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Methicillin
 
 
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Meticillin (INN
International Nonproprietary Name

An International Nonproprietary Name is the official non-proprietary or generic name given to a pharmaceutical substance, as designated by the World Health Organization ....
, BAN
British Approved Name

A British Approved Name is the official non-proprietary or generic name given to a pharmaceutical substance, as defined in the British Pharmacopoeia....
) or methicillin (USAN
United States Adopted Name

United States Adopted Names are unique nonproprietary names assigned to pharmaceuticals marketed in the United States. Each name is assigned by the USAN Council, which is co-sponsored by the American Medical Association , the United States Pharmacopeial Convention , and the American Pharmacists Association ....
) is a narrow spectrum beta-lactam antibiotic
Beta-lactam antibiotic

?-lactam antibiotics are a broad class of antibiotics that include penicillin derivatives, cephalosporins, monobactams, carbapenems, and Beta-lactamase inhibitors, that is, any antibiotic agent that contains a beta-lactam nucleus in its molecular structure....
 of the penicillin
Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They are Beta-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms....
 class. It was developed by Beecham
Beecham (pharmaceutical company)

Beecham was a British pharmaceutical company. It was once a constituent of the FTSE 100 Index but is now owned by GlaxoSmithKline.History...
 in 1959. It was previously used to treat infection
Infection

An infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host resources to multiply ....
s caused by susceptible Gram-positive
Gram-positive

Gram-positive Bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink....
 bacteria
Bacteria

The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
, particularly beta-lactamase
Beta-lactamase

Beta-lactamases are enzymes produced by some bacteria and are responsible for their antibiotic resistance to beta-lactam antibiotics like penicillins, cephalosporins , cephamycins, and carbapenems ....
-producing organisms such as Staphylococcus aureus
Staphylococcus aureus

Staphylococcus aureus is the most common cause of staph infections. It is a spherical Bacteria, frequently found in the nose and skin of a person....
 that would otherwise be resistant to most penicillin
Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They are Beta-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms....
s, but is no longer clinically used. Its role in therapy has been largely replaced by flucloxacillin
Flucloxacillin

Flucloxacillin or floxacillin is a narrow-spectrum antibiotic beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria....
 and dicloxacillin
Dicloxacillin

Dicloxacillin is a narrow-spectrum antibiotic beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria....
, however the term methicillin-resistant Staphylococcus aureus
Methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus is a Bacteria responsible for difficult-to-treat infections in humans. It may also be referred to as multidrug-resistant Staphylococcus aureus or oxacillin-resistant Staphylococcus aureus ....
 (MRSA) continues to be used to describe Staphylococcus aureus
Staphylococcus aureus

Staphylococcus aureus is the most common cause of staph infections. It is a spherical Bacteria, frequently found in the nose and skin of a person....
 strains resistant to all penicillin
Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They are Beta-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms....
s.






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Encyclopedia


Meticillin (INN
International Nonproprietary Name

An International Nonproprietary Name is the official non-proprietary or generic name given to a pharmaceutical substance, as designated by the World Health Organization ....
, BAN
British Approved Name

A British Approved Name is the official non-proprietary or generic name given to a pharmaceutical substance, as defined in the British Pharmacopoeia....
) or methicillin (USAN
United States Adopted Name

United States Adopted Names are unique nonproprietary names assigned to pharmaceuticals marketed in the United States. Each name is assigned by the USAN Council, which is co-sponsored by the American Medical Association , the United States Pharmacopeial Convention , and the American Pharmacists Association ....
) is a narrow spectrum beta-lactam antibiotic
Beta-lactam antibiotic

?-lactam antibiotics are a broad class of antibiotics that include penicillin derivatives, cephalosporins, monobactams, carbapenems, and Beta-lactamase inhibitors, that is, any antibiotic agent that contains a beta-lactam nucleus in its molecular structure....
 of the penicillin
Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They are Beta-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms....
 class. It was developed by Beecham
Beecham (pharmaceutical company)

Beecham was a British pharmaceutical company. It was once a constituent of the FTSE 100 Index but is now owned by GlaxoSmithKline.History...
 in 1959. It was previously used to treat infection
Infection

An infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host resources to multiply ....
s caused by susceptible Gram-positive
Gram-positive

Gram-positive Bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink....
 bacteria
Bacteria

The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
, particularly beta-lactamase
Beta-lactamase

Beta-lactamases are enzymes produced by some bacteria and are responsible for their antibiotic resistance to beta-lactam antibiotics like penicillins, cephalosporins , cephamycins, and carbapenems ....
-producing organisms such as Staphylococcus aureus
Staphylococcus aureus

Staphylococcus aureus is the most common cause of staph infections. It is a spherical Bacteria, frequently found in the nose and skin of a person....
 that would otherwise be resistant to most penicillin
Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They are Beta-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms....
s, but is no longer clinically used. Its role in therapy has been largely replaced by flucloxacillin
Flucloxacillin

Flucloxacillin or floxacillin is a narrow-spectrum antibiotic beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria....
 and dicloxacillin
Dicloxacillin

Dicloxacillin is a narrow-spectrum antibiotic beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria....
, however the term methicillin-resistant Staphylococcus aureus
Methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus is a Bacteria responsible for difficult-to-treat infections in humans. It may also be referred to as multidrug-resistant Staphylococcus aureus or oxacillin-resistant Staphylococcus aureus ....
 (MRSA) continues to be used to describe Staphylococcus aureus
Staphylococcus aureus

Staphylococcus aureus is the most common cause of staph infections. It is a spherical Bacteria, frequently found in the nose and skin of a person....
 strains resistant to all penicillin
Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They are Beta-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms....
s. Methicillin is no longer manufactured because the more stable and similar penicillins such as oxacillin
Oxacillin

Oxacillin sodium is a narrow-spectrum antibiotic beta-lactam antibiotic of the penicillin class....
 (used for clinical antimicrobial susceptibility testing), flucloxacillin and dicloxacillin are used medically.

Mode of action


Like other beta-lactam antibiotics, methicillin acts by inhibiting the synthesis of bacterial cell wall
Cell wall

A cell wall is a tough, flexible and sometimes fairly rigid layer that surrounds some types of cell . It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism....
s. It inhibits cross-linkage between the linear peptidoglycan
Peptidoglycan

Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria, forming the cell wall....
 polymer chains that make up a major component of the cell wall of Gram-positive
Gram-positive

Gram-positive Bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink....
 bacteria. It does this by binding to and competitively inhibiting the transpeptidase
Transpeptidase

A transpeptidase is a bacterial enzyme that cross-links the peptidoglycan chains to form rigid cell walls. This enzyme is also known by several other names including DD-peptidase, DD-transpeptidase, D-alanyl-D-alanine carboxypeptidase and serine-type D-Ala-D-Ala carboxypeptidase....
 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
Penicillin binding proteins

Penicillin-binding proteins are a group of proteins that are characterized by their affinity for and binding of penicillin. They are a normal constituent of many bacteria; the name just reflects the way by which the protein was discovered....
 (PBPs). (Gladwin and Trattler, 2004)

Medicinal chemistry


Methicillin is insensitive to beta-lactamase
Beta-lactamase

Beta-lactamases are enzymes produced by some bacteria and are responsible for their antibiotic resistance to beta-lactam antibiotics like penicillins, cephalosporins , cephamycins, and carbapenems ....
 (also known as penicillinase) enzymes secreted by many penicillin-resistant bacteria. The presence of the ortho-dimethoxyphenyl group directly attached to the side chain
Side chain

A side chain in organic chemistry and biochemistry is a part of a molecule that is attached to a core structure. The placeholder R is often used as a generic placeholder for side chains, the R historically being derived from radical or rest....
 carbonyl group of the penicillin nucleus facilitates the ß-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
Peptidoglycan

Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria, forming the cell wall....
 crosslinking, but is not bound by or inactivated by ß-lactamases.

Clinical use


Methicillin is not used to treat patients because it is toxic to humans. But, it serves a purpose in the laboratory
Laboratory

A laboratory is a facility that provides controlled conditions in which science research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories....
 to determine the antibiotic sensitivity of Staph aureus to other beta-lactamase
Beta-lactamase

Beta-lactamases are enzymes produced by some bacteria and are responsible for their antibiotic resistance to beta-lactam antibiotics like penicillins, cephalosporins , cephamycins, and carbapenems ....
-resistant penicillins.

See also


  • Beta-lactam antibiotic
    Beta-lactam antibiotic

    ?-lactam antibiotics are a broad class of antibiotics that include penicillin derivatives, cephalosporins, monobactams, carbapenems, and Beta-lactamase inhibitors, that is, any antibiotic agent that contains a beta-lactam nucleus in its molecular structure....
  • Flucloxacillin
    Flucloxacillin

    Flucloxacillin or floxacillin is a narrow-spectrum antibiotic beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria....
  • Methicillin-resistant Staphylococcus aureus
    Methicillin-resistant Staphylococcus aureus

    Methicillin-resistant Staphylococcus aureus is a Bacteria responsible for difficult-to-treat infections in humans. It may also be referred to as multidrug-resistant Staphylococcus aureus or oxacillin-resistant Staphylococcus aureus ....