2024 PORTAGE PHARMACOLOGY
MODULE 6 INFECTIOUS
DISEASES/ANTIBIOTICS WITH
ANSWERS
Antibiotic - CORRECT-ANSWERSdrugs that have the ability to destroy or
interfere with the development of a living organism, typically bacteria.
Infectious diseases - CORRECT-ANSWERScaused by pathogenic (disease-
causing) organisms such as bacteria, fungi, and parasites as well as by
viruses.
Penicillins - CORRECT-ANSWERS- a large group of antibiotics that were first
derived from a mold often seen on bread or fruit. There are four subgroups of
penicillins: natural penicillins, penicillinase resistant penicillins,
aminopenicillins, and extended spectrum penicillins.
Mechanism of Action- Penicillins are bactericidal, specifically working to
inhibit the synthesis of the bacterial peptidoglycan cell wall. Some bacteria
have acquired the ability to produce an enzyme that is able to destroy the
penicillin called beta-lactamase. Beta-lactamase inhibitors have been
developed that can be added to the original chemical structure of penicillin
to prevent this from happening. One very common example of this is
Augmentin (amoxicillin combined with clavulanic acid which is the beta-
lactamase inhibitor).
Spectrum of Activity- The spectrum of activity is dependent on the subgroup.
- Natural penicillins- Gram-positive infections
- Penicillinase resistant penicillins- Resistant Staphylococcal infections
- Aminopenicillins- Gram-positive infection/ common Gram-negative
- Extended spectrum penicillins- Serious Gram-negative infections
Example Drug
Natural penicillins- Penicillin
Penicillinase resistant penicillins- Cloxacillin
Aminopenicillins- Amoxicillin
Extended spectrum penicillins- Piperacillin/tazobactam* (Zosyn) *tazobactam
is a beta lactamase inhibitor.
, Common Uses
Natural penicillins- Strep throat
Penicillinase resistant penicillins- Used to treat resistant staph infections
(*not MRSA)
Aminopenicillins- Ear infections, sinusitis, respiratory and skin infections,
urinary tract infections
Extended spectrum penicillins- Reserved for resistant Gram-negative
infections for example pneumonia, intraabdominal infections and sepsis
(infection in the blood).
Cephalosporins - CORRECT-ANSWERS- also within the beta lactam family.
They are structurally and pharmacologically related to penicillins
Mechanism of Action- Cephalosporins are bactericidal and work by interfering
with bacteria cell wall synthesis.
Spectrum of Activity- Cephalosporins can destroy a wide range of bacteria
related to the generation that they fall into. Scientists have modified the
original chemical structure over time to develop five generations of
cephalosporins all with varied spectrums of activity. In general, the amount
of Gram-negative coverage increases with each generation. The first
generation has the most Gram-positive coverage, and the last generation
has the most Gram-negative coverage. The only generation with any
anaerobic coverage is the second generation. The fifth generation has the
broadest covering Gram-positive (including MRSA) and Gram-negative.
Drug Interactions - Examples include increasing the risk of bleeding when
taken with warfarin, decreasing the effectiveness of oral contraceptives, and
increasing the antibacterial effect when used in combination with
aminoglycosides.
Example Drug and Common Uses of the Cephalosporins - CORRECT-
ANSWERS1st generation: Cephalexin (Kelflex)
- Example Use: Simple staphylococcal infections
2nd generation: Cefoxitin (Mefoxin)
- Example Use: Prophylaxis for patients undergoing abdominal surgery
because it can kill intestinal bacteria including anaerobes.
3rd generation: Ceftazidime (Fortaz)
- Example Use: Meningitis caused by pseudomonas (gram-negative)
Resistance is beginning to limit its usefulness.
4th generation: Cefepime (Maxipime)
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