Extended spectrum beta lactamase (ESBL)-producing organisms pose unique challenge to clinical microbiologists, clinicians, infection control professionals and scientists. ESBLs are enzymes produced by some bacteria or germs that can make them resistant to certain antibiotics. ESBLs are enzymes capable of hydrolyzing penicillin, broadspectrum cephalosporins and monobactams that are generally der...

Sixty nosocomial infections caused by Pseudomonas aeruginosa and Acinetobacter baumannii resistant to aminoglycosides, cephalosporins, quinolones, penicillins, monobactams, and imipenem were treated with colistin (one patient had two infections that are included as two different cases). The infections were pneumonia (33% of patients), urinary tract infection (20%), primary bloodstream infection...

b-Lactam or azetidin-2-one is an important structural motif of the penicillin, cephalosporin, carbapenem, and carbecephem classes of antibiotics.1 Naturally occurring as well as synthetic monobactams, such as nocardicins and tabtoxin, are also known for their unique antibacterial activities.2e4 Besides their importance as the key structural component of b-lactam antibiotics, b-lactams have been...

The methodology for the discovery of new biologically active betalactams is proposed. The one of the two ways proposed is specific modification, which is peculiar to any betalactam structure and involves introduction of substitutes changing particular physico-chemical properties of the natural or synthetic analogous. The principle of similarity is discussed as an alternative of the specific mod...

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...

β-lactams are antibiotic molecules able to inhibit cell wall biosynthesis. Among other mechanisms, resistance in Gram-negative bacteria is mostly associated with production of β-lactamase enzymes able to bind and hydrolyze the β-lactam ring. Extended-spectrum β-lactamases extend this ability also to third- and fourth-generation cephalosporins, as well as to carbapenems and monobactams. Vibrio c...

β-lactamases production represents a determining factor in bacterial resistance to β-lactam antimicrobial agents. Over 200 enzymes have been characterized for their nucleotidic sequences and/or biochemical properties [1]. Among class A β-lactamases [2] TEM-1 is the commonest enzyme in Enterobacteriaceae. Because of wide spread use of antibiotics there has been the emergence of different variant...

Extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases are plasmid (but also chromosomally) encoded enzymes found in Enterobacteriaceae, determining resistance to a variety of important antibiotics including penicillins, cephalosporins, and monobactams. In recent decades, the prevalence of ESBL/AmpC-producing bacteria has increased rapidly across the world. Here, we evaluate the potential...

The emergence of acquired metallo-beta-lactamase (MBL) in gram-negative bacilli is regarded as a therapeutic challenge since such enzymes are capable of hydrolyzing all beta-lactams in vitro except the monobactams. The clinical characteristics and outcome of 8 episodes of gram-negative bacteremia caused by MBL-producing isolates from January 1997 through December 2000 (Klebsiella pneumoniae, 6 ...