Episode 22- One-time IV antibiotics prior to discharge

Hello and welcome to episode 22 of ER-Rx. How many of you have given IV antibiotics prior to sending your patient home from the ER? My guess is that it is a large majority of you. But is this necessary? Is it even helpful? Let’s talk a little bit about this in a few different clinical scenarios.

To start, we have to remember that a lot of the antibiotics that we use have very high oral bioavailability. Examples include cephalexin (> 95%), clindamycin (> 90 % bioavailable), Bactrim (>95% % bioavailable), doxycycline (>90 % bioavailable), levofloxacin (> 95%), and metronidazole ( >95%) which all have >90 – >95% oral bioavailability. And although bioavailability isn’t the only factor that determines an antibiotic’s efficacy, it is a good place to start.

In the setting of cellulitis, giving someone a one-time dose of an antibiotic prior to discharging them from the ER is unnecessary. For example, let’s look at vancomycin. Vancomycin’s efficacy is typically measured by checking trough levels, which may remain sub-therapeutic for a number of doses (even days)-especially if no loading dose was given. There is no benefit in giving your patient one dose of vancomycin, then sending them home on an oral antibiotic. On the contrary, this wastes money, leads to extra time in the department, and theoretically it could breed resistance due to sub therapeutic dosing. Also, we increase the risk of phlebitis, thrombosis, extravasation, and even bacteremia- risks that we have when giving any IV medication. To make it worse, previous in vitro work has shown that any exposure to vancomycin in the previous 30 days increases the MIC of vancomycin needed to treat MRSA in the future. All in all, this is harmful for our patients.

We actually have a study from the Journal of Emergency Medicine that found that a large majority of patients given vancomycin then discharged from the ER had conditions that did not warrant the use of vancomycin at all (ie. uncomplicated SSTIs). In this study, some patients weren’t even discharged on any antibiotics after the initial vancomycin dose, and to make matters worse, they weren’t given a dose of the oral discharge antibiotic in the ER. This delays the administration of the potentially therapeutic antibiotic which again prolongs the time it takes for that antibiotic to achieve steady state. Also, by not giving the oral antibiotic in the ER we lose the ability to monitor the patient for any allergic reactions, which can be especially important for patients with vague drug allergies.

What about those patients who are seen in the ER for “worsening cellulitis” due to “antibiotic failure?” In this case, we have to ask ourselves: 1) How many doses of the antibiotic have they taken? Cellulitis can get a little worse before it gets better, and we should not expect the cellulitis to improve after 1-2 doses of antibiotics. 2) What dose of the antibiotic did they get? A lot of patients, especially obese patients, are under-dosed. 3) Was the spectrum correct? If we did not cover MRSA, we can add doxycycline or Bactrim this time around. You have to be very familiar with your site’s antibiogram. For example, at my site, clindamycin’s staph coverage is poor, and MRSA coverage is even worse, so if the patient was sent home with clindamycin only, this may not have been appropriate first-line therapy. So, I would remind the provider that this may not be a “worsening cellulitis” due to “antibiotic failure”, rather, the patient just wasn’t treated appropriately to begin with.

This rule is also true in the setting of pneumonia, where we have a number of studies that show oral antibiotics are equivalent to IV antibiotics and may even show less drug toxicity. This is true even though some antibiotics used to treat community-acquired pneumonia have low bioavailability (such as Augmentin (60%)) and azithromycin (37%))- which highlights the point that bioavailability is not the only factor that determines oral antibiotic efficacy.

Although this rule is true for cystitis, please remember the only exception to this rule is in the setting of pyelonephritis. Here, the IDSA guidelines recommend the administration of a one-time dose of IV ceftriaxone or an aminoglycoside prior to discharge. This gives us time to change outpatient therapy if needed once sensitivities from the urine culture are back.

In conclusion, remember that there is no magic with using IV antibiotics versus oral antibiotics for a large majority of your patients, especially those that are stable enough to discharge home. Instead of giving a patient an IV dose prior to discharge, try giving them a one-time dose of the oral antibiotic you plan to discharge them with. This will save time and allow you to monitor them for any side effects. Of course, there are clear indications for IV antibiotics including for those patients that can’t swallow, those that have intestinal absorption problems, or in emergent scenarios such as sepsis or septic shock. But once again, these patients are likely not being discharged home.

I would recommend creating a discharge antibiotic order-panel that guides providers to selecting the correct antibiotic, dose, and duration for common infections such as cellulitis, cystitis, and pyelonephritis. This order-panel can include higher doses for obese patients and lower doses for those with kidney disease, and it can take into account your institutions antibiogram to ensure patients don’t bounce back due to inappropriate antibiotic therapy. We instituted a tool like this named the “ER Germ Genius” which has seemed to work well- feel free to contact us on errxpodcast.com if you would like to see this panel so you can implement it as well.

As always, thank you so much for your time. Please remember to subscribe to our podcast – we are on Apple Podcasts, Google Podcasts, Spotify, Pandora, and even YouTube. That’s “ER-Rx.” Also, if you could leave a review, that would be very helpful.