life-threatening infections with the majority requiring surgical intervention, such as NF, and
are often admitted to intensive care unit (12). Guidelines developed by the Infectious Disease
Society of America are written in references to specific disease entities, mechanism of injury,
or host factors (13).
Systemic syndromes mediated by toxin and affecting the skin cause staphylococcal
scalded skin syndrome (SSSS), toxic shock syndrome (TSS), and purpura fulminans.
Classification of skin and soft tissue infections based on uncomplicated and complicated
infections, and systemic syndromes is depicted in Table 1.
Here we review causes of skin and soft tissue infection with emphasis on severe skin and
soft tissue infection, highlighting the clinical presentation, diagnosis, and approach to
management in the critical care setting.
IMPETIGO
Impetigo is the most common, contagious, superficial skin infection nearly always caused by
S. aureus or Streptococcus. There are two clinical presentations: bullous impetigo and
nonbullous impetigo, and both begin as a vesicle (14). Bullous impetigo, like SSSS and the
staphylococcal scarlatiniform syndrome, represents a form of cutaneous response to the two
extracellular exfoliative toxins produced byS. aureusof phage group II (usually type 71). The
group A streptococci responsible for impetigo belong to different M serotypes (2,15–21) from
those of strains that produce pharyngitis (1,2,4,6,22) (23,24). Crusted impetigo is usually
associated with a mixed flora of bothS. aureusand streptococci.S. aureusis known to be the
primary pathogen in both bullous and nonbullous impetigo. They are common in exposed
areas such as hands, feet, and legs, and are often associated with traumatic events such as
minor skin injury or insect bite. Predisposing factors include warm ambient temperature,
humidity, poor hygiene, and crowded conditions. Systemic complications are very uncommon.
Cutaneous infection with nephritogenic strains (2,15,17–21) of group A streptococci can lead
to poststreptococcal glomerular nephritis. For extensive bullous impetigo, treatment with
antistaphylococcal agents is selected with consideration of susceptibility testing.
FURUNCLES AND CARBUNCLES
Furuncle is a deep inflammatory nodule that develops from predisposing folliculitis. A
carbuncle is a more extensive process that extends into the subcutaneous fat in areas covered
by thick, inelastic skin. Multiple abscesses separated by connective tissue septa develop and
drain to the surface along the hair follicle.S. aureusis the most common etiological agent.
Infections occur in areas that contain hair follicles such as neck, face, axillae and buttocks, sites
predisposed to friction, and perspiration. Predisposing factors include obesity, defects in
neutrophil dysfunction, and diabetes mellitus. Bacteremia can occur and result in
osteomyelitis, endocarditis, or other metastatic foci. Larger furuncles and all carbuncles
require incision and drainage. Systemic anti-staphylococcal antibiotics are recommended in
the presence of surrounding cellulitis and large abscesses or when there is a systemic
inflammatory response present.
ERYSIPELAS
Erysipelas is a distinctive superficial cellulitis of the skin with prominent lymphatic
involvement. In typical erysipelas, the area of inflammation is raised above the surrounding
skin, and there is a distinct demarcation between involved and normal skin, the affected area
has a classic orange peal (peau d’orange) appearance. The induration and sharp margin
distinguish it from the deeper tissue infection of cellulitis in which the margins are not raised
and merge smoothly with uninvolved areas of the skin (Fig. 1). Systemic signs of chills and
fever are common. Flaccid bullae filled with clear fluid may develop on the second or third
day. Occasionally, the infection spreads more deeply and causes cellulitis, abscess, and NF.
Desquamation may occur in 5 to 10 days, and scarring is very uncommon. Erysipelas is almost
always caused by group AStreptococcus, though streptococci of groups G, C, and B and rarely
S. aureuscan also be responsible. Formerly, the face was commonly involved, but now up to
85% of cases occur on the legs and feet largely due to lymphatic venous disruptions (25,26).
Severe Skin and Soft Tissue Infections in Critical Care 297