00:01
Next we have the cephalosporins.
00:03
The cephalosporins are
divided into generations.
00:06
Let's start with the
first generation cephalosporins.
00:10
The most commonly
used is Cefazolin.
00:13
Cefazolin has excellent coverage
against gram positive organisms.
00:17
And if you think about it,
it's an excellent antibiotic to use
in surgical infections.
00:22
Now, if you have a skin infection,
Cefazolin is probably
your go to drug.
00:28
However, cefazolin does not have
much effectiveness
against gram-negative bacteria.
00:33
So for example, if you had
a urinary tract infection,
cefazolin is not going to be
very intelligent empiric antibiotic choice.
00:41
Okay, I had said before that the
first generation cephalosporins
had excellent
gram-positive coverage,
but not so great
gram-negative coverage.
00:51
As we move down in the generations,
you'll start to see that the
higher generation medications
have better and better coverage
for gram-negative organisms.
01:00
Now, those gram-negative
organisms can be seen
in respiratory tract infections.
01:05
We often think of as a
second-generation cephalosporins
as being respiratory drugs.
01:10
Why is that?
Because for
upper respiratory infections
have a lot of
gram-positive organisms
and some
gram-negative organisms.
01:18
For example, cefuroxime
works against gram-negative
bacteria quite nicely,
and it works very well against
Haemophilus influenza.
01:26
So if we have a
person who has either
a strep infection or
Haemophilus infection,
but we don't know,
will often use cefuroxime.
01:35
Now, the nice thing about
cefuroxime and these drugs
is that they also have a little
bit of anaerobic activity.
01:43
Generally speaking, we don't see
anaerobic activity much in the lung.
01:49
Now we move on to the
third generation cephalosporins.
01:52
So what do you think
based on my logic
that these are going to cover?
Well, you'd be right.
01:57
These drugs like cefotaxime,
are very effective at
gram-negative organisms.
02:03
Unfortunately, you make a trade off
because they're less effective
at gram-positive organisms.
02:08
They will often work
against organisms
that are resistant
to many penicillins.
02:15
So sometimes we'll either use it
as an agent
that we know a person
has had a penicillin before
and didn't respond.
02:23
Now, we only use this
particular type of cephalosporin
and serious infections.
02:28
I like to say that these are
intensive care unit drugs,
but not really.
02:32
I would say that
they're ward at drugs.
02:35
So we tend to use them
on the medical floor
when people have
really bad infections.
02:40
Let's move on to the
fourth generation cephalosporins.
02:44
This category involves
a very complicated drugs
Cefepime
is a perfect example of that.
02:51
Now, these drugs are zwitterions.
02:54
What's a zwitterion?
A zwitterion is an ion or a drug
that has two different charges
on the same molecule.
03:02
Normally, we think of
molecules as either being
positively charged
or negatively charged,
A zwitterion has a
positive charge on one end
and the negative charge on another.
03:11
Okay, let's move on.
03:13
So a fourth generation
cephalosporin like cefapime
is more resistant to beta
lactamase producing organisms.
03:21
Enterobacter is a particularly
difficult infection to treat.
03:26
We often see this
in very sick patients
who are in the
intensive care unit or on the ward.
03:34
So, let's say a person comes in.
03:36
You suspect that they have a
beta-lactamase based infection.
03:39
Cefepime is a really good choice
in this particular type of patient.
03:44
Now we move on to
fifth generation cephalosporins.
03:48
It includes drugs
like ceftaroline.
03:50
Now, I want to make a mention
that not everyone accepts
the whole nomenclature behind
fifth generation cephalosporins.
03:57
There are some people
who just say that
all fifth generations
are unclassified.
04:02
I'll leave that debate
alone for a moment.
04:04
Now take a look at this structure.
It's a very complicated structure.
04:08
So you can see,
that these fifth generation
cephalosporins are larger,
more complicated molecules.
04:15
Ceftaroline,
has excellent MRSA coverage,
and we will often use it in
patients who are sick with MRSA.
04:23
This is another agent.
04:24
You can see it's a
slightly simpler structure.
04:27
It has powerful
antipseudomonas activity,
and it also can work against VRE,
which stands for
Vancomycin-resistant Enterococcus.
04:37
Ceftolozane is another
fifth generation cephalosporin.
04:41
We will often use this in
intraabdominal infections
that are complicated.
04:45
So intra abdominal infections
tend to have a lot of
gram-negative organisms.
04:50
They sometimes have
gram-positive organisms.
04:53
And more importantly,
they have anaerobic organisms.
04:58
And treating anaerobic organisms
is notoriously difficult.
05:01
We have to resort to
very complicated drugs.
05:04
This is an excellent choice
for an abdominal infection.
05:08
Sometimes complicated
urinary tract infections
can be treated with
this drug as well.
05:13
And when you think about it,
urinary tract infections
also tend to have
a lot of gram-negative.
05:19
Sometimes they'll have anaerobic.
05:20
and sometimes they'll have
Pseudomonas infections.
05:23
We will often combine it
with tazobactam.
05:26
And remember that tazobactam
is combined with other agents to
like Piperacillin.
05:31
Finally we have the unclassified.
05:33
Now, maybe someday we'll call this
the sixth generation. I don't know.
05:37
There's a whole host of them.
05:39
They haven't really
been studied very much.
05:41
They're brand new.
05:43
And information will come out
as they start to get
more and more clinical usage.