β-lactamases

β-lactamases are hydrolytic enzymes which cleaves the β-lactam ring and are the primary mechanism of conferring bacterial resistance to β-lactam antibiotics, such as penicillins and cephalosporins. According to the most popular classification of β-lactamases, name as Ambler classification, these enzymes are grouped into four primary classes (A-D) on the basis of amino acid similarities. Class B enzymes are metallo-β-lactamases, while enzymes of class A, C and D are members of the superfamily of penicilloyl serine transferases that includes penicillin-binding proteins involved in the terminal steps of bacterial-cell-wall synthesis. Antibiotic resistance is a natural phenomenon. It is the result of selection for genetic elements in bacteria that confer the ability to grow in the presence of otherwise toxic compounds (antibiotics). Furthermore, the ability of bacteria to exchange these genes through mobile genetic elements such as plasmids ensures that antibiotic resistance traits can be spread efficiently through bacterial communities thereby further aggravating the situation.

β-Lactam antibiotics

β-Lactam antibiotics are a broad class of antibiotics, characterized by its four-membered, nitrogen-containing beta-lactam ring at the core of their structure, which is key to the mode of action of this group of antibiotics. The most notable members of β-lactam antibiotic are penicillins, cephalosporins, monobactams, and carbapenems. β-lactam antibiotics target the penicillin-binding proteins or PBPs-a group of enzymes found anchored in the cell membrane, which are involved in the cross-linking of the bacterial cell wall. The β-lactam ring portion of this group of antibiotics binds to these different PBPs, rendering them unable to perform their role in cell wall synthesis. This then leads to death of the bacterial cell due to osmotic instability or autolysis.

β-lactam antibiotics classified as follows:

Beta- lactam antibiotics Penicillin Cephalosporins Carbapenems Monobactams Penicillin Penicillin Methicillin Cloxacillin Dicloxacillin Amoxicillin Carbenicillin Ticarcillin Piperacillin Mezlocillin Cefoxitin Azlocillin Nafcillin Oxacillin Ampicillin Cefadroxil Cephalexin Cephalothin Cephapirin Cephradine Cefazolin Cefamandole Cefonicid Cefmetazole Cefotetan Cefuroxime Cefaclor Cefoperazone Ceftizoxime Ceftazidime Ceftriaxone Cefixime Moxalactam Cefepime Cefozopran Cefpirome Cefquinome Ceftobiprole http://en.wikipedia.org/wiki/Ceftaroline_fosamil Ceftaroline_fosamil Biapenem Ertapenem Doripenem Imipenem Panipenem Aztreonam Tigemonam Carumonam Nocardicin_A

β-lactamase Inhibitors:

β-lactamase Inhibitors are group of molecule used in conjunction with β-lactam antibiotics to extend its spectrum activity.Inhibitors(clavulanic acid,sulbactam,tazobactam) generally have little antimicrobial properties themselves and so are combined with β-lactam  antibiotics. It functions by binding to the β-lactamase enzyme more "efficiently" than the actual β-lactam antibiotic itself.