Download Antibiotics are substances produced by living organisms that can

Macrolide
By Agana Gnanakuruparan
Antibiotics are substances produced by living organisms that can destroy or inhibit the growth of other
microorganisms. Although most are produced by bacteria a few such as penicillin are made by fungi.
Antibiotics can be used to treat relatively mild conditions such as acne as well as potentially life-threatening
conditions such as pneumonia.
What do Macrolides target?
Antibiotic macrolides have a broad spectrum of
activity and are used to treat infections caused by
Gram-positive bacteria (e.g., Streptococcus
pneumoniae) and Haemophilus influenza
infections such as respiratory tract and soft-tissue
infections. The antimicrobial spectrum of
macrolides is slightly wider than that of penicillin,
and, therefore, macrolides are a common
substitute for patients with a penicillin allergy or
treat penicillin-resistant strains of bacteria.
Streptococcus
pneumoniae
Haemophilus influenza
infections
How do Macrolides kill the bacteria?
The mechanism of action of macrolides is inhibition of bacterial protein
synthesis .Antibiotics in the macrolide group affect ribosomes, the cell’s
protein-building organelles. Ribosomes build proteins in both bacteria and
human cells, but there are differences between bacterial and human
ribosomes, for example humans have 80S ribosomes while bacteria have
70S ribosomes. Macrolides block only bacterial ribosomes and prevent
them from building proteins. They do this by binding to 23S ribosomal
target sites in bacteria. A bacterium that cannot build proteins cannot
survive. Erythromycin, which is commonly used to treat respiratory tract
and skin infections, is a macrolide.
Side effects?
Is there any resistance?
Bacteria resist macrolide antibiotics in 3 ways:
(1) Through target-site modification by methylation or
mutation that prevents the binding of the antibiotic to
its ribosomal target. Mutations affecting the binding
site or its tertiary structure can alter the shape and
therefore the antibiotic can no longer bind on to it.
(2) Through efflux of the antibiotic caused by the
production of active ATP-dependent efflux proteins
that transport the drug outside of the cell
(3) By drug inactivation caused by the production of
drug-inactivating enzymes
Macrolide can cause serious side effects. One is
called pseudomembranous colitis, which can cause
severe diarrhoea after you stop using macrolides.
This is because the antibiotics may kill some of the
harmless bacteria in your intestines and allow
other bacteria to overgrow; leading to a strong
bacterial infection Because macrolides can also be
toxic to the liver inflammation and congestion of
bile ducts in the liver may occur.
References: http://en.wikipedia.org/wiki/Macrolide#Uses
http://learn.genetics.utah.edu/content/microbiome/antibiot
ics/ http://www.livestrong.com/article/38199-macrolideside-effects/