Know about the molecule: Penicillin

Mr IntMol: Hello everyone this is your host as Mr. Interview Molecule, today we have a very special guest with us named penicillin. Who is an antibiotic of beta-lactam family. And this is the Molecule Interview Show By MicrobiologyMadeEasy.com, let begin!

Mr IntMol: So, Penicillin tell us about yourself, your origin and other stuff.

Penicillin: Hello, I am Penicillin, discovered by Alexander Fleming when he was working with the mold Penicillium notatum. I am a beta-lactam antibiotic.

Mr IntMol: And people say that you are very historically significant, is that true?

Penicillin: Yes it is, because we Penicillins were the first drugs that were effective against many previously serious diseases like syphilis, and infections caused by staphylococci and streptococci.

Mr IntMol: And what about now?

Penicillin: Various organisms have been resistant and we cannot eliminate them. However we are still widely used.

Mr IntMol: When the humans consume you do they have any ill effects?

Penicillin: Not directly, but some humans when given Penicillins they give an 'adverse drug reaction' in this case it will be called as 'Penicillin drug reaction'. Diarrhea, hypersensitivity, nausea, rash, neurotoxicity, urticaria, and superinfection is usually associated with 'Penicillin drug reaction'.

Mr IntMol: And what is your route of administration?

Penicillin: Oral Route, Injection Route, Intravenous Route, Intramuscular Route. But many Penicillin are unstable so parenteral route is usually used. Oral route may lead to acid inactivation in stomach.

Mr IntMol: How to you go about with the killing of your target?

Penicillin:  PBP's or Penicillin binding proteins are used by bacteria for cell wall synthesis. We bind to these molecules and interfere with cell wall synthesis, which leads to target cell lysis.

Mr IntMol: Oh, I see. what are you effective against?

Penicillin:  We are most effective against gram positive cocci, anaerobic pathogens and spirochetes. But however most semi-synthetic penicillins are effective against a wide range of bacteria.

Mr IntMol: We thank penicillin to be on our show. We end this show today with a funny saying about penicillins

"When life gives you molds, make Penicillin"

Antibiotics made easy

Blog by Mufaddal IfuM Dewaswala

Antibiotics are compounds which are either of biological or chemical origin which stop the growth of bacteria or kill them. They act on various process of the bacteria like DNA replication, cell wall synthesis, protein synthesis etc.

They are divided into two groups:
 
Bacteriostatic (antibiotics which inhibit the growth)
Bactericidal (antibiotics which kill the organisms)

The bacteriostatic antibiotics stop the growth of the organisms until they are killed by the body's immune system they include some protein synthesis inhibitors.



Classes of antibiotics:

 
Antibiotics are classified among various classes with respect to their action, chemical structure, or spectrum of activity.

Action: As mentioned earlier, different antibiotics have different action such as inhibiting DNA replication, cell wall synthesis, protein synthesis etc.

Spectrum of activity: Microorganisms are of different types eg. gram postivie organisms, gram negative organisms, fungi etc. Due to the different modes of action the antibiotics maybe effective on some organisms and may not have any action on others.
Due to this, the antibiotics are classified as 'narrow spectrum antibiotics' which are effective against only a narrow range of bacteria while 'broad spectrum antibiotics' are effective on various types of bacteria.

Chemical structure: Classification usually is on the basis of chemical structures and chemical names.

Lists of various antibiotics and important examples

Protein synthesis inhibitors:
Aminoglycosides: Streptomycin, Gentamicin etc
Macrolides: Azithromycin, Erythromycin etc
Tetracyclines: Tetracycline, Doxycycline etc

Cell wall synthesis inhibitors:
Penicillins: Mithicillins, Penicillin G etc
Cephalosporin: Ceftobiprole, cefeprime etc

DNA synthesis inhibitors:
Quinolones: Ciprofloxacin, Norfloxacin etc

Folic acid inhibitors:
Sulfonamides: Sulfadiazine, Silver sulfadiazine etc

Production of antibiotics:
Antibiotics are produced by chemical methods or biological methods or both combined. Fungi like Streptomyces, Pencillium produce certain antibiotics in their stationary phase.
Some of the penicillins are first synthesised biologically by Peinicillium species and then the strutures of these penicillin are chemically modified to produce more effective antibiotics.