(See also Overview of Bacterial Skin Infections Overview of Bacterial Skin Infections Bacterial skin infections can be classified as skin and soft tissue infections (SSTI) and acute bacterial skin and skin structure infections (ABSSSI). SSTI include Carbuncles Ecthyma Erythrasma... read more .)
Risk factors for cutaneous abscesses include the following:
Antecedent trauma (particularly when a foreign body is present)
Bacteria causing cutaneous abscesses are typically indigenous to the skin of the involved area. For abscesses on the trunk, extremities, axillae, or head and neck, the most common organisms are Staphylococcus aureus (with methicillin-resistant S. aureus [MRSA] being the most common in the US) and streptococci.
Abscesses in the perineal (ie, inguinal, vaginal, buttock, perirectal) region contain organisms found in the stool, commonly anaerobes or a combination of aerobes and anaerobes (see Table: Classification of Common Pathogenic Bacteria Classification of Common Pathogenic Bacteria Bacteria are microorganisms that have circular double-stranded DNA and (except for mycoplasmas) cell walls. Most bacteria live extracellularly. Some bacteria (eg, Salmonella typhi; Neisseria... read more ).
Carbuncles and furuncles Furuncles and Carbuncles Furuncles (boils) are skin abscesses caused by staphylococcal infection, which involve a hair follicle and surrounding tissue. Carbuncles are clusters of furuncles connected subcutaneously,... read more are types of cutaneous abscesses.
Symptoms and Signs of Cutaneous Abscess
Cutaneous abscesses are painful, tender, indurated, and usually erythematous. They vary in size, typically 1 to 3 cm in length, but are sometimes much larger. Initially the swelling is firm; later, as the abscess points, the overlying skin becomes thin and feels fluctuant. The abscess may then spontaneously drain. Local cellulitis, lymphangitis, regional lymphadenopathy, fever, and leukocytosis are variable accompanying features.
Diagnosis of Cutaneous Abscess
Culture to identify MRSA
Diagnosis of cutaneous abscess is usually obvious by examination. Culture is recommended, primarily to identify MRSA.
Conditions resembling simple cutaneous abscesses include hidradenitis suppurativa Hidradenitis Suppurativa Hidradenitis suppurativa is a chronic, scarring, acnelike inflammatory process that occurs in the axillae, groin, and around the nipples and anus. Diagnosis is by examination. Treatment depends... read more and ruptured epidermal cysts. Epidermal cysts Cutaneous Cysts Epidermal inclusion cysts are the most common cutaneous cysts. Milia are small epidermal inclusion cysts. Pilar cysts are usually on the scalp and may be familial. Benign cutaneous cysts are... read more (often incorrectly referred to as sebaceous cysts) rarely become infected; however, rupture releases keratin into the dermis, causing an exuberant inflammatory reaction sometimes clinically resembling infection. Culture of these ruptured cysts seldom reveals any pathogens. Perineal abscesses may represent cutaneous emergence of a deeper perirectal abscess or drainage resulting from Crohn disease Crohn Disease Crohn disease is a chronic transmural inflammatory bowel disease that usually affects the distal ileum and colon but may occur in any part of the gastrointestinal tract. Symptoms include diarrhea... read more via a fistulous tract. These other conditions are usually recognizable by history and rectal examination.
Treatment of Cutaneous Abscess
Incision and drainage
Some small abscesses resolve without treatment, coming to a point and draining. Warm compresses help accelerate the process. Incision and drainage are indicated when significant pain, tenderness, and swelling are present; it is unnecessary to await fluctuance. Under sterile conditions, local anesthesia is given as either a lidocaine injection or a freezing spray.
Patients with large, extremely painful abscesses may benefit from IV sedation and analgesia during drainage. A single puncture with the tip of a scalpel is often sufficient to open the abscess. After the pus drains, the cavity should be bluntly probed with a gloved finger or curette to clear loculations. Irrigation with normal saline is optional. Packing the cavity loosely with a gauze wick reduces the dead space and prevents formation of a seroma. The wick is typically removed 24 to 48 hours later. However, recent data have not proved the effectiveness of routine irrigation or packing (1 Treatment references A cutaneous abscess is a localized collection of pus in the skin and may occur on any skin surface. Symptoms and signs are pain and a tender and firm or fluctuant swelling. Diagnosis is usually... read more , 2 Treatment references A cutaneous abscess is a localized collection of pus in the skin and may occur on any skin surface. Symptoms and signs are pain and a tender and firm or fluctuant swelling. Diagnosis is usually... read more ). Local heat and elevation may hasten resolution of inflammation.
Antibiotics have traditionally been considered unnecessary Treatment references A cutaneous abscess is a localized collection of pus in the skin and may occur on any skin surface. Symptoms and signs are pain and a tender and firm or fluctuant swelling. Diagnosis is usually... read more unless the patient has signs of systemic infection, cellulitis, multiple abscesses, immunocompromise, or a facial abscess in the area drained by the cavernous sinus. In these cases, empiric therapy should be started with a drug active against MRSA MRSA and purulent or complicated cellulitis Cellulitis is acute bacterial infection of the skin and subcutaneous tissue most often caused by streptococci or staphylococci. Symptoms and signs are pain, warmth, rapidly spreading erythema... read more (eg, trimethoprim/sulfamethoxazole, clindamycin; for severe infection, vancomycin) pending results of bacterial culture. However, recent studies have suggested marginally better results when antibiotics are added to usual treatment of even uncomplicated abscesses (3 Treatment references A cutaneous abscess is a localized collection of pus in the skin and may occur on any skin surface. Symptoms and signs are pain and a tender and firm or fluctuant swelling. Diagnosis is usually... read more ).
1. Chinnock B, Hendey GW: Irrigation of cutaneous abscesses does not improve treatment success. Ann Emerg Med 67(3):379-383, 2016. doi: 10.1016/j.annemergmed.2015.08.007
2. O'Malley GF, Dominici P, Giraldo P, et al: Routine packing of simple cutaneous abscesses is painful and probably unnecessary. Acad Emerg Med 16(5):470-473, 2009. doi: 10.1111/j.1553-2712.2009.00409.x
3. Talan DA, Mower WR, Krishnadasan A: Trimethoprim-sulfamethoxazole versus placebo for uncomplicated skin abscess. N Engl J Med 374(9):823-832, 2016. doi: 10.1056/NEJMoa1507476
Pathogens reflect flora of the involved area (eg, S. aureus and streptococci in the trunk, axilla, head, and neck), but methicillin-resistant S. aureus (MRSA) has become more common.
Culture abscesses to identify MRSA.
Drain abscesses accompanied by significant pain, tenderness, and swelling and provide adequate analgesia and, when indicated, sedation.
Avoiding antibiotics for simple abscesses is often recommended unless the patient has signs of systemic infection, cellulitis, multiple abscesses, immunocompromise, or a facial abscess.