Cutaneous Bacterial Infections


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Cutaneous Bacterial Infections

  1. 1. Cutaneous Bacterial Infections Nastaran Tavakoli Guilan University of medicine
  2. 2. IMPETIGO : <ul><li>There are two classic forms of impetigo: </li></ul><ul><li>1)Nonbullous impetigo </li></ul><ul><li>2)Bullous Impetigo </li></ul>
  3. 3. Nonbullous impetigo: <ul><li>More than 70% of cases </li></ul><ul><li>Lesions typically begin on the skin of the face or on extremities that have been traumatized </li></ul><ul><li>A tiny vesicle or pustule forms initially </li></ul><ul><li>Rapidly develops into a honey-colored crusted plaque that is generally <2 cm in diameter </li></ul>
  4. 4. Nonbullous impetigo                                                                                 
  5. 6. differential diagnosis : <ul><li>viral (herpes simplex, varicella-zoster) </li></ul><ul><li>fungal (tinea corporis, kerion) </li></ul><ul><li>parasitic infestations (scabies, pediculosis capitis), </li></ul>
  6. 7. Etiology: <ul><li>Staphylococcus aureus </li></ul><ul><li>Group A β-hemolytic streptococci (GABHS) </li></ul><ul><li>Generally spread from the nose to normal skin </li></ul>
  7. 8. Bullous Impetigo : <ul><li>This is mainly an infection of infants and young children </li></ul><ul><li>Always caused by S. aureus </li></ul><ul><li>Ruptured bullous impetigo </li></ul>
  8. 9. Bullous Impetigo
  9. 10. <ul><li>Flaccid, transparent bullae develop most commonly on skin of the face, buttocks, trunk, perineum, and extremities </li></ul><ul><li>Rupture of bullae occurs easily </li></ul><ul><li>Neonatal bullous impetigo can begin in the diaper area </li></ul>
  10. 11. Bullous Impetigo
  11. 12. Bullous Impetigo
  12. 13. Bullous Impetigo
  13. 14. DIAGNOSIS: <ul><li>Cultures of fluid from an intact blister or moist plaque </li></ul><ul><li>Nonbullous impetigo has histopathologic findings similar to those of the bullous variant, except that blister formation is slight </li></ul>
  14. 15. <ul><li>Nonbullous impetigo has histopathologic findings similar to those of the bullous variant, except that blister formation is slight </li></ul>
  15. 16. Differential diagnosis : <ul><li>In neonates: </li></ul><ul><li>Herpetic infection </li></ul><ul><li>Early scalded skin syndrome </li></ul><ul><li>In older children: </li></ul><ul><li>Allergic contact dermatitis </li></ul><ul><li>Burns </li></ul><ul><li>Erythema multiforme </li></ul><ul><li>Pemphigus </li></ul><ul><li>Bullous pemphigoid </li></ul>
  16. 17. COMPLICATIONS: (Very rare) <ul><li>Osteomyelitis </li></ul><ul><li>Septic arthritis </li></ul><ul><li>Pneumonia </li></ul><ul><li>Septicemia </li></ul><ul><li>Nephritogenic strains of GABHS may result in acute poststreptococcal glomerulonephritis </li></ul>
  17. 18. TREATMENT : <ul><li>Mupirocin (Applied topically 3 times daily for 7–10 days) </li></ul><ul><li>Oral erythromycin ethylsuccinate (30–50 mg/kg/24 hr for 7–10 days) </li></ul><ul><li>Topical fusidic acid </li></ul><ul><li>Systemic therapy with a β-lactamase–resistant oral antibiotic (for patients with widespread involvement) </li></ul>
  18. 19. SUBCUTANEOUS TISSUE INFECTIONS <ul><li>The principal determination for soft tissue infections is whether it is non-necrotizing or necrotizing </li></ul>
  19. 20. CELLULITIS: <ul><li>Characterized by infection and inflammation of loose connective tissue </li></ul><ul><li>With limited involvement of the dermis and relative sparing of the epidermis </li></ul><ul><li>More common in individuals with lymphatic stasis, diabetes mellitus, or immunosuppression </li></ul>
  20. 22. Etiology : <ul><li>Streptococcus pyogenes and S. aureus are the most common etiologic agents </li></ul><ul><li>In neonates, group B streptococci or, rarely, Escherichia coli are the causal organisms </li></ul><ul><li>In patients who are immunocompromised or have diabetes mellitus, a number of other bacterial or fungal agents may be involved </li></ul>
  21. 23. Clinical Manifestations : <ul><li>An area of edema </li></ul><ul><li>Warmth </li></ul><ul><li>Erythema </li></ul><ul><li>Tenderness </li></ul><ul><li>Regional adenopathy and constitutional signs and symptoms of fever, chills, and malaise are common </li></ul>
  22. 24. Diagnosis : <ul><li>Aspirates from the site of inflammation </li></ul><ul><li>Skin biopsy </li></ul><ul><li>Blood cultures </li></ul>
  23. 25. Treatment : <ul><li>Cellulitis in a neonate should prompt a full sepsis evaluation </li></ul><ul><li>β-lactamase-stable antistaphylococcal antibiotic such as methicillin (vancomycin is another choice) </li></ul><ul><li>Aminoglycoside such as gentamicin </li></ul><ul><li>Cephalosporin such as cefotaxime </li></ul>
  24. 26. STAPHYLOCOCCAL SCALDED SKIN SYNDROME: <ul><li>Occurs predominantly in infants and children younger than 5 yr of age </li></ul><ul><li>Onset of the rash may be preceded by malaise, fever, irritability, and exquisite tenderness of the skin </li></ul>
  25. 27. <ul><li>Scarlatiniform erythema </li></ul><ul><li>accentuated in flexural and periorificial areas </li></ul><ul><li>The conjunctivas are inflamed and occasionally become purulent </li></ul><ul><li>Circumoral erythema </li></ul>
  26. 28. <ul><li>Radial crusting and fissuring around the eyes, mouth, and nose </li></ul><ul><li>Nikolsky sign </li></ul><ul><li>Initially in the flexures and subsequently over much of the body surface </li></ul>
  27. 29. May lead to: <ul><li>Secondary cutaneous infection </li></ul><ul><li>Sepsis </li></ul><ul><li>Fluid and electrolyte disturbances </li></ul>
  28. 30. <ul><li>The desquamative phase begins after 2–5 days of cutaneous erythema </li></ul><ul><li>Healing occurs without scarring in 10–14 days </li></ul>
  29. 32. ETIOLOGY AND PATHOGENESIS : <ul><li>Phage group 2 staphylococci </li></ul><ul><li>Foci of infection include the: </li></ul><ul><li>Nasopharynx </li></ul><ul><li>Less commonly, the umbilicus, urinary tract, a superficial abrasion, conjunctivae, and blood </li></ul>
  30. 33. <ul><li>The clinical manifestations of staphylococcal scalded skin syndrome are mediated by: </li></ul><ul><li>Hematogenous spread, in the absence of specific antitoxin antibody of staphylococcal epidermolytic or exfoliative toxins A or B </li></ul>
  31. 34. DIAGNOSIS : <ul><li>Cultures should be obtained from all suspected sites of localized infection and from the blood </li></ul><ul><li>Frozen biopsy specimen of the desquamating epidermis </li></ul><ul><li>Tzanck preparation </li></ul>
  32. 35. TREATMENT : <ul><li>Semisynthetic penicillinase-resistant penicillin </li></ul><ul><li>Clindamycin (to inhibit bacterial protein (toxin) synthesis) </li></ul><ul><li>The skin should be gently moistened and cleansed </li></ul><ul><li>Emollient </li></ul><ul><li>Topical antibiotics are unnecessary </li></ul>
  33. 36. <ul><li>Thanks for your attention </li></ul>