Bone & Joint Infections Flashcards
Bone & Joint Infections
- Osteomyelitis
- Prosthetic Joint Infection - prosthetic material
- Septic Arthritis
Osteomyelitis
- Infection of the bone
- May be acute or chronic
- Up to 24% of patients with diabetic foot ulcers
- Progressive destruction of the bone and the formation of sequestra
bacterial or fungal in nature
seen in community, too, long durtion
Osteomyelitis Risk Factors
• Circulatory disorders ▫ Diabetes ▫ Peripheral vascular disease • Open fracture or surgery • Chronic soft tissue infection • Immunocompromise • IV drug or catheter use • Pressure ulcers
Clinical Presentation
Acute Osteomyelitis
usually young children
Acute Osteomyelitis • Typically within 2 weeks of initial infection • More common in children • Systemic symptoms ▫ Fever ▫ Lethargy ▫ Irritability • Local signs/symptoms ▫ Acute onset pain/tenderness at affected site ▫ Erythema, swelling ▫ Delayed wound healing
Clinical Presentation
Chronic Osteomyelitis
• Months or years after initial infection
• More common in adults
• Signs/symptoms
▫ Low grade fever
▫ Chronic pain
▫ Delayed wound healing
▫ Persistent sinus tract or wound drainage
▫ Soft tissue damage
▫ Exposed bone
▫ Bone instability
• In patients with generalized vascular insufficiency (e.g., diabetes)
▫ Perforating foot ulcer may be present
▫ May be painless (if peripheral neuropathy)
Investigations
- Blood cultures - not likely to come back but they are helpful
- Bone cultures - radiographic
- CBC/diff
- SCr
- ESR or CRP
Imaging
• Plain x-ray ± MRI, or
• Bone scan ± WBC scan
Diagnosis of OM usually first suspected based on clinical findings and confirmed with a combination of radiologic, microbiologic, and pathologic tests
Etiology
Most common pathogens > 50% of cases: • Staphylococcus aureus ▫ MRSA may account for more than 1/3 of staphylococcal isolates in adults • Coagulase-negative staphylococci
< 25% of cases: • Streptococcus spp • Enterococcus spp • Enterobacterales • Pseudomonas spp • Anaerobes • Mycobacterium tuberculosis
Rarely (< 5% of cases): • Mycobacterium avium complex • Mycoplasma spp • Fungi • Brucella spp • Salmonella spp
Management
• Most cases of OM in adults require combination of antibacterial and surgical therapy for successful eradication of infection
• Wherever possible, antimicrobial therapy should be withheld until percutaneous aspirate or deep surgical cultures have been obtained (e.g., unless concomitant soft tissue infection or sepsis syndrome)
• Duration of therapy often depends on results of surgical interventions
▫ e.g., if margins not clear following debridement, 4-6 weeks of parenteral antibacterial generally required. If amputation and clear margins at surgery, shorter course (2-5 days) can be given (remove where infection is, dont have to treat as long)
▫ For patients not suitable for surgery, consider long-term suppressive therapy (6 months to lifelong)
Empiric Pharmacologic Management
Hematogenous, Long bones
MSSA/MRSA Rare: Streptococcus spp Enterobacterales M. tuberculosis Fungi
Cloxacillin 2 g IV q4h (not covering enterobacterales, fungir or myco) - cover MSSA, strep
or
Cefazolin 2 g IV q8h (less entero) - cover MSSA, strep
Penicillin and Cefazolin allergy or MRSA suspected
- Vancomycin (target trough 10-20 mg/L)
Consider MRSA if:
Preceding trauma, multifocal lesions, or disease in adjacent muscle
Surgical management (e.g., debridement and drainage of associated soft tissue abscesses)
recommended
4-6 weeks
(Recommended minimum 2weeks with IV, then switch to PO agents with good bioavailability and bone penetration may be considered with clinical improvement) (minimum 8 weeks for MRSA)
Empiric Pharmacologic Management
Contiguous, vascular insufficiency, diabetic foot
MILD-MOD
MSSA/MRSA Streptococcus spp Enterococcus spp Enterobacterales P. aeruginosa Anaerobes Candida spp (Often polymicrobial)
Amoxicillin-clavulanate 875mg PO BID (no pseudo, yes entercoc)
or
[Cefazolin 2 g IV q8h ± Metronidazole 500 mg PO BID]*
- cefazole does not cover enterococus or pseudo
If MRSA suspected:
Add TMP/SMX 2 DS tabs PO BID, or
Doxycycline 100 mg PO BID to regimen above
consider MRSA if:
Previous (prior 12 months) or current MRSA infection/colonization, recent antibacterial use, or recent hospitalization
Anaerobic coverage recommended if:
Severe ischemia, foul-smelling discharge, necrosis, or gangrene
≥ 6 weeks
(Switch to POtherapy be guided by clinical improvement and deep tissue C&S results)
Empiric Pharmacologic Management
Contiguous, vascular insufficiency, diabetic foot
MOD-SEVERE
SEVERE/LIM THREATENING
MSSA/MRSA Streptococcus spp Enterococcus spp Enterobacterales P. aeruginosa Anaerobes Candida spp (Often polymicrobial)
[Vancomycin (target trough 10-20) \+ Ceftriaxone* 1 -2 g IV daily \+ Metronidazole 500 mg q12h] or Amoxicillin-clav* 1.2 g IV q8h - anything after decimal pt = 0.2 clav acid
Pip-tazo 3.375 g (or 4.5 g) IV
{or meropenem 500 mg IV if ESBL enterobac} q6h
+ Vancomycin (target trough 10-20)
- If known/suspected P. aeruginosa, use piperacillin-tazobactam
instead of ceftriaxone and metronidazole (or instead of amox-clav)
Consider MRSA if:
Previous (prior 12 months) or current MRSA infection/colonization, recent antibacterial use, or recent hospitalization
≥ 6 weeks (Switch to PO therapy should
be guided by clinical improvement
and deep tissue C&S results)
FEmpiric Pharmacologic Management
Vertebral (spinal OM, spondylodiscitis, septic discitis, disc space infection)
MSSA/MRSA Rare: Streptococcus spp Enterococcus spp Enterobacterales P. aeruginosa M. tuberculosis Brucella Fungi If spinal implant, also: CoNS C. acnes
Vancomycin (target trough 10-20)
+ Ceftriaxone 1-2 g IV daily
If blood culture positive for Gram-positive cocci in cluster Vancomycin (target trough 10-20) \+ Cefazolin 2 g IV q8h
6 weeks (prolonged therapy if abscesses cannot be drained or if spinal implant, MRSA, and/or end-stage renal disease. Often need lifelong suppression with implants)
Prosthetic Joint Infections (PJI)
• Infection of prosthetic joint – may involve joint space, adjacent bone, or
periprosthetic tissue
• Most commonly affects total knee or hip arthroplasty
• Estimated incidence 1-2% of patients receiving total knee or hip
arthroplasty in US
Prosthetic Joint Infections (PJI)
Risk Factors
Patient characteristics • Previous revision arthroplasty • Previous PJI at same site • Smoking • Obesity • Diabetes • Rheumatoid arthritis • Malignancy • Immunosuppression
Surgery-related factors - increasing duration
• Operative time > 2.5 hours
• Simultaneous bilateral arthroplasty
• Allogeneic blood transfusion
Postoperative-related factors
• Wound healing complications
(e.g., delayed healing, dehiscience, necrosis, superficial infection, etc.)
• Cardiovascular complications (e.g., atrial fibrillation, MI)
• UTI
• Prolonged hospital stay
• S. aureus bacteremia
Clinical Presentation
PJI
Acute PJI • Local inflammation • Pain • Systemic symptoms (e.g., fever, chills) Chronic PJI • Symptom persistence for several weeks • Less local inflammation compared with acute • Chronic joint effusion • Pain • Sinus tracts
