Anaerobic soft tissue infection of right arm (after initial aggressive surgery)

Tissue hypoxia, traumatic muscle injury and bacterial contamination are major causes. These infection can affect widespread areas involving various parts of the body and is mainly caused by Clostridial bacteria

Clostridial myonecrosis (‘gas gangrene’) is caused by anaerobic bacteria, which thrive in low oxygen levels. This occurs in:
· Direct injury to an artery
· Arterial obstruction by foreign body
· Haemorrhage
· Micro vascular disease (atheromatous plaques)

Often, there is also reduced immunity, from chronic illness or malnutrition.
The bacteria include clostridium perfringens (‘welchii’) in 80-95% of these infections, although there are often other clostridial bacteria, as well as non-anaerobic bacteria mixed with them. Clostridium perfringens functions at different levels, depending on oxygen availability:

After the initial trauma, a short period of incubation usually follows. Local signs include;
Pale and non-healing wound
Sharp local pain
Local paresthesias
A feeling of fullness in the area.
The area soon becomes swollen and painful. The infection develops rapidly.

The alpha-exotoxin, produced by the clostridial bacterium, causes local toxicity, including tissue necrosis and haemolysis. It also affects other organs of the body, causing:
· Renal failure
· Cardiotoxicity
· Cerebral toxicity
· Adult Respiratory Distress Syndrome (ARDS)
· Haemolysis
· Coagulopathy

Other toxins (q,k,µ) are produced by the bacteria: these may cause local and distant harm.

When incised during surgery, the tissue is pale, necrotic and there is little bleeding. A cloudy exudates is normally present. Multiple thromboses cause extensive oedema and severe local hypoxia.

Radiography of the soft tissue can show gas bubbles or ‘feathering’ tissue

Necrotizing faciitis sometimes called Fourniers gangrene (for scrotum and penis).
Subcutaneous (anaerobic) infection spreading along the deep fascia (layer covering the muscles), causing secondary skin lesions and sparing muscles until the late stages of the infection.Symptoms as described above.

Septic shock, acute kidney, or respiratory failures sometimes associated with these conditions require conventional intensive care treatment.

Antibiotic Therapy - Penecillin is the antibiotic of choice for treating and preventing anaerobic infections.

Surgery - Before antibiotics mutilating surgery, involving amputation at the root of the limb could save a patients life if carried out early on before the infection spread. With the development of antibiotics and HBO therapies, surgery is now used to eliminate necrotic tissue and reduce oedema related compression.

Hyperbaric Oxygen Therapy - The management of these infections includes Hyperbaric Oxygen, adjunctive to general resuscitation, intensive care, surgery and antibiotics. The order in which they are given is dictated by the patient’s condition; however, if Hyperbaric Oxygen can be given before or during surgery, the patient’s general condition can be improved by reducing the level of exotoxin. The use of Hyperbaric Oxygen is determined by the patient’s general condition rather than the local infection.
Hyperbaric Oxygen:
· Directly inhibits action of a-toxin
· Inhibits the secretion of exotoxin
· Directly damages anaerobic bacteria
· Promotes white-cell (leukocyte) activity
· Decreases oedema, by causing constriction of arterioles
· Promotes the formation of new blood vessels into the recovering tissues
· Promotes the action of aminogycoside antibiotics (such as gentamicin)

1.Bakker D.J. ‘Pure and mixed aerobic and anaerobic soft tissue infections. Classification and role of Hyperbaric oxygen treatment. HBO Rev., 1985, 6, 65-96
2. Mathieu D. (Ed.) Handbook on Hyperbaric Medicine, 263-289. Springer 2006