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
How is a culture taken for osteomyelitis?
Bone sample/biopsy, commonly obtained via surgical intervention
How is culture taken for septic arthritis and prosthetic joint infection?
Joint aspiration with examination of synovial fluid to establish diagnosis and/or surgical intervention
What pathogen is most common in bone and joint infections?
Staph aureus
Why is antibiotic therapy more intense in bone and joint infections?
Antibiotic penetration into infected bone and joints is typically low
How long is treatment for osteomyelitis?
4-8 weeks
How long is treatment for septic arthritis?
2-4 weeks
How long is treatment for prosthetic joint infection?
6-12+ weeks
What are some key considerations when selecting antibiotic therapy for a patient?
-Will the patient need long-term IV access for antibiotic therapy?
-If IV antibiotic therapy is selected, where will the patient receive it?
-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?
What are the three main sections of the bone?
-Epiphysis
-Metaphysis
-Diaphysis
What are the three main pathways in which osteomyelitis develops?
-Hematogenous spread
-Contiguous spread
-Vascular insufficiency
How does a microbe cause osteomyelitis through hematogenous spread?
Microbe reaches bone via bloodstream
How does a microbe cause osteomyelitis through contiguous spread?
-Microbe reaches bone from soft tissue infection or direct inoculation
-Commonly polymicrobial
How does a microbe cause osteomyelitis through vascular insufficiency?
-Microbe reaches bone from soft tissue infection
-Commonly polymicrobial
What are risk factors for vascular insufficiency?
-Diabetes
-Peripheral vascular disease
What is the most common type of osteomyelitis in adults?
Vertebral
Which predisposing factors can result in a pseudomonal infection?
-Post-surgical
-Penetrating trauma
Acute symptoms of osteomyelitis
-Fever
-Localized pain/tenderness/swelling
-Decreased range of motion
Chronic symptoms of osteomyelitis
-Pain
-Drainage/sinus tract
-Decreased range of motion
Laboratory findings consistent with osteomyelitis
Elevated WBC count, ESR, CRP
What diagnostic tests would you do for osteomyelitis?
-X-ray
-CT or MRI
-Nuclear bone scan
What are the two approaches to treatment of osteomyelitis?
-Surgical intervention
-Antibiotic therapy
When can you hold antibiotic therapy in osteomyelitis?
While awaiting biopsy/surgical intervention if patient is clinically stable
What are the empiric options for osteomyelitis?
-Cefazolin
-Ceftriaxone
-Cefepime
-Zosyn
-Unasyn
-Meropenem
-Cipro
-Levo
What medications would you use to cover MRSA in osteomyelitis?
-Vanco
-Dapto
-Linezolid
What medication would you use if you need to cover anaerobes in osteomyelitis?
Metronidazole
When would you cover for MRSA?
Pretty much all the time since everywhere has a MRSA prevalence above 20%
What is the treatment duration for vertebral osteomyelitis due to MRSA?
8 weeks
What is the treatment duration for diabetic foot infection osteomyelitis where there is a complete resection of all infected bone/tissue?
2-5 days
What is the treatment duration for diabetic foot infection osteomyelitis where there is a complete resection of all infected osteomyelitis but soft tissue infection remains?
1-2 weeks
What is the treatment duration for diabetic foot infection osteomyelitis where there is a resection performed, but osteomyelitis remains?
3 weeks
Can oral antibiotics be used to treat osteomyelitis?
Yes, they were proven to be non-inferior but they must be highly bioavailable for bone and joint infections
Which highly bioavailable oral antibiotics can be used for streptococci?
-Amoxicillin
-Cephalexin
-Clindamycin (if susceptible)
-May add rifampin
Which highly bioavailable oral antibiotics can be used for MSSA?
-Dicloxacillin
-Cephalexin
-Cefadroxil
-Bactrim
-Linezolid
-May add rifampin
Which highly bioavailable oral antibiotics can be used for MRSA?
-Linezolid
-Bactrim
-Clindamycin (if susceptible)
-May add rifampin
Which highly bioavailable oral antibiotics can be used for GNRs?
-Bactrim
-FQs
-May add rifampin
What is the half-life of dalbavancin?
346 hours, so only two doses need to be taken
What are the three pathways to develop septic arthritis?
-Hematogenous
-Direct inoculation
-Contiguous
Risk factors for septic arthritis
-Joint disease
-Advanced age
-Chronic disease
-Sexually transmitted infection
-Immunosuppression
-Trauma
-Prosthetic joint
-IV drug use
-Endocarditis
Most common pathogens for septic arthritis
Staph aureus
What is the most common pathogens for septic arthritis in sexually active adults?
Neisseria gonorrhoeae
Signs and symptoms of septic arthritis
-Joint pain
-Decreased range of motion
-Swelling
-Erythema
-Warmth
-Fever
-Chills
-Monoarticular in the majority of cases
What are the cases in which septic arthritis can be polyarticular?
-Rheumatoid arthritis
-Immunosuppression
-Prolonged bacteremia
What laboratory findings are important when diagnosing septic arthritis?
-Increased WBC count
-ESR
-CRP
What is an arthrocentesis used to find in septic arthritis?
-Polymorphonuclear neutrophil (PMN) count greater than 50,000
-Gram stain and culture
What radiologic tests are done in septic arthritis?
-X-ray
-CT
-MRI
What antibiotics are chosen for septic arthritis?
Same as osteomyelitis, acceptable to use narrowest possible agent
Staph. Aureus, GNR treatment duration in septic arthritis
4 weeks
Streptococci treatment duration in septic arthritis
2 weeks
N. gonorrhoeae treatment duration in septic arthritis
7-10 days
What are the three pathways to develop prosthetic joint infection?
-Hematogenous
-Direct inoculation
-Contiguous
Most common pathogen in prosthetic joint infections
Staph. aureus
Why are prosthetic joint infections difficult to treat?
They involve the development of biofilm which impedes antibiotic penetration
Signs and symptoms of a prosthetic joint infection
-Joint pain
-Decreased range of motion
-Swelling
-Erythema
-Warmth
-Fever
-Chills
-Sinus tract or persistent wound drainage over joint prosthesis
-Loosening of prosthesis
-Review history of prosthesis
What laboratory findings are important when diagnosing a prosthetic joint infection
-Increased WBC count
-ESR
-CRP
What is an arthrocentesis used to find in a prosthetic joint infection?
-Cell count/differential
-Gram stain
-Culture
What radiologic tests would you use for a prosthetic joint infection?
X-ray
What are the two approaches to treatment of prosthetic joint infection?
-Surgical intervention
-Antibiotic therapy
What are the primary types of surgical intervention for a prosthetic joint infection?
-Debridement and retention of prosthesis
-1-stage exchange (taking joint out and putting a new one in)
-2-stage exchange (implanting a prosthetic spacer while on antibiotic therapy before putting in the new joint)
What is the empiric antibiotic selection for prosthetic joint infection
Same as osetomyeltitis
Why do you withhold antimicrobial therapy in stable patients with a prosthetic joint infection?
Increases chances of isolating an organism from culture
When is rifampin added to antimicrobial therapy in the treatment of a prosthetic joint infection?
Retention of prosthesis or a one stage exchange
How do you treat a patient with a prosthetic joint infection who retained prosthesis?
-Pathogen directed treatment + rifampin for 2-6 weeks
-Oral antibiotic treatment + rifampin for 3 months (hip) or 6 months (knee or other joint)
-May consider long-term antibiotic suppression after completion of treatment
How do you treat a patient with a prosthetic joint infection who got a 1-stage exchange?
-Pathogen directed treatment + rifampin for 2-6 weeks
-Oral antibiotic treatment + rifampin for 3 months
How do you treat a patient with a prosthetic joint infection who got a 2-stage exchange?
Pathogen directed treatment for 4-6 weeks
How do you treat a patient with a prosthetic joint infection who got a 1-stage exchange?
Pathogen directed treatment for 24-48 hours
