Penicillin - Caangay.com
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Transcript Penicillin - Caangay.com
Case 1
Tunyapon Sasithorn
Pharmacology
Clinical case
Problem 1
A clinical study evaluating the efficiency
of the antibiotic treatment of the
meningitis was carried out. One group
of patients with pneumococcal
meningitis received parenteral
penicillin. A second group received
penicillin plus tetracycline therapy.
A.
How do penicillin and
tetracycline differ in
their mechanism of
action?
Penicillin
Mechanism of Action
B- lactam antibiotics work by inhibiting the
formation of peptidoglycan cross links in the
bacterial cell wall.
The B- lactam moiety of penicillin binds to the
enzyme (transpeptidase) that links the
peptidoglycan molecules in bacteria, and this
weakens the cell wall of the bacterium when it
multiplies
This causes cell cytolysis or death when the
bacterium tries to divide.
The build-up of peptidoglycan precursors
triggers the activation of bacterial cell wall
hydrolases which further digest the bacteria's
existing peptidoglycan.
Tetracycline
Mechanism of Action
Tetracyclines inhibit bacterial protein
synthesis by blocking the attachment of
the transfer RNA-amino acid to the
ribosome.
They are inhibitors of the codonanticodon interaction.
Mechanism of Action
Penicillin
Bactericidal
Tetracycline
Bacteriostatic
2.
Which group had a
lower mortality rate?
Mortality was significantly higher in the
penicillin– tetracycline group compared
to the single drug penicillin group:
Mortality rate
Penicillin – tetracycline group
79%
∞one of seven patients survived
Penicillin group
30%
∞ nine of 20 patients survived
3.
If there was a
difference, what would
account for the
observation?
Penicillin group experienced a bactericidal
effect which is very important in treating
patients with pneumococcal meningitis.
Penicillin – tetracycline – a combination of a
cell wall agent, the bactericidal activity of which
depends on cell growth (penicillin), with a
reversible protein synthesis inhibitor that
interferes with cell growth (tetracycline), is a
classical example of antibiotic antagonism,
resulting in the lower mortality rate of
penicillin – tetracycline group.
Antagonist reaction of Penicillin
and tetracycline renders these
drugs in combination ineffective.
The mutual antagonist reaction
produces an overall bacteriostatic
activity which proves ineffective in
treating patients with
pneumococcal meningitis.
4.
Any other drug
combination that you
can recommend? On
what basis?
Other drug recommendations
due to:
Meningitis with penicillin
resistant pneumococcus
Other synergistic reaction
Drug combinations
Drugs of first choice
Children
Ceftriaxone
Cefotaxime +/Vancomycin
Adults
Ceftriaxone
Cefotaxime
Others
Rifampin
B lactam antibiotic
Ex: Penicillin, Ampicillin,
Piperacillin and Cefuroxime
+ Gentamicin
Alternative drugs
Children
Chloramphenicol
Systematic
corticosteroids
Adults
Vancomycin +
Ceftriaxone
Vancomycin +
Cefotaxime
Thank You
sir, mam.
Come again!
:P