Module 16 - Part 2 Flashcards
Penicillin
- Discovered by?
- Mechanism of action?
- Net result?
- Antibiotic type?
- Effective against which type of bacteria?
Sir Alexander Fleming
Inhibits Transpeptidases and activates autolysins
Causes breakdown of the cell wall, influx of water and lysis of the bacterium
Bactericidal
Effective against gram positives due to large cell wall
What are the two PBPs?
PBPs = penicillin binding proteins
Transpeptidase
Autolysin
Enzymes that function to form cross-bridges between the peptidoglycan strands, therefore making the cell wall strong.
Transpeptidases
Bacterial enzymes that degrade the peptidoglycan cell wall
Autolysins
How may penicillin resistance come about?
Inability to reach its target (see efflux/uptake)
Inactivation of penicillin
Mutations in PBPs making them have low affinity for penicillins (e.g. MRSA)
Predominant mechanism of resistance against penicillins.
Beta lactamases
What are the different classes of penicillins?
Narrow spectrum penicillins
Narrow spectrum penicillinase resistant penicillins
Broad spectrum penicillins
Extended spectrum penicillins
Narrow spectrum penicillins:
- Effective against what?
- Administration and reasoning behind it.
- Effective in treating what infections?
- Adverse effect profile
Effective against gram positives
Administered by IV or IM since some are destroyed by gastric acid
Effective in treating pneumonia and meningitis
Drug allergy is the primary side effect
How are narrow spectrum penicillinase resistant penicillins resistant to penicillinase?
Have an altered side chain that makes them not susceptible to inactivation by beta-lactamase enzymes
Why aren’t narrow spectrum penicillinase resistant penicillins always used?
Less effective against non-penicillinase producing bacteria
Narrow spectrum penicillinase resistant penicillins:
Effective against?
No effective against?
What bacteria are resistant?
Effective against penicillinase producing Staphylococci
Less effective vs. non penicillinase producing bacteria
Not effective in treating abscesses or penetrating into bone
MRSA
Broad spectrum penicillins:
Effective against?
Reason for being broad spectrum (i.e. mechanism)?
Inactivated by?
Effective against both gram +ve and -ve bacteria
Able to penetrate the outer membrane of gram negatives and are thus broader in spectrum
Readily inactivated by beta lactamases
Have the same mechanism of action as penicillins.
Cephalosphorins - inhibit transpeptidases and activate autolysins
Cephalosporins:
- Antibiotic type (i.e. bacteri______)
- As we move from 1st generation to the 4th generation, what occurs?
- Most frequently reported side effect?
- Why are these used when a person has an allergy to penicillin?
Bactericidal (same as penicillins)
1st –> 4th = drugs tend to increase in terms of their activity against gram negative bacteria, increase their ability to penetrate CSF and increase their resistance to beta-lactamase enzymes
Allergy
Cross reactivity of people with penicillin allergy is very rare, thus cephalosporins can be used in penicillin allergic persons
When is vancomycin used?
Potentially toxic drug - used only to treat resinous infections such as those caused by MRSA, including osteomyelitis, meningitis, pneumonia and septicemia