Table 1.

Skin and soft tissue infections—types, pathogens, features, and treatment

Infection type	Predominant pathogens	Characteristic features	Treatment
Impetigo	Staphylococcus aureus, Streptococcus pyogenes	Honey-crusted lesions, less common bullous variant	PO penicillins, 1 st generation cephalosporins, or clindamycin
Ecthyma	S. aureus, S. pyogenes	Dry crusted lesions that involve the dermis and lead to scarring, predilection for the lower extremities	PO penicillins, 1 st generation cephalosporins, or clindamycin. If MRSA suspected, doxycycline, TMP-SMX, or clindamycin
Ecthyma gangrenosum	Pseudomonas aeruginosa, S. aureus, S. pyogenes, less commonly other Gram-negative rods, fungi, mold	Cutaneous vasculitis, typically seen between umbilicus and knees, have potential for rapid increases in size. Erythematous nodules that evolve into necrotic ulcers with eschar	Broad spectrum antibiotics, pathogen directed therapy when culture results available
Purulent SSTI—abscesses, furuncles, carbuncles	S. aureus	Pustules surrounded by erythema. Furuncles and carbuncles centered on hair follicles. May exhibit 5 cardinal signs of infection—calor, rubor, dolor, tumor, fluor	Incision and drainage. Antibiotic therapy for MRSA in patients meeting SIRS criteria or immunocompromised
Cellulitis	Beta-hemolytic streptococci, S. aureus	Diffuse, superficial spreading erythema. May be associated with lymphangitis	Mild: PO therapy directed against MSSA and streptococci. Moderate: PO or IV therapy directed against MSSA and streptococci. Severe: surgical consultation, broad spectrum antibiotics directed against MRSA, Pseudomonas, and anaerobes
Pyomyositis	S. aureus	Localized pain in a single muscle group with fever. Overlying skin may have”woody”feel	Surgical consultation, vancomycin. Addition of gram-negative agents if immunocompromised or penetrating trauma
Surgical site infections	Dependent on surgical site	Wound drainage, local inflammation	Surgical consultation, antimicrobials dependent on surgical site and severity of illness
Toxic shock syndrome	S. aureus, S. pyogenes, rarely other streptococci	Staphylococcal disease: erythroderma that starts on the trunk and spreads to extremities (including palms and soles). Streptococcal disease: scarlitinform rash may be seen	Vancomycin PLUS clindamycin for toxin production OR linezolid monotherapy (limited studies)
Gas gangrene/myonecrosis	Clostridium spp., C. perfringens—trauma related, C. septicum—non-traumatic	Bullae, crepitus	Immediate surgical consultation, broad spectrum agents—vancomycin PLUS piperacillin-tazo- bactam, an anti-pseudomonal carbapenem OR cefepime PLUS metronidazole
Necrotizing fasciitis	Polymicrobial aerobes and anaerobes (type 1), Group A streptococcus or S. aureus (type II)	Classic finding of pain out of proportion to exam. Spectrum from normal external appearance to woody feeling subcutaneous tissues with obliterated fascial planes/muscle groupings	Immediate surgical consultation, vancomycin or linezolid PLUS cefepime and metronidazole OR an anti-pseudomonal carbapenem OR pipera- cillin/tazobactam