Block 2 - Endocarditis, Bacteremia, Bone/Joint infection Flashcards
Pathophysiology of osteomyelitis (OM)?
Hematogenous, vascular insufficiency
Difference between acute, chronic, hematogenous, and contiguous OM?
Acute = Sx onset <1wk from infection
Chronic = 10 days to 1 month
Hematogenous = spread through blood
Contiguous = spread through connecting soft tissue
Pathophysiology of diabetic foot osteomyelitis (DFO)?
Starts with DFI and contiguous spread
Periosteum is compromised and bone infection
Risk factors of DFO?
Deep ulcers
Ulcer that doesnt heal after 6 wks of wound care
Ulcer >2cm
DFO diagnosis?
Probe to bone test
ESR, CRP, MRI!
Bone culture (avoid swab if can)
DFO bugs
S. aureus
CoNS
GNR and anaerobes (site specific)
Special cases = salmonella and TB
Main DFO treatment?
Source control!
Through surgery or non-surgical interventions
When is surgery required for DFO?
Gas in deeper tissue
Abscess
Necrotizing fasciitis
When is surgery opted out for DFO?
Pt doesnt want amputation
Confined to forefoot and minimal soft tissue loss
Risk > Benefit
Signs of beneficial response for DFO treatment?
Decreased ESR, CRP
Radiographic changes that suggest healing
CLEAR MARGINS!!!
If pt is stable with DFO, how do you treat them?
Culture it, then surgery
If pt is NOT stable with DFO, how do you treat them?
Anti-MRSA + Anti-Pseudomonal
Vertebral OM (VOM) presentation?
Back pain
Normal WBC
ESR, CRP elevated
+/- fever
NVO diagnosis?
MRI (takes 3-6 wks for bone destruction to show up)
Intraoperative aspiration or biopsy
Risk factors for NVO?
Age
IVDU
Indwelling catheter such as HD
Immunocompromised
Bacteremia w/ S. aureus
Which Abx have good bone penetration?
Azith
Bactrim
Clinda
Tetra
RFML
Rifampin
Fluoro
Metro
Linezolid
Abx and Sacral OM?
Do not give, they only offer transient response
If there is no source control for OM, what is the duration of Tx?
6 weeks
When should you suspect prosthetic joint infection (PJI)?
SINUS TRACT
persistent wound drainage
Early, delayed, and late PJI
What causes them and what is the time frame?
Early and delayed caused by surgery
Late is hematogenous
Early 1-3 months after implantation
Delayed is several months to 1-2 yrs
Late >2 yrs
How is PJI diagnosed?
Arthrocentesis (>65% neutro + >1700 leukocytes)
Microbiology (synovial fluid + blood)
PJI bugs?
Most common - S. aureus
Then Strep spp., GNR STDs
Least common (special) - arbovirus
PJI Treatment?
Source control
2 stage exchange is gold standard in US; 2 surgeries by removing hardware, spacers and Abx, then new hardware
PJI Abx treatment?
2-6 wks IV + (Rifampin if hardware is added)
Then 3-6 months PO therapy
Septic arthritis presentation?
Painful joint in absence of trauma
Joint motion restriction
Joint warmth
Septic arthritis pathophysiology?
Synovial membrane has bugs, pressure from effusions destroy joint cartilage and causes bone loss
Septic arthritis diagnosis?
Arthrocentesis (50-200WBC and Glucose <40)
Microbiology
Treatment regimen for septic arthritis?
Depends on gram stain
If gonococcal, ceftriaxone 24-48hrs then oral
If not, hold empiric until we can tailor to bug for 3-4 weeks
Bugs for bacteremia?
CoNS
HACEK
Haeomphilus spp
Actinobacillus spp
Cardiobacterium spp
Eikenella spp
Kingella spp
G+ MSSA bacteremia, first line Abx?
CON
Cefazolin
Oxacillin
Nafcillin
x14 days
MRSA bacteremia, Abx?
Uncomplicated: Vanco or dapto (6mg/kg/dose) for at least 2 weeks
Complicated: Same drug but for 4-6 weeks, maybe even higher dapto dose (8-10mg/kg/dose)
What should you rule out with gram + bacteremias?
Endocarditis
Bacteremia and vanco use
Just make sure MIC≤2, continue using vanco if there is clinical AND microbiological response
If MIC=2, use an alternative
What are the alternative agents for MRSA bacteremia
High dose dapto (10mg/kg/day) + one of these agents
Genta Rifampin Zyvox Bactrim B-lactam (ceftaroline)
What are the CoNS?
S. epidermidis (#1 cause), S. hominis, S. lugdenesis