Skin and Soft Tissue Infections - Incision, Drainage, and Debridement

Skin and soft-tissue infections (SSTIs), which include infections of skin, subcutaneous tissue, fascia, and muscle, encompass a wide spectrum of clinical presentations, ranging from simple cellulitis to rapidly progressive necrotizing fasciitis. Diagnosing the exact extent of the disease is critical for successful management of a patient of soft-tissue infection. ^{[1, 2, 3, 4, 5]}

The various types of SSTIs, listed according to clinical presentation and anatomic location, include the following:

• Impetigo

• Folliculitis

• Furuncles

• Carbuncles

• Erysipelas

• Cellulitis

• Necrotizing fasciitis, also known as hemolytic streptococcal gangrene, Meleney ulcer, synergistic gangrene, and Fournier gangrene (when localized to the scrotum and perineal area)

• Pyomyositis

SSTIs may be caused by any of a formidable number of pathogenic microorganisms, and they may be either monomicrobial or polymicrobial. The following are the most important pathogens:

• Staphylococcus aureus (the most common pathogen)

• Streptococcus pyogenes

• Site-specific infections - Indigenous organisms (eg, gram-negative bacilli in perianal abscesses)

• Immunocompromised hosts and complicated SSTIs - Multiple organisms or uncommon organisms (eg, Pseudomonas aeruginosa, beta-hemolytic streptococci, Enterococcus)

• Polymicrobial necrotizing fasciitis - Mixed infection with both aerobes (eg, streptococci, staphylococci, or aerobic gram-negative bacilli) and anaerobes (eg, Peptostreptococcus, Bacteroides, or Clostridium)

• Monomicrobial necrotizing fasciitis: S pyogenes

Classification of SSTIs

For the purposes of this article, SSTI may be divided into the following categories:

• Uncomplicated SSTI

• Nonnecrotizing complicated SSTI

• Necrotizing fasciitis

Uncomplicated SSTIs include superficial cellulitis, folliculitis, furunculosis, simple abscesses, and minor wound infections. These infections respond well to either source control management (ie, drainage or debridement) or a simple course of antibiotics. These infections pose little risk to life and limb.

Complicated SSTIs involve the invasion of deeper tissues and typically require significant surgical intervention. The response to therapy is often complicated by underlying disease states. Complicated SSTIs include complicated abscesses, infected burn wounds, infected ulcers, infections in diabetics, and deep-space wound infections. They are often limb- or life-threatening.

Necrotizing fasciitis is a progressive, rapidly spreading, inflammatory infection that is located in the deep fascia and is associated with secondary necrosis of the subcutaneous tissues. The inflammation of the deep fascia causes thrombosis of the dermal vessels, and it is this thrombosis that is responsible for the secondary necrosis of the overlying subcutaneous tissue and skin.

It is imperative to distinguish necrotizing infections from nonnecrotizing infections. Early diagnosis and intervention may save a life; delayed diagnosis and treatment may lead to loss of a limb or a life.

Predisposing factors

Factors predisposing to the development of SSTIs include the following:

• Breach in the epidermis

• Dry and irritated skin

• Immunocompromised status - Malnutrition, hypoproteinemia, burns, diabetes mellitus, AIDS

• Chronic venous insufficiency

• Chronic lymphatic insufficiency

• Chronic neuropathy

Any abscess, however small, must be drained for complete resolution. Any ulcer covered with dead and necrotic tissue must be debrided to promote growth of healthy granulation tissue and healing. Necrotizing fasciitis is a surgical emergency; early surgical treatment optimizes outcomes for these patients.

There are no absolute contraindications for incision, drainage, and debridement of SSTIs. If the patient's physical condition is compromised, stabilization to render him or her fit for anesthesia should be carried out before these procedures are undertaken.

In the drainage of an abscess, the incision should be made at the point of maximal fluctuance. If possible, it should be made in a dependent area; however, a dependent incision should not be made if a tubercular etiology is suspected. Ideally, the direction of the incision should be in line with the natural skin crease.

A bold incision must be made that goes all the way into the abscess cavity. However, if there are any major vessels or nerves in the area, additional care should be taken in making the incision, and blunt dissection should be used instead to enter the abscess cavity. Any necrosed or unhealthy skin on the roof of the abscess should be excised completely.

Debridement should be done until healthy dermal bleeding is seen on the edges of the skin. There should be no loose undermined skin edges at the end of surgical debridement. However, overzealous debridement should be avoided in nonnecrotizing SSTIs; a staged debridement should be planned to minimize damage to healthy tissue.