Original subtitles

It is a dark time for penicillins. Although the first death caucus has been

destroyed, beta -lactamase -producing staphylococcal species have crushed the

rebellion. A group of anti -staphylococcal freedom fighters,

naphthalene, have established a new secret base on a remote planet and

the fight.

And so, our tour of beta -lactam antibiotics continues.

And believe me, this sequel is way better than the first one.

Arguably the best in the series.

Okay, so beta -lactam antibiotics are again represented by our beta -lactam

ringed planet.

Construction has secretly begun on a new death caucus, and notice again that the

D -ala -D -ala structure is exposed, as the penicillin -binding proteins,

represented by construction workers, build the cell wall.

Just like we covered in the penicillin sketch, these anti -staph penicillins

inhibit the transpeptidation reaction at the bacterial cell wall by covalently

binding, or in this case shooting down, PBPs, halting peptidoglycan synthesis

and killing the cell. That makes it bactericidal.

This time the rebels came prepared, because their tips have bulky armor,

representing bulky R -groups that prevent beta -lactamase binding.

So the plasmid -encoded beta -lactamase guards strike back, but their

retaliatory fire is deflected.

These anti -staphylococcal penicillins have a narrow spectrum of activity, and

they're often the drug of choice for methicillin -sensitive, penicillin

-resistant strains of staphylococci.

Remember that the bugs susceptible to these bulked -up penicillins are called

methicillin -sensitive, but methicillin is no longer used clinically due to high

rates of adverse events.

Instead, remember naff for staff, and oxacillin for

staffoxacillin. Just rolls right off the tongue.

Anyways, take a look at the foreground here, and we have naffcillin represented

by this rebel fighter with a purple pencil -shaped staff.

Look familiar?

Yep, it's the same naffcillin staff from the sketchy micro staff aureus sketch.

And if you haven't seen the Staff Warrior sketch yet, it's like the

Part 2 of our Sketchy Micro series.

It's pretty good. You should check it out.

The horned creature that he's sitting on will represent oxacillin, cloxacillin,

dicloxacillin, which all have ox in them, hence the ox horn.

To emphasize their narrow spectrum of activity, notice how all the space

stations around the Death Caucus are purple spheres and clusters.

to represent gram -positive staphylococci.

When given orally, anti -staph penicillins are suitable for treatment

moderate localized staph infections.

For example, they're commonly used empirically to treat skin and soft

infections like folliculitis and abscesses, for which staph aureus is a

cause. And notice how our staph -wielding rebel is sitting on one of the

big... red, yet surprisingly supportive, hump, which almost looks like a big

inflamed abscess.

When given by IV infusion, anti -staph penicillins can be the drugs of choice

for serious systemic staphylococcal infections, including staph

represented here by these tricuspid pyramids on the horizon, and staph

osteomyelitis, represented by these fish skeletons.

strewn in the sand.

In general, remember that these staph -killing drugs have a similar side

profile as penicillin, such as hypersensitivity reactions and

nephritis. So check out that penicillin video for important beta -lactam side

effects.

Alright, before we move on with our tour, let's talk about methicillin

-resistant staph aureus.

MRSA produces PBPs that have low affinity for binding.

beta -lactam antibiotics.

These altered penicillin -binding proteins, then, render our anti

-staphylococcal freedom fighters, like naphthalene, completely powerless.

So the anti -staph ships that were initially shooting down the PVP

workers to halt cell wall synthesis are now thwarted by altered PVPs,

represented by these upgraded troops who continue peptidoglycan wall synthesis

as the rebel missiles bounce off.

In previous sketches, Mertha is always associated with a merciless, golden

-staff -wielding pharaoh, and it looks like he's back, as none other than the

fan -favorite Dark Lord Mertha.

I find your lack of activity against altered PBPs disturbing.

And then he chokes that one British guy. I mean, why would you talk back to him?

I mean, look at him. Alright, let's sum up this sketch.

Remember that your anti -staphylococcal penicillins, are more resistant to beta

-lactamases. They can be used for localized and systemic staph infections

are not active against MRSA.

Next on our tour, I think we'll take a little detour. I know a cantina near

here.