Bone and Joint Infections Flashcards
Key Concept #1 – Types of bone and joint Infections
___ – infection of the bone causing inflammation of the bone marrow and surrounding bone
____– inflammatory reaction within the joint tissue and fluid due to a microorganism
___ – infection of a prosthetic joint and joint fluid
1) Osteomyelitis
2) Septic arthritis
3) Prosthetic joint infection
Key Concept #2 – We need tissue/fluid samples and cultures!
Culture and susceptibility information is critical to guide antimicrobial treatment
- Osteomyelitis – bone sample/biopsy, commonly obtained via surgical intervention
- Septic arthritis and prosthetic joint infection – joint aspiration with examination of synovial fluid to establish diagnosis and/or surgical intervention
- Blood cultures important to help further increase likelihood of isolating a pathogen
Primary Organism: ___
Staphylococcus aureus
Think outside the box
Many patients experience barriers to appropriate antibiotic therapy due to the
intensity of treatment for bone and joint infections
Emerging data for novel approaches to treatment
- Lipoglycopeptides with long half-lives (e.g., ___ , ___ )
- ___ antibiotic therapy for eligible patients
- dalbavancin, oritavancin
- oral
Bone Anatomy – Refresher
3 main sections: ___ , ___ , ___
The anatomy of blood supply to bone connected to infection risk
- Nutrient arteries enter on metaphyseal side of epiphyseal growth plate
- Lead to capillaries forming sharp loops in the epiphyseal growth plate
- Capillaries lead to large sinusoidal veins
that exit metaphysis
- Bottom line: Blood flow ___ significantly
- Epiphysis, Metaphysis, Diaphysis
- slowed
Osteomyelitis – Pathogenesis
Osteomyelitis develops via 3 main pathways
1) Hematogenous spread
- Microbe reaches bone via ___
- Children – involves growing long bones (e.g., femur, tibia, humerus, fibula)
- Adults – involves vertebrae (e.g., lumbar, thoracic)
- Typically ___
2) Contiguous spread
- Microbe reaches bone from ___ infection or direct ___ (e.g., puncture wound, trauma, surgery)
- Commonly ___
3) Vascular insufficiency
- Microbe reaches bone from ___ infection
- Risk factors – diabetes mellitus, peripheral vascular disease
- Commonly ___
- bloodstream
- monomicrobial
- soft tissue, innoculation
- polymicrobial
- soft tissue
- polymicrobial
Osteomyelitis – Most Common Pathogens (Adults)
Most common: ___
S. aureus
Osteomyelitis – Presentation and Diagnosis
Signs and symptoms of osteomyelitis – depend on site of infection
- Acute symptoms – ___ , localized pain/tenderness/swelling, decreased range of motion
- Chronic symptoms – pain, ___ /sinus tract, decreased range of motion
Diagnostic considerations
- Laboratory findings – elevated ___ count, ESR, ___
Radiologic findings
⎻ X-ray – soft tissue swelling, periosteal thickening, bone destruction
⎻ CT or MRI (standard of care)
⎻ Nuclear bone scan (“Tagged WBC Scan”) – Technetium 99m methylene diphosphate, gallium citrate 67, indium 111-labeled WBCs
Bone aspiration, biopsy, and/or surgical debridement for cultures and
pathology
- fever
- drainage
- WBC, CRP
Osteomyelitis – Antibiotic Selection
May ___ antibiotic therapy initially while awaiting biopsy/surgical intervention if
patient clinically stable
- hemodynamically stable, no neurologic effects, no concern for additional site of severe infection
Empiric antibiotic selection dependent upon most likely pathogens and involves
___ IV options
- hold
- high dose
Osteomyelitis – Empiric Antibiotic Selection
MRSA coverage generally needed
Osteomyelitis – Treatment Duration
General duration range of 4-8 weeks
Specific considerations:
- Vertebral osteomyelitis due to MRSA = __ weeks
- Diabetic foot infection related osteomyelitis:
- Complete resection of all infected bone/tissue = 2-5 days
- Resection of all osteomyelitis, soft tissue infection remains = 1-2 weeks
- Resection performed, osteomyelitis remains = 3 weeks
- No resection = 6 weeks
Historically, ___ therapy for the entire treatment duration has been utilized in
many cases
- 8
- IV
Osteomyelitis – Novel Approaches
Oral antibiotic therapy for osteomyelitis
- Literature has been growing for decades supporting use of highly bioavailable oral
antibiotic therapy for bone and joint infections
- Landmark trial – OVIVA – showed PO antibiotic therapy ___ to IV antibiotic therapy
Oral antibiotic options
- Streptococci – amoxicillin, cephalexin, clindamycin (if susceptible)
- MSSA – dicloxacillin, cephalexin, cefadroxil, TMP/SMX, linezolid
- MRSA – linezolid, TMP/SMX, clindamycin (if susceptible)
- GNRs – TMP/SMX, fluoroquinolones
For streptococci, MSSA, and MRSA, may consider the addition of ___
___ 2-dose strategy
- 1500 mg IV on day 1 and 8 - provides 6-8 weeks of coverage
- Half-life = 346 hours
- non-inferior
- rifampin
- Dalbavancin
Septic Arthritis – Pathogenesis
Septic arthritis develops via 3 main
pathways (3):
Risk factors
- Joint disease
- Advanced age
- Chronic disease (e.g., diabetes mellitus)
- Sexually transmitted infection
- Immunosuppression
- Trauma
- Prosthetic joint
- IV drug use
- Endocarditis
Most common pathogen: ___
1) Hematogenous
2) Direct inoculation
3) Contiguous
S. aureus
Septic Arthritis – Presentation and Diagnosis
Signs and symptoms of septic arthritis
- Joint pain, decreased range of motion, swelling, erythema, warmth, fever, chills
- ___ in the majority of cases
- Polyarticular can occur – rheumatoid arthritis, immunosuppression, prolonged bacteremia
Diagnostic considerations
- Laboratory findings – increased ___ count, ___ , CRP
- ___ – purulent, low viscosity synovial fluid
- Polymorphonuclear neutrophil (PMN) count > 50,000 cells/mm3
- Gram stain and culture
- Radiologic findings – x-ray, CT, MRI
- Monoarticular
- WBC, ESR
- Arthrocentesis
Septic Arthritis – Approach to Treatment
Expedited joint drainage and antibiotic therapy critical to reduce joint destruction and long-term consequences
Empiric antibiotic selection comparable to that of ___
- If gram stain available prior to antibiotic initiation, acceptable to use narrowest possible agent
IV or highly bioavailable oral is acceptable
Treatment duration – ranges from __ - __ weeks
- S. aureus, GNR – 4 weeks
- Streptococci – 2 weeks
- N. gonorrhoeae – 7-10 days
- osteomyelitis
- 2-4
Prosthetic Joint Infection – Pathogenesis
Prosthetic joint infections develop via same 3 mechanisms as previously
discussed
- Involves development of ___ – impedes antibiotic penetration
Most common pathogens similar to bone and joint infections:
- ___
- Streptococci
- Enterococci
- Coagulase negative Staphylococci
- Pseudomonas aeruginosa
- Enterobacterales (e.g., E. coli, K. pneumoniae, P. mirabilis)
- biofilm
- S. aureus
Prosthetic Joint Infection – Presentation and Diagnosis
Signs and symptoms of prosthetic joint infection
- Joint pain (acute or chronic), decreased range of motion, swelling, erythema, warmth, fever, chills
- Sinus tract or persistent wound drainage over joint prosthesis
- ___ of prosthesis
- Important to review history of prosthesis (e.g., type of prosthesis, implantation date, history of wound healing)
Diagnostic considerations
- Laboratory findings – increased WBC count, ESR, CRP
- Arthrocentesis – cell count/differential, gram stain, and culture
- Radiologic findings – x-ray
- Loosening
Prosthetic Joint Infection – Approach to Treatment
- ___ antimicrobial therapy in stable patients appropriate to increase chances of isolating an organism from culture
- Empiric antibiotic selection comparable to that of osteomyelitis
Proceed with pathogen-directed treatment once culture and susceptibilities are known
- IV or highly bioavailable oral is acceptable
- ___ added to treatment for retention of prosthesis or 1-stage exchange
- dosing: 300-450 mg PO BID
- Withholding
- Rifampin
