Table 1.

Skin and soft tissue infections: risk factors and common causative pathogens

Risk factors
Local	Systemic
• Soft tissue trauma • Animal or human bites • Burns • Operative or highly contaminated wounds • Diminished perfusion due to peripheral vascular disease, obesity • Poor hygiene • Exposure to contaminated water • Presence of foreign body (eg, piercing, tattoos) • Venous insufficiency and stasis	• Poorly controlled diabetes mellitus • Immunocompromised comorbidities (eg, HIV infection, cellular or humoral immune deficiencies) • Concomitant drugs (ie, corticosteroids, cyclosporine) • Sensory neuropathies • Chronic systemic illness (eg, cirrhosis)
Infection or risk factor	Causative pathogen
Abscess	Staphylococcus aureus
	Polymicrobial
Cellulitis	S. aureus
	GABHS
Associated with injection use	S. aureus
Associated with water exposure	Aeromonas hydrophila, Vibrio vulnificus, Mycobacterium marinum
Associated with animal bite	Pasteurella multocida, Capnocytophaga canimorsus
Associated with human bite	Human oral flora
Surgical site infections	Anaerobes
	Enterococcus spp.
	Enterobacter spp.
	Gram-negative bacilli
	Staphylococcus spp.
	Streptococcus spp.
	Escherichia coli
Necrotizing fasciitis	Monomicrobial:
	S. pyogenes, S. aureus, Enterobacteriaceae, Bacteroides, and Peptostreptococcus species
	Polymicrobial:
	Clostridium perfringens, S. aureus, Pseudomonas aeruginosa
Myonecrosis	C. perfringens
Recurrent hospital admissions	MRSA
Diabetes	S. aureus (MRSA and MSSA), GABHS, anaerobes, Gram-negative bacilli
Diabetic foot ulcers	S. aureus, Enterococcus spp., Streptococcus spp.
	P. aeruginosa, Enterobacter spp., Acinetobacter spp.
	Bacteroides spp
Cirrhosis	Campylobacter fetus, Klebsiella pneumoniae, E. coli, Capnocytophaga canimorsus, other
	Gram-negative bacilli, Vibrio vulnificus
Neutropenia	Gram-negative bacilli, P. aeruginosa

Abbreviations: GABHS, group A β-hemolytic streptococci; MRSA, methicillin-resistant Staphylococcus aureus; MSSA, methicillin-sensitive S. aureus.