Folliculitis, furuncles, and carbuncles: Clinical sciences

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Introduction0:00–0:42

0:02

Folliculitis is a common skin condition where a hair follicle becomes infected and forms a papule or pustule over the hair-bearing skin.

0:10

The infection is most commonly bacterial, but in rare cases, it can be fungal, viral, or parasitic. As the infection brews, it can form a furuncle which is an abscess involving the hair follicle and its surrounding tissue.

0:26

When there are multiple furuncles, they can grow and connect subcutaneously forming a carbuncle. The diagnosis of folliculitis, furuncle, or carbuncle is clinical, so performing a thorough history and physical examination is very important.

History & Physical0:42–1:48

0:44

When a patient presents with chief concern suggesting folliculitis, a furuncle, or a carbuncle, the first step is to obtain a focused history and physical in addition to labs such as a CBC.

0:55

Patients typically report skin redness, pain, pruritus over a skin bump, and sometimes even fever. They might also report recent or frequent waxing or hair removal over the affected area, or that they had a pimple they tried to pop.

1:11

Finally, patients might have a history of uncontrolled diabetes. When it comes to the physical exam, it typically reveals erythema, swelling, tenderness, and possibly induration surrounding a folliculocentric papule, pustule, or nodule within the hair-bearing skin.

1:31

You might also see a focal area of fluctuance with or without purulent drainage. Lastly, CBC is often normal or may show mild leukocytosis.

1:39

If your patient presents with these clinical findings, suspect folliculitis, furuncle, or carbuncle.Alright, let’s start with folliculitis, which is usually limited to the superficial dermis.

Folliculitis1:48–3:34

1:57

On further examination, you can expect to find superficially inflamed papule around a hair follicle without any areas of fluctuance.

2:06

This is very characteristic of folliculitis, so that’s your diagnosis. Once you have made the diagnosis, your next step is to treat with topical antibiotics and advise cessation of hair removal.

2:17

Then, assess the response between 48 to 72 hours of starting treatment.If there is an adequate response with improvement or resolution of redness, inflammation, and pain, the patient can complete the course of antibiotics.

2:33

However, if there is an inadequate response, meaning no change in clinical status or the condition has worsened, start empiric oral antibiotics and assess for a spreading infection or formation of an abscess.

2:51

If the condition does not improve with continuing treatment, assess for unlikely microorganisms like fungal, viral, or parasitic infection.

2:57

Obtaining a culture might be helpful to identify the organism and tailor your treatment accordingly. Here is a high-yield fact!

3:07

Bacterial folliculitis is most commonly caused by Staphylococcus aureus, which is part of the skin flora. In some cases, gram-negative organisms like Pseudomonas aeruginosa can cause what is known as “hot tub” folliculitis.

3:23

Infections with less common bacteria like Klebsiella and Enterobacter are associated with folliculitis that arises after long-term oral antibiotic therapy.

Furuncle3:34–4:47

3:43

Okay, let’s move on to furuncles. Typically, you will see an erythematous area of skin with a fluctuant pustule or nodule in the deeper subcutaneous space involving a hair follicle.

3:52

There might be some purulent drainage coming from the pustule, but there is usually no surrounding cellulitis. With these clinical features, you can diagnose your patient with a furuncle.

4:03

Your first step in treatment is to perform an incision and drainage of the furuncle to evacuate all of the pus that was trapped in the skin.

4:14

Then, assess the patient’s clinical response between 48 to 72 hours. Most of the time, patients have an adequate response with improvement or resolution of their symptoms, and no further treatment is required.

4:27

However, if there is an inadequate response and you notice an area of fluctuance is still present or has become larger, the next step is to start the patient on oral antibiotics and repeat incision and drainage with cultures.

4:40

Once the cultures identify the organism, you can tailor antibiotic therapy accordingly.Finally, let’s turn our focus to carbuncles.

Carbuncle4:47–6:59

4:58

In this case, you can expect to find clusters of multiple, erythematous, subcutaneous fluctuant pustules or nodules with purulent drainage.

5:08

Remember that a carbuncle is a cluster of furuncles that connect through the subcutaneous space, so the area of fluctuance is usually larger than furuncles and there might be multiple clusters.

5:19

Additionally, in some situations, there might also be cellulitis surrounding the area. These features all support your diagnosis of a carbuncle.

5:28

Once you’ve made your diagnosis, your next step is to treat with an incision and drainage. Make sure to open and drain all pus pockets to ensure complete evacuation of the infection.

5:42

Additionally, if there’s surrounding cellulitis, start oral antibiotics. Once that’s done, assess the patient between 48 to 72 hours of therapy.

5:52

If there’s an adequate response with improvement or resolution of symptoms, no further treatment is needed and your therapy is considered complete.

5:58

On the other hand, if there is an inadequate response, the patient likely has a refractory carbuncle.In this case, repeat the incision and drainage and obtain cultures from the purulent fluid.

6:13

Consider broadening the antibiotic coverage or switching to a different antibiotic class. If the symptoms still do not improve, you might need to start IV antibiotics.

6:25

Remember to tailor your antibiotics once the cultures come back and continue to assess for improvement. Finally, you should also consider testing for methicillin-resistant Staphylococcus aureus, better known as MRSA, and treat it if tests come back positive.Here’s a clinical pearl!

6:40

If the patient has recurrent carbuncles, think about eliminating the source of bacteria, which is usually the nares. This is done by decolonization of Staphylococcus aureus, which might involve intranasal topical antibiotics.Alright, as a quick recap… Folliculitis is a superficial infection of the hair follicle that can be treated with topical antibiotics.

Review6:59–7:41

7:09

Furuncles are caused by a deeper infection with an abscess formation around the hair follicle. These can be treated with incision and drainage, and oral antibiotics if symptoms persist.

7:20

Carbuncles, on the other hand, are formed by a collection of furuncles that connect within the subcutaneous tissue. These are similarly treated with incision and drainage and oral antibiotics if there are signs of cellulitis.

7:33

Repeat incision and drainage or IV antibiotics might be needed in cases where the condition does not improve with initial
Folliculitis, furuncles, and carbuncles: Video | Osmosis