Chapter 26 ICU Infections

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CHAPTER 26 • ICU Infections

Anatomy

Syndrome

Epidermis

Erysipelas Impetigo Folliculitis Ecthyma Furunculosis Carbunculosis

Dermis

Skin

Cellulitis

Superficial fascia

Necrotizing fasciitis

Subcutaneous fat, nerves, arteries, veins

Subcutaneous tissue

Deep fascia (DF) Muscle

Myonecrosis (clostridial and non-clostridial)

FIGURE 26-7. Layers of integument and associated infections.

and those for whom malignancy is a strong alterna- tive possibility.

sites. The overall mortality rate for necrotizing soft tissue infections remains approximately 25%. Many skin infections seen in the ICU are polymicrobial because they result from wounds incurred in surgical or accidental trauma, decu- bitus ulcers, and therapeutic or illicit vascular punctures or because they occur in patients with compromised defenses and vascular insufficiency (especially diabetes). Necrotizing infections of the soft tissues are characterized by fulminant destruc- tion of tissue, often (but not invariably) accompanied by impressive systemic toxicity and always associated with substantial risk of mortality. Microthrombosis, a tendency to spread along facial planes, and rela- tively little inflammatory cellular infiltrate charac- terize their pathology. Eponyms such as Fournier gangrene (pelvicoperineal necrotizing cellulitis), Ludwig angina (cervicofacial necrotizing fasciitis), and Lemierre syndrome (pharyngeal–jugular throm- bophlebitis) have been applied to recognized variants of necrotizing cellulitis and necrotizing fasciitis. Among the most impressive of these are gas-producing infections, which usually develop in

Soft Tissue Infections A wide variety of skin and soft tissue infections can be encountered upon admission and after care is administered in the ICU (Fig. 26-7). These can be diagnostically obvious, superficial, and simple to treat or deceptively deep and life threatening. They are not always simple to distinguish from one another, so that high levels of suspicion and vigilance is advisable (Fig. 26-8). The frequency of soft tis- sue infections has increased significantly in recent decades predominantly because of an increase in infections caused by community-associated MRSA. Staphylococcus aureus is the most common patho- gen isolated from complicated soft tissue infections, accounting for more than 40% of all cultured organ- isms. Pseudomonas aeruginosa is the second most fre- quently encountered isolate. Staphylococcus aureus , coagulase-negative Staphylococcus , and enterococci comprise more than half of infections at surgical