Horses and Zebras and Flesh-eating Bacteria…oh my!!


It’s a well-known observation that some staff, more commonly new doctors, jump to a farfetched diagnosis when often the simplest is the most likely. Hence the phrase “hear hooves: think horses not zebras”.

Think back to the patient with a rattly cough who has a differential of something obscure like lymphangioleiomyomatosis when actually they smoke 40 a day and COPD makes way more sense.

Sometimes however a common presentation such as diarrhoea and vomiting can mask something far more sinister.

As was previously mentioned in Kirsty’s blog post about cognitive bias, it’s easy to be steered down a certain path by a set of symptoms and sometimes miss a bigger picture. It’s also often difficult to stand up and advocate for your decisions and your patient against someone far more senior.

For the record this story and the pictures are being shared with the full support of Jackie, her family and colleagues.


Let me set the scene…

It’s Christmas morning in the Emergency Department. You come in as normal for an early shift and during hand over become aware that one of the patients waiting to be seen is actually a colleague!

Jackie and I have worked together through her role working for the ATACC group, the business arm for the world-renowned Anaesthesia, Trauma and Critical Care (ATACC) course, for which I have been a faculty member for four years.

Jackie had presented to the ED that morning following a five-day history of diarrhoea and vomiting. Based on her presentation and observations she had been appropriately triaged and was waiting to be seen. The general consensus of everyone who knew her though, was that she looked bloody awful! Knowing Jackie as I did meant I could tell that her condition appeared worse in person than it did on paper, and I saw her next.

I asked if there were any other symptoms at all and Jackie said, “Now you mention it, I’ve just started with this rash”. It had appeared whilst she was in the department but she described it as “it

feels like my arm is on fire”

Jackie’s examination was largely unremarkable. She had some abdominal tenderness as one would expect after 5 days of gastroenteritis, and she’d tried over the counter remedies such as Imodium, which hadn’t helped.

She did, however, have a purply rash which spread rapidly during her time in the department. This, combined with the pain, which appeared out of proportion to the rash itself, led me to a differential diagnosis of necrotizing fasciitis.

In the time it took me to discuss the case with my consultant (who observed that this was a dramatic differential even by my usual standards) it had spread further still.

I discussed the case with the on call team for plastic surgery. They assessed Jackie, but as there was no gas formation seen on the wrist x-ray deemed it unlikely.

Jackie was referred to the medical team as cellulitis but I discussed my concerns with the med reg. I couldn’t shake the gut feeling that this was more than a nasty case of cellulitis.

I saw the med reg again later that day and he informed me the rash had spread further and he had called plastics back to review her.

As I sat down for my Christmas dinner that evening I received a phone call from our colleague to say the plastics team agreed and Jackie was on her way to theatre.

After a few weeks in ICU and multiple repeat theatre trips Jackie went home with all her limbs.


So firstly, how did I get to this random differential?

I’d recently read of a case where it had been missed and the patient had died. The take home message from this case had been that the pain the patient was experiencing was completely out of proportion to how it looked. Hence me worrying when Jackie said she felt her arm was on fire from what was, at the time, a relatively discreet rash.

Secondly, what is necrotising fasciitis?

*Necrotising fasciitis is a rapidly spreading inflammatory infection of the fascia and subsequent necrosis of the underlying subcutaneous tissues.[1]

*Mortality of patients with necrotizing fasciitis has been reported as high as 80%.

Its often called flesh-eating bacteria, although this isn’t actually the case. The bacteria release toxins, which damage the nearby tissue. In later cases this ‘gas’ can be seen on x-ray. It is more commonly seen in the limbs and perineum, and usually gets into the body via damaged skin such as a wound or a burn.


When assessing a patient, always bear in mind that there are other causes of symptoms out there, not just the most common ones. Keep and eye on your patients and review them regularly for signs of deterioration. And most importantly, if you feel something is seriously wrong, speak up!

Liz xx

[RCN Emergency Nurse Competencies: CCT2 levels 1&2]

[1] Schultz S, Bronze M (2017)Nectrotizing Fasciitis


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