a platform for development of new materials with a variety of biological activities, a prospect that has recently begun to receive experimental support. Nylon-3 homo- and copolymers can be prepared v...

BACKGROUND: The presence of aflatoxin M1 (AFM1) andantibiotic residues in milk and milk products is a public healthconcern. Milk and milk powder have the potential forintroducing AFM1 and antibiotic into human diet. In recentyears, milk powder has been used on a large scale in dairyfactories. Consequently, antibiotic residues and aflatoxincontamination control in these products has gained impor...

A diastereoselective access to β-lactam fused spirocyclic oxindoles and related compounds bearing all carbon spiro centers is described. This N-heterocyclic carbene-catalyzed process employed challenging β,β-disubstituted α,β-unsaturated imines to react with enals.

Fifteen novel β-lactams bearing the N-ethyl tert-butyl carbamate group 5a-o and fifteen N-(2-aminoethyl) β-lactams 6a-o were synthesized by the ketene-imine [2+2] cycloaddition reaction (Staudinger ). The cycloaddition reaction was found to be totally diastereoselective leading exclusively to the formation of the cis-β-lactam derivatives. These newly synthesized β-lactams were evaluated for the...

Recent developments in the chemistry and biology of βlactam antibiotics which culminated with the introduction of several clinically useful classical and nonclassical β-lactams have been most thrilling and highly rewarding. While this review touches upon the historical development of β-lactams and their reactivity in a nutshell, it provides an overview of various aspects of chemical and enzymat...

BACKGROUND & OBJECTIVES Multidrug-resistance of methicillin-resistant Staphylococcus aureus (MRSA) is a serious therapeutical problem. Chalcones belong to a group of naturally occurring flavonoids, usually found in various plant species, and have potent antibacterial, antiviral and antifungal activities. The goal of this study was to evaluate the antibacterial effect of three newly-synthesized ...