Soft Tissue Infection


Infection in the soft tissues (skin, fat, and muscles) of the extremities can range from a minor cellulitis to something life-threatening like a necrotizing fasciitis.  It’s important that any soft tissue infection, regardless of the severity, be evaluated by a medical specialist as soon as possible. Early diagnosis and treatment help minimize more significant complications.

Cellulitis – this is an infection of the skin and subcutaneous tissues (just below the skin) and is usually caused when a bacterial organism invades the tissue through a crack in the skin.  

Symptoms of a less severe cellulitis infection include:

  • Redness and warmth of the affected area
  • Swelling
  • Pain

Symptoms of a more serious cellulitis infection include: 

  • Fatigue
  • Fever & chills
  • Red lines streaking from the affected area (indicated the infection has moved into the lymph system)
  • Loss of skin over the area
  • Extreme pain

When the symptoms are less severe, there is little need for an extensive diagnostic workup and a physician can prescribe a course of oral antibiotics that will manage the infection very effectively.  When the symptoms are more serious, a more thorough workup is often necessary to determine the exact organism causing the infection as well as the extent of the infection in the soft tissues.  

Diagnostic testing for more serious cellulitis includes blood cultures to determine the extent of the body’s response to the infection, as well as cultures of the infected area. To obtain cultures the infected area could be biopsied or aspirated (removal of fluid). An MRI scan may be requested if there is concern that the infection has moved in to deeper tissues.

Antibiotic therapy is the treatment of choice for a cellulitis infection.  In less severe cases, oral antibiotics that are effective for a broad number of organisms are usually prescribed and quite successful in management of the problem. When the symptoms are those of a more severe infection, IV antibiotics may be necessary. 

Some people experience recurrent cellulitis infections due to an underlying disease that makes them more susceptible to infection such as diabetes or an autoimmune disease. In cases of recurrence, a longer (12-month) course of antibiotics may be recommended 1

Necrotizing Fasciitis –  this is a rare but serious bacterial skin infection that can spread quickly, killing soft tissues and leading to limb loss or death. Necrotizing fasciitis is more commonly known as a “flesh-eating” disease because of the death of soft tissue that it can cause.  

  Necrotizing fasciitis is the result of bacteria invading the layers of connective tissue below the skin. These connective tissue layers are found between muscles, around vessels and nerves and down to the bones. While the development of necrotizing fasciitis is somewhat random, once the bacteria start to grow along these layers of fascia, the organisms moves very quickly, destroying healthy tissues. This rapid death of tissues can have a devastating effect on the body, causing the kidneys to overwork, eventually leading to kidney failure. The body works so hard in combating the infection that without proper and rapid treatment a person can become septic (total body infection) and die. 
  The type of bacteria most commonly associated with this condition is group A Streptococcus but a number of other bacteria can cause the same soft tissue loss. Group A strep is not a rare bacteria but these extreme necrotizing infections are rare.  Some people who develop necrotizing fasciitis have other health problems like diabetes or other chronic diseases that may lower their body's ability to fight infection. 
  Symptoms often start within hours after an injury and may be ignored because they seem to be related to the original injury.  Pain, swelling, and warmth of the injured area are common. When the pain is more than what would be expected and swelling or redness is out of proportion with the injury, a more serious process could be occurring.  Blisters or black spots on the skin can develop, and often people describe flu-like symptoms. Emergency medical care is necessary when the symptoms aren’t consistent with the injury.
  Treatment of a necrotizing infection involves high doses of intravenous (IV) antibiotics. In many cases, multiple surgical procedures are needed to remove any tissue that is affected by the infection.   This is necessary to remove dead tissue and stop the infection from affecting other healthy tissues. The extent of surgery needed to control the infection can lead to amputation of affected limbs, and need for reconstructive procedures once the infection has been eliminated.

While necrotizing fasciitis is a frightening condition, fortunately it is rare. Individuals who have developed necrotizing infections have a long road of recovery but can get back to a high level of function due to the availability of prosthetic devices and rehabilitative services.

 


References
1. Thomas KS, Crook AM, Nunn AJ, Foster KA, Mason JM, Chalmers JR, et al. Penicillin to prevent recurrent leg cellulitis. N Engl J Med. 2013 May 2. 368(18):1695-70