Bone Infection - Block 1 Flashcards
RF of bone infection?
- Diabetes (DFI)
- Peripheral vascular disease
Complications of bone infection?
- Amputation
- Bone deformity
What is the difference between OM and infectious arthritis?
OM: infection of bone
Infectious/septic arthritis: inflammation of the joint cavity
Acute vs chronic OM?
Acute: <1week
Chronic: >1 month
What are the types of OM?
- Hematogenous
- Contiguous
- Vascular insufficiency
- Direct inoculation
What is hematogenous OM?
Spread via bloodstream to the bone:
* Lumbar and thoracic vertebrae -> vertebral osteomyelitis
* Common in >50YO
* Staphylococci spp.
What is contiguous OM?
Shares a common border/adjacent infection reach to the bone (untreated DFI wound):
* Polymicrobial infections
* Staphylococci spp.
What is vascular insufficiency OM?
Polymicrobial infection (e.g. sacrum wounds, DFI)
What is direct inoculation OM?
Trauma, puncture wound, surgery:
* Step, S. epidermis, E.coli, P. aeruginosa
Sites of hematogenous OM?
- Long bones and joints
- Vertebrae
Sites of contiguous OM?
Foot in DMF, femur, tibia, and mandible
Sites of direct inoculation?
Foot
Sites of vascular insufficiency?
Sacrum wound, feet, and toes
Common pathogens of OM in adults? Children
Adults: S. aureus
less than 4 YO: Kingella kingae
>4 YO: S. aureus
Presentations of vertebral OM?
- Constant back pain
- Nuerological complication if infection compressess spinal cord
Clinical presentation of direct inoculation OM?
S/swithin 1 month from surgery or bone trauma
Clinical presentation of contiguous spread OM?
- Localized tenderness, warmth, edema, erythema
- In patients with vascular insufficiency
GOld standard of OM diagnosis?
MRI: as early as 1 day after onset of infection
Lab abnormalities of OM?
- Elevated WBC
- Elevate ESR and CRP (more sensitive)
- Bone cultures
- Blood culture is + in hematogenous
What location is most common for contiguous osteomyelitis to occur in adults?
Foot
Consideration to treat S. aureus OM?
- 10% -> MRSA -> vancomycin and daptomycin (alt)
- MSSA -> 1st gen cephalosporin (cefazolin)
- Pediatric -> Clindamycin
How do you get adequate drug into the bone?
- High doses with adj of weight and renal/hepatic function
- Empiric therapy
Tx for adult OM?
S. aureus: Vanc TDM or Daptomycil 6-10 mg/kg/day
OR
Cefazolin (no risk for MRSA)
Vascular insufficiency tx?
G-: Vancomycin + ceftriaxone 2 g IV Q24H
IV drug use OM tx?
MRSA and P. aeruginosa: Vancomycin + ciprofloxacin, ceftazidime, or cefepime
Postop/trauma OM Tx?
MRSA and Pseudomonas: Vanc + Cefepime
Necrotic OM Tx?
MRSA, Pseudomonas, anaerobes:
* Vancomycin + Cefepime or ceftazidime or cefepime PLUS metronidazole 500 mg IV Q8 or clindamycin 900 IV Q8
OR
* Vancomycin + zosyn or merrem (meripenum)
Newborn OM tx?
S. aureus, S. pyogenes, E. coli: Cefazolin
Children ≤ 3 years old OM tx?
K. kingae: cefazolin, cefuroxime, ceftriaxone, or augmentin
Children ≥ 4 years old OM tx?
S. aureus: Vancomycin, clindamycin, cefazolin
When is definitive therapy used?
- Should be delayed until bone cultures can be obtained (surgical debridement, chronic OM)
- Discontinue antibiotics for at least two weeks prior to debridement
- Antibiotic therapy should be tailored to culture and susceptibility data when available.
Staph MSSA Tx?
Nafacillin, oxacillin, cefazolin: Q4-8H (inpatient)
Ceftriaxone: QD (outpatient)
Staph MSRA OM tx?
Vancomycin
Alt: Daptomycin
* Hold statin, check baseline CPK -> rhabdomylysis
Strep-pen sensitive OM?
Penicillin G and Ampicillin: 6 divided doses)
Ceftriaxone: high dose -> not as strong
E. coli OM tx?
Ceftriaxone
Pseudomonas OM tx?
- Ceftazidime
- Cefepime
- Meropenem
- Ciprofloxacin/Levofloxacin
Duration of OM therapy in adults?
4-6 weeks
Duration of MRSA OM?
8 weeks
Duration of therapy GNB OM?
≥8 weeks
Duration of OM in children?
min 3 weeks
What is OPAT?
IV antibiotics administered at home or infusion clinic
Criteria for at-home admin of IV ABX?
- Patients receiving stable treatment
- Interested/motivated to receive treatment at home
- Good venous access
- Support from family or caregivers
- Safe, stable housing situation, including refrigerated drug storage capability
Exclusion criteria for at-home administration of IV antibiotics
- Vision or dexterity
- Recent IV drug use
What do you need to monitor dialy in OM/
- Inflammation
- Fever
- Redness
- Tenderness
- WBC
What do you need to monitor Weekly in OM?
- WBC and CRP: Reduction of inflammatory markers
- MRI to rule out abscess
- Vanc levels are collected aat least weekly after stabilization
Describe follow up of OM?
- Follow up cultures not typically indicated
- Suppressive therapy:
* Patients who fail surgery + antibiotics or chronic Osteomyelitis -> long-term oral suppressive therapy, month
* Recurrent with prosthetic -> life long
Suppression OM of methicillin susceptible?
- Cefadroxil
- Cephalexin
- Dicloxacillin
- FLucloxacillin
Suppression OM of MRSA?
- BActrim
- Doxycycline
- Minocycline
- Clindamycin
Suppression OM of G-?
- Bactrim
- Ciprofloxacin
- Levofloxacin
Suppression OM of penicillin sensitive strep and entero?
- Amoxicillin
- Penicillin VK
Suppression OM of Cutibacterium?
- Amoxicillin
- Penicillin VK
Who are more susceptible to joint infections?
Children and oldre adults
Types of septic arthritis?
Acquired via adjacent bone infection, or trauma/surgery: monoarticular
Hematogenous via blood: 2 or more joints
What are the different causes of septic arthritis?
Native: S. aureus, strep; E. coli
* Pseudomonas If IV drug user or nosocomial
* N. gonorrhea from GUT
Prosthetic: S. aureus, strep, enterococcus, GNRs
What is the septic arthritis triad?
- Dermatitis
- Tenosynovitis
- Migratorily polyarthralgia(comes and go)
Tx of spetic arthritis?
Source:
* Joint drainage
* Remove prosthesis
* Empiric antibiotics cover
* Tailoring ABX
Joint rest:
* Avoid weight-bearing initially
* Passive ROM exercises
IA empiric therapy?
MRSA + ceftriaxone 2 gram IV Q12
IV drug user IA tx?
MRSA + pseudomonas
PCN allergy IA tx?
MRSA + Aztreonam or cephalosporin
N. gonorrhea tx of IA?
Ceftriaxone
IA from bite wound tx?
Ampicillin/Sulbactam 3 g IV Q6
Or
Clindamycin 600 mg IV Q8 + Cipro 400 mg IV Q12 if PCN allergy
Hardware retention in prosthetic joint IA tx?
If staph isolated, add rifampin 600 (breaking down the slime layer produce by s.ar)mg po Q24
How long is IA duration of therapy?
4-6 weeks IV therapy
If prosthesis retained, most patients will require at least 3 months of oral abx +/- rifampin