Antibiotic:Chemicalproducedbyamicroorganismthatkillsorinhibitsthegrowthofanothermicroorganism

1. Dr. Aejaz Ahmed M.Pharm Ph.D
Department of Pharmaceutical Chemistry
Ali-Allana College of Pharmacy, Akkalkuwa
*

2. *Antibiotic: Chemical produced by a
microorganism that kills or inhibits the
growth of another microorganism
*Antimicrobial agent: Chemical that kills
or inhibits the growth of microorganisms
*Antibiotic/Antimicrobial

3. *Alexander Fleming and Penicillin's
*Sir Alexander Fleming’s accidental discovery of the antibacterial properties of
penicillin in 19291 is largely credited with initiating the modern antibiotic era.
*Florey and Chain introduced penicillin into therapy later in1938, however, when
did practical medical exploitation of this important discovery begin to be realized.
*

4. *Ehrlich Magic Bullet
*The magic Bullet Scientific concept
developed by a German Nobel
Laureate's Paul Ehrlich in 1900.
*Paul Ehrlich formed an idea that it
could be possible to kill specific
microbes(such as bacteria) which
causes a disease in body, without
harming the body itself.
*Discovered Salvarsan the first
effective drug in 1909 for the
treatment of Syphilis is the first Magic
Bullet

5. *Selective Toxicity
A drug that kills
harmful microbes
without damaging
the host

6. Microbial Sources of Antibiotics
Six important Steps of Commercial Production
(a) Preparation of a pure culture of the desired
(b) Fermentation
(c) Isolation of the antibiotic
(d) Purification
(e) Assays for potency, sterility, absence of
Pyrogens etc.
(f) Formulation into suitable dosage forms.

7. *
*The ability of some antibiotics, such as chloramphenicol and
the tetracyclines, to antagonize the growth of numerous
pathogens has resulted in their designation as broad
spectrum antibiotics.
*Designations of spectrum of activity are of somewhat
limited use to the physician, unless they are based on
clinical effectiveness of the antibiotic against specific
microorganisms.
* Many of the broad-spectrum antibiotics are active only in
relatively high concentrations against some of the species of
microorganisms often included in the “spectrum.”

8. * No antibiotic is effective against all microbes

9. *MECHANISM OF ANTIBIOTIC ACTION

10. *Mechanism of action: The cell wall of bacteria is
essential for the normal growth and development.
Peptidoglycan is a heteropolymeric component of the cell
wall that provides rigid mechanical stability by virtue of
its highly cross-linked lattice-wise structure.
*The peptidoglycan is composed of glycan chains, which are
linear strands of two alternating amino sugars (N-acetyl
glucosamine and N-acetyl muramic acid) that are cross-
linked by peptide chains.
*The biosynthesis of peptidoglycan involves three stages.

12. *The last step in peptidoglycan synthesis is inhibited by β-lactam
antibiotics. The transpeptidase enzyme contains serine, which is
probably acylated by β-lactam antibiotics with cleavage of -CO-N-
bond of the β-lactam ring. This renders the enzyme inoperative
and inhibits peptidoglycan synthesis.

14. *
The penicillins are commonly named as penams, a
designation in which the sulphur atom is given the
top priority.

15. Conversion of natural penicillin to synthetic penicillin.

16. *

18. *
Figure 20.6

19. *
Figure 20.8

20. *Polypeptide antibiotics
*Bacitracin
*Topical application
*Against gram-positives
*Vancomycin
*Glycopeptide
*Important "last line" against antibiotic resistant S. aureus
*

21. *
*Penicillins cause hypersensitivity reactions
(allergy) in several percentages of patients
and this may be due to formation of
antigenic penicilloyl proteins formed in
vivo by the reaction of nucleophilic groups
(e.g., ε-amino) on specific body proteins
with the β-lactam carbonyl groups.

22. *
*Excellent gram-positive potency against susceptible Staphylococci,
Streptococci
*Useful against some gram-positive cocci
*Good oral absorption but relatively acid-labile
*Ineffective against gram-negative bacilli
*Susceptible by deactivation by penicillinase

23. *

26. *