Selective toxicity is the important characteristic of antimicrobial drugs which means that any drug is selective against a particular microorganism and also selectively act on a particular site. Not all drugs can act on every site. There are many sites at which any drug acts such as cell wall, cell membrane of the bacterial cell. Basically selective toxicity explains that any drug will only act on the pathogen and not on the host.
ANTI-CELL WALL DRUGS
Anti-cell drugs are those drugs which act on the cell wall of the bacterial pathogen and not the host. There are variety of drugs which fall under this category. The major class is of beta-lactam antibiotics among which penicillin is the drug which is studied the most. The drugs can be administered into the patient’s body by different ways like intramuscular, intravenous, or can be applied as topical preparations. But mostly, these drugs are intramuscular or intravenous drugs. The following points explain the further different mechanisms of anti-cell wall drugs.
There are 3 different mechanisms by which anti-cell wall drugs work and thus they are also classified as following:
- First classification involves the drugs that directly interact with Penicillin-Binding-Proteins (PBPs) and inhibit the transpeptidase activity which in turn inhibits the attachment of newly formed peptidoglycan subunit to the pre-existing one.
This is the main mechanism of β-lactam antibiotics. These antibiotics include Penicillin (penams), cephalosporins, Penems, Carbapenems, and monobactams.
These antibiotics bind to the penicillin-binding proteins which are enzymes present in the bacterial cell wall. Different β-lactam antibiotics bind in a different way. After the antibiotics bind to the enzyme, it changes the morphological response of the bacteria to the antibiotic. - Second classification involves the drugs that bind to the peptidoglycan subunit, blocking different processes.
The important class of compounds called as glycopeptides are mainly involved in this mechanism of anti-cell wall antibiotics.
Vancomycin and Teicoplanin are the major examples of glycopeptide antibiotics.
Vancomycin kills only gram-poitive bacteria whereas Teicoplanin is active against both. The overall mode of action of glycopeptides antibiotics is blocking transpeptidation i.e. similar to β-lactam antibiotics, they also inhibit the transpeptidase activity, and transglycosylation i.e. they being large in size attach to the peptidoglycan subunits thus creating a blockage which does not allow the cell wall subunits to attach to the growing peptidoglycan backbone. - Third classification involves the drugs that block the transport of peptidoglycan subunits across cytoplasmic membrane.
The main example of such type of drugs is bacitracin, which is a simple peptide antibiotic originally isolated from Bacillus subtilis.
The mode of action of these class of drugs is blocking the activity of specific cell membrane lipid carriers which act as the attachment surface for peptidoglycan precursors and help in their movement from cell cytoplasm to exterior of the cell. This activity of lipid carriers is inhibited by bacitracin like drugs and they finally prevent the incoroporation of those precursors into cell wall thus inhibiting its biosynthesis.
Although, its route of administration is mostly oral or intramuscular, bacitracin is also known to show its effects when used as topical ointments like Neosporin.

Access to a phone, computer, or any other communication device puts the kids in the way of cyber-bullying. Here are some of the common signs to look out for if you think a child is being cyber-bullied.
Talk: The first thing to do is make your ward comfortable around you and ask him questions to learn what is happening, how it started, and who is involved. Be a part of his virtual and real life.





Talking about online anonymity is like trying to see the world as either black or white, without any shades of grey in it. Today only a hermit could be termed as a totally private person and even then it is not necessary that he or she would be anonymous. For all we know, he or she could be a famous and influential hermit!
One could even argue that it’s even detrimental not to divulge at least some information online. But it is privacy fatigue that you have become so dependent on social media which is giving you a lazy attitude toward staying anonymous. Today each of us leaves breadcrumbs that an investigator can very easily use to follow back to us.
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Many fellow writers do not agree with this, however. According to them, the writer’s block is just some excuse used for procrastination, instead of actually working on writing your project.
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