[Fan Favorite] Antimicrobial Therapy

As we step away for a holiday break, we’re excited to revisit some of the most popular episodes of the FNP Certification Q & A Podcast. These listener favorites have informed, inspired, and empowered aspiring NPs on their journey to certification success. Enjoy some of our favorites. We'll catch you in 2025 with fresh questions from Dr. Fitzgerald!

Josh is a well 16-year-old male who presents with a reporting a 4-day history of moderate left-sided otalgia with intermittent fever.  Clinical assessment is consistent with acute otitis media (AOM).  No drug allergy or recent (within the past month) antimicrobial use is reported.  Which of the following represents the most appropriate first-line antimicrobial therapy?

A. Oral moxifloxacin

B. Oral amoxicillin

C. Oral trimethoprim-sulfamethoxazole

D. Oral azithromycin
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Transcript

Welcome to NP Certification Q&A presented by Fitzgerald Health  Education Associates. This podcast is for NP students studying to pass their NP certification exam. Getting to the correct test answers means breaking down the exam questions themselves. Leading NP expert Dr. Margaret Fitzgerald shares her knowledge and experience to help you dissect the anatomy of a test question so you can better understand how to arrive at the correct test answer. So if you're ready, let's jump right in.  

Josh is a well, 16-year-old male who presents reporting a four-day history of moderate, left-sided otalgia with intermittent fever. Clinical assessment is consistent with acute otitis media (AOM). No drug allergy or recent antimicrobial use is reported, particularly within the last month. 

Which of the following represents the most appropriate first-line antimicrobial therapy? 

 Would it be... 

A. Oral Moxifloxacin. 

B. Oral amoxicillin. 

C. Oral trimethoprim-sulfamethoxazole. 

D. Oral azithromycin. 

 Where do you start? 

 First, of course, determine what kind of a question this is. We're told the diagnosis acute otitis media, and we're prompted to prescribe an antimicrobial. This is a plan slash intervention question. 

What are the key components in the history here?  

Here are some of the key components.  No drug allergies are reported. Therefore, what we can do is prescribe any antimicrobial that's consistent with evidence-based practice. Next, no recent antimicrobial use, therefore significantly limits the risk of infection with a resistant pathogen. And please keep in mind, most outpatient infections are the result of non-resistant organism. 

 We have acute otitis media in a teen or adult without chronic health problems. We're told he's well. If a question says the patient is well, they're well. Leave it be. They don't have any hidden significant health problem. 

 Therefore, we don't need to think about second or third-line antimicrobial therapies. And with the choice of any antimicrobial, regardless of what kind of disease pathogen is causing it, knowledge of the causative organism is key. Another way of putting this in, in order to know which drug to pick in any infectious disease, you need to know the causative bug. 

The primary treatment target in acute otitis media is one of three organisms: Streptococcus pneumoniae, which will usually be the most common a gram-positive organism, as well as two gram-negative organisms: Haemophilus influenzae and Moraxella catarrhalis. 

 I want to point out to you these are also the causative organisms in acute bacterial rhinosinusitis and with COPD exacerbation when bacterial contribution is the trigger. 

 As a result, you're going to see similar antimicrobials are recommended in all of these diseases. 

 And what I often will hear from people getting ready for their NP awards is they'll say, I struggle so much with antimicrobial choices. 

 What I would encourage you to do, learn the bugs, then see what bugs are eradicated by what drugs, and the same bugs come up over and over and over again, which is why the same drugs come up over and over again. 

 Clinical recommendations for antimicrobial therapies in acute otitis media based on the recommendations of the Stanford Guide, a helpful clinical reference that reflects evidence-based practice highlights the use of the following antimicrobials. 

 A. Oral moxifloxacin. This is a respiratory fluoroquinolone. How can I tell it's a fluoroquinolone? It has the -floxacin suffox on it. All the fluoroquinolones do. This drug is typically only used in acute otitis media when there is significant risk for resistant organism such as the person who recently, particularly within the past month, took a systemic anti-microbial. 

 B. Oral amoxicillin. This is actually the correct answer. The reasons for this are many, including great activity against strep pneumo, the most likely causative organism when given in a sufficient dose. In many strains of Haemophilus influenzae, particularly those that do not produce beta-lactamase. Another part of this is when acute otitis media is caused by H. flu and M. cat, it usually resolves without any microbial even being taken. So that is another way of saying our true treatment target with acute otitis media is strep pneumo. Give enough of a dose of oral amoxicillin, $4 drug, very well tolerated. This young man has no notation of antibiotic allergy, penicillin allergy. We're good to go with this very well-tolerated inexpensive medication.  

 But let's take a look at the rest of the options.  

 C. Oral Trimethoprim sulfamethoxazole — that is brand name Bactrim. And if I was to roll the clock back 15, 20 years ago, I would be saying, well, that's a possibility we're going to use that medication. But this is now and what I'm going to tell you is Trimethoprim sulfamethoxazole is no longer considered to be an acceptable choice of antimicrobial therapy in acute otitis media, and for that matter, an acute bacterial rhino sinusitis in any age group because of the high rate of treatment failure with the three major causative organisms. 

 Option D. Oral azithromycin. And what I have to say is sadly, due to overuse azithromycin’s activity against Streptococcus pneumoniae is waning, and this is an anti-microbial that's only been on the market about 25 years and unfortunately, this degree of resistance developed rather quickly because azithromycin a.k.a zithromax has been handed out unfortunately indiscriminately by many health care providers when it was not needed, and it's used in acute otitis media and ABRS is no longer advocated even with penicillin allergy, it's activity against the acute otitis media gram-negative organisms does remain intact, but given strep pneumo is truly our treatment target, its use is not recommended in acute otitis media or acute bacterial Rhinosinusitis. 

Key takeaway to choose the drug, you must know the bug. Watch for patterns in the selection of antimicrobials, particularly in the treatment of bacterial respiratory tract infections. Anticipate on boards that you're going to be asked about first-line antimicrobial therapy in an individual suitable for outpatient treatment.  

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