Since the antibiotic properties of penicillin were first discovered in the beginning of the last century, b-lactam antibiotics have been well developed as miracle drugs in the treatment of bacterial infections in clinics. However, increased bacterial resistance to b-lactam antibiotics has been extensively documented and has now become a serious public health threat. The most common mechanism fo...

The expression of penicillin binding protein 2a (PBP2a) is the basis for the broad clinical resistance to the β-lactam antibiotics by methicillin-resistant Staphylococcus aureus (MRSA). The high-molecular mass penicillin binding proteins of bacteria catalyze in separate domains the transglycosylase and transpeptidase activities required for the biosynthesis of the peptidoglycan polymer that com...

In Gram-negative bacteria, TEM-1 beta-lactamase provides the major mechanism of plasmid-mediated beta-lactam resistance. Natural variants of TEM-1 with increased antibiotic resistance have appeared in response to the use of extended-spectrum beta-lactam antibiotics (e.g., ceftazidime) and beta-lactamase inhibitors (e.g., clavulanic acid). Some of the variant enzymes are more efficient at cataly...

Beta-lactam resistance in mycobacteria results from an interplay between the following: (i) beta-lactamase production, (ii) affinity of the penicillin-binding proteins (PBPs) for the drugs, and (iii) permeation of the drugs. A laboratory mutant of Mycobacterium smegmatis was studied in order to evaluate the roles of these factors in beta-lactam resistance. Mutant M13 was between 7- and 78-fold ...

Combination of lactam antibiotic with lactamase inhibitor has been proven to overcome resistance caused by lactamase production. An evaluation to the MIC of some lactam antibiotics to b-lactamase producing isolates will be reported. A.anitratus, E.coli, K.pneumoniae, Proteus sp, Pseudomonas sp, S.aureus, S.epidermidis, S.pneumoniae, S.viridans, and hemolytic Streptococcus, were challe...

Steadily increasing resistance among Shigella to beta-lactams, aminoglycosides, and tetracycline has compromised the utility of these commonly used antimicrobial agents. Also, undesirable side effects of certain antibiotics have triggered immense interest in search of alternative therapies using medicinal plants. One such medicinal plant used since ancient times to cure diarrhea is Aegle marmel...

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most prevalent multidrug-resistant pathogens worldwide, exhibiting increasing resistance to the latest antibiotic therapies. Here we show that the triple β-lactam combination meropenem-piperacillin-tazobactam (ME/PI/TZ) acts synergistically and is bactericidal against MRSA subspecies N315 and 72 other clinical MRSA isolates in vit...

We encountered three clinical isolates of methicillin-resistant Staphylococcus aureus which were susceptible to netilmicin and arbekacin in the absence of beta-lactam antibiotics but which were resistant to them in the presence of beta-lactam antibiotics. One of these strains, KU5801, was used to further investigate the antagonism between aminoglycosides and beta-lactam antibiotics. beta-Lactam...

Following the discovery of the first analog of penicillin by A. Fleming (1929), the ┚-lactam antibiotics are still a developing group of chemotherapeutics and are used in treatment of majority of diseases with bacterial etiology. ┚-lactam antibiotics have a broad spectrum of antibacterial activity, favourable pharmacokinetic parameters and low side effects. In ┚lactam therapy two main problems ...