Bone and Joint Infections Flashcards
What are the types of bone and joint infections?
osteomyelitis, septic arthritis, prosthetic joint infection
What is osteomyelitis?
infection of the bone causing inflammation of the bone marrow and surrounding bone
What is septic arthritis?
inflammatory reaction within the joint tissue and fluid due to a microorganism
What is prosthetic joint infection?
infection of a prosthetic joint and joint fluid
What samples and cultures do we need?
tissue/fluid!
▪Culture and susceptibility information is critical to guide antimicrobial treatment
▪Blood cultures important to help further increase likelihood of isolating a pathogen
staphylococcus aureus!
What samples and cultures do we need for osteomyelitis?
bone sample/biopsy, commonly obtained via surgical intervention
What samples and cultures do we need for septic arthitis and prosthetic joint infection?
joint aspiration with examination of synovial fluid to establish diagnosis and/or surgical intervention
Antibiotic therapy is more intense for bone and joint infections
▪Antibiotic therapy given for longer durations and higher doses compared to other types of infection
▪Commonly involves intravenous (IV) antibiotic therapy for the entire duration
▪Antibiotic penetration into infected bone and joints is typically low
What is the standard treatment duration for bone and joint infections?
▪Standard treatment duration ranges from 2-8+ weeks depending upon type of infection
▪Osteomyelitis – 4-8 weeks
▪Septic arthritis – 2-4 weeks
▪Prosthetic joint infection – 6-12+ weeks
Patient-centered care is important
▪Antibiotic therapy can be more difficult for patients to tolerate due to adverse effects, insurance coverage/cost, and patient adherence
▪Key considerations:
▪Will the patient need long-term IV access for antibiotic therapy?
▪If IV antibiotic therapy is selected, where will the patient receive it?
⎻ Home vs. facility vs. outpatient infusion
▪If oral antibiotic therapy is selected, will the patient adhere to the regimen if it requires
multiple antibiotics and doses per day?
▪Does the patient have insurance coverage/ability to pay for the treatment plan?
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., dalbavancin, oritavancin)
▪Oral antibiotic therapy for eligible patients
What is osteomyelitis pathogenesis?
▪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 slowed significantly (things slow down, bacteria start to grow)
What are the 3 ways osteomyelitis can develop?
hematogenous spread
continguous spread
vascular insufficiency
What is hematogenous spread?
microbe reaches bone via bloodstream; typically monomicrobial
What is contiguous spread?
Microbe reaches bone from soft tissue infection or direct inoculation (e.g., puncture wound, trauma,
surgery); Commonly polymicrobial
What is vascular insufficiency?
⎻ Microbe reaches bone from soft tissue infection
⎻ Risk factors – diabetes mellitus, peripheral vascular disease
⎻ Commonly polymicrobial
What are the most common pathogens in osteomyelitis?
staphylococcus aureus
post-surgical: pseudomonas aeruginosa
What is the presentation of osteomyelitis?
▪Signs and symptoms of osteomyelitis – depend on site of infection
▪Acute symptoms – fever, localized pain/tenderness/swelling, decreased range of
motion
▪Chronic symptoms – pain, drainage/sinus tract, decreased range of motion
What are the diagnostic considerations for osteomyelitis?
▪Laboratory findings – elevated WBC count, ESR, CRP
▪Radiologic findings
⎻ X-ray – soft tissue swelling, periosteal thickening, bone destruction
⎻ CT or MRI
⎻ Nuclear bone scan
▪Bone aspiration, biopsy, and/or surgical debridement for cultures and pathology
What are the approaches to osteomyelitis treatment?
surgical intervention
antibiotic therapy
Osteomyelitis - antibiotic selection
▪May hold antibiotic therapy initially while awaiting biopsy/surgical intervention if patient clinically stable
▪Examples: hemodynamically stable, no neurologic effects, no concern for additional site of severe infection
▪Empiric antibiotic selection dependent upon most likely pathogens and involves high-dose IV options
What is the empiric antibiotic selection for osteomyelitis?
have a beta-lactam plus an anti-MRSA agent
cefazolin, ceftriaxone, cefepime, piperacillin/tazobactam, ampicillin/sulbactam, meropenem, ciprofloxacin, or levofloxacin PLUS vancomycin, daptomycin, or linezolid
if anaerobic coverage desired, metronidazole should be added
What is the treatment duration for osteomyelitis?
▪General duration range of 4-8 weeks
▪Specific considerations:
▪Vertebral osteomyelitis due to MRSA = 8 weeks
▪Diabetic foot infection related osteomyelitis
⎻ Complete resection of all infected bone/tissue = 2-5 days (ex. below knee amputation)
⎻ Resection of all osteomyelitis, soft tissue infection remains = 1-2 weeks
⎻ Resection performed, osteomyelitis remains = 3 weeks
⎻ No resection = 6 weeks
What are the oral antibiotic therapy options for osteomyelitis?
▪Streptococci – amoxicillin, cephalexin, clindamycin (if susceptible)
▪MSSA – dicloxacillin, cephalexin, cefadroxil, TMP/SMX, linezolid
▪MRSA – linezolid, TMP/SMX, clindamycin (if susceptible)
▪GNRs – TMP/SMX, fluoroquinolones
may consider the addition of rifampin with strep, MSSA, MRSA to help prevent biofilm production
Why is dalbavancin a novel approach in osteomyelitis?
▪Dalbavancin 2-dose strategy
▪Dalbavancin 1500 mg IV on day 1 and 8 – provides 6-8 weeks of coverage because it has a half-life of 346 hours
What is the pathogenesis of septic arthritis?
▪Septic arthritis develops via 3 main pathways: Hematogenous, Direct inoculation, Contiguous
infection in joint cavity of synovial fluid
What are the risk factors for septic arthritis?
▪Joint disease
▪Advanced age
▪Chronic disease (e.g., diabetes mellitus) ▪Sexually transmitted infection ▪Immunosuppression
▪Trauma
▪Prosthetic joint
▪IV drug use
▪Endocarditis
What are the most common pathogens in septic arthritis?
staphylococcus aureus
sexually active adults: neisseria gonorrhoeae
What is the presentation of septic arthritis?
▪Joint pain, decreased range of motion, swelling,
erythema, warmth, fever, chills
▪Monoarticular in the majority of cases
▪Polyarticular can occur – rheumatoid arthritis, immunosuppression, prolonged bacteremia
What are the diagnostic considerations of septic arthritis?
▪Laboratory findings – increased WBC count, ESR, CRP
▪Arthrocentesis – purulent, low viscosity synovial fluid
⎻ Polymorphonuclear neutrophil (PMN) count > 50,000 cells/mm3
⎻ Gram stain and culture
▪Radiologic findings – x-ray, CT, MRI
What is the approach to treatment for septic arthritis?
▪Expedited joint drainage and antibiotic therapy critical to reduce joint destruction and long-term consequences
What is the empiric antibiotic therapy for septic arthritis?
comparable to that of osteomyelitis
▪If gram stain available prior to antibiotic initiation, acceptable to use narrowest possible agent
⎻ Example: Gram negative diplococci – likely N. gonorrhoeae – ceftriaxone alone
What is the treatment duration of septic arthritis?
ranges from 2-4 weeks
▪S. aureus, GNR – 4 weeks
▪Streptococci – 2 weeks
▪N. gonorrhoeae – 7-10 days
What is the pathogenesis of prosthetic joint infections?
▪Prosthetic joint infections develop via same 3 mechanisms as previously discussed (Hematogenous, Direct inoculation, Contiguous)
▪Involves development of biofilm – impedes antibiotic penetration
What are the most common pathogens of prosthetic joint infections?
staphylococcus aureus
What is the presentation of prosthetic joint infections?
▪Joint pain (acute or chronic), decreased range of motion, swelling, erythema, warmth,
fever, chills
▪Sinus tract or persistent wound drainage over joint prosthesis
▪Loosening of prosthesis
▪Important to review history of prosthesis (e.g., type of prosthesis, implantation date, history of wound healing)
What are diagnostic considerations for prosthetic joint infections?
▪Laboratory findings – increased WBC count, ESR, CRP
▪Arthrocentesis – cell count/differential, gram stain, and culture
▪Radiologic findings – x-ray
What is the approach to treatment of prosthetic joint infections?
surgical intervention and antibiotic therapy
What are the primary types of surgical intervention for prosthetic joint infections?
- Debridement and retention of
prosthesis (rinse out the joint) - 1-stage exchange (take out infected joint, put new one in infected area)
- 2-stage exchange (take infected one out, put a spacer in, wait 6 weeks on IV antibiotics, put in new joint)
What is the approach to treatment for prosthetic joint infections?
▪Withholding antimicrobial therapy in stable patients appropriate to increase chances of isolating an organism from culture
What is the empiric therapy in prosthetic joint infections?
comparable to that of osteomyelitis
▪If gram stain available prior to antibiotic initiation, acceptable to use narrowest possible agent
What is the pathogen-directed treatment of prosthetic joint infections?
▪Proceed with pathogen-directed treatment once culture and susceptibilities are known
▪IV or highly bioavailable oral is acceptable
▪Rifampin added to treatment for retention of prosthesis or 1-stage exchange
preferred oral agents same as for osteomyelitis
What is the treatment after debridement and retention of prosthesis?
pathogen direct treatment + rifampin x 2-6wks
oral antibiotic treatment + rifampin x 3 mo (hip), 6 mo (knee/other joint)
What is the treatment after 1-stage exchange?
pathogen-directed treatment + rifampin x 2-6wks
oral antibiotic treatment + rifampin x 3mo
What is the treatment after stage-2 exchange?
pathogen-directed treatment x 4-6wks
What is the treatment after amputation with complete removal of infected bone/hardware?
pathogen directed treatment x 24-48hrs
