Friday, February 13, 2015

A Promising New Class of Antibiotics

As mentioned in an earlier report, the current classes of antibiotics (See table below) being utilized to fight infection are no longer effective in regards to certain diseases, especially since many pathogenic organisms have developed an effective immunity against them. 

Classes of Antibiotics Currently in Use -

Mode of Action
Inhibits bacterial cell wall biosynthesis
Inhibits protein synthesis in Gram-negative bacteria  such as Streptomyces griseus
Inhibits protein synthesis in Gram-positive bacteria such as Streptococcus pneumoniae by preferentially binding to the  50S component of the bacterial ribosome
Inhbits protein synthesis by preferentially binding to the  30S component of the bacterial ribosome
Irreversibly binds to and inactivates key enzymes that maintain bacterial DNA

Note: Antibiotics are of no use in treating viral infections since the biology of the virus is markedly different than that of bacterial agents.

There is, however, some basis for renewed optimism in regard to this global public health concern.  Most antibiotics currently being utilized are natural products produced by cultured soil micro-organisms.  For varied reasons, some economic in nature, the synthetic production of antibiotics has been unable to adequately supply new and effective classes of antibiotics.  Uncultured bacteria, on the other hand, although large in number, have been an untapped resource for new antibiotics.

Dr  Losee Ling and his colleagues at the Novobiotic Team,  NovoBiotic Pharmaceuticals, LLC.  767C Concord Ave, Cambridge, MA have developed specific methodologies to grow uncultured organisms thereby opening up a vast new resource.  As a result of an exhausted screening of uncultured bacteria,  they discovered a new antibiotic that they have called teixobactin (see the structure below).

Teixobactin acts by inhibiting cell wall synthesis.  It  accomplishes this by binding to highly conserved constituents of the bacterial cell wall and, in this way, effectively interfering with cell wall synthesis resulting in bacterial cell death.  The investigators were able to demonstrate that no resistant strains were produced when teixobactin was used to undermine the growth of both Staphylococcus aureus and Mycobacterium tuberculosis- pathogens responsible for Staphylococcus infections and Tuberculosis, respectively .   According to Dr. Ling, “The properties of this compound suggest a path towards developing antibiotics that are likely to avoid development of resistance.”

This is a very exciting development in regards to global public health.

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