This is the protocol for Cellulitis:



Let’s break it down!

Cellulitis is a bacterial skin infection, which is significant because out of the handful of dermatology protocols we need to know, this is the only one that we can treat and cure with antibiotics. The incidence of cellulitis is 200 cases per 100,000 patients, affecting primarily middle-aged and older-aged adults. Due to austere living conditions and multiple opportunities for penetrating skin injuries, soldiers may be at particularly high risk.

Cellulitis is always preceded by some break in the skin, even if it’s not noticeable. Due to the massive amount of naturally occurring bacteria in the saliva of animals, cellulitis can occur quite rapidly following animal bites. Human bites are even worse; with a 10%-30% guarantee of getting an infection 

By itself, cellulitis isn’t life-threatening. By definition, it’s only affecting the dermis and sometimes subcutaneous layers of the skin. However, it can become life-threatening if it progresses into the lymphatic tissue or blood and causes sepsis. That’s why it’s important to treat it promptly. 

For a more in-depth review, check out the video on cellulitis below:



Cellulitis causes an strong inflammatory response.  Damaged cells from the infection release chemicals like histamine, bradykinin, and prostaglandins, which cause blood vessels to leak fluid into the interstitial space and lymph nodes, which is what causes the swelling.  In addition, white blood cells like phagocytes are recruited in order to fight off the bacteria.  The war that wages between them causes warmth, erythema (redness), pain, and even a fever if it becomes systemic.

You’ll be able to differentiate cellulitis from other things because it’s one of the only dermatological conditions (within our scope) that causes a consistent, red, and well-demarcated border.  Other conditions like contact dermatitis or fungal infections will have a more splotchy, inconsistent pattern.

The video below shows a classic example of cellulitis:

Ok, so we know that this is a bacterial infection and we know that we need to fix it with antibiotics….but why TWO antibiotics?

Because the most common bacteria that cause cellulitis is Staphylococcus aureus and Streptococcus (gram-positive bacteria), both of which can be covered by Moxifloxacin (our favorite broad-spectrum oral battlefield antibiotic) and Augmentin (great for gram-positive bacteria).


Sometimes it’s not enough.  MRSA (Methicillin-resistant Staphylococcus aureus) is extremely resistant to our traditional choices of antibiotics, so we have to add in additional coverage.  That’s where TMP-SMZ and Rifampin come in.  Both of those can kill MRSA in case that happens to be the causative bacteria.  Since there’s no good way to tell in the field what bacteria is causing the cellulitis, we just cover for everything.

Laboxa-400 Moxifloxacin 400mg Tablet, Packaging Size: 10*1*10 Alu ...

SMZ TMP for Dogs, Cats Horses Generic (brand may vary) - Safe ...

Cellulitis can be very painful and uncomfortable, so you’ll want to treat that with Acetaminophen and/or your choice of NSAID (ex. Ibuprofen) from the Pain Management protocol Limiting activity will also help reduce pain and inflammation.  You probably won’t need any narcotics.


Cleaning/and dressing the wound makes sense, especially if you’re out in the field and there’s a particular chance for re-infection

Using a marker is to demarcate the infection border is incredibly important.  This will allow you to track the progress of the infection and hopefully determine if your diagnosis and treatment are correct.  Check daily so that you can react quickly if it turns out to be incorrect! 👀


Here’s where things get tricky.  We’ll get more into what an abscess really is in the Cutaneous Abscess review, but basically it’s just a collection of pus that can occur in both superficial and deep areas of the skin.  It’s pretty common with cellulitis, but sometimes it can be difficult to determine whether or not someone actually has it.  The key thing that we’re looking for in order to diagnose it is “Fluctuance“, which is whether or not you can physically feel fluid or squishy pus underneath the skin.  If you feel fluctuance, or you’re somehow able to diagnose it with an ultrasound in the field (not likely), then you may consider draining the abscess.  This will help reduce the pain for the patient and also aid in recovery.  But again, this is a whole other protocol!


Typically, we should be seeing improvement pretty quickly with our initial double antibiotic regimen.  So if we’re not seeing it improve or it’s actually getting worse, then that means our antibiotics aren’t strong enough or we haven’t covered for the causative agent.  Thus, we’re going to add another broad-spectrum IV/IM antibiotic, like Ceftriaxone or Ertapenem, IN CONJUNCTION with the antibiotics that they are already on.

Invanz      Ceftriaxone

Bonus InformationAlthough it’s been commonly thought that IV/IM antibiotics are superior to PO antibiotics for cellulitis, there is evidence to suggest that they really don’t add that much benefit.  Not to say that you shouldn’t follow the protocol, but manage your expectations and don’t just skip to IV/IM antibiotics just because the cellulitis “looks bad”.

It’s not the boogeyman you should be looking under your bed for….it’s necrotizing fasciitis

Necrotizing fasciitis is a rare, flesh-eating disease typically caused by Group A Streptococcus. It’s a lot like cellulitis, but instead infecting the superficial layers of skin, it infects the deeper layers of subcutaneous fat, fascia, and muscle. It’s rapidly spreading and it carries extremely high mortality rates of 30-40%, even with treatment. In it’s beginning stages, it often mimics cellulitis. However, there are a few red flags you can look for:

  • Pain out of proportion (Patient may appear in extreme pain)


  • Skin necrosis or hemorrhagic bullae (can be a late sign)


  • Hypotension (occurs in 21%)


  • Febrile (occurs in 40%)



The only suggested treatment for this one (other than getting them the hell out of there and to a hospital) within our scope is to treat them under the Sepsis/Septic Shock protocol.  Even though having necrotizing fasciitis doesn’t necessarily mean that they are septic at the moment, we’re going to treat them as such just because they’re at such a high risk for it. Eventually, these patients may also need surgical debridement of the necrotized tissue.

If you can’t handle it, ship em out!  And of course, if you suspect the big bad necrotizing fasciitis, you should definitely have a low threshold for doing so.


Till Next Time!


Brandon Simpson, PA-C
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