Bone and Joint Flashcards
Osteomyelitis
infection of the bone causing inflammation of the bone marrow and surrounding bone
Septic arthritis
inflammatory reaction within the joint tissue and fluid due to a microorganism
Prosthetic joint infection
infection of a prosthetic joint and joint fluid
Osteomyelitis cultures
bone sample/biopsy, commonly obtained via surgical intervention
blood cultures important to isolate pathogen
Septic arthritis and prosthetic joint infection cultures
joint aspiration with examination of synovial fluid to establish diagnosis and/or surgical intervention
blood cultures important to isolate pathogen
Osteomyelitis common pathogens
STAPHYLOCOCCUS AUREUS
Post-surgical: also pseudomonas
Penetrating trauma: also pseudomonas
Antibiotic therapy is more intense!
Given for longer durations at higher doses compared to other infections
Commonly given IV for the entire duration
Antibiotic penetration into infected bone and joint is typically low
Osteomyelitis duration
4-8 weeks
Vertebral osteomyelitis due to MRSA= 8 weeks
Diabetic foot infection related to osteomyelitis
- complete resection of all infected bone/tissue= 2-5 days
- resection of all osteomyelitis, but soft tissue remains= 1-2 weeks
- resection perform, osteomyelitis remains= 3 weeks
- no resection= 6 weeks
Septic arthritis duration
Ranges from 2-4 weeks
S. aureus, GNR: 4 weeks
Streptococci: 2 weeks
N. gonorrhoeae: 7-10 days
Prosthetic joint infection duration
6-12 + weeks
Osteomyelitis pathogenesis
Hematogenous spread
- microbe reaches bone via bloodstream
Contiguous spread
- microbe reaches bone from soft tissue infection or direct inoculation (puncture wound, trauma, surgery)
Vascular insufficiency
- microbe reaches bone from soft tissue infection
- risk factors: DM, peripheral vascular disease
Osteomyelitis Presentation
Acute symptoms: fever, localized pain, tenderness, swelling, decreased range of motion
Chronic symptoms: pain, drainage/sinus tract, decreased range of motion
Osteomyelitis Diagnosis
Elevated WBCs, ESR, CRP
X-Ray: soft tissue swelling, periosteal thickening, bone destruction
CT or MRI: STANDARD OF CARE
Nuclear bone scan
Osteomyelitis antibiotic selection
May hold 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 therapy is dependent upon most pathogens and involves high dose of IV options
Osteomyelitis Empiric Antibiotic selection
Cefazolin
Ceftriaxone
Cefepime
Zosyn
Unasyn
Meropenem
Cipro/Levo
MRSA coverage is generally needed:
Vancomycin
Linezolid
Daptomycin
Osteomyelitis Pathogen directed therapy
MSSA: Nafcillin, Cefazolin
MRSA: Vancomycin, Linezolid, Daptomycin, Bactrim, Dalbavancin
PSSP: Penicillin G, Ceftriaxone
Enterococci: Penicillin G, Ampicillin, Vancomycin, Daptomycin, Linezolid
GNR (non-P. aeruginosa): Ceftriaxone, Ciprofloxacin
P. aeruginosa: Cefepime, Zosyn, Ciprofloxacin
Polymicrobial: Meropenem, Zosyn, Ertapenem, Unasyn
Osteomyelitis oral options
Streptococci: Amoxicillin, cephalexin, clindamycin (if susceptible)–> may consider rifampin
MSSA: Dicloxacillin, cephalexin, cefadroxil, bactrim, linezolid–> may consider rifampin
MRSA: linezolid, bactrim, clindamycin (if susceptible)–> may consider rifampin
GNRs: bactrim, FQs
Septic arthritis risk factors
Joint disease
Advance age
Sexually transmitted infection
Chronic disease
Immunosuppression
Trauma
Prosthetic Joint
IVDU
Endocarditis
Septic arthritis common pathogens
S. aureus
Sexually active adults: Neisseria
Cat or dog bite: Pasteurella
Septic arthritis signs and symptoms
Joint pain, decreased ROM, swelling, erythema, warmth, fever, chills
Monoarticular in majority of cases
Polyarticular can occur: RA, immunosuppression, prolonged bacteremia
Septic arthritis diagnosis
Increased WBC, ESR, CRP
Arthrocentesis: purulent, low viscosity synovial fluid
- PMN
- Gram stain and culture
X-ray/CT/MRI
Septic arthritis treatment
Expedited joint drainage and antibiotic therapy critical to reduce joint destruction
Empiric antibiotic selection comparable to osteomyelitis
- if gram stain is available prior to initiation can use narrowest possible
- gram (-): likely N. gonorrhoeae–ceftriaxone alone
IV or highly bioavailable oral is acceptable
Prosthetic Joint Infection pathogenesis
Develop via the same 3 mechanisms as discussed
Involves development of biofilm–>impedes antibiotic penetration
Prosthetic joint infection pathogens
Similar to other bone infections
S. aureus
Streptococci
Enterococci
Pseudomonas
Enterobacterales
Prosthetic joint infection signs and symptoms
Joint pain, Decreased ROM, Swelling, Erythema, Warmth, Fever, Chills
Sinus tract or persistant wound drainage over joint prosthesis
Loosening of prosthesis
Important to view history of prosthesis
Prosthetic joint infection diagnosis
Increased WBC, ESR, CRP
Arthrocentesis: cell count/differential, gram stain, culture
X-ray
Prosthetic joint infection approach to treatment
Withholding antibiotics in stable patients to increase chances of isolating an organism from culture
Empiric selection comparative to osteomyelitis
Proceed with pathogen directed therapy once culture and susceptibility’s are known
IV or highly bioavailable oral agent
Rifampin added to treatment of 1-stage exchange
Debridement and retention of prosthesis
Pathogen-directed therapy + rifampin x 2-6 weeks
Oral antibiotic + rifampin x 3 mo (hip) and 6 mo (knee, other joint)
1-stage exchange
Pathogen-directed treatment + rifampin x 2-6 weeks
Oral antibiotic (same as osteomyelitis) + rifampin x 3 mo
If we had gram (-) wouldn’t add rifampin
2-stage exchange
Pathogen-directed therapy x 4-6 weeks
Amputation with complete removal
Pathogen-directed therapy x 24-48 hours
