MSK Infections Flashcards
(40 cards)
What is osteomyelitis?
Inflammation of bone and medullary cavity, usually located in one of the long bones
How can osteomyelitis be classified?
Acute or chronic, contiguous or haematogenous, host status
What is needed for a bone to become infected?
Only with necrosis +/- high inoculum
What are the principles of surgery for osteomyelitis?
Remove infected tissue, drain and debride (may recur after treatment)
When should antimicrobials be given before culture results have been obtained?
Sepsis syndrome or soft tissue infection
What are some appropriate cultures?
Percutaneous aspirate or deep surgical cultures
When are sinus/drain cultures useful?
If they yield staph. or resistant organisms
What are some antibiotics active against staph. aureus?
Flucloxacillin (MSSA only), doxycycline, vancomycin, cotrimoxazole, teicoplanin, linezolid, daptomycin, clindamycin
What are some causes and classes of osteomyelitis?
Open fracture, diabetes/vascular insufficiency, haematogenous, vertebral, prosthetic joint infections
What are some features of osteomyelitis caused by open fractures?
Polymicrobial, contiguous infection, staph. aureus and aerobic gram negative bacteria, symptoms are non-union and poor wound healing
How is open fracture osteomyelitis treated?
Early management is key = aggressive debridement, fixation, soft tissue cover
What are some features of osteomyelitis caused by diabetes/venous insufficiency?
Polymicrobial, diagnosed by a probe to the bone, treated by debridement and antimicrobials
What is the gram positive cover used to treat diabetes-linked osteomyelitis?
Flucloxacillin = IV, for staph (and strep) Vancomycin = people with penicillin allergy (can't take fluclox) Doxycycline = oral switch, excellent bone penetration
What is the gram negative cover for diabetic osteomyelitis?
Gentamicin/aztreonam IV if severe
Oral cotrimoxazole/doxycycline if able to use oral route
Only if needed
What antibiotic is used to treat anaerobic organisms that may cause osteomyelitis in diabetics?
Metronidazole
What are significant causative organisms of osteomyelitis in patients with diabetes?
Staph. aureus, Groups A-C strep, Milleri group, anaerobes
What colonisers may be present in an osteomyelitis infection in a diabetic?
P. aeruginosa, E.coli, proteus, klebsiella, Enterobacter, bacillus sp, coagulase negative staph
May be present on culture but not causing infection = only prescribe antibiotics if signs of infection in patient
What patient groups get haematogenous osteomyelitis?
Prepubertal children, people who inject drugs, central lines/dialysis/elderly
What are some features of haematogenous osteomyelitis?
Caused by presence of bacteria in blood, acute onset illness
What are some features of haematogenous osteomyelitis in IV drug users?
Spread = haematogenous, contiguous, direct inoculation
Unusual sites = SCJ, SChoJ, SIJ, pubic symphysis
What organisms cause haematogenous osteomyelitis in IV drug users?
Most commonly staph. and strep
Less commonly pseudomonas, candida, eikenella corrodens (needle lickers) and myobacterium tuberculosis
What are some features of haematogenous osteomyelitis in dialysis patients?
7% with tunnelled line, high staph. colonisation rates, peripheral vascular disease and diabetes are risk factors, staph. aureus is most common cause, sometimes gram negative organisms are the cause
What are some examples of unusual site osteomyelitis?
Osteitis pubis and Clavicle osteomyelitis
What are some features of osteitis pubis?
Predisposed by urogenital procedures
Aseptic osteitis pubis = triggered by surgery, can be up to 18 months later, athletes get it
