A 2-year-old girl in Ethiopia is brought to see the visiting American doctor for a painful swollen hand. The hand was massively swollen and the child did not want to use it. On examination she had a temperature of 99º F and there was visible pus under the skin (Figure 104-1). An incision and drainage was performed and much pus and blood squirted from the abscess. The abscess was packed lightly to stop any bleeding and to prevent it from closing prematurely. Oral antibiotics were given to cover the surrounding cellulitis and any deeper infections. A culture to look for methicillin-resistant Staphylococcus aureus (MRSA) was not available in rural Ethiopia, but close follow-up was set for the next day and the patient was doing much better. The medical team performed twice daily home visits and administered the oral trimethoprim-sulfamethoxazole while changing the dressings. Within one week, the child was playing happily, the erythema and swelling were resolving, and she was beginning to use her hand again.
A large abscess of the hand in a 2-year-old girl in Ethiopia. Incision and drainage was performed and antibiotics were given to cover the surrounding cellulitis and any deeper infections. (Used with permission from Richard P. Usatine, MD.)
An abscess is a collection of pus in the infected tissues. The abscess represents a walled-off infection in which there is a pocket of purulence. In abscesses of the skin the offending organism is almost always S. aureus.
MRSA was the most common identifiable cause of skin and soft-tissue infections among patients presenting to emergency departments in 11 US cities. S. aureus was isolated from 76 percent of these infections and 59 percent were community-acquired MRSA (CA-MRSA).1
Risk factors for MRSA infection and other abscesses—Intravenous drug abuse, homelessness, dental disease, contact sports, incarceration, and high prevalence in the community.
In one review of serious skin infections in children admitted to a hospital in New Zealand, the most common types of infection were cellulitis (38%) and subcutaneous abscesses (36%).2 The most frequent sites of infection were the head, face and neck (32%), and lower limbs (32%). The most frequently isolated organisms were Staphylococcus aureus (48%) and Streptococcus pyogenes (20%).2
Etiology and Pathophysiology
Most cutaneous abscesses are caused by S. aureus.
Risk factors for developing an abscess with MRSA include patients who work or are exposed to a health-care system, intravenous drug use, previous MRSA infection and colonization, recent hospitalization, being homeless, African American, and having used antibiotics within the last 6 months.3
Risk factors for hospitalization for staphylococcal skin infections in children in California were age less than 3 years, being Black, and lacking private insurance.4
CA-MRSA has become prevalent in the US. One study that evaluated management of skin abscesses drained in the emergency department showed that there was no significant association between amount of surrounding cellulitis or abscess size with the likelihood of MRSA-positive cultures.3
Collection of pus in or below the skin. Patients often feel pain and have tenderness at the involved site. There is swelling, erythema, warmth, and fluctuance in most cases (Figures 104-1 to 104-3). Determine if the patient is febrile and if there is surrounding cellulitis.
An atopic boy with bilateral abscesses on the elbows. This abscess drained spontaneously once gentle pressure was applied to the area of fluctuance. The culture revealed S. aureus sensitive to methicillin and all the skin infections cleared with oral antibiotics. The atopic dermatitis was treated successfully with 0.1 percent triamcinolone ointment. (Used with permission from Richard P. Usatine, MD.)
MRSA abscess on the back of the neck that patient thought was a spider bite. Note that a ring block was drawn around the abscess with a surgical marker to demonstrate how to perform this block. (Used with permission from Richard P. Usatine, MD.)
Skin abscesses can be found anywhere from head to feet. Frequent sites include the hands, feet, extremities (Figure 104-2), head, neck, buttocks, and breast.
One type of abscess occurring in the pulp of a distal digit (usually a finger) is called a felon (Figures 104-4). This is particularly painful and requires a digital block for incision and drainage.
Felon. An abscess in the pulp of the distal finger. A digital block was required to incise and drain this soft tissue abscess. (Used with permission from Emily Scott, MD.)
Clinical cure is often obtained with incision and drainage alone so the benefits of pathogen identification and sensitivities are low in low-risk patients.3 Most clinical studies have excluded patients who were immunocompromised, diabetic, or had other significant comorbidities.3 Consequently, it may be reasonable to obtain wound cultures in high-risk patients, those with signs of systemic infection, and in patients with history of high recurrence rates.3,5
Epidermal inclusion cyst with inflammation/infection—These cysts (also known as sebaceous cysts) can become inflamed, swollen, and superinfected. Although the initial erythema may be sterile inflammation, these cysts can become infected with S. aureus. The treatment consists of incision and drainage and antibiotics if cellulitis is also present. If these are removed before they become inflamed, the cyst may come out intact (Figure 104-5).
Cellulitis with swelling and no pocket of pus—When it is unclear if an area of infected skin has an abscess, needle aspiration with a large-gauge needle may be helpful to determine whether to incise the skin. Cellulitis alone should have no area of fluctuance (see Chapter 103, Cellulitis).
Hidradenitis suppurativa—Recurrent inflammation surrounding the apocrine glands of the axilla and inguinal areas (see Chapter 98, Hidradenitis Suppurativa).
Furuncles and carbuncles—A furuncle or boil is an abscess that starts in hair follicle or sweat gland. A carbuncle occurs when the furuncle extends into the subcutaneous tissue.
Acne cysts—More sterile inflammation than true abscess, often better to inject with steroid rather than incise and drain (see Chapter 96, Acne Vulgaris).
Epidermal inclusion cyst removed intact. There is no need for antibiotics in this case. (Used with permission from Richard P. Usatine, MD.)
The evidence strongly supports the incision and drainage of an abscess.3,6 SOR A Inject 1 percent lidocaine with epinephrine into the skin at the site you plan to open using a 27-gauge needle. A ring block can be helpful rather than injecting into the abscess itself (Figure 104-3). Open the abscess with a linear incision using a #11 blade scalpel following skin lines if possible.7
Although many physicians still pack a drained abscess with ribbon gauze, there is limited data on whether or not packing of an abscess cavity improves outcomes. A small study concluded that routine packing of simple cutaneous abscesses is painful and probably unnecessary.8 SOR C The author of this chapter often packs abscesses lightly and has the patient remove the packing in the shower 2 days later, avoiding additional visits and painful repacking of the healing cavity. SOR C However, if a large abscess is not packed it can seal over and the pus may reaccumulate.
Routine use of antibiotics for an initial abscess in addition to incision and drainage is not supported by current evidence.3,9–11 SOR A Three randomized controlled trials (RCTs) performed since the emergence of CA-MRSA have demonstrated that antibiotics do not significantly improve healing rates of superficial skin abscesses, but two of these studies suggest that antibiotics do decrease short-term rates of new lesion development.9–11
A recent meta-analysis of systemic antibiotics after incision and drainage of simple abscess in children and adults showed that antibiotics did not significantly improve the percentage of patients with complete resolution of their abscesses 7–10 days after treatment.12
Consider the use of oral antibiotics to treat an abscess with suspected CAMRSA in patients who are febrile or have systemic symptoms, have significant surrounding cellulitis, have failed incision and drainage alone, have frequent recurrences, or have a history of close contacts with abscesses.3 SOR C
If an antibiotic is to be used, CA-MRSA is close to 100 percent sensitive to trimethoprim-sulfamethoxazole.3 SOR B Alternative antibiotics include oral clindamycin, tetracycline (for children 8 years of age and older), or doxycycline (for children 8 years of age and older). Local sensitivity data should be consulted when available.3 SOR B
There is no current data to support the use of an antimicrobial medication (mupirocin or rifampin) in the eradication of MRSA colonization.3 SOR C
Patients may shower daily 24 to 48 hours after incision and drainage and then reapply dressings. Patients should be given return precautions for worsening of symptoms or continued redness, pain, or pus.
In patients or wounds at higher risk for complications, follow-up should be scheduled in 24 to 48 hours. If packing was placed, it can be removed by the patient or a family member.
et al Methicillin-resistant S. aureus
infections among patients in the emergency department. N Engl J Med. 2006;355:666–674.
MG. Serious skin infections in children: a review of admissions to Gisborne Hospital (2006-2007). N.Z. Med J. 2012;55–69.
R. How do you treat an abscess in the era of increased community-associated methicillin-resistant Staphylococcus aureus
(MRSA)? J Emerg Med. 2011;41:276–281.
et al Staphylococcal infections in children, California, USA, 1985-2009. Emerg. Infect. Dis. 2013;10–20.
SD. Use of routine wound cultures to evaluate cutaneous abscesses for community-associated methicillin-resistant Staphylococcus aureus
. Ann Emerg Med. 2007;50:66–67.
M. Linear incision and curettage vs. deroofing and drainage in subcutaneous abscess. A randomized clinical trial. Acta Chir Scand. 1987;153:659–660.
R. Dermatologic and Cosmetic Procedures in Office Practice. Philadelphia: Elsevier; 2012.
et al Routine packing of simple cutaneous abscesses is painful and probably unnecessary. Acad Emerg Med. 2009;16:470–473.
S. Randomized, controlled trial of antibiotics in the management of community-acquired skin abscesses in the pediatric patient. Ann Emerg Med. 2010;55:401–407.
et al Randomized controlled trial of trimethoprim-sulfamethoxazole for uncomplicated skin abscesses in patients at risk for community-associated methicillin-resistant Staphylococcus aureus
infection. Ann Emerg Med. 2010;56:283–287.
et al Randomized, double-blind, placebo-controlled trial of cephalexin
for treatment of uncomplicated skin abscesses in a population at risk for community-acquired methicillin-resistant Staphylococcus aureus infection. Antimicrob Agents Chemother. 2007;51:4044–4048.
Jr: Systemic antibiotics after incision and drainage of simple abscesses: a meta-analysis. Emerg. Med. J. 2013. Published online May 18, 2013.