Skin abscess: Clinical sciences

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Introduction0:00–0:42

A skin abscess is a common skin and soft tissue infection that occurs when a collection of pus accumulates, usually in the dermis or subcutaneous space.
An abscess can result from a disruption in the skin barrier or prior skin infection, which allows the bacteria to get into the subcutaneous space.
The most common cause of a skin abscess is bacteria, especially Staphylococcus aureus, either methicillin-susceptible or methicillin-resistant.
When it comes to presentation, a skin abscess can present with or without systemic symptoms.Alright, when assessing a patient who presents with signs and symptoms suggestive of a skin abscess, you should first perform an ABCDE assessment to determine if your patient is unstable or stable.

Unstable patient0:42–1:31

If the patient is unstable, stabilize the airway, breathing, and circulation first. Next, obtain IV access and initiate IV fluids for resuscitation.
Here’s a clinical pearl! Keep in mind that most patients with skin abscesses wouldn't be unstable, and if they are unstable, then they’ve likely developed sepsis or even septic shock.
So be sure to evaluate these patients for systemic signs and symptoms like hypotension, fever, and chills.Now that acute management for unstable patients is initiated, let’s talk about stable patients.

Stable patient1:31–1:54

If the patient is stable, your first step is to obtain a focused history and physical examination, evaluating the affected area while also looking for associated systemic signs and symptoms like fevers or chills; along with labs like CBC.Let’s first look at a patient without systemic signs and symptoms.

Abscess without systemic signs/symptoms1:54–2:31

Your patient might report a small painful, erythematous nodule, with or without spontaneous drainage. On a physical exam, you might see a fluctuant nodule with or without erythema and tenderness.
Finally, labs might be normal or show mild leukocytosis. In this case, you can diagnose a skin abscess.
Now, since the patient doesn’t have any systemic signs or symptoms, we can refer to it as an abscess without systemic signs and symptoms.Okay, now that you have made the diagnosis, the next step is to proceed with a surgical consultation for simple incision and drainage with daily dressing changes.

Management2:31–2:42

Reaccumulation2:42–3:32

Once the abscess has been drained, you should wait for 24 to 48 hours to assess the response to treatment. Logically, if the abscess is gone, no further treatment is needed, but remember that dressings will need to be changed daily until the abscess cavity resolves too.
Now, in some cases, the abscess might reaccumulate in those 24 to 48 hours. This means that the patient has a refractory abscess secondary to loculations or inadequate drainage procedure.
If this is the case, you should consider repeating the incision and drainage, performing debridement, or adding an antibiotic that would cover skin flora, like trimethoprim-sulfamethoxazole, or a first generation cephalosporin such as cephalexin..
Alright, now that the treatment for abscess without systemic signs and symptoms is complete, let’s go back to history and physical exam and talk about a different presentation.

Abscess with systemic signs/symptoms3:32–4:23

Your patient might report a moderate to a large, painful, erythematous nodule, with or without spontaneous drainage. Importantly, they might report systemic signs of infection like fever and chills.
When it comes to the physical exam, it usually reveals a fluctuant nodule with or without erythema and tenderness. Finally, labs will typically show leukocytosis.
Okay, based on these findings you can make a diagnosis of a skin abscess. Since the patient now has fever and chills, we can refer to this one as an abscess with systemic signs and symptoms.Now that the diagnosis is made, let’s move on to management.

Cultures and ultrasound4:23–5:08

As we are now talking about systemic infection, the patient will need antibiotics. Therefore, you should first obtain cultures so that you can tailor antibiotics.
For this, you can get cultures of the fluid that’s draining from the abscess, called pus, as well as blood cultures to rule out bacteremia.
Additionally, you could order an ultrasound to better characterize the size and depth of the abscess before surgical drainage.
On ultrasound, an abscess will show as an irregular, hypoechoic, centrally avascular fluid collection surrounded by a hypervascular rim.

Treatment5:08–5:39

Alright, let’s switch gears and talk about treatment. In patients who have an abscess with systemic signs and symptoms, you should start IV empiric antibiotics, such as vancomycin to cover skin flora, and obtain a surgical consultation for simple incision and drainage.
Then, if cultures come back positive, you should tailor antibiotics according to the culture pathogen and its susceptibility.
Just like before, once the treatment is started, you’ll wait 24 to 48 hours to assess the patient’s response to it.Now, if in 24 to 48 hours, you notice clinical improvement and resolution, meaning the fever has resolved, and there’s decreased drainage and receding of the surrounding erythema, you can say that the patient has had an adequate response to treatment.

Adequate response5:39–6:04

In this case, you can switch from IV antibiotics to oral ones and complete their course of antibiotics that way.On the other hand, if at 24 to 48 hours, your patient shows an inadequate response, you should think about a refractory abscess or a deeper soft tissue infection, or even underlying necrosis.

Inadequate response6:04–6:49

At this point, order an ultrasound to confirm your suspicion. If you see a remaining fluid collection or a loculated abscess on the ultrasound, then a diagnosis of refractory abscess or soft tissue infection is confirmed.
For these patients, you should repeat incision and drainage and again obtain cultures from the drainage, as well as blood cultures.
In addition, consider performing debridement. Lastly, tailor antibiotics after you get the culture results.Alright, as a quick recap… Patients with a skin abscess who present without systemic signs and symptoms can be managed with simple incision and drainage with daily dressing changes.

Review6:49–7:46

If there’s reaccumulation after 24 to 48 hours, there might be a refractory abscess or soft tissue infection, so consider repeating incision and drainage, performing debridement, and adding antibiotics.
On the other hand, patients who have a skin abscess with systemic signs and symptoms should be treated with IV antibiotics in addition to simple incision and drainage.
If there’s adequate response after 24 to 48 hours, you can switch the patient to oral antibiotics and complete the course.
However, if there’s an inadequate response, order an ultrasound to assess for a refractory abscess or soft tissue infection, which should be treated with repeat incision and drainage or debridement, as well as obtaining cultures and tailoring antibiotics according