1. ANIBIOTICS AND CHEMOTHERAPUETIC AGENTS (I)
Antibiotics:
Substances produced by living organisms and active against other living organisms, e.g. Penicillin,
Chemotherapeutic agents:
Substances not produced by living organisms, active against living organisms, e.g. INAH

3. USES OF ANTIBIOTICS:
@ Treatment of patients
@ As selective agents in culture media,
e.g.: VCNT
@ To prevent contamination of tissue
cultures to isolate viruses
@ In sensitivity tests to select the drug
suitable to treat an infection.

5. Antibiotics in current use:
Classified as follows:
@ Antibiotics against G+ve bacteria
e.g.: penicillin.
Exception Neisseria is sensitive and
E.fecalis is resistant to penicillin
@ Antibiotics against G-ve bacteria,
e.g. streptomycin.
Exception Mycobacteria sensitive and
Neisseria resistant to streptomycin

7. @ Antibiotics against both G-ve & G+ve
bacteria (broad spectrum antibiotics)
e.g. tetracycline
@ Antibiotics against fungi, e.g. Nystatin
@ Bacteriostatic antibiotics:
Prevent multiplication of bacteria,
e.g.: erythromycin.
@ Bactericidal antibiotics:
Kill bacteria, e.g.: penicillin,

9. Synergism:
@ Two or more drugs are given together
to patient to increase the effect of
treatment.
@ This combined therapy is indicated:
* When organism isolated is slightly
sensitive to any of these drugs

10. * When more than one organism is
isolated and each has a different
sensitivity.
* To save life in severe infections
* For diseases known to be treated by
combined therapy, e.g.TB
* To prevent development of resistance
when drugs used are suspected to be
resistant.

12. Antagonism:
@ One antibiotic may stop the action of
the other when tested in vitro.
@ The effect of the two is less efficient
in killing the organism than using each
drug separately.

14. Synergism and Antagonism
@ Two from group (1) are synergistic never antagonistic.
@ Two from group (2) are synergistic never antagonistic.
@ One from group (1) and one from group (2):
* If organism is sensitive to group (1), antagonism occurs.
* If organism is resistant to group (1), synergism occur.
(1)
Bactericidal drugs
(2)
Bacteriostatic drugs
Penicillin
Tetracycline
Streptomycin
Chloramphenicol
Kanamycin
Sulphonamides
Gentamycin
Erythromycin