Osteomyelitis Flashcards
Origin of infections in bone
Haematogenous spread ()
Direct ioculation
Contiguous spread
Haemotogenous spread in osteomyelitis
staph aureus, slamonells in children w sickle cell
TB
Brucellosis - ulcers in diabetic foot - deep enough to get to bone
What type of bacteria form biofilms on prosthetics
Negative staphylococci
Why are biofilms esp dangerous
Resistant to immune defenses and antibiotics
What diseases and devices are biofilms implicated in
Infective endocarditis
Ventilator ass pneumonia
Central line infection
Cystic fibrosis lung infections
Chronic oseteomyelitis
What are biofilms
Structured community microorganisms adhering to surface and producing extra cellular matrix of polysaccharides
Bacteria free vs biofiml
Planktonic = free
sessile = biofilm
Why are most antibiotics not effective against sessile bacteria/biofilms
Bacteria are quiescent - not dividing, and antibiotics target beta lactamase within the cell wall
Difficulty penetrating thrugh ECM biofilm also phagocytes struggle
Epidemiology of osteomyelitis
Diabetes increasing
Arthroplasty surgery increSING
Prosthetic joint infection presentation
Joont pain
Evidence inflammation surgical site - sometimes looks asbolutely clean
Vertebral osteomyelitis presentation
Back pain - localised, weeks/months
Nerve roots - reticular, landscape pain
May -> neuro signs if vertebral column unstable, weakness arms and legs
Presentaton of chronic osteomyelitis
Sinus tracts
>2cm3 ulcer in DM
Non healing fractures
loosening prosthesis #
Investigation tests in osteomyelitis
No fever
Bloods - FBC, U+Es, CRP, blood cultures (ACUTE)
Joint aspiration, bone biopsy, tissue biopsy, sonication of excised prosthetic material
Plain X ryas, CT scans, MRI scan
What see on xray osteomyelitis
Has to be severe
Bone loss - lucency and bone deposition - sclerosis
Why are antibiotic courses for osteomyelitis prolonged and how long for
Infected bone loses blood supply - antibiotics wont reach - need time for bone to revascularise
6 week course for vertebral and prosthetic koint infections
How long course antibiotics for septic arthritis
Four weeks
How are antibiotics delivered
Recent research - IV and oral antibiotics just as affective
OVIVA trial - v similar, shorter stay in hospital with oral+ therefore less complications
What is main component of treatmnet
Debridement of area - orthopaedics and plastics (soft tissue), vascular if diabetic
May need to replace joint
What bacteria are polymorphs and gram negative intracellular diplococci consistent with
Neisseria species
What is DAIR
Debridemnet
Antibiotics
Implant retention
What antibiotic use to treat skin staph aureus infection
Flucloxacillin
Manamgeent immediate of chronic prosthetic joint infection presentaiton
The best course of action would be to take a swab of the discharge and send for bacterial culture and organise plain x ray of the knee and discuss with senior member of orthopaedic team (patient is stable so need to commence antibiotic immediately)
Gram positive cocci on Gram stain, catalase positive, coagulase negative
Likely organisms coagulase negative
Staphylococcus
Management of chronic prosthetic infection
Removal and bone cmeent w generous debridement to remove all infected and necrotic tissues
Implant cement spacer containing vancomycin
Minimum 6 weeks teicoplanin therapy
Reimplantation new prosthesis after
Causative organisms of prosthetic joint infection 0-3 months post op
S.aureus
Strp pyogenes
Enterococcus sp
Gram negative bacilli
Causative oragnisms of delayed presentation prosthetic infection (4-24 months post op)
Coag negative staph
Propionibacterium acnes
Other skin commensals
Causative oragnisms of late infection (>24 months post op)
Coag negative staph
S.aurues
Viridans streptococci
Gram negative rods, esp E coli
Anaerobes
Gram positive cocci species causing native joint infection
Staph aureues
Step - pyogenes, pneumoniae, group B, viridans group
Gram negative bacilli species causing native joint infection
Enteric gram negative bacilli eg eschericia coli
Pseudomonas aeruginosa
Eikenella corodens (human bite)
Pasteurella multicoda (animal bite)
In paeds esp:
Kingella kingae
H. influenzae
Gram + bacilli and gram - cocci causes of native joint infection
Gram + bacilli - clostridium sp
Gram - cocci - n.gonorrhea
Clinical presentation of chronic perprosthetic joint infection
Chronic pain
Loosening of prosthesis
Sinus tract - fistula - to surface, may be discharging
What causative organsims of acute prosthesis are most common and why
Highly virulent
S.aureus
Gram -
e.coli
Klebsiella
Pseudomonas
Causes of chronic prosthetic infection and why common
Coag negative staph
Cultibacterium acnes
Low virulence - dormant
Surgical management acute prosthesis infection vs chronic
Acute - DAIR
chronic - Remove prosthesis, exchange in 1 stage, 2 stage or 3 stage eg bone cement and antibitoic placement and oral antibitoics
Antibiotic management osteomyelitis
IV or oral
flucloxacillin (clindamycin if allergic)
MRSA/some chronic -> vancomycin (implant), teicoplanin
6 weeks minimum treatment
+/- fusidic acid and rifampacin
Ass conditions osteomelitis
DM
PAD
Venous insufficiency
IVDU -> haematogenous spread
Peripheral neuropathy -> non haem spread
Sickle cell- infracted bone
