Bone and soft tissue infections Flashcards
What are the most common bone and soft tissue infections?
Osteomyeltis
Septic athritis
TB infection
What is osteomyeltis?
Who typically gets it?
Infection within the bone itself, can be acute or chronic
Tends to effect children, boys more than girls.There can be a history of trauma and the individual may have co-morbidities such as diabetes, rheumatoid arrthritis, immune compromisation, long term steroid treatment and sickle cell
How does one develop a osteomyeltic infection?
Can spread through the bone or bloood. Can spread from a contagous site of infection, open fracture, bone surgery or joint replacement. Can also occur secondary to vascular insufficiency
What are the common sites of infection?
Umbilical cord- infants
Boils, tonsillitis, skin abrasions- children
UTI, arterial line- adults
What are the common organisms that cause osteomyeltis?
Infants:staph auresu, grou b strep, e.coli
Older children:staph aureus, strep pyogenes, flu
Adults:staph aureus, coag negative staphlococci, pseudomonas aeroginosa
What rare organisms may cause osteomyeltis in certain subpopulations?
Diabetic foot and pressure sores: mixed infection including anaerobes
Sickle cell: salmonella spp
Fishermen, fileters: myocobacterium marinum
Immunoinsufficiency, AIDS: Candida
Where is osteomyeltis typically found?
Long bones e.g. distal femur, proximal tibia, proximal humerus.
Joints with intra-articular metaphysis: hip, elbow
What are the clinical features of osteomyeltis in infants?
May be minimal signs or may be very ill Failure to thrive Possible drowsy or irritable Metaphyseal tenderness and swelling Decreased range of movement Positional change Most common around the knee
What are the clinical features of osteomyeltis in children
Severe pain
Reluctant to move
May be tender, fever, swinging pyrexia and tachycardia
malaise (fatigue, nausea, vomiting)
toxaemia (degraded bacterial enzymes in the blood)
What are the clinical features of osteomyeltis in adults?
Primary OM seen in thoracolumbar spine
backache
history of UTI or urological procedure
elderly, diabetic, immunocompromised
What are the clinical features of secondary osteomyeletis in adults
Secondary OM much more common
often after open fracture, surgery especiialy ORIF
How do you diagnose osteomyeltis?
History and clinical examination (pulse and temp)
FBC and WBC, ESR, CRP
Blood culturesx3 at peak ofswinging pyrexia
U&Es
What are some differential diagnosis for osteomyeltis
acute spetic athritis acute inflammatoy arthritsi trauma transient synovitis cellulitis necrotising fascitis toxic shock syndrome
What imaging procedures would be carried out for soemone suspected to have osteomyeletis
X0ray Ultrasound Aspiration Isotope bone scan labelled white cell scan MRI
What is seen in an x-ray of someone with osteomyeltsi?
no change first two weeks
10-20 days periosteal change
Late osteonecrosis
late periosteal new bone
How would you diagnose osteomyeltis with micbiology
Blood cultures
Bone biopsy
Tissue or swabs from 5 sites around prosthetic joints
Superifical swaps of skin may be misleading
How do you treat osteomyeltis
Rest and splintage, empiracal antibioticcs (fluclox and benzylepen) while waiting for blood cultures
Why may antibiotics fail in osteomyeltis
Drug resistance, MRSA Dormant bacteria in dead bone poor host defence poor drug absorbtion poor tissue penetration
What are the surgical indications for osteomyeltis
Aspirtions of pus for diagnosis and culture.
Abscess drainage
Debridmen of dead/infected/ contaminated tissue
infected joint replacement
What are the complications of osteomyeltis
Septicemia, death, metastatic infection, septic athrtits, altered bone growth, chronic osteomyelitis
What causes osteomyetis pathology
Cavities, sinuses
dead bone
involucrum
chronic inflammation
What causes chronic ostemyeltis?
Often mixed infection
usually same organism each flare up
typically staph aureus, e coli, strep pyogenes
What is the treatment of chronic osteomyeltis
Long term antibiotics Eradicate bone infection Treat soft tissue problems Reconstruction Amputation
What is septic athritis?
Infection of a joint that causes athritis
How does septic athritis occur?
carried in the blood
Eruption of a bone abscess
Direct invasion- penetrating wound, iatrogenic, joint infection, intra-articular injury, arthroscopy
What organsims cause septic athritis?
Staph.aureus
flu
strep. pyogenes
e. coli
What happens during septic athritis
Acute synovitis with pruelnt joint effusion
Articular cartilage attacked by bacterial toxin and cellular enzyem
complete destruction of the articular cartilage
What may occur after septic atrhitis?
Complete recovery
Partial loss of articular cartilage and therfore OA
Fibrous or bony ankylosis
Describe how septic athritis presents in an neonate
Like septicaemia
iiritable
resistant to movement
ill
How does septic athritis occur in a child
Acute pain ina single large joint reluctant to movethe joint reduced range of movement Increased temperature and pulse increased tenderness
How does septic athritis occur in an adult?
Often involves superificial joint (knee, ankle, wrist)
Rare in healthy adult
May be a delayed diagnosis
What investigations are carried out if septic athritis is suspected
FBC, WBCM ESR, CRP, blood cultures
X-ray
Ultrasound
Aspiration
What are the differential diagnosis for septic arthritis?
Acute osteomyeltis Trauma irratibel joint haemophilia rheumantic fever gout gauchers disease
What is the treatment of septic athritis
Generally supportive mesures
antibiotics for 3-4 weeks
surgical drainge and lavage- never let the sun set on pus
Infected joint replacement
Describe a TB infection of the bone
Can be extra-articular (epiphyseal, bones with haemodynamic marrow)
Intra-articular (large joints)
Vertebral body
Multiple lesions in 1/3 of patients
What are the clinical signs of a TB infection of the bone
Insidious onset and general ill health Pain (at night), swelling, loss of weight low grade pyreaxia joint swelling decreased range of movement ankylosis deformitiy Contact with TB
Describe the presentation of TB in the spine
Little pain
present with abscess or kyphosis
How do you diagnose TB infection from an examination
Long history Involvemnt of signle joint Marked thickening of synovium marked muscle wasting periarticular osteoperosis
TB investigations
FBC, ESR, Mantoux test, sputum/urine culture
X ray- soft tissue swelling, preiarticular osteopaenia, articular space narrowing
Joint aspiration and biopsy AAFB indeitified in 10-20%
What is the differential of TB
Transient synovitis Monoarticular RA Haeorrhagic athritis Pyogenic arthritis Tumour
What is the treatment of TB
Rifampicin
Isoniazid
Ethambutol for 8 weeks
Rifampcina dn isoniazid for 6-12 months
rest and splint
operative drainage rarely necessary
