The macrolides are a group of drugs (typically antibiotics) whose activity stems from the presence of a macrolide ring, a large lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, are attached. The lactone ring can be either 14, 15 or 16-membered. Macrolides belong to the polyketide class of natural products. Oral medication A medication is a licenced drug taken to cure or reduce symptoms of an illness or medical condition. ... An antibiotic is a drug that kills or slows the growth of bacteria. ... In chemistry, the condensation of an alcohol group and a carboxylic acid group which are atached to the same molecule, leads to a cyclic ester. ... Polyketides are secondary metabolites from bacteria, fungi, plants, and animals. ... Secondary metabolites, also known as natural products, are those products (chemical compounds) of metabolism that are not essential for normal growth, development or reproduction of an organism. ...

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Commonly prescribed Macrolides

• erythromycin
• azithromycin (Zithromax®)
• clarithromycin (Biaxin®)
• dirithromycin (Dynabac®)
• roxithromycin (Rulid®, Surlid®)

Erythromycin is a macrolide antibiotic which has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people who have an allergy to penicillins. ... Azithromycin is an azalide, a subclass of macrolide antibiotics. ... Clarithromycin is a macrolide antibiotic used to treat pharyngitis, tonsillitis, acute maxillary sinusitis, acute bacterial exacerbation of chronic bronchitis, pneumonia (especially atypical pneumonias associated with Chlamydia pneumoniae or TWAR), skin and skin structure infections, and, in HIV and AIDS patients to prevent, and to treat, disseminated Mycobacterium avium complex or... Roxithromycin is a semi-synthetic macrolide antibiotic. ...

Developmental Macrolides

• carbomycin A
• josamycin
• kitasamycin
• oleandomycin
• spiramycin
• troleandomycin
• tylosin/tylocine (Tylan®)

Ketolides

• cethromycin
• telithromycin (Ketek®)

Others are: spiramycin (used for treating toxoplasmosis), ansamycin, oleandomycin, carbomycin and tylocine. Telithromycin is the first ketolide antibiotic to enter clinical use. ...

There is also a new class of antibiotics called ketolides that is structurally related to the macrolides. Ketolides such as telithromycin are used to fight respiratory tract infections caused by macrolide-resistant bacteria. Ketolides are antibiotics belonging to the macrolide group. ... Telithromycin is the first ketolide antibiotic to enter clinical use. ...

Non-antibiotic macrolides

The drug Tacrolimus, which is used as an immunosuppressant, is also a macrolide. It has similar activity to cyclosporine. Tacrolimus (also FK-506 or Fujimycin) is a 23-membered macrolide lactone discovered in 1984 from the fermentation broth of a Japanese soil sample that contained the bacteria Streptomyces tsukubaensis. ... Immunosuppression is the medical suppression of the immune system. ... Cyclosporine (IPA: ), ciclosporin (INN), or cyclosporin (former BAN), is an immunosuppressant drug. ...

Uses

Macrolides are used to treat infections such as respiratory tract infections and soft tissue infections. The antimicrobial spectrum of macrolides is slightly wider than that of penicillin. Beta-hemolytic streptococci, pneumococci, staphylococci and enterococci are usually susceptible to macrolides. Unlike penicillin, macrolides have been shown to be effective against mycoplasma, mycobacteria, some rickettsia and chlamydia. Penicillin nucleus Penicillin refers to a group of β-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms. ... Species S. pneumoniae S. pyogenes S. viridans Streptococcus is a genus of spherical, Gram-positive bacteria of the phylum Firmicutes. ... Binomial name Streptococcus pneumoniae Streptococcus pneumoniae is a species of Streptococcus that is a major human pathogen. ... Species S. aureus Staphylococcus (in Greek staphyle means bunch of grapes and coccos means granule) is a genus of gram-positive bacteria. ... Species Enterococcus is a genus of bacteria of the phylum Firmicutes. ... Species M. genitalium M. hominis M. pneumoniae etc. ... Species see text Mycobacterium is the a genus of actinobacteria, given its own family, the Mycobacteriaceae. ... Species Rickettsia felis Rickettsia prowazekii Rickettsia rickettsii Rickettsia typhi etc. ... Chlamydia is one of the most common sexually transmitted infections worldwide — about four million cases of chlamydia occur in the United States each year. ...

Mechanism of action

The mechanism of action of the macrolides is inhibition of bacterial protein synthesis by binding reversibly to the subunit 50S of the bacterial ribosome, thereby inhibiting translocation of peptidyl-tRNA. This action is mainly bacteriostatic, but can also be bactericidal in high concentrations. Macrolides tend to accumulate within leukocytes, and are therefore actually transported into the site of infection. An overview of protein synthesis. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Ribonucleic acid (RNA) is a nucleic acid polymer consisting of covalently bound nucleotides. ... White Blood Cells is also the name of a White Stripes album. ...

• A novel,non-antibiotic,anti-inflamatory effect of 14-membered macrolides was discovered in Japan(Kudo S. et al.),which is especialy effective in improving control of diffuse panbronchiolitis(DPB). Research on the anti-inflammatory properties of the macrolide ring is ongoing.

Resistance

Bacterial resistance to macrolides occurs by alteration of the structure of the bacterial ribosome. This resistance can be either plasmid-mediated or chromosomal, i.e through mutation. Figure 1: Schematic drawing of a bacterium with plasmids enclosed. ...

External links

• Macrolides with extended spectrum "Family Practice Notebook" page for macrolides with extended spectrum
• Antibiotics bound to the 50S subunit Riboworld on the 50S ribosome and antibiotics
• Structure Activity Relationships "Antibacterial Agents; Structure Activity Relationships," André Bryskier MD; beginning at pp143