The rising of bacterial strains that
have antibiotic resistance is causing the search for new antimicrobial agents.
In recent years, there is a number of new agents to treat patogenic diseases.
These agents show considerable improved activity against bacteria that have
resistance or show lower sensitivity to previous antimicrobial
agents. Changing the chemical structure of molecules and introduction of
molecules with new chemical structure have provided agents able to overcome the
present resistance mechanism. These search workings are especially at
penicillins, quinolones and macrolides.
Eritromycin, the typical macrolide, was
discovered in early 1950s. After this, macrolide antibiotics used for the
therapy of Streptococcus pneumoniae infections.
At the same time, macrolides showed broad spectrum antimicrobial activity
against patogens.The one of the advantages of macrolides is that it is an
alternative treatment of b-lactam intolerant patients.
But, in the last two decades, there is
an increasing resistance to macrolides such as erythromycin, azithromycin and
clathromycin. To overcome this problem, ketolides were developed. Ketolides are
new major class of semisynthetic eritromycin derivatives with 10-fold greater
ribosomal binding affinity because of secondary interaction.The main chemical
characteristics of a ketolide is the displacement of cladinose attached to the macrolide
ring of 6-O-methylerytromycin ring at
C-3 position with a ketone moiety.
Telithromycin is the first available
oral ketolide. It is approved by the US Food and Drug Administration (FDA) in
2001 and it is introduced into clinical practice.. Telithromycin was developed
at Aventis and reached the market as Ketek. Telithromycin is used for treatment
of respiratory tract infections such as mild-to-moderately-severe CAP, chronic
bronchitis and acute bacterial sinusitis. Also it is quite effective against
macrolide resistant Streptecoccus