Ep #152: Intro to Antibiotics: Classes, First-Line Treatments & Key Exceptions

Welcome to the Real Deal Nurse Practitioner Club, the podcast for nurses who are ready to pass their boards and thrive in their careers as real deal nurse practitioners. I’m Anna and I’m the Director of Nursing Content at Blueprint Test Prep. Whether you’re deep in exam prep or stepping into practice, I’ve got you. It is time to become the confident, knowledgeable NP that you’re meant to be. Let’s dive in. 

Hey, everyone. Welcome back to another episode of The Real Deal Nurse Practitioner Club Podcast. I’m Anna, a family nurse practitioner and your host today, and I do apologize. I’m losing my voice a little bit, but stick with me because we are kicking off our Pharmacology November today. That’s right. For the rest of the month, we are bringing you pharmacology-related content that you want to know as you are preparing for your exams.

Today, we’re going to talk all about antibiotics. Now, I only have a short time on this episode. So, this is not going to be everything that you need to know for your boards, but it’s going to be a very small little taste and content review for you, and you can even quiz yourself as we go.

We are going to walk through just a couple of the major drug classes that you’re going to want to know for boards and practice, and we’ll do a little of what we call a lightning round where I’ll just do rapid fire question and answers.

Let’s kick this episode off by starting to talk about one of the oldest, safest, and most commonly prescribed classes. Can you guess which one I’m talking about? Penicillins. All of these end in the “-cillin” ending, which makes them pretty easy to identify. And a little pro tip here for you, if you aren’t already memorizing drug classes by their suffixes, this is your sign to do so, because it is so much easier for your brain to learn material grouped together. So, knowing the common suffixes to include within each class is much easier than remembering every single individual drug within each class.

Now, a big thing to remember with penicillins is that they are a safe choice in every trimester of pregnancy, and penicillins are a broad coverage class, so they treat a lot of common conditions like acute otitis media, sinusitis, and even pneumonia. What do you all think about Augmentin? What makes that different than your typical penicillin or amoxicillin?

Well, we know that Augmentin is made up of amoxicillin plus clavulanate, so that makes it a special type of penicillin because that clavulanate is what we call a beta-lactamase inhibitor. So ask yourself, what does that help overcome? Bacterial resistance. It makes it really useful for infections where resistance is common, like recurrent sinusitis, for example. Or, for example, often the first-line treatment for otitis media is amoxicillin, but if the patient doesn’t improve, we can switch over to Augmentin because it could mean that they have a resistant bacteria.

Can you think of something else we use Augmentin for? Augmentin is also our go-to choice for dog and cat bites. In our courses, we love the memory trick, dog bitten, Augmentin. It kind of rhymes a little bit there.

All right, let’s apply this basic knowledge about penicillin to a case scenario. Let’s say we have a 12-year-old patient who presents with a sore throat and lymphadenopathy. They test positive for streptococcal pharyngitis or strep throat. What is our first-line treatment in this scenario? Well, penicillin V potassium is technically our first choice, but amoxicillin is a great choice too. For pediatric patients especially, because it tastes a lot better.

Now, what if this patient is allergic to penicillin? Say it just makes them a little nauseous. It’s a mild allergy. Well, we could do a cephalosporin like cephalexin or Keflex as a great, great option. But what if the patient had a true IgE-mediated allergy to penicillin? So think hives, wheezing, or anaphylaxis. What’s an appropriate alternative treatment in this case?

This is where I would lean towards a macrolide like azithromycin or Zithromax. That’s really the go-to option here for patients with a severe penicillin allergy. And this is why it’s so important to understand allergy history and the severity of reactions because it completely changes your next step in treatments.

Cephalosporins are related to penicillins, so there’s a small cross-allergy risk, but they’re generally safe unless the patient has that IgE-mediated allergy. These ones are pretty easy to spot since they start with “cef-,” and they’re versatile. So, for boards, just focus on the big ones. Some examples here are going to be cephalexin or Keflex. This one is one of those first-line agents for non-purulent cellulitis. There’s ceftriaxone, which when given IM is the first-line treatment for gonorrhea, or there’s cefdinir, which is a common alternative for otitis media when penicillin isn’t used.

All right. Let’s chat about one more major class here, and that’s going to be macrolides. Macrolides are pretty easy to spot because they end in “-mycin.” So, some common examples include azithromycin or Zithromax and erythromycin. Macrolides are also great because they offer broad coverage, and they are generally safe for most patients.

Now, I will say macrolides are really only considered first-line for one major condition. What do you think it is? Pertussis. It used to be the main antibiotic for chlamydia, but azithromycin is actually now considered an alternative antibiotic for chlamydia. So what is the first-line treatment for chlamydia now?

It’s actually doxycycline. So, when we’re thinking about this, what kind of patient might be a better candidate for azithromycin over doxycycline if they have chlamydia? Well, patients who are pregnant, for example. Azithromycin is a safe choice in pregnancy, while doxycycline is often avoided. We can also use macrolides in pneumonia treatment, but there’s a catch. Resistance to macrolides is rising, especially with azithromycin. So, really they’re only recommended if you are positive that local resistance is low. But we go over all of the ins and outs of pneumonia treatment in our courses because it’s a lot more nuanced. So, definitely check that out if you are not familiar with our main first options.

Let’s finish out here and do some lightning questions to test your knowledge over various antibiotics, not just penicillins, cephalosporins, and macrolides. Let’s go off that pregnancy caveat that we just talked about. What illness do we treat with doxycycline even in pregnancy? I’m going to give you a hint. It’s a tick-borne disease, and that’s going to be Rocky Mountain Spotted Fever. So, with Rocky Mountain Spotted Fever, we like to say, “With Rocky, give Doxy.”

Now, the other tick-borne disease, Lyme disease, that first-line treatment is doxycycline, even in children, but the exception with Lyme disease is going to be pregnancy. But with Rocky Mountain Spotted Fever, even if they’re pregnant, give Doxy. What is the first-line treatment then for patients with Lyme disease who are pregnant? That’s when we’re going to switch and do amoxicillin.

All right, what are some antibiotics that treat MRSA? Well, Bactrim is really our main one. We’ve got that trimethoprim-sulfamethoxazole or Bactrim, but you can also see clindamycin and doxycycline used here as well. And once again, another fun memory trick for you, think BCD for Bactrim, clindamycin, and doxycycline when it comes to MRSA. And really, between those three, how do we know which one to pick?

Just like we prefer amoxicillin over azithromycin for pneumonia treatment, Bactrim, like I mentioned, is our first choice for MRSA. Doxycycline is another great alternative, and then really, clindamycin would be what I pick last due to its side effects and that risk of C. diff with clindamycin.

And another little caveat here for MRSA, these are all really great outpatient options, but if the infection worsens or the patient spikes a fever, definitely send them to the ED for IV antibiotics.

All right, and then we just mentioned C. diff. So let’s do one final little question here. What is our first-line treatment for C. diff? Oral vancomycin. Fidaxomicin is another first-line option that you may want to know too, but typically oral vancomycin.

All right, that is going to wrap up this first little pharmacology episode. Thank you for tuning into another episode. And if you liked this episode on pharm, especially if you liked the few content review questions at the end, definitely tune into our next main episode in two weeks where Courtney and I are going to go through some rapid fire questions over high-yield pharmacology. And of course, don’t forget our new little mini episodes that we’re doing. And we have a short episode all about boxed warnings coming to you next week. Talk to you soon.