Table 1. Open in new tab Concordance of...

Skin and Soft Tissue Infections	Infected Diabetic Foot Ulcers
Class 1	Superficial skin infections • Impetigo • Ecthyma • Superficial, limited wound infections	Drainage (if required) and oral antibiotics in the outpatient setting. Occasionally topical antibiotics	Mild	Local infection involving only the skin and the subcutaneous tissue (without involvement of deeper tissues and without systemic signs as described below). If erythema, must be >0.5 cm to ≤2 cm around the ulcer. Exclude other causes of an inflammatory response of the skin (eg, trauma, gout, fracture).	Usually treated with oral antibiotics in the outpatient setting	Yes
Class 2A	Systemically well Erysipelas & cellulitis Purulent skin and soft infections • Abscess • Furuncle, carbuncle Traumatic wounds • Surgical site infections • Animal bites • Other trauma (eg, pressure, thermal, pun cture, crush)	Oral or intravenous (often outpatient) antibiotic therapy; may require short period of hospital observation	Moderate - Class A	Local infection (as described above), but with erythema extending >2 cm from rim of ulcer	May be treated with oral, or initial parenteral with rapid switch to oral, antibiotics	Potentially, but as adjunctive to systemic antibiotic therapy
Class 2B	Systemically unwell, but no systemic inflammatory response syndrome (SIRS) Erysipelas & cellulitis Purulent skin and soft infections • Abscess • Furuncle carbuncle Traumatic wounds • Surgical site infections • Animal bites Other trauma (eg, pressure, thermal, puncture, crush)	Oral or outpatient parenteral antibiotic therapy; may require short period of hospital observation	Moderate - Class B	Local infection (as described above) involving structures deeper than skin and subcutaneous tissues (eg, abscess, osteomyelitis, septic arthritis, fasciitis), but with no evidence of systemic inflammatory response syndrome (as described below)	May be treated with oral or initial parenteral antibiotics	No
Class 3	Sepsis syndrome and life-threatening infection Necrotizing infections of skin and soft tissues • Necrotizing fasciitis • Gas gangrene • Pyomyositis	Likely to require admission to intensive care unit, urgent surgical assessment, and treatment with parenteral antibiotics	Severe	Local infection (as described above) with evidence of SIRS, as manifested by ≥2 of the following: • Temperature >38°C or <36°C • Heart rate >90 beats/ min • Respiratory rate >20 breaths/min or PaCO₂ <32 mm Hg • White blood cell count >12 000 or <4000 cells/μL or ≥10% immature (band) forms	Treat, at least initially with parenteral antibiotic(s)	No

Skin and Soft Tissue Infections

Infected Diabetic Foot Ulcers

Skin and Soft Tissue Infections	Infected Diabetic Foot Ulcers
Class 1	Superficial skin infections • Impetigo • Ecthyma • Superficial, limited wound infections	Drainage (if required) and oral antibiotics in the outpatient setting. Occasionally topical antibiotics	Mild	Local infection involving only the skin and the subcutaneous tissue (without involvement of deeper tissues and without systemic signs as described below). If erythema, must be >0.5 cm to ≤2 cm around the ulcer. Exclude other causes of an inflammatory response of the skin (eg, trauma, gout, fracture).	Usually treated with oral antibiotics in the outpatient setting	Yes
Class 2A	Systemically well Erysipelas & cellulitis Purulent skin and soft infections • Abscess • Furuncle, carbuncle Traumatic wounds • Surgical site infections • Animal bites • Other trauma (eg, pressure, thermal, pun cture, crush)	Oral or intravenous (often outpatient) antibiotic therapy; may require short period of hospital observation	Moderate - Class A	Local infection (as described above), but with erythema extending >2 cm from rim of ulcer	May be treated with oral, or initial parenteral with rapid switch to oral, antibiotics	Potentially, but as adjunctive to systemic antibiotic therapy
Class 2B	Systemically unwell, but no systemic inflammatory response syndrome (SIRS) Erysipelas & cellulitis Purulent skin and soft infections • Abscess • Furuncle carbuncle Traumatic wounds • Surgical site infections • Animal bites Other trauma (eg, pressure, thermal, puncture, crush)	Oral or outpatient parenteral antibiotic therapy; may require short period of hospital observation	Moderate - Class B	Local infection (as described above) involving structures deeper than skin and subcutaneous tissues (eg, abscess, osteomyelitis, septic arthritis, fasciitis), but with no evidence of systemic inflammatory response syndrome (as described below)	May be treated with oral or initial parenteral antibiotics	No
Class 3	Sepsis syndrome and life-threatening infection Necrotizing infections of skin and soft tissues • Necrotizing fasciitis • Gas gangrene • Pyomyositis	Likely to require admission to intensive care unit, urgent surgical assessment, and treatment with parenteral antibiotics	Severe	Local infection (as described above) with evidence of SIRS, as manifested by ≥2 of the following: • Temperature >38°C or <36°C • Heart rate >90 beats/ min • Respiratory rate >20 breaths/min or PaCO₂ <32 mm Hg • White blood cell count >12 000 or <4000 cells/μL or ≥10% immature (band) forms	Treat, at least initially with parenteral antibiotic(s)	No

Category

Clinical Features

Current Management

IDSA Infection Severity

Clinical Features

Current Management

Amenable to Topical Therapy?

Class 1

Superficial skin infections
• Impetigo
• Ecthyma
• Superficial, limited wound infections

Drainage (if required) and oral antibiotics in the outpatient setting. Occasionally topical antibiotics

Mild

Usually treated with oral antibiotics in the outpatient setting

Yes

Class 2A

Oral or intravenous (often outpatient) antibiotic therapy; may require short period of hospital observation

Moderate - Class A

Local infection (as described above), but with erythema extending >2 cm from rim of ulcer

May be treated with oral, or initial parenteral with rapid switch to oral, antibiotics

Potentially, but as adjunctive to systemic antibiotic therapy

Class 2B

Oral or outpatient parenteral antibiotic therapy; may require short period of hospital observation

Moderate - Class B

May be treated with oral or initial parenteral antibiotics

Class 3

Sepsis syndrome and life-threatening infection
Necrotizing infections of skin and soft tissues
• Necrotizing fasciitis
• Gas gangrene
• Pyomyositis

Likely to require admission to intensive care unit, urgent surgical assessment, and treatment with parenteral antibiotics

Severe

Treat, at least initially with parenteral antibiotic(s)

Table 1.

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Concordance of IDSA Classification Schemes for Severity of SSTIs (COCLASSTI) and Infected DFUs (Adapted From 3 and 4)^a

Skin and Soft Tissue Infections			Infected Diabetic Foot Ulcers
Category	Clinical Features	Current Management	IDSA Infection Severity	Clinical Features	Current Management	Amenable to Topical Therapy?
Class 1	Superficial skin infections • Impetigo • Ecthyma • Superficial, limited wound infections	Drainage (if required) and oral antibiotics in the outpatient setting. Occasionally topical antibiotics	Mild	Local infection involving only the skin and the subcutaneous tissue (without involvement of deeper tissues and without systemic signs as described below). If erythema, must be >0.5 cm to ≤2 cm around the ulcer. Exclude other causes of an inflammatory response of the skin (eg, trauma, gout, fracture).	Usually treated with oral antibiotics in the outpatient setting	Yes
Class 2A	Systemically well Erysipelas & cellulitis Purulent skin and soft infections • Abscess • Furuncle, carbuncle Traumatic wounds • Surgical site infections • Animal bites • Other trauma (eg, pressure, thermal, pun cture, crush)	Oral or intravenous (often outpatient) antibiotic therapy; may require short period of hospital observation	Moderate - Class A	Local infection (as described above), but with erythema extending >2 cm from rim of ulcer	May be treated with oral, or initial parenteral with rapid switch to oral, antibiotics	Potentially, but as adjunctive to systemic antibiotic therapy
Class 2B	Systemically unwell, but no systemic inflammatory response syndrome (SIRS) Erysipelas & cellulitis Purulent skin and soft infections • Abscess • Furuncle carbuncle Traumatic wounds • Surgical site infections • Animal bites Other trauma (eg, pressure, thermal, puncture, crush)	Oral or outpatient parenteral antibiotic therapy; may require short period of hospital observation	Moderate - Class B	Local infection (as described above) involving structures deeper than skin and subcutaneous tissues (eg, abscess, osteomyelitis, septic arthritis, fasciitis), but with no evidence of systemic inflammatory response syndrome (as described below)	May be treated with oral or initial parenteral antibiotics	No
Class 3	Sepsis syndrome and life-threatening infection Necrotizing infections of skin and soft tissues • Necrotizing fasciitis • Gas gangrene • Pyomyositis	Likely to require admission to intensive care unit, urgent surgical assessment, and treatment with parenteral antibiotics	Severe	Local infection (as described above) with evidence of SIRS, as manifested by ≥2 of the following: • Temperature >38°C or <36°C • Heart rate >90 beats/ min • Respiratory rate >20 breaths/min or PaCO₂ <32 mm Hg • White blood cell count >12 000 or <4000 cells/μL or ≥10% immature (band) forms	Treat, at least initially with parenteral antibiotic(s)	No

Skin and Soft Tissue Infections			Infected Diabetic Foot Ulcers
Category	Clinical Features	Current Management	IDSA Infection Severity	Clinical Features	Current Management	Amenable to Topical Therapy?
Class 1	Superficial skin infections • Impetigo • Ecthyma • Superficial, limited wound infections	Drainage (if required) and oral antibiotics in the outpatient setting. Occasionally topical antibiotics	Mild	Local infection involving only the skin and the subcutaneous tissue (without involvement of deeper tissues and without systemic signs as described below). If erythema, must be >0.5 cm to ≤2 cm around the ulcer. Exclude other causes of an inflammatory response of the skin (eg, trauma, gout, fracture).	Usually treated with oral antibiotics in the outpatient setting	Yes
Class 2A	Systemically well Erysipelas & cellulitis Purulent skin and soft infections • Abscess • Furuncle, carbuncle Traumatic wounds • Surgical site infections • Animal bites • Other trauma (eg, pressure, thermal, pun cture, crush)	Oral or intravenous (often outpatient) antibiotic therapy; may require short period of hospital observation	Moderate - Class A	Local infection (as described above), but with erythema extending >2 cm from rim of ulcer	May be treated with oral, or initial parenteral with rapid switch to oral, antibiotics	Potentially, but as adjunctive to systemic antibiotic therapy
Class 2B	Systemically unwell, but no systemic inflammatory response syndrome (SIRS) Erysipelas & cellulitis Purulent skin and soft infections • Abscess • Furuncle carbuncle Traumatic wounds • Surgical site infections • Animal bites Other trauma (eg, pressure, thermal, puncture, crush)	Oral or outpatient parenteral antibiotic therapy; may require short period of hospital observation	Moderate - Class B	Local infection (as described above) involving structures deeper than skin and subcutaneous tissues (eg, abscess, osteomyelitis, septic arthritis, fasciitis), but with no evidence of systemic inflammatory response syndrome (as described below)	May be treated with oral or initial parenteral antibiotics	No
Class 3	Sepsis syndrome and life-threatening infection Necrotizing infections of skin and soft tissues • Necrotizing fasciitis • Gas gangrene • Pyomyositis	Likely to require admission to intensive care unit, urgent surgical assessment, and treatment with parenteral antibiotics	Severe	Local infection (as described above) with evidence of SIRS, as manifested by ≥2 of the following: • Temperature >38°C or <36°C • Heart rate >90 beats/ min • Respiratory rate >20 breaths/min or PaCO₂ <32 mm Hg • White blood cell count >12 000 or <4000 cells/μL or ≥10% immature (band) forms	Treat, at least initially with parenteral antibiotic(s)	No

Abbreviations: DFU, diabetic foot ulcer; IDSA, Infectious Disease Society of America; SIRS, systemic inflammatory response syndrome.

^aNote that in the original publications, the rows in boldface type are not separated into “A” and “B”, as shown here. Infection defined as presence of at least 2 of the following items: (1) local swelling or induration; (2) erythema; (3) local tenderness or pain; (4) local warmth; (5) purulent discharge (thick, opaque to white or sanguineous secretion).

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