Skin And Soft Tissue Infections


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Skin And Soft Tissue Infections

  1. 1. Skin and Soft Tissue Infections <ul><li>Lecture objectives : Define and describe common infections that affect the skin, soft tissues, bones and joints. </li></ul><ul><li>Recognize the clinical manifestations and differential diagnosis of infections that involve the skin, soft tissues, bones and joints. </li></ul><ul><li>Comprehend the general principles of antimicrobial therapy, i.e. organism-based treatment and empirical therapy. </li></ul>
  2. 2. Skin and Soft Tissue Infections <ul><li>Skin and soft tissue infections can be caused by either direct penetration of a pathogen or by hematogenous spread of the pathogen from the initial site. </li></ul><ul><li>Skin and soft tissue infection can be classified on the basis of the anatomic level at which infection, i.e., either superficial or deep. </li></ul>
  3. 3. Symptoms of skin infections <ul><li>Skin inflammation that begins in a small area and spreads. This includes: </li></ul><ul><ul><li>Redness </li></ul></ul><ul><ul><li>Pain or tenderness </li></ul></ul><ul><ul><li>Swelling </li></ul></ul><ul><ul><li>Warmth </li></ul></ul><ul><ul><li>Blisters </li></ul></ul><ul><ul><li>A red streak (possibly) </li></ul></ul>
  4. 4. Symptoms of skin infections <ul><ul><li>A red streak (possibly) </li></ul></ul><ul><li>Swollen lymph nodes </li></ul><ul><li>Fever or chills </li></ul><ul><li>Fatigue </li></ul><ul><li>Irritability </li></ul><ul><li>Loss of appetite, nausea, or vomiting </li></ul>
  5. 5. Skin and Soft Tissue Infections <ul><li>Infections by either group A streptococci, staphylococci or anaerobic bacteria are particularly important causes of more serious forms of disease. </li></ul><ul><li>Classification of clinically distinguishable cutaneous infections caused by streptococcus pyogenes: Impetigo, Ecthyma, Cellulitis, Erysipelas and Necrotizing fasciitis. </li></ul>
  6. 6. Skin and Soft Tissue Infections <ul><li>Impetigo is a superficial infection of the skin caused by group A streptococci or S. aureus it begins as a transient vesiculopustular lesion that quickly ruptures and exudes serous fluid which then dries to form a characteristic dry thick honey (golden) crust. </li></ul><ul><li>A bullous type, particularly in children, suggest bullous impetigo caused by S. aureus. </li></ul><ul><li>Ecthyma is a deeper form of impetigo with ulceration and scarring, commonly on the legs and associated with trauma or debility. </li></ul>
  7. 7. Impetigo
  8. 8. Skin and Soft Tissue Infections <ul><li>Differential diagnosis : the differential diagnosis of impetigo includes contact dermatitis, herpes simplex and varicella. </li></ul><ul><li>Contact dermatitis may be suggested by the history or by linear distribution of the lesions, and culture should be negative for staphylococci and streptococci. </li></ul><ul><li>Herpes infection usually presents with grouped vesicles or discrete erosions and may be associated with a history of recurrences. Viral culture and Tzanck smears of the lesions are positive. </li></ul>
  9. 9. Skin and Soft Tissue Infections <ul><li>Treatment : topical antibiotics are not as effective as systemic antibiotics. Two percent mupircon ointment (Bactroban) used three times daily after hygenic measures for 10 days, may be effective for limited disease. </li></ul><ul><li>Crusts and weepy areas may be treated with with compresses, and washcloths and towels must be segregated and washed separately. </li></ul>
  10. 10. Skin and Soft Tissue Infections <ul><li>For large areas, fever or toxicity- or if there is concern a nephritogenic strain may be causative, then systemic antibiotics should be given. </li></ul><ul><li>Penicillin is the drug of choice for impetigo, and if S. aureus is suspected a penicillinase- resistant penicillin such as cloxacillin or dicloxacillin, 250mg orally qid daily, is usually effective and should be used.Erythromycin 250mg four times daily, is a reasonable alternate for the penicillin-allergic patient. </li></ul>
  11. 11. Skin and Soft Tissue Infections <ul><li>Erysipelas is a superficial form of cellulitis that classically occurs on the cheek; It is almost always caused by group A streptococci. This infection is seen primarily in children and the elderly. </li></ul><ul><li>Erysipelas is a bright red to violaceous raised lesion that is sharply demarcated and expands rapidly in a centrifugal fashion. </li></ul><ul><li>Vesicles or bullae may occur. Fever, pain, malaise and chills are generally present, but bacteremia is uncommon. </li></ul>
  12. 12. Erysipelas
  13. 13. Erysipelas
  14. 14. Skin and Soft Tissue Infections <ul><li>Treatment with IV penicillin 1-2 million units every 4 hours and clindamycin 900mg q8h IV is curative, but defervescene is gradual. </li></ul><ul><li>Cellulitis, a diffuse spreading infection of the subcutaneous tissue, may be due to one of several organisms, usually gram-positive cocci, though gram-negative rods (E. coli, Pasturella multocida, Erysipelothrix and Vibrio) may also be responsible. </li></ul>
  15. 15. Skin and Soft Tissue Infections <ul><li>Cellulitis is said to occur after a break in the skin, but this is often not apparent. </li></ul><ul><li>The lesion is hot and red and linear streaks of erythema and tenderness indicate lymphatic spread (lymphangitis). </li></ul><ul><li>Regional lymph node enlargement and tenderness are common. </li></ul>
  16. 16. Skin and Soft Tissue Infections <ul><li>Progression and systemic symptoms are quite variable, but most patients are febrile. </li></ul><ul><li>In cases of venous stasis, the only clue to cellulitis may be a new localized area of tenderness. </li></ul>
  17. 17. Skin and Soft Tissue Infection
  18. 18. Skin and Soft Tissue Infection
  19. 19. Periorbital Cellulitis
  20. 20. Skin and Soft Tissue Infections <ul><li>Two potentially life threatening entities that can mimic cellulitis, a painful, red, swollen leg. They are deep venous thrombosis and necrotizing fascitiis. </li></ul><ul><li>The presence of a positive Homans sign or palpable venous cord may suggest DVT, but these are insensitive signs. </li></ul><ul><li>If clinical suspicion is high an imaging modality should be utilized for DVT. </li></ul>
  21. 21. Skin and Soft Tissue Infections <ul><li>The diagnosis of necrotizing fasciitis should be suspected in a patient with a toxic appearance, bullae, crepitus or anaesthesia of the involved skin, overlying skin necrosis, and laboratory evidence of rhabdomyolysis or DIC. </li></ul><ul><li>While these findings may be present with severe cellulitis and bacteremia, it is essential to rule out necrotizing fasciitis because rapid surgical debridement is essential. </li></ul>
  22. 22. Skin and Soft Tissue Infections <ul><li>Therapy with parenteral antibiotics, with a penicillinase-resistant pcn, IV nafcillin or oxacillin 2gm q4h or cefazolin 1gm q8h IV or unasyn 3gm q6h, usually suffices. </li></ul><ul><li>In mild cases or following the initial parenteral therapy, dicloxacillin or cephalexin, 500 mg qid orally for 7-10 days, is usually adequate. </li></ul>
  23. 23. Skin and Soft Tissue Infections <ul><li>Necrotizing fasciitis, pyomyositis and myonecrosis are examples of deeper infections of the skin and soft tissues. </li></ul><ul><li>Necrotizing fasciitis is an uncommon severe infection of the subcutaneous tissue that results in destruction of fascia and fat. </li></ul><ul><li>It is grouped under the classification of necrotizing soft tissue infections that include clostridial cellulitis, synergistic necrotizing cellulitis (Meleney’s gangrene), and gas gangrene. </li></ul>
  24. 24. Skin and Soft Tissue Infections <ul><li>necrotizing fasciitis due to group A streptococcus previously called streptococcal gangrene, has been known for years, with a dramatic increase in the recognition and reporting of such infections. </li></ul>
  25. 25. Skin and Soft Tissue Infections <ul><li>Moreover, these infections are commonly associated with the early onset of shock and organ failure. </li></ul><ul><li>Predisposing factors include varicella, penetrating injuries, minor cuts, burns, splinters, surgical procedures, childbirth, blunt trauma, and muscle strain. </li></ul>
  26. 26. Skin and Soft Tissue Infections <ul><li>The most common primary site is the extremities. </li></ul><ul><li>The first cutaneous clue to fasciitis is diffuse swelling of an arm or leg, the skin may appear normal or have a red or dusky hue, followed by the appearance of bullae filled with clear fluid, which rapidly takes on a maroon or violaceous color. </li></ul><ul><li>In some instances crepitus may be present. </li></ul>
  27. 27. Skin and Soft Tissue Infections <ul><li>In situations in which there is no cutaneous evidence of infection, yet severe pain and symmetric swelling are present or fever with unexplained severe musculoskeletal pain is an important clue to necrotizing fasciitis. </li></ul><ul><li>Plain radiographs, CT or MRI, can be useful in locating the site and depth of infection. </li></ul>
  28. 28. Necrotizing Fasciitis
  29. 29. Necrotizing Fasciitis
  30. 30. Fasciitis
  31. 31. Skin and Soft Tissue Infections <ul><li>Although necrotizing cutaneous infections are classified into specific entities (ie, fasciitis, clostridum myonecrosis) based on clinical characteristics and etiology, the initial clinical manifestations are not distinctive. </li></ul><ul><li>Regardless of the etiology, the primary therapy is emergent surgical debridement and treatment with antibiotics that are active against streptococci, clostridium species, and mixed aerobes and anaerobes. </li></ul><ul><li>Clindamycin and pen G IV or Ceftriaxone 2gm q12h IV . </li></ul>
  32. 32. Skin and Soft Tissue Infections <ul><li>Pyomyositis is a deep infection of muscle usually caused by S. aureus and occasionally by group A streptococci or enteric bacilli. Most cases occur in warm or tropical regions, and most among children. </li></ul><ul><li>Patients present with fever and tender swelling of the muscle;Following exercise or muscle injury, the skin is usually minimally involved. </li></ul>
  33. 33. Skin and Soft Tissue Infections <ul><li>The diagnosis can be readily made, if suspected, by needle aspiration and x-rays. Surgical debridement and appropriate antibiotics are curative (nafcillin-oxacillin or vanco 1 gm q12h IV). </li></ul><ul><li>Myonecrosis or clostridial gas gangrene generally occurs after a contaminated injury to muscle (knife or GSW). </li></ul><ul><li>Within 1-2 days of injury, the involved extremity becomes painful and swollen. Gas present in tissue may be obvious by physical exam, x-ray or CT. </li></ul>
  34. 34. Skin and Soft Tissue Infections <ul><li>Furuncles and carbuncles are subcutaneous abscesses caused by S. aureus. </li></ul><ul><li>The lesions are red, tender nodules that may have a surrounding cellulitis. They often drain spontaneously. </li></ul><ul><li>If fluctuant, these lesions should be incised and drained in conjunction with antibiotics, especially if systemic symptoms or cellulitis is present. </li></ul>
  35. 35. Paronychia
  36. 36. Paronychia
  37. 37. Skin Abscess
  38. 38. Skin and Soft Tissue Infections <ul><li>Folliculitis is a superficial infection of hair follicles. The lesions are crops of red papules or pustules that are often pruritic. Staphylococci, yeast, and occasionally, pseudomonas species are the responsible pathogens. </li></ul><ul><li>Local treatment with cleansing and hot compresses is usually sufficient. Topical antibacterial (bactroban-cleocin) or antifungal agents also may be helpful. </li></ul>
  39. 39. Folliculitis
  40. 40. Skin and Soft Tissue Infections <ul><li>Ecthyma gangrenosum is an ulcerating lesion associated with disseminated gram-negative rod infection, commonly pseudomonas, and observed in neutropenic patients. </li></ul><ul><li>Treatment should be started with an aminoglycoside and plus a 3 rd generation cephalosporin (ceftazidime) until the results of biopsy, culture and sensitivity are known. </li></ul>
  41. 41. Skin and Soft Tissue Infections <ul><li>Paronychia is an infection of the soft tissue around the nails due to S. aureus when acute. </li></ul><ul><li>Chronic infection may involve candida or herpes simplex (herpetic whitlow). </li></ul>
  42. 42. Pyoderma Gangrenosum
  43. 43. Skin and Soft Tissue Infections <ul><li>Herpetic skin infections: Subclinical primary infection with the herpes viruses is more common than clinically manifest illness. </li></ul>
  44. 44. Skin and Soft Tissue Infections <ul><li>Each persists in a latent state for the remainder of the host’s life. With HSV and VZV, virus remain latent in sensory ganglia, and upon reactivation lesions appear in the distal sensory nerve distribution. </li></ul><ul><li>Herpes 1 and 2 affect primarily the oral and genital areas, respectively. Varicella-zoster virus is HHV 3. </li></ul><ul><li>Disease manifestations are referred to as either chickenpox or shingles (zoster). </li></ul>
  45. 45. Herpes Zoster
  46. 46. Varicella Zoster
  47. 47. Herpes
  48. 48. Skin and Soft Tissue Infections <ul><li>Fungal skin infections, or Mycotic infections are traditionally divided into two principal groups: superficial and deep. We will only discuss the superficial infections </li></ul>
  49. 49. Skin and Soft Tissue Infections <ul><li>Dermatophytosis is a superficial infection of the epidermis due to dermatophytic fungi, Trichophyton, Microsporum, and Epidermophyton species. Athlete’ foot and ringworm are examples. </li></ul><ul><li>These fungal infections may be confused with eczema. </li></ul><ul><li>Candidiasis is a red, tender edematous rash occurring in moist body parts and caused by C. albicans </li></ul>
  50. 50. Skin and Soft Tissue Infections <ul><li>The diagnosis of fungal infections of the skin is usually based on the location and characteristics of the lesions and on the following laboratory examinations, 10% KOH preparation or culture. </li></ul><ul><li>Dermaphytosis of the trunk (tinea corporis,cruris-capitum) can be caused by several species (T. rubrum-mentagrophytes) resulting in inflamed patches with scaling and, at times vesiculopapular borders with central clearing. </li></ul>
  51. 51. Tinea Corporis
  52. 52. Tinea cruris
  53. 53. Skin and Soft Tissue Infections <ul><li>Tinea versicolor, a common superficial fungus infection caused by Pityrosporon orbiculare, is identified by scaling, red to brown or white patches over the neck, trunk, and upper arms. As the name implies, the lesions vary in color. </li></ul><ul><li>Either topical or systemic agents can treat fungal infections of the skin and in general topicals are preferred, e.g. miconazole, clotrimazole, ciclopirox, or terbinafine creams. </li></ul>
  54. 54. Bone and Joint Infections <ul><li>This class of infections includes those localized to the skeletal system and adjacent structures, septic bursitis, septic arthritis and osteomyelitis. </li></ul><ul><li>Inflammation of the synovium-like cellular membrane overlying bony prominences may be secondary to trauma, infection, or arthritic conditions such as gout, rheumatoid arthritis or osteoarthritis. </li></ul><ul><li>Septic bursitis is almost always caused by staphylococcus aureus. </li></ul>
  55. 55. Bone and Joint Infections <ul><li>The two most common sites are the olecranon and prepatellar bursae. In most instances, there is a history of prior infection or irritation of the skin overlying the bursa. </li></ul><ul><li>Acute swelling, redness and peeling are frequently present. </li></ul>
  56. 56. Bone and Joint Infections <ul><li>The absence of fever does not exclude infection, and one—third of those with septic olecranon bursitis have no fever. Bursal fluid analysis averages 50k wbc/ml. </li></ul><ul><li>Treatment involves nafcillin or oxacillin IV and repeated aspirations. Followed by oral dicloxacillin for 3-4 weeks. </li></ul>
  57. 57. Bone and Joint Infections <ul><li>In adults, almost all cases of infective arthritis of natural joints occur through hematogenous spread. </li></ul><ul><li>Occasionally, intra-articular trauma can result in septic arthritis. This disease process can be polyarticular or monoarticular. </li></ul>
  58. 58. Bone and Joint Infections <ul><li>Causative organisms for infective arthritis include bacteria, viruses, myocbacteria and fungi. </li></ul><ul><li>S. aureus is the most common cause of septic arthritis. In sexually active young adults, N. Gonorrhea is a frequent pathogen. </li></ul>
  59. 59. Septic Arthritis
  60. 60. Bursitis
  61. 61. Septic Bursitis
  62. 62. Bone and Joint Infections <ul><li>Gonococcal infection may present as a bacteremic illness with polyarticular tenosynovitis and skin lesions, or as a monoarticular septic arthritis. </li></ul><ul><li>Other common causative agents are streptococcus, group A streptococci and salmonella. </li></ul>
  63. 63. Bone and Joint Infections <ul><li>Viral agents associated with infectious arthritis are rubella, mumps, hepatitis B and parvovirus. </li></ul><ul><li>These are usually a polyarthritis with minimal joint effusions, and a result of the host immune response. </li></ul>
  64. 64. Bone and Joint Infections <ul><li>Tuberculous and fungal (sporothrix) arthritis is usually monoarticular and an indolent, chronic disease. </li></ul><ul><li>The joints commonly affected are the knee, hip, ankle and wrist. </li></ul><ul><li>As a general rule, patients with inflammatory chronic monoarticular arthritis should have a synovial biopsy for culture and histology. </li></ul>
  65. 65. Bone and Joint Infections <ul><li>The synovial fluid should be gram-stained and cultured, analyzed for cell count, glucose and crystals. </li></ul><ul><li>Blood cultures should be obtained in all cases of suspected septic arthritis (prsp and ceph 3). </li></ul>
  66. 66. Bone and Joint Infections <ul><li>Osteomyelitis, in general bone infections develop in three ways: by hematogenous spread, secondary to contiguous infection, or by direct inoculation during surgery, as a result of trauma. </li></ul><ul><li>The term acute osteomyelitis is used clinically to signify a newly recognized bone infection; the relapse of a previously treated, or untreated infection is considered a sign of chronic disease. </li></ul><ul><li>Clinical signs persisting for more than 10 days correlate roughly with chronic osteomyelitis. </li></ul>
  67. 67. Bone and Joint Infections <ul><li>Hematogenous osteomyelitis develops mostly in prepubertal children and in elderly patients. In children, infection is usually located in the metaphyseal area of long bones (tibia-femur), usually as a single focus. </li></ul><ul><li>The clinical features of this form of osteomyelitis are typically, the acute onset of chills, fever and malaise, local pain, and swelling over a bone. </li></ul><ul><li>Blood cultures are often positive for the infection. </li></ul>
  68. 68. Bone and Joint Infections <ul><li>Other individuals at risk of hematogenous osteomyelitis are IVDA ( S. aureus and P. aeruginosa) as well as patients with urinary catheters, patients with hemoglobinopathy, in which salmonella and pneumococcus often infect infarcted regions of bone. </li></ul><ul><li>In most instances, physical examination distinguishes septic arthritis from acute osteomyelitis, because range of motion is preserved in osteomyelitis. </li></ul>
  69. 69. Bone and Joint Infectins <ul><li>Vertebral infection, is the principal form of osteomyelitis occurring in adults, typically it involves two adjacent vertebrae and the disk space between them. </li></ul><ul><li>Neck or back pain and fever are the main symptoms. Acute spinal epidural abscess is a surgical emergency. </li></ul><ul><li>Blood cultures are often negative, so needle biopsy for cultures and histology are the procedures of choice. </li></ul>
  70. 70. Bone and Joint Infections <ul><li>Bone scan helpful and sensitive but not specific and does not distinguish very well bone infection vs. Soft tissue infection. CT/MRI can reveal periosteal reaction-cortical destruction when regular x-rays are normal. </li></ul><ul><li>In the event of failure to establish a diagnosis via biopsy, empirical therapy for 4-6 weeks with nafcillin or oxacillin plus a 3 rd cephalosporin or vanco for MRSA. ESBL (timentin,unasyn,zosyn) are alternatives. </li></ul>
  71. 71. Bone and Joint Infections <ul><li>Osteomyelitis from a contiguous focus of infection-prosthetic joint replacement, decubitus ulcer, neurosurgery and trauma are frequent causes of soft tissue infections that can spread to bone. S. aureus and S. Epidermidis are the most frequent organisms. </li></ul><ul><li>A traumatic incident often associated with osteomyelitis is either a human or an animal bite. Human bites if deep enough, may result in osteomyelitis caused by anaerobic mouth flora. </li></ul>
  72. 72. Animal Bites
  73. 73. Animal Bites
  74. 74. Animal Bites
  75. 75. Bone and Joint Infections <ul><li>Cat bites notoriously result in the development of osteomyelitis because the thin, sharp, long cat’s teeth often penetrate the periosteum. Both cats and dogs harbor pasturella multocida, as part of their oral flora, which is a frequent pathogen in this setting. </li></ul><ul><li>Therapy is with PCN G or augmentin or fluoroquinolones plus clindamycin. </li></ul>
  76. 76. Bone and Joint Infections <ul><li>Chronic osteomyelitis results from untreated or inadequately treated bone infections. Some patients have tolerated chronic osteomyelitis for decades with intermittent episodes of disease activity manifested by local pain and drainage from a sinus tract. </li></ul><ul><li>Complications include an anemia of chronic disease, and occasionally amyloidosis-fibrosarcoma. Diagnosis and cure are best effected by surgical debridement and long term antibiotics directed at organisms from the surgical specimen. </li></ul>