Osteomyelitis

This set of flashcards covers key terms and concepts related to osteomyelitis, including causative organisms, mechanisms of infection, symptoms, and virulence factors.

Trauma/Open Wound Infection Risk

Staph aureus

Pseudomonas aeruginosa

Hematogenous Spread Infection Risk

Staph aureus

Streptococcus spp

Prosthetic Joint Infection Risk

Staph epidermidis

Staph aureus

Cutibacterium acnes

Diabetic Foot Ulcer Infection Risk

Pseudomonas aeruginosa

Sickle Cell Infection Risk

Salmonella

Staph aureus

IVDU Infection Risk

Staph aureus

Pseudomonas aeruginosa

Candida albicans

Bites Infection Risk

Eikenlla corrodens

Pasteurella multocida

Post Surgical Infection Risk

Staph aureus

coagulase negative Staphylococci

Candida albicans

General Signs

pain over affected bone

swelling, redness, warmth

tenderness to palpation

reduced ROM

fever, chills, malaise

Acute Hematogenous Spread

more common in kids

sudden onset of pain, fever, irritability, refusal to weight bear

impacts long bones

redness and swelling may be delayed

Acute Continuous Spread

common in adults

non healing ulcer, sinus tract, drainage

systemic symptoms possibly absent

most common on foot or vertebrae

Chronic Osteomyelitis

presents with persistent bone pain, chronic sinus tract, and swelling

recurrent or intermittent

minimal systemic symptoms

may see sequestra or involucrum on imaging

Protein A

Staph aureus virulence factor preventing opsonization and phagocytosis

MecA

MRSA virulence factor causing methicillin resistance

Adhesins

Staph aureus virulence factor causing collagen and fibronectin binding in the bone

matrix

Exotoxin A

Pseudomonas virulence factor

AB toxin prevents protein synthesis and causes cell death

Diagnostic Labs

elevated WBC count (<15,000)

elevated CRP/ESR

50% positive blood culture

Radiology Diagnostics

Radiograph will only show late stage

MRI is best for definitive dx

Diagnostic Gold Standard

bone biopsy

should be done before antibiotics started

Empiric Therapy: Concern for Staph spp

vancomycin

daptomycin

Empiric Therapy: Concern for Gram Neg Rods

3rd gen cephalosporin (ceftriaxone, cefepime)

Empiric Therapy: Concern for Pseudomonas

piperacillin-tazobactam

Empiric Therapy: Concern for Possible Drug Resistant Gram Neg Rods

carbapenem

meropenem

Empiric Therapy: Concern for Anaerobic Infections

metronidazole

Vancomycin

only targets gram positive

binds peptidoglycan and prevents synthesis

Daptomycin

only targets gram positive

binds cell membrane and causes lysis

Carbapenem

broadest spectrum antibiotic

Empiric Therapy: Risk Factor of Community Acquired Infection

vancomycin (cover MRSA)

ceftriaxone or cefepime

pipercillin-tazobactam (if pseudomonas concern)

Empiric Therapy: Risk Factor of PostOp/Trauma Infection

vancomycin

cefepime, piperacillin-tazobactam, meropenem

Empiric Therapy: Risk Factor of Diabetes Infection

vancomycin

piperacillin-tazobactam

metronidazole

Empiric Therapy: Risk Factor of Sickle Cell Infection

vancomycin and ceftriaxone

Targeted Therapy: Acute Infection

4-6 weeks total

start with IV antibiotics

switch to oral antibiotics after

Targeted Therapy: Chronic Infection

6-12 weeks, up to 3-6 months

2-6 weeks IV, then 4-8 weeks oral

may need debridement

Targeted Therapy: MSSA

IV nafcillin or oxacillin

IV cefazolin (better tolerated)

Targeted Therapy: MRSA

IV vancomycin

Targeted Therapy: Pseudomonas

IV cefepime or ceftazidime

IV piperacillin-tazobactam

Targeted Therapy: Salmonella

IV ceftriaxone or cefotaxime

Targeted Therapy: Pasturella/Eikenella

IV ampicillin-sulbactam

Targeted Therapy: Hardware Associated Infection

add rifampin to any other meds

Pseudomonas Risk Factors

diabetes

puncture wound

IVDU

hospital/nosocomial 

prosthetics

Prevention

prevent skin and soft tissue infections

manage chronic conditions

avoid progression from acute infection

reduce device and trauma related risk

Causative Organisms

staph aureus

staph epi

cutibacterium acnes

pseudomonas

salmonella

pasteurella multocida

candida