Welcome to chapter four immune:
vancomycin, MRSA and C. Diff, that's
methicillin-resistant staph aureus and clostridium difficile
which we'll talk about a little bit as well. The four drugs were going to use, and I put vancomycin and some resistant infections.
Penicillin, so amoxicillin we're bringing that back, and I'm going to talk a little bit about methicillin, brand Staphcillin.
They don't make it anymore as I understand, but it's useful to talk a little bit about the history.
Oxazolidinone, Linezolid, brand Zyvox, the lincosamide
clindamycin, Brand Cleocin, and the glycopeptide
vancomycin,
Vancocin. The stems are '-cillin' for the penicillin, '-zolid' for the oxazolidinone,
'-mycin' for the licosamide, but that just tells you it's from streptomyces strain, same as the glycopeptide vancomycin.
Practice question one, just looking at the drug classes: 'If methicillin, brand Staphcillin, is beta-lactamase resistant, which
antibiotic is beta-lactamase sensitive? Select all that apply.
A) the beta-lactam aminopenicillin antibiotic amoxicillin is beta-lactamase sensitive. That is the enzyme
that attacks the beta-lactam ring
will destroy the aminopenicillin. The other ones are not beta-lactam antibiotics
so
that begs the question, you know, what are these other ones good for and what are the issues that we're going to see with them.
These don't really group nicely the way that penicillins have amoxicillin and ampicillin
and so forth and we'll see that in a minute.
So there's the answer, the beta-lactam aminopenicillin antibiotic amoxicillin is beta-lactamase sensitive.
Let's go to the drug names because that's what we're really going to see on the exam, so
methicillin is beta lactamase resistant. Which is beta-lactamase sensitive?
Amoxicillin, now without the clavulanic acid as Augmentin would be beta lactamase sensitive, and then
clindamycin, linezolid and
vancomycin are not Beta-Lactam antibiotics.
Vancomycin does affect cell wall as do penicillins and cephalosporins,
they just do it in a different way The reason that vancomycin works where penicillins fail
is that they don't use the penicillin binding proteins as their mechanism of action. They use an alternate mechanism of action,
disrupting the bacterial cell wall.
Our drugs again are amoxicillin, clindamycin, linezolid, and vancomycin.
Let's make B) correct, practice question three: 'Which of the following antibiotics is most likely to result in clostridium difficile associated diarrhea (CDAD)?'
Clindamycin is notorious for this. Amoxicillin and penicillins are broad-spectrum,
it's less likely. Linezolid actually would be a possible treatment for C. Diff, and
then vancomycin is a treatment that's recognized for
Clostridium difficile.
Practice question four, make C) correct: 'Which of the following antibiotics can treat both
vancomycin-resistant enterococci (VRE) and
methicillin-resistant staph aureus (MRSA)?'
It's kind of giving it away because on an exam you would likely see VRE
and MRSA without the actual organism spelled out, so
amoxicillin no, clindamycin no, they're not going to do that, but linezolid yes.
This is both good against vancomycin resistant enterococci, and it's also good against MRSA,
methicillin-resistant staph aureus.
Vancomycin would be one of those it's partially right, so it's wrong.
If something is vancomycin resistant, obviously vancomycin is not going to work, but it does work against MRSA,
so because it's partly right, it doesn't answer the question properly.
The last one is one of those questions where this is common knowledge.
It's expected that when you hear red man syndrome, the first thing you're going to think is vanco. Practice question five, make D) correct:
'Which of the following antibiotics is associated with the infusion related reaction Red Man syndrome?'
Select all that apply.
In this case,
vancomycin, yes, it involves this erythematous rash on the neck, torso,
all over and then pruritis as well which
loosely translates to hives. Again, this is an infusion related reaction,
but this is something that as soon as you see Red Man syndrome,
immediately you should thank vancomycin or vice-versa. Amoxicillin again
is beta-lactamase
sensitive,
clindamycin you're going to see CDAD with that one, linezolid is good for VRE and MRSA,
vancomycin is good for MRSA
but we're going to have this very unique side effect or reaction of Red Man syndrome as an infusion related reaction.