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MANAGEMENT OF SKIN AND SOFT TISSUE INFECTIONS

MANAGEMENT OF SKIN AND SOFT TISSUE INFECTIONS. Jose A. Vazquez, M.D. Senior Staff Division of Infectious Disease Henry Ford Hospital Professor of Medicine Wayne State University. Skin and Soft Tissue Infections General Considerations. Primary vs. Secondary infections Portal of entry

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MANAGEMENT OF SKIN AND SOFT TISSUE INFECTIONS

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  1. MANAGEMENT OF SKIN AND SOFT TISSUE INFECTIONS Jose A. Vazquez, M.D. Senior Staff Division of Infectious Disease Henry Ford Hospital Professor of Medicine Wayne State University

  2. Skin and Soft Tissue InfectionsGeneral Considerations • Primary vs. Secondary infections • Portal of entry • Status of host defenses • Associated manifestations • Toxicity, severity of illness • Localization and morphology of lesions • Environmental exposure

  3. PRIMARY PYODERMAS • Impetigo • Bullous impetigo • Staphylococcal Scalded Skin Syndrome • Folliculitis • Furuncles and Carbuncles • Erysipelas • Cellulitis

  4. PRIMARY PYODERMASImpetigo • >90% due to group A Streptococcus • Most occur in children • <10% mixture of Staph with Strep • Manifestations - small vesicles with erythematous halo - pustulates - ruptures - characteristic golden-yellow thick stuck-on crusts - painless - minimal constitutional symptoms

  5. PRIMARY PYODERMASImpetigo Therapy • Penicillin still drug of choice • Alternatives: - 1st generation cephalosporin (Duricef, Keflex) - If Pen allergic: Erythromycin or Azithromycin • Local wound care wet-to-dry dressings • Topical antimicrobials far inferior

  6. PRIMARY PYODERMASBullous Impetigo • Primarily in kids • Due to Staphylococcus group II (Type 71) • Manifestations: - Begin as vesicles that turn into bullae - Bullae rupture and leave moist red surface - No Nikolsky sign - Finally form a thin “varnish”-like” light brown crust • Therapy - Dicloxacillin - 1st generation ceph - Erythromycin or Azithromycin

  7. PRIMARY PYODERMASErysipelas • A superficial cellulitis of the skin with prominent lymphatic involvement • Generally due to group A Strep (rarely group C or G) • Most common in: - infants - young kids - older adults - immunocompromised (diabetics, alcoholic, nephrotic syndrome, venous statsis, paraparesis) • Portal of entry - skin ulcers, local trauma, abrasions, primary dermatologic conditions, Tineas

  8. PRIMARY PYODERMASErysipelas - Manifestations • 70-80% of lesions are on the lower extremity 5-20% are on the fact • A painful lesion with a bright red edematous indurated appearance and an advancing raised border-sharply demarcated • Fever • Bacteremia ~ 5% • Occasional spread to deeper structures • Leukocytosis very common

  9. PRIMARY PYODERMASErysipelas - Manifestations • Penicillin oral vs parenteral • Alternatives - 1st generation ceph. - Erythromycin or Azithromycin

  10. PRIMARY PYODERMASCellulitis • Acute spreading infection of the skin extending into the subcutaneous tissue • Etiology: - Staph and Strep most common - Erysipeloid- E. rhusiopathiae - salt water fish, poultry - Anthrax - Bacillus - raw wool - Pseudomonas - spas, heel tennis shoe puncture wounds - Aeromonas - lesions in water - Sporotrichosis - Blastomycosis

  11. PRIMARY PYODERMASCellulitis • Generally due to: - Previous trauma - Underlying skin condition • Skin lesion: borders are not sharply demarcated with erythema, tenderness, warmth, edema • Fever - malaise - chills • Regional adenopathy • Bacteremia ~ 20%

  12. PRIMARY PYODERMASCellulitis • If strong suspicion of etiologic agent treat with specific antimicrobial. • If etiologic agent unknown: - No underlying risk factors 1st generation ceph (cover Staph and Strep) Alternative: if Pen allergic - Erythromycin or Azithromycin (Zithromax)

  13. Staphylococcus aureus • Frequent cause of cellulitis, especially in diabetic patients • 2nd – 3rd most common cause of BSIs in hospitalized patients. • Etiology: > 80 % line infections: • Susceptibility has evolved dramatically over the past few year

  14. What about resistant S. aureus ??

  15. Resistance in S. aureus • HA-MRSA • CA-MRSA • VISA or GISA • MIC 8-16 to vancomycin • VRSA • MIC > 32 to vancomycin • HR-SA • MIC < 4 (susceptible) to vancomycin • subpopulations that are VISA Cosgrove SE. et al CID;39:539-45.

  16. Community-Associated MRSA • Prevalence ~ 36 % • Risk Factors: • Recent hospitalization • Recent antimicrobials • Surgery • Exposure to MRSA colonized person • Athletes (wrestlers, football players) • Chronic illness • Nursing home, jails, IVDU Eguia JM, Chambers HF. Hosp Epidemiol 5:2003

  17. Community-Associated MRSA • Most common infections are SSTI and Resp. tract • Many remain susceptible to: clindamycin (89 v 21%); genta (94 v 80%);rifampin (96 v94%); TCN (92%); Bactrim (95v90%) • ~ 60 % probably originate from hospitals or long-term care facilities • Risk Factors: • Recent hospitalization` OR • 0-6 months 3.5 • 6-12 months 2.2 • Nursing home 2.1 Charlebois ED. Et al. CID 2004;39:47-54: Naimi TS. Et al. JAMA;290:2976-84.

  18. Community-Associated MRSAManagement • Outpatient • Mild Infection • Clindamycin 450mg q8 hrs • Doxycycline 100mg BID • Bactrim DS 2 tabs po BID • Moderate to severe • Zyvox 600mg BID • Inpatient • Vancomycin 15mg/kg q12 hrs • Zyvox (linezolid) 600mg IV/PO BID • Daptomycin (Cubicin) 4mg/kg Charlebois ED. Et al. CID 2004;39:47-54

  19. Management of Gram Positives • MSSA • Nafcillin 2 gm q4 h • Cefazolin (ancef) 2gm q 8 h IV • PCN allergy (vanco or linezolid) IV • Linezolid oral • MRSA • Vancomycin • Linezolid • Daptomycin

  20. Michigan Case 1 Gangrenous foot – VRE, MRSA, multiple courses of vanco VRE + MRSA = VRSA ( van A ) PA Case 2 Foot ulcer, VRE in the past. Allergic to Vanco MRSA 1:132 ( van A) VRSA – Its All About Sex

  21. Vancomycin-ResistantStaphylococcus aureus June 2002: First case of vancomycin-resistant S aureus (VRSA) isolated from a swab obtained from a catheter exit site. • The isolate was resistant to: • Oxacillin (MIC>16 μg/mL) • Vancomycin (MIC>128 μg/mL) • The isolate contained: • The oxacillin resistance gene mecA • The vanA vancomycin resistance gene from enterococci MIC = minimal inhibitory concentration. CDC. MMWR. 2002;51:565-567.

  22. SECONDARY PYODERMAS • Bite wounds • Infections of burns, wounds, or underlying dematitis • Diabetic wound infections • Decubitus ulcers • Surgical wound infections

  23. BITEWOUNDS AND INFECTIONS • ANIMAL - Dog - Cat - Snake ~ 8,000/year - few get infected - venom is sterile - Exotic animals - monkey tend to be the most serious - organisms will reflect habitat of animals • HUMAN - Occlusional bites - Clenched-fist injuries

  24. CAT BITESEpidemiology • ~ 400,000/year • Primarily in women • Infection rates > 50%/bite - Teeth slender, sharp, closer together - High colony counts - Teeth penetrate into bones, capsules, and bones easier

  25. CAT BITESMICROBIOLOGY • Pasturella multocida isolated > 50% of bites • Otherwise same isolates as dog • Rochalimea spp. - R. hensenulae May cause Cat Scratch Disease May produce disseminated disease in immunocompromised host Tx. Erythromycin

  26. BITE WOUNDS AND INFECTIONSDog Bites • ~ 80% of all animal bites • ~ 15-20% become infected • Generally a polymicrobial infection • Role of prophylactic antimicrobial therapy ??? - No good prospective studies • Probably prudent to provide antimicrobial coverage for at least 3-5 days after the bite

  27. DOG BITESMicrobiology • Gram positive cocci - alpha hemolytic streptococci ~ 30% - S. aureus ~ 15% - S. intermedium ~ 27% - generally in dogs < 40 lbs. - Beta-hemolytic streptococci - Enterococci - Micrococcus

  28. DOG BITESMicrobiology • Gram negative rods - Haemophilus - Proteus - E. coli - Enterobacter cloacae

  29. Pasturella multocida ~ 10-15% Eikinella corrodens Capnocytophagia carimorsus Actinomyces Bacteroides spp. non Fragilis Fusobacterium Peptostreptococci Peptococci Veillonella Eubacterium Rods DOG BITESMicrobiology Anaerobes

  30. HUMAN BITES/CLENCHED FIST INJURIESEpidemiology • Like monkey bites, generally more serious and more prone to develop infection and complications than are animal bites • Most tend to occur during fights • ~ 20% of injuries are “love nips” and are related to sexual activity

  31. HUMAN BITES/CLENCHED-FIST INJURIES • Unfortunately most patients tend to wait until the infection has set in before seeking medical attention • Generally results in cellulitis • Frequently however, it produces: - deep-space infection - septic arthritis - osteomyelitis • ~ 20% of injuries require amputation if no antibiotic is provided

  32. HUMAN BITESMicrobiology • ~ 55% are mixed polymicrobial infections with anaerobes • E. corrodens ~ 25% • S. aureus • Streptococci • Hemophilus influenzae

  33. BITE WOUND AND INFECTIONMANAGEMENT • Tetanus immunization • Rabies vaccintion/Rabies immune globulin - if indicated • Incision/Drainage/Debridement - if indicated • Gram stain and culture of all material • Elevation of injured area - frequent cause of failure • Follow-up - preferably within 24-48 hours

  34. BITE WOUNDS AND INFECTIONSAntimicrobial Therapy - Outpatient • Amoxicillin-clavulanate (Augmentin) 250-500 mg TID oral • Doxycycline 100 mg BID oral • Tetracycline 500 mg QID oral

  35. BITE WOUNDS AND INFECTIONSAntimicrobial Therapy - Inpatient • Ampicillin-sulbactam (Unasyn) 3.0 gm IVPB Q 6 hrs. • Cefoxitin or cefotetan 2 gm Q 8-12 hrs. IVPB (No enterococcal coverage) • Imipenem/cilastin (Primaxin) 500-1000 mg IVPB QID • Piperacillin/tazobactam (Zosyn) 3.75 gm Q 8 hrs.

  36. Building a better mouse trap ?

  37. Zyvox (Linezolid) • 1st oxazolidinone – inhibits protein synthesis at the initiation of 50S ribosome • Spectrum: gram positive pathogens: • Staph aureus (MSSA or MRSA) • Enterococcus • E. fecalis or E. faecium and VRE • Streptococcus Group A • S. pneumonia including (PCN-Resistant SP) • Nocardia spp.

  38. Zyvox (Linezolid) • Dose : 600mg BID • Oral and IV • Bioavailability ~ 100% • Metabolism: • ~ 65 % non-renal • AE: diarrhea ~ 8-10 % thrombocytopenia ~ 2.5%

  39. CUBICIN™ (daptomycin) Overview • Lipopeptide natural product • Activity in Gram-positive organisms only • Bactericidal in vitro and in vivo • Safety profile similar to vancomycin • Long T1/2 (once-daily IV dosing) • No oral formulation • FDA approved for SSTI only.

  40. Future Antimicrobial Agents For Gram Positives Organisms • Glycopeptides • Telavancin • Oritavancin • Dalbavancin • Tetracyclines • Tigecycline (broad spectrum activity) • Cephalosporins • Ceftibiprole (5th generation) • Excellent gram positive activity (MRSA & Enterococcus)

  41. Recent data has shown us: Emerging resistance CA-MRSA greatest concen ?? MRSA, GISA, VRSA Better understanding of mechanisms of antimicrobial resistance - e.g., selective pressure Better understanding of risk factors predisposing to CA-MRSA infection Future Molecular testing for resistance organisms Newer antimicrobials Conclusions

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