Osteomyelitis Flashcards by Hannah Nolan

Origin of infections in bone

Haematogenous spread ()
Direct ioculation
Contiguous spread

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Haemotogenous spread in osteomyelitis

staph aureus, slamonells in children w sickle cell
TB
Brucellosis - ulcers in diabetic foot - deep enough to get to bone

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What type of bacteria form biofilms on prosthetics

Negative staphylococci

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Why are biofilms esp dangerous

Resistant to immune defenses and antibiotics

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What diseases and devices are biofilms implicated in

Infective endocarditis
Ventilator ass pneumonia
Central line infection
Cystic fibrosis lung infections
Chronic oseteomyelitis

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What are biofilms

Structured community microorganisms adhering to surface and producing extra cellular matrix of polysaccharides

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Bacteria free vs biofiml

Planktonic = free
sessile = biofilm

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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

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Epidemiology of osteomyelitis

Diabetes increasing
Arthroplasty surgery increSING

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Prosthetic joint infection presentation

Joont pain
Evidence inflammation surgical site - sometimes looks asbolutely clean

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Vertebral osteomyelitis presentation

Back pain - localised, weeks/months
Nerve roots - reticular, landscape pain
May -> neuro signs if vertebral column unstable, weakness arms and legs

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Presentaton of chronic osteomyelitis

Sinus tracts
>2cm3 ulcer in DM
Non healing fractures
loosening prosthesis #

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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

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What see on xray osteomyelitis

Has to be severe
Bone loss - lucency and bone deposition - sclerosis

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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

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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