Skin and Soft-Tissue Infections: From Superficial Lesions to Deadly Disease

1. Skin and Soft-Tissue InfectionsSuperficial lesions vs Deadly diseaseOutpatient Management and Indications for Hospitalization Nayef El-Daher, MD, PhD Richard Magnussen, MD J Crit Illness, 1998; 13(3):151-160 medslides.com

2. Skin and soft-tissue Infections • Localized infections • cellulitis • erysipelas • Potentially lethal infections • necrotizing fascitis • myonecrosis • pyomyositis medslides.com

3. Cellulitis and Erysipelas pathogenesis • Cellulitis • group A streptococci typically follows an innocuous or unrecognized injury; inflammation is diffuse, spreading along tissue planes • staphylococcus aureususually associated with wound or penetrating trauma; localized abscess become surrounded by cellulitis medslides.com

4. Cellulitis and Erysipelas pathogenesis • Erysipelas • caused most often by group A streptococci • rarely cased by ß-hemolytic streptococci of the B, C, or G serologic group medslides.com

5. Cellulitis and Erysipelas diagnosis • General features • varying degrees of skin or soft-tissue erythema, warmth, edema, and pain • associated fever and leukocytosis • history of trauma, abrasion, or skin ulceration (not reported by every patient) medslides.com

6. Cellulitis and Erysipelas diagnosis • physical exam • cellulitis has an ill-defined border that merge smoothly with adjacent skin; usually pinkish to redish • erysipelas has an elevated and sharply demarcated border with a fiery-red appearance medslides.com

7. Cellulitis and Erysipelas diagnosis • laboratory exam • needle aspiration of the leading edge of the cellulitis should be obtained (1) • elevated antistrptolysin O titer supports diagnosis of streptococcal infection • blood cultures for patients with symptoms of toxicity or temp > 1020F 1. Arch Intern Med 1990; 150:1907-1912 medslides.com

8. Cellulitis and Erysipelas management • Local care • immobilization • elevation to reduce swelling • 2 weeks of antibiotic therapy • penicillin and dicloxacillin for most pts • many new, potent and expensive antibiotics offer no advantage medslides.com

9. Outpatient Therapy Infection Most patients Pencillin allergic patients Cellulitis mild-mod Dicloxacillin Cephalexin 500mg po q6h (500 mg po q6h) Clindamycin 450mg po q6h severe Nafcillin 1-2g iv q4h Cefazolin 1g iv q8h Vancomycin 1g iv q12h Erysipelas mild-mod Penicillin V Cephalexin 500mg po q6h (500 mg po q6h) Erythromycin 500mg po q6h Clindamycin 450mg po q6h severe Pen G 1-2 million U q6h Cefazolin 1g iv q8h Clindamycin 900mg iv q8h medslides.com

10. Admission Criteria for Cellulitis • Animal bite on patient’s face or hand • Area of skin involvement >50% of limb or torso, or >10% of body surface • Coexisting morbidity (diabetes, heart failure, renal failure, generalized edema) • Edge of cellulitis advancing at rate exceeding 5cm, or 2 in, per hour • History of saphenous venectomy, pelvic surgery, pelvic irradiation, or neoplastic pelvic lymph nodes (with lower extremity cellulitis) medslides.com

11. Admission Criteria for Cellulitis • Immunosuppression • Intolerance of oral or IM antibiotic therapy • Lack of response after 72 hours of oral therapy • Noncompliance with medication and follow-up visits • Purpuric or petechial rash, numbness at skin surface, or impaired tendon or nerve function • shock or disseminated intravascular coagulation • Signs and symptoms suggestive of bacteremia • Total WBC < 1000 / uL medslides.com

12. Necrotizing Fasciitispathogenesis • a polymicrobial infection, commonly caused by a mixture of anaerobic and aerobic bacteria • clostridium species, enterobacteriaceae ( E. coli, Enterobacter, Klebsiella, and Proteus species), and “flesh-eating” streptococci • usually starts at the site of nonpenetrating trauma (a bruise) medslides.com

13. Necrotizing Fasciitisdiagnostic clues • Underlying diabetes mellitus, peripheral vascular disease, alcoholism, intravenous drug use or immunosupression • Most often involve the lower extremities • Infected area is swollen, erythematous, painful, warm, and very tender • Rapidly advancing border (5 cm, or 2 in, per hour) of discoloration (red to blue-gray) medslides.com

14. Necrotizing Fasciitisdiagnostic clues • Bulllae formation and cutaneous gangren • Frank pus in discolored area (revealed by needle aspiration or surgical exploration) • Numerous bacteria evident on the Gram stain • Tendon or nerve impairment (superficial nerve destruction and small vessel thrombosis) • Systemic toxicity and/or hypotension medslides.com

15. Necrotizing Fasciitismanagement • Immediate surgical debridement is critical and life saving • empiric antibiotics to cover anaerobes, gram negative bacilli, streptococci, and Staph aureus • pen+metronidazole+clindamycin+ceftriaxone • vancomycin+chloramphenicol • monotherapy with imipenem • antibiotics for a minimum of 3 wks medslides.com

16. Myonecrosis (Gas Gangrene) • a pure Clostridium perfringens infection • gas in a gangrenous muscle group • incubation period of hours to days • local edema and pain accompanied by fever and tachycardia • discharge is serosanguinous, dirty, and foul • pen G (3-4 million U q4h) or chloramphenicol • surgical removal of infected muscle medslides.com

17. Pyomyositis (tropical myositis) • 50% with co-morbidity (diabetes, alcoholic liver disease, concurrent corticosteroid therapy, immunosuppression) • endemic in the tropics • area is indurated with a “woody” consistency; erythema and tenderness is minimal initially • fever and marked muscle tenderness may develop in 1-3 weeks medslides.com

18. Pyomyositis (tropical myositis) • Rhabdomyolysis - along with myoglobinuria and acute renal failure - may develop • Staph aureus is the most common organism • MRI or CT may show muscle enlargement • surgical drainage is essential • empiric antibiotics directed against Staph • nafcillin 2 g iv q4h • vancomycin 1 g iv q12h or cefazolin 1g iv q8h medslides.com