Necrotizing Fasciitis Type II - Symptoms, Diagnosis, and Treatment

What Is Necrotizing Fasciitis Type II?

Necrotizing fasciitis is an uncommon soft-tissue infection characterized by rapidly spreading inflammation and subsequent necrosis (tissue death) of the muscle, connective tissue, and skin. Its clinical manifestations resemble other necrotizing soft tissue infections like necrotizing cellulitis, gas gangrene, clostridial cellulitis, etc. Still, the former differs from others with respect to the depth (which extends to the top of the muscle fascia) of the infection and inflammation.

Cases of necrotizing fasciitis can be classified into two types:

• Type I - Comprises of polymicrobial infections with mixed anaerobic (can live without oxygen) and aerobic (need oxygen to survive) organisms.

• Type II - It is caused by one species of bacteria known as Streptococcus pyogenes and has become popular in recent years due to its increased incidence.

Infection often follows a penetrating or blunt traumatic injury to the site involved but may occur without any preceding injury. Other predisposing factors include varicella (chicken pox), chronic skin conditions, and previous surgery.

Affected individuals require appropriate antibiotics (with beta-lactam and Clindamycin) and expeditious surgical management, often followed by multiple debridements.

What Is Streptococcus pyogenes (S. pyogenes)?

It is a member of the group A beta-hemolytic streptococcus bacteria. Other hemolytic (destruction of red blood cells) Streptococcus bacteria include S. anginosus and S. equisimilis; however, only S. pyogenes are capable of causing type II necrotizing fasciitis.

S. pyogenes are ubiquitous in nature and found in humans and animals. It is one of the most common pathogens capable of causing diseases like

1. Pharyngitis - A term used to describeinflammation of the windpipe.

2. Pyoderma - A rare condition that causes large painful skin ulcers, most commonly on the legs.

3. Scarlet Fever - Fever that features a bright red rash covering most of the body.

4. Cellulitis - Infection that causes redness, swelling, and pain in the infected area.

5. Necrotizing Skin Infections - Typically seen as diffuse erythematic swellings accompanied by pain and tenderness.

S. pyogenes also cause postinfectious sequelae such as rheumatic fever and acute glomerulonephritis. When accompanied by shock, organ failure, bacteremia, necrotizing fasciitis, and death, these infections are known as streptococcal toxic shock syndrome.

What Are the Risk Factors for Necrotizing Fasciitis Type II?

The following features have been known to increase the incidence of S. pyogenes infection:

1. Factors in the organism, like M-protein and exotoxins (also known as superantigens) specific to S. pyogenes, have made it more invasive and virulent.

2. Lack of immunity in the host.

3. Prolonged use of non-steroid anti-inflammatory drugs (NSAIDs).

What Are the Symptoms of Necrotizing Fasciitis Type II?

The disease has a slight predilection to individuals with predisposing risk factors like diabetes, alcohol abuse, chronic cardiac disease, etc., but it can also affect healthy individuals. Infection often follows a penetrating or blunt traumatic injury to the site involved.

The most common site is the extremities, followed by the trunk, groin, and face. The infection follows a set of sequences which is described below:

1. The first symptom of type II necrotizing fasciitis includes diffuse erythema (redness) and swelling, accompanied by pain and tenderness.

2. The swelling is followed by fluid-filled bullae (large blisters). The bullous lesions rapidly become maroon or violaceous (violet in color).

3. The bullous lesions are followed by cutaneous gangrene (tissue death) that spreads rapidly along the fascial planes (space between two discrete fascial layers).

How Is Necrotizing Fasciitis Type II Differentiated From Cellulitis?

Clinical features that differentiate necrotizing fasciitis from cellulitis are as follows:

1. Pain (severe, followed by anesthesia).

2. Rapidly spreading swelling and inflammation.

3. Bullae (large lesions).

4. Necrosis (which is a delayed symptom).

5. Toxic shock syndrome.

6. Elevated creatinine kinase levels.

7. Predisposing factors like varicella and long-term use of non-steroidal inflammatory drugs.

Apart from these, necrotizing fasciitis is accompanied by fever and unexplained musculoskeletal pain. A few conditions suggestive of the same are trauma with hematoma (blood-filled bruise), phlebitis (inflammation of a vein), bursitis (inflammation of the fluid-filled sacs that cushion the joints), and arthritis (inflammation of joints).

How Is Necrotizing Fasciitis Type II Diagnosed?

A definite case of type II necrotizing fasciitis contains all three of the following features.

1) Necrosis of soft tissues with involvement of the fascia.

2) On or more of the below-mentioned systemic diseases:

• Death.

• Shock (systolic blood pressure less than 90 mm of Hg).

• Disseminated intravascular coagulopathy.

• Respiratory, hepatic, or renal failure.

3) Isolation of S. pyogenes from a normally sterile body site.

The laboratory findings of type II necrotizing fasciitis typically show leukocytosis (increased white blood cell count), elevated serum creatinine kinase levels, and positive gram stain.

Computed tomography, magnetic resonance imaging, and soft tissue roentgenograms may help demonstrate the involvement of the subcutaneous tissue but are often nonspecific and inconclusive.

How Is Necrotizing Fasciitis Type II Treated?

Streptococcal necrotizing fasciitis should be recognized early and treated quickly. Primary treatment is surgery and antibiotics, which are active against S. pyogenes.

1) Surgery - The goals of surgery are three-fold:

• To remove necrotic tissues by radical debridement (medical removal of dead and damaged tissue).

• To preserve as much viable skin as possible.

• To maintain hemostasis.

In a few cases, amputation might be necessary to remove all the non-viable tissues. A second-look procedure will be necessary within 12 to 24 hours to re-culture and remove all non-viable tissues. Multiple debridements are often needed for type II necrotizing fasciitis.

2) Antimicrobial Therapy - The antimicrobial agents chosen should have activity against S. pyogenes and mixed aerobic-anaerobic organisms as a precautionary measure. This can be done with a combination of beta-lactam (antibiotics that contain a beta-lactam ring in their chemical structure) and a beta-lactamase inhibitor (antibiotics that prevent resistance). A few examples of such combinations are Ticarcillin-Clavulanate, Piperacillin-Tazobactam, or a Carbapenem should provide an adequate spectrum. Between Penicillin and Clindamycin, the latter has a greater affinity for Streptococcal infections. Clindamycin, unlike other beta-lactams, inhibits protein synthesis and is unaffected by the size and type of bacterial growth. In addition, Clindamycin suppresses bacterial toxin synthesis and increases the phagocytosis (engulfing) of the bacteria.

Other experimental therapies include hyperbaric oxygen therapy, which uses pure breathing oxygen in a pressurized environment to promote healing, and intravenous immunoglobulins (antibodies).

Conclusion

Diagnosis of type II necrotizing fasciitis is difficult due to its rapid nature and similarities with other necrotizing conditions. Treatment should be started after the initial diagnosis itself to prevent life-threatening complications that may arise while waiting for the gram-stain results. The prognosis is good in patients who undergo multiple debridement and complete the entire antibiotic course.