Torches & Consumables ,
Mode of action
Main article: Beta-lactam antibiotic
Like other beta-lactam antibiotics, methicillin acts by inhibiting the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria. It does this by binding to and competitively inhibiting the transpeptidase enzyme used by bacteria to cross-link the peptide (D-alanyl-alanine) used in peptidoglycan synthesis. Methicillin and other beta-lactam antibiotics are structural analogs of D-alanyl-alanine, and the transpeptidase enzymes that bind to them are sometimes called penicillin binding proteins (PBPs). (Gladwin and Trattler, 2004)
Medicinal chemistry
Methicillin is insensitive to beta-lactamase (also known as penicillinase) enzymes secreted by many penicillin-resistant bacteria. The presence of the ortho-dimethoxyphenyl group directly attached to the side chain carbonyl group of the penicillin nucleus facilitates the -lactamase resistance, since those enzymes are relatively intolerant of side-chain steric hindrance. Thus it is able to bind to penicillin binding proteins (PBPs) and inhibit peptidoglycan crosslinking, but is not bound by or inactivated by -lactamases , led mouse pad .
Clinical us , heat transfer media .
Methicillin is not used to treat patients because of its unfavorable side effect profile. But, it serves a purpose in the laboratory to determine the antibiotic sensitivity of Staph aureus to other beta-lactamase-resistant penicillins.
See also
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Beta-lactam antibiotic
Flucloxacillin
Methicillin-resistant Staphylococcus aureus
References
Mitscher LA. Antibiotics and antimicrobial agents. In: Williams DA, Lemke TL, editors. Foye’s Principles of medicinal chemistry, 5th edition. Philadelphia: Lippincott Williams & Wilkins; 2002.
Gladwin M., Trattler B. Clinical Microbiology made ridiculously simple. 3rd edition. Miami: MedMaster, Inc.; 2004.
v d e
Antibacterials: cell envelope antibiotics (J01C-J01D)
Internal to membrane/
(inhibit peptidoglycan subunit
synthesis and transport)
NAM synthesis inhibition (Fosfomycin) DADAL/AR inhibitors (Cycloserine) bactoprenol inhibitors (Bacitracin)
Glycopeptide/
(inhibit PG chain elongation)
Vancomycin# (Oritavancin, Telavancin) Teicoplanin (Dalbavancin) Ramoplanin
-lactams/
(inhibit cross-links
with PBP)
Penicillins/
(penams)
Extended sp.
aminopenicillins: Amoxicillin# Ampicillin# (Pivampicillin, Hetacillin, Bacampicillin, Metampicillin, Talampicillin) Epicillin
carboxypenicillins: Carbenicillin (Carindacillin) Ticarcillin Temocillin
ureidopenicillins: Azlocillin Piperacillin Mezlocillin
other: Mecillinam (Pivmecillinam) Sulbenicillin
Narrow sp.
-lactamase sensitive
Benzylpenicillin (G)#: Clometocillin Benzathine benzylpenicillin# Procaine benzylpenicillin# Azidocillin Penamecillin
Phenoxymethylpenicillin (V)#: Propicillin Benzathine phenoxymethylpenicillin Pheneticillin
-lactamase resistant
Cloxacillin# (Dicloxacillin, Flucloxacillin) Oxacillin Meticillin Nafcillin
Penems
Faropenem
Carbapenems
Biapenem Doripenem Ertapenem Imipenem Meropenem Panipenem
Cephalosporins/
(cephems)
1st (PEcK)
Cefazolin# Cefacetrile Cefadroxil Cefalexin Cefaloglycin Cefalonium Cefaloridine Cefalotin Cefapirin Cefatrizine Cefazedone Cefazaflur Cefradine Cefroxadine Ceftezole
2nd (HEN)
Cefaclor Cefamandole Cefminox Cefonicid Ceforanide Cefotiam Cefprozil Cefbuperazone Cefuroxime Cefuzonam cephamycin (Cefoxitin, Cefotetan, Cefmetazole) carbacephem (Loracarbef)
3rd
Cefixime# Ceftazidime# Ceftriaxone# Cefcapene Cefdaloxime Cefdinir Cefditoren Cefetamet Cefmenoxime Cefodizime Cefoperazone Cefotaxime Cefpimizole Cefpiramide Cefpodoxime Cefsulodin Cefteram Ceftibuten Ceftiolene Ceftizoxime oxacephem (Flomoxef, Latamoxef )
4th
Cefepime Cefozopran Cefpirome Cefquinome
5th
Ceftobiprole
Veterinary
Ceftiofur Cefquinome Cefovecin
Monobactams
Aztreonam Tigemonam
-lactamase inhibitors
penam (Sulbactam, Tazobactam) clavam (Clavulanic acid)
Combinations
Co-amoxiclav (Amoxicillin/clavulanic acid)# Imipenem/cilastatin# Ampicillin/sulbactam (Sultamicillin) Piperacillin/tazobactam
Other
polymyxins/detergent (Colistin, Polymyxin B) depolarizing (Daptomycin) hydrolyze NAM-NAG (Lysozyme)
#WHO-EM. ndergoing clinical trials, not FDA approved. Withdrawn from market. Development halted.
Categories: Beta-lactam antibiotics
