Infections Flashcards
Which part of skeleton does TB most commonly affect?
Spine
Then hip
What is Pott’s disease
TB spondylitis (spine) - complication Paraplegia
What is bac load of spine TB
Low-paucibacillary
How does tb spine spread? (4)
Along ant long ligament
Post into spinal cord → cord compression and paralysis
Down psoas muscle to groin
Posterior: triangle of petit (inf lumbar triangle)
4 symptoms spinal TB
- Slow growing bac-prolonged constitutional symptoms
- Malnourished
- Severe pain late sign - ass W/ bone collapse
- Neuro symps eg lower limb weak and numb- Potts paraplegia
2 possible findings on Clin examination of back in spinal TB
Gibbus. (prominent spinous process)
Psoas abscess
Which part of spine most commonly affected by tb
Thoracic
Xr features spinal TB early and late (9)
Early:
• local osteoporosis of 2 adjacent vertebrae
• Narrow disc spaces
• fuzziness of end plates
Late
• disc space destruction
• lucency and compression of adjacent vertebral bodies
• severe kyphosis (gibbus)
• paraspinal soft tissue shadows due to oedema, swelling or paravertebral abscess
• paraspinal abscess
. Sclerotic + lytic lesions
Microscopy stains available to diagnose TB (2)
Ziehl - Nielsen stain: acid fast bacilli
H&E stain: TB granuloma
Where does TB hip begin (3)
Superior rim acetabulum (early joint invasion)
Epiphysis
Greater trochanter
3 radiological signs of hip TB
Phemister triad: periarticular osteoporosis, femoral head and neck erosions, decreased joint space
Kissing sequestra: femoral and acetabular sides wedge shaped necrosis
“Wandering acetabulum”
What is a “fight bite” (3)
Attacker with finger in full flexion punches another penson in mouth with clenched fist.
Presents as pt fingers in extension
Superficial puncture wound
Much deeper into MPJ - “closing off”
Extremely dangerous palymicrobial infection!
If you see a fist wound, what should you suspect?
fight bite - human bite
What do kanavel’s 4 cardinal signs indicate?
Septic tenosynovitis
What are kanavel’s four cardinal signs
(Indic tenosynovitis of hand )
- Slight flexion finger
- Swelling
- Pinpoint tenderness over sheath
- Pain on passive extension
What is osteomyelitis
Bone infection involving medullary cavity with progressive inflammatory destruction, typically bacterial
Etiology osteomyelitis? (2)
- Most commonly S aureus. Also group B strep in neonates, kingElla kingae, pseudomonas in direct puncture wounds to foot…
- mechanism of spread mostly hematogenous, also direct inoculation and contiguous focus
Name 6 risk factors osteomyelitis
- Diabetes mellitus , peripheral neuropathy, poor vascular supply
- hemoglobinopathy, especially sickle cell disease
- immune compromise, iv drug use, malnutrition
- recent trauma / surgery
- poor hygiene, male
- children at risk !
Clinical features (symptoms and exam) of osteomyelitis? (7)
Symptoms:
. pain with limp or refusal to bear weight
• may have fever
Examination • erythema (rubor) • tenderness (dolor) •Edema (tumor) • hot (calor) • may have abscess or draining sinus tract
Which investigations should be done for osteomyelitis? (5)
- WBC count elevated, not very sensitive
- ESR elevated, very sensitive for diagnosis
- CRP increased, most sensitive to monitor treatment response
- blood culture: only positive in 50% or less
- aspirate culture/bone biopsy if really not sure - do surgical drainage if pus is aspirated
Treatment acute osteomyelitis? (4)
Iv antibiotics 4-6 weeks, started empirically and adjusted after obtaining blood and aspirate cultures
. S aureus: first line flucloxacillin; second line ceftriaxone / clindamycin
. MRSA: first line vancomycin and rifampicin; second line linezolid or daptomycin
Surgery incision and drainage if abscess, significant involvement, chronic infection, failure to respond to antibiotics
Treatment chronic osteomyelitis? (5)
- Surgical debridement
- Dead space management
- Bone stability: may need external fixation
- Antibiotics: local and systemic after cultures
- Soft tissue cover
Name 5 complications osteomyelitis
- DVT, especially older children and adults
- meningitis
- septic arthritis, especially neonates
- growth disturbances and limb length discrepancy from growth plate involvement
- pathologic fractures
Septic arthritis etiology? (4)
- Adults: S aureus mostly
- prior joint replacement: coagulase negative staphylococcus
- sexually active adults and newborns: neisseria gonorrhoea
• most common route = haematogenous
Name 7 risk factors septic arthritis
- Young and elderly >80
- any pre-existing joint disease eg ra, oa, Uraemia
- immune suppression: diabetes mellitus, alcoholism
- hip or knee joint prosthesis
- iv drug use
- skin infection or ulcer
- previous intra-articular corticosteroid injection
Clinical features septic arthritis? (5)
- rubor (redness)
- dolor (pain) ! And Inability to weight bear , pseudoparalysis children
- tumor (oedema)
- Color (warmth)
- fever in 60%
• paeds hip: leg held in flexion and external rotation, fullness palpable in loin and upper thigh(late sign),
If child can flex and extend joint, IT IS NOT SEPTIC ARTHRITIS!
Name the kocher criteria
To differentiate between septic arthritis and transient tenosynovitis in child with painful hip. If present, give 1 point
• unable to weight bear
• pyrexia >38,5
• wcc >12 x10^9 cells/l
• ESR>40 mm/h
Score of 3 or more = 93% probability of septic arthritis
Which investigations should be done if suspect septic arthritis? (6)
• Xray to rule out #, tumour, metabolic bone disease
• ESR (>40 mm/h)
• CRP
• WBC (>12 x10^9 cells/L)
• blood cultures
. Joint aspiration for gram stain, leukocyte count, microscopy and culture - best to do during arthrotomy, not aspiration
• listen for heart murmur (infective endocarditis)
Treatment septic arthritis? (2)
- Empirical antibiotics (cloxacillin) ASAP adjusted when culture comes back after /during arthroscopy
- arthroscopy = definitive treatment for irrigation and debridement and drainage
Name the 4 joints in order that are most commonly affected by septic arthritis
- Hip
- elbow
- ankle
- sternoclavicular joint
Name 3 complications septic arthritis
- Adults: secondary osteoarthritis, ankylosis (fused joint), contractures
- Paediatrics destroy epiphysis: osteonecrosis and osteomyelitis!, (fixed flexion) deformities
What is sequestrum?,
a piece of dead bone tissue formed within a diseased or injured bone, typically in chronic osteomyelitis. Appear sclerotic (white) on xr
What is involucrum?
a complication of osteomyelitis - a thick sheath of periosteal new bone surrounding a sequestrum. To protect bone from breaking
What is a cloaca?
a gap in the cortex of a bone affected by chronic osteomyelitis that allows the drainage of pus or other material from the bone into the adjacent tissues.
