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CNSLF Micro - Bone & Joint Infections (iii) Osteomyelitis 2 (Chronic…
CNSLF Micro - Bone & Joint Infections (iii) Osteomyelitis 2
Chronic OM
usually due to contiguous spread from pressure sore/diabetic foot ulcer
patients with poor mobility + multiple comorbidities - DM, PVD (predilection
non acute presentation, usually resent for some time @ dx
usually polymicrobial e.g. S aureus + GNB + anaerobes (i.e. organisms that colonise ulcers)
S aureus in >50% of cases
anaerobes (10-20%) incl bacteroides/actinomyces
GNB
P aeruginosa
E coli
Klebsiella
nosocomial
open wound/fracture
may complicate trauma or surgery
IVDU
Features
evolves over months/yrs with low grade inflamm, dead bone (sequestrum) + fistulous tracts
chronic pain
patient systemically well
usually co-morbidities
often relapses despite apparently appropriate tx
non-healing ulcer overlying bone or a chronically discharging sinus, often a sign of underlying chronic OM
management
based on C+S
can't be managed with antibiotics alone = surgical debridement to remove necrotic bone if present (send for C+S)
MDT approach: diabetes nurse specialist, tissue viability nurse, podiatrist, endocrinologist, vasc surgeon, radiologist, microbiologist/ID physician
tx more prolonged - min 3 months antibiotics, up to 6 months
success depends on extent of removal os necrotic bone
Microbiological dx
identification of causative organism
essential in order to choose best tx
bone bx for culture + histology = gold standard
sensitivity = 87%, specificity = 93%
gram stain
C+S
consider TB culture if chronic
molecular - 16S rRNA
if chronic, hold antibiotics until after bx taken
NOT swab of ulcers/sinuses - may grow colonising organisms + not deep pathogens
blood cultures if acute (systemic symptoms e.g. fever) - dx if patient is bacteraemic