Classification Of Soft Tissue Infections

There has been multiple descriptions of soft-tissue infections due to anaerobic germs. Altemeier1 and later Finegold2 proposed classifications based on clinical and bacteriological criteria. However, these classifications offer little to the clinical diagnostic process necessary to expedite appropriate management3. Nowadays, more and more authors use a clinico-anatomic classification which offers more practical advantages (Table 2.2.4-1)4'5.

Thus depending on the tissue initially infected, these infections can be divided into myonecrosis - whether due to Clostridium (gas gangrene) or not - and infections of the subcutaneous tissue. This later can be sorted into groups depending on their depth: (1) necrotizing fasciitis involves the deep fascia, the subcutaneous tissue and superficial fascia to variable degrees whereas (2) cellulitis involves the superficial fascia and the subcutaneous tissue to a variable extent but not the deep fascial layer.

Table 2.2.4-1. Anaerobic soft tissue infections clinico-anatomic classification_

Initial infected tissue Mode of Development Germ Disease Specific Locations

Muscles Acute Clostridium Clostridial myonecrosis

(gas gangrene)

Other than Clostridium Non clostridial myonecrosis

Subcutaneous tissue & Acute Mixed flora Necrotizing fasciitis deep fascia

Subcutaneous tissue Progressive Aerobic & anaerobic Cellulitis

Streptococcus Staphylococcus

The striking elements common to all these infections are the fact that (1) they affect widespread areas involving various parts of the body, irrespective of the usual propagation barriers, and (2) that typical purulence is not present, usually replaced by a small amount of cloudy serous exudate. When incised, the tissue is pale, necrotic and there is little bleeding. It can be parted easily by hand or a blunt instrument. Microscopic examination reveals massive infiltration by leucocytes and the presence of both necrotic areas and developing micro-abscesses. Most of the time the causal organisms are found in these areas. The necrotizing aspect of these infections can be explained by a wide-spread thrombosis affecting practically all the small vessels in the infected area. The multiple thromboses cause extensive oedema and severe local hypoxia; even though blood

Penis & scrotum : Fournier's gangrene Submandibular area : Ludwig's angina circulation is maintained in the larger vessels, it is not able to supply oxygen to the infected tissue.

Although these various infections have enough in common to be captured within a common framework, there are certain unique and distinguishing features that have clinical and therapeutic implications. They include (1) the tissue initially infected (muscle, subcutaneous tissue, fascia); (2) location on the body; and (3) mode of development6.

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