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Osteomyelitis & Diabetic Foot UlcerBrent Gunderson, PharmDInfectious Diseases Research FellowUniversity of MinnesotaCollege of PharmacyObjectivesObjectiveso To describe the pathogenesis and clinical characteristics of osteomyelitiso To identify the most likely etiologic agent for osteomyelitiso To suggest appropriate empiric and definitive antimicrobial therapy for osteomyelitiso To describe pathogenesis and clinical characteristics of diabetic foot ulcerso To identify the most likely etiologic agent for diabetic foot ulcerso To suggest appropriate empiric and definitive antimicrobial therapy for diabetic foot ulcersOsteomyelitisOsteomyelitiso Inflammation of bone marrow and surrounding boneo Almost always due to infecting organismo Infection by three routes:»Hematogenous spread»Direct infection from contiguous source»Infection of bone due to vascular insufficiency (diabetic foot ulcer could lead to this)OsteomyelitisOsteomyelitiso Capillaries in epiphyseal growth plate near the end of bone have sharp loops» Capillaries enter into larger veins, where blood flow slows, can allow bacteria to settleo Edema and inflammation associated with infectious process can compromise blood flow, lead to necrosiso Necrosis can lead to sequestra (devitalized bone that has separated from healthy bone)OsteomyelitisOsteomyelitiso Surgery often important part of treatment, esp. if devitalized bone present, abscess, etc.o Important to get specific microbiologic diagnosisHematogenous OsteomyelitisHematogenous Osteomyelitiso Result of seeding from bloodo More common in infants & children (< 16 years)o Frequently involve metaphyses of long boneso Bacteria» most common organism: S. aureus (60-90%)» GNB (E. coli, Klebsiella, Proteus, Pseudomonas)» group B streptococci» SalmonellaHematogenous OsteomyelitisHematogenous Osteomyelitiso Abrupt onset of high fever, malaise,localized pain, tenderness, swelling, decreased motiono X-ray changes lag clinical features by 2 wks»Bone scan may be helpfulo Lab abnormalities: Increased ESR, WBCo Risk factors: anything promoting bacteremia (indwelling catheter, IVDA)Hematogenous OsteomyelitisHematogenous Osteomyelitiso Blood and bone aspirate culture before antibiotics, change empiric therapy on resultso Antibiotics (start ASAP, IV, high doses)» Newborn (< 4 mo)» S. aureus, GNB, group B strep» Nafcillin (150 mg/kg/day [QID])+ cefotaxime (50 mg/kg q 6 hr)» Child » S. aureus, group A strep, rarely coliforms» Nafcillin + cefotaxime (if GNB on gram stain)» Adult (>21 years)» S. aureus» Nafcillin, cefazolinHematogenous OsteomyelitisHematogenous Osteomyelitiso Duration of antibiotics» 4-6 weekso Oral antibiotics» Always start with IV (usually continue about 2 wks)» In kids, can switch to PO when there is clinical improvement, decrease in signs of inflammation, and patient afebrile 3 days» Candidates should have:» Disease of recent onset» Identification of infecting organism» Enforced compliance» Surgery as neededContiguous OsteomyelitisContiguous Osteomyelitiso Direct infection of bone from exogenous source or spread from adjacent tissueo Common etiology: history of surgery for an open reduction of a fractureo Usually in adults over 50 (due to factors such as more hip fracture, ortho procedures, etc.)o Bacteria» S. aureus» Pseudomonas (e.g., puncture to foot)» Proteus» Klebsiella» E. coli» anaerobes (may be in mixed infection; Bacteroides)Contiguous OsteomyelitisContiguous Osteomyelitiso Systemic signs not usually present (unlike hematogenous)»Most frequent symptom: pain in area of infectiono Local tenderness, swelling, erythema, decreased motiono Treatment should be based on culture of bone biopsyContiguous OsteomyelitisContiguous Osteomyelitiso Empiric therapy (while awaiting results)» Post reduction & internal reduction of fracture» S. aureus, coliforms, P. aeruginosa– Nafcillin 2 g q 4 hr IV + ciprofloxacin 750 mg BID PO– Nafcillin 2 g q 4 hr IV + ceftazidime 2 g IV q 8 hr» Post-op infection of prosthetic joint» S. epidermidis, S. aureus, Enterobacteriaeceae– Vancomycin + ciprofloxacino 4-6 weeks of antibiotic therapyo Vascular insufficiency» Difficult to manage: freq. req. amputation» Broad spectrum antibiotics» Nafcillin + ceftazidime» Also consider anaerobic coverageChronic OsteomyelitisChronic Osteomyelitiso Inadequate treatment of acute osteomyelitis can lead to sequestra, recurrent symptomso Therapy based on results from bone biopsyo Surgery has important role in removing all sequestra, necrotic areaso Parenteral therapy 4-6 weeks, follow with 1-2 months oral antibioticsOsteomyelitis: Special CasesOsteomyelitis: Special Caseso IVDA»50% of osteomyelitis cases are vertebral»Usually gram-negative: P. aeruginosa, Klebsiella, Enterobacter, Serratia.»Nafcillin + ciprofloxacino Sickle cell anemia patients»Salmonella»Usually in long bones»CiprofloxacinOsteomyelitis: Special CasesOsteomyelitis: Special Caseso Vertebral Osteomyelitis»Pts in 50-60s»Lumbar, thoracic regions»60% due to staph»E. coli also important cause; from urinary tract»CefazolinProphylaxis in Bone SurgeryProphylaxis in Bone Surgeryo Administer antibiotics IV 30 minutes prior to incision of the skin and for no longer than 24 hours after the operationo In orthopedic surgery for closed fractures, antistaphylococcal penicillins and first- or second-generation cephalosporins are indicatedo In patients who can receive antibiotics within 6 hours after trauma and who receive prompt operative treatment, a first or second generation cephalosporin for one day is appropriateo Complex fractures with extensive soft tissue damage requires broader antimicrobial coverage for longer durationOsteomyelitis CaseOsteomyelitis Caseo 59 year old male suffered severe leg fracture two weeks ago.o Fracture set by open reduction,completed a 7 day course of cefazolin, started on day of surgeryo 2 days ago, developed pain, swelling in calf» Calf tender, warm, swollen, erythematous» Patient afebrileo All laboratory findings WNLo Bone scan consistent with left tibial inflammation, due to healing or infectionOsteomyelitis CaseOsteomyelitis Caseo What findings are consistent with osteomyelitis?» History of surgical repair of fracture» Local pain, tenderness, erythema» Absence of systemic signs, labs WNL?o Should he have cultures done?» Yes-requires surgical exploration, and biopsy of bone at infected site, and blood cultureso What antibiotics while waiting for culture


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U of M PHAR 6124 - Osteomyelitis & Diabetic Foot Ulcer

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