L: infections of bones and joints

incomplete

What age groups is septic arthritis more common in?

Elderly and young children

What can delayed treatment of septic arthritis result in?

Irreversible joint damage

What is the case fatality for septic arthritis?

approximately 11-50%

What could potentially be a future problem in septic arthritis?

Increasing antimicrobial resistance

What are 4 points that must be met in Newman’s definition of septic arthritis?

• isolation of pathogenic organism from affected joint

• isolation of pathogenic organism from another source in the context of a red hot joint (eg blood) (suspicion)

• typical clinical features and turbid joint fluid in the presence of previous antibiotic treatment

• post mortem or pathological features suspecting septic arthritis

What is the typical presentation of septic arthritis?

• 1-2 week history of red, painful joint

• fever

• sweats

• rigors

• common in larger joints

• can be more than one joint affected

In what percentage of patients was fever recorded in in patients who had bacteria cultured from synovial fluid?

34%

In what percentage of patients was sweats recorded in in patients who had bacteria cultured from synovial fluid?

34%

In what percentage of patients was rigors recorded in in patients who had bacteria cultured from synovial fluid?

6%

What are three joints commonly affected by septic arthritis?

Knee, hip, lumbosacral

What percentage of patients have more than one joint affected?

up to 20%

What happens if a patient with septic arthritis had arthritis before it became septic?

their symptoms will be out of proportion with the usual presentation of arthritis

what are three things that can delay presentation of septic arthritis?

low virulence causative organisms, fungal infections and mycobacterial infections

List some predisposing conditions for septic arthritis?

• rheumatoid arthritis

• joint prosthesis

• IV drug use

• alcohol excess

• diabetes

• previous intra-articular corticosteroid injection

• cutaneous ulcers

List some causative organisms for septic arthritis?

• staph. aureus

• strep. pyogenes

• mycobacterium tuberculosis

• salmonella

• brucella

• neisseria gonorrhoea (se+ually active)

• kingella (children)

• pasturella (animal virus)

• staph. epidermis (prosthetic material)

List some conditions that could be differential diagnosis of septic arthritis?

• Crystal arthritis (gout, calcium pyrophosphate disease (aka pseudogout))

• reactive arthritis

• monoarticular presentation of polyarthritis

• intra-articular injury (fracture, meniscal tear)

• haemarthrosis

• inflammatory osteoarthritis

• cellulitis, bursitis, phlebitis

How can infection be introduced to a joint?

Haematogenous spread or direct inoculation by trauma or iatrogenically

What does iatrogenic mean?

unintentional harm caused by medical treatment

Which is a more common source of septic arthritis - haematogenous spread or direct inoculation?

Haematogenous spread

What is required if there is concern around septic arthritis?

Joint aspiration

Joints other than ….. should be in contact with the orthopaedic team

Knee ( or of prosthetic → orthopaedics)

what is joint aspiration?

removing synovial fluid from a joint capsule using a needle and syringe

if crystals are in the synovial fluid sample what does this indicate?

crystal arthritis (gout + pseudogout)

what other tests can be done when there is suspicion of septic arthritis?

• peripheral blood cultures

• PCR

• FBC

• U&Es

• CRP

• urate

• xray

• coagulation screen

• MRI

What does PCR stand for and what is it used to test for in septic arthritis?

Polymerase chain reaction and it tests for gonorrhoea

What does FBC stand for and what does it test?

Full blood count - white blood cells (in response to infection)

What does U&Es stand for and what does it test for?

urea and electrolytes and it tests kidney function and salt in the blood

What is CRP and what does it test for?

C-reactive protein and it acts as a general inflammation marker

What is urate test for?

To test uric acid levels in the blood

What does normal urate levels NOT rule out?

acute gout

Why would an x ray be done in suspicion of septic arthritis?

can show chondrocalcinosis - calcium deposits in cartilage seen in pseudogout

Why would an MRI be done when there is suspicion of septic arthritis?

If there is also suspicion of osteomyelitis (bone infection)

What is the immediate treatment for acute septic arthritis?

IV flucloxacillin 2g (4x a day) for two weeks then oral therapy (total 4-6 weeks)

What is the alternative to IV flucloxacillin if the patient has a penicillin allergy?

IV clindamycin 600g (4x a day)

What other organisms should be considered?

Neisseria spp. and in young adults chlamydia spp.

What does a recent surgery or GI procedure likely indicate in cases of septic arthritis?

Gram negative organism - discuss with infectious disease or microbiology

What is reactive arthritis also known as?

Reiter’s syndrome

what is the classic triad of reactive arthritis and what rhyme can be remembered for this?

• conjuctivitis

• urethritis

• arthritis

• can’t see, can’t pee, can’t climb a tree

what does reactive arthritis occur after?

an infection such as urogenital or GI tract

What gender is reactive arthritis more common in?

men

What genetic marker is associated with reactive arthritis?

HLA-B27

List some dermatological manifestations of reactive arthritis.

• keratoderma blennorrhagicum

• circinate balanitis

• ulcerative vulvanitis

• nail changes

• oral lesions

what organisms can cause reactive arthritis?

•Chlamydia trachomatis

•Shigella flexneri

•Salmonella enteritidis/typhimurium/muenchen

•Yersinia enterocolitica

•Yersinia pseudotuberculosis (Pseudotuberculosis)

•Campylobacter jejuni/fetus

•Ureaplasma urealyticum

•Clostridium difficile

•Neisseria gonorrhoeaa

•Borrelia burgdorferi

•Chlamydia pneumoniae

•Escherichia coli

what is the treatment for reactive arthritis?

can be treated with full dose NSAID with gastric protection and treatment of factors such as chlamydia

What is osteomyelitis?

Infection of the bone causing inflammation of the bone and bone marrow

What bacteria is osteomyelitis usually caused by?

Pyogenic bacteria

What bacteria is osteomyelitis rarely caused by?

myogenic bacteria or fungi

How do bones become infected?

• haematogenous spread

• local spread (from septic arthritis)

• compound fracture (open)

• foreign body

What are characteristics of haematogenous spread of osteomyelitis?

usually asymptomatic although skin sepsis may be present hat w

where do organisms causing osteomyelitis through haematogenous spread settle?

In growing metaphysis near the growth plate

What are examples of foreign body causing osteomyelitis?

• trauma

• shrapnel/gunshot wound

• orthopaedic incident (IM nail)

• nail through trainer (pseudomonas - gram negative bacteria)

What are some areas commonly affected by osteomyelitis?

• humerus

• femur

• tibia

• fibula

• calcaneum

what percentage of osteomyelitis is humerus?

8-10%

what percentage of osteomyelitis is femur?

30-35%

what percentage of osteomyelitis is tibia?

25-30%

what percentage of osteomyelitis is fibula?

5%

what percentage of osteomyelitis is calcaneum?

10-12%

what organisms cause osteomyelitis?

• s. aureus

• s. pyogenes

• gram negative bacteria

• m. tuberculosis

What are some conditions that can predispose to osteomyelitis and what organisms cause them?

• sickle cell disease - salmonella

• travel/milk - brucella

• prosthetic - s. epidermis

• unvaccinated children under 5 - H. influenzae

• UTI - E.coli and others

what are symptoms and signs of osteomyelitis?

• painful swollen site

• fever

• reduced movement (may be only sign in very young)

• paraplegia

What are some preliminary tests for osteomyelitis?

• fever

• WBC

• CRP

• ESR/PV

What things could be taken for an investigation into osteomyelitis?

• blood culture

• x ray

• MRI/CT/Bone scan

• pus

What is the minimum amount of cultures to take for osteomyelitis?

3 (although surgeons may take 6 operatively)

What may cultures be early on in the course of infection in osteomyelitis?

They may be negative for any red flags

what are signs of osteomyelitis on a plain film or CT?

• periostea elevation

• focal osteopenia

• cortical thinning

• scalloping

What is one problem with x rays being used in early osteomyelitis?

The signs can be delayed

what sign of osteomyelitis would show up on a MRI?

marrow edema

What imaging technique is preferred for vertebral osteomyelitis and why?

MRI as it can exclude paravertebral abscess and cord impingement

what is the old dead bone called in osteomyelitis?

sequestrum

what is the live bone surrounding the dead bone called?

Involucrum

What can be used to show focal accumulation?

radioactive tracer

what organism causes acute osteomyelitis?

staph.aureus

What medication is given for acute osteomyelitis?

Flucloxacillin IV 2g qds

What medication is given for acute osteomyelitis if they are allergic to penicillin?

clindamycin IV 600mg qds

what organism causes chronic osteomyelitis?

staph. aureus (occaisonally coliforms)

What treatment is given for chronic osteomyelitis?

oral flucloxacillin 1g qds

What medication is given for chronic osteomyelitis if they are allergic to penicillin or MRSA?

orał doxycycline or co-trimoxazole

What organism causes MRSA osteomyelitis?

MRSA

What medication is given for MRSA osteomyelitis?

Vancomycin 15-20mg

What are alternative medicines for osteomyelitis?

• ciproflaxin (for salmonella infection)

• isonaid, rifampicin, pyrazinamide, ethambutol (TB)

• drainage/ removal of the sequestrum

where are prosthetic joint infections most common?

hips and knee

how many primary hip and knee replacements performed annually?

almost 200,000

What is the percentage rate of deep infection for hip and knee replacement?

0.5-2%