MSK microbiology 03/10/18 Flashcards by K M

What is osteomyelitis?

Inflammation of bone and medullary cavity

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What bones does osteomyelitis usually occur in?

long bones

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How can osteomyelitis be classified?

Acute/Chronic
Contiguous/Haematogenous
Host status

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What is the generic treatment for infection?

Debridement

Antimicrobials

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If you can see a tendon in an open wound or see a bone in a swab what is the diagnosis?

Osteomyelitis

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What is the gold standard for osteomyelitis?

Bone biopsy

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Is osteomyelitis a medical emergency?

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When are emperic antibiotics needed in osteomyelitis?

NOT UNLESS SEPTIC

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Is bone resistant to infection?

Yes, very

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When can bone infection occur?

Necrosis/High inoculum

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How long does debrided bone take to be covered by soft tissue?

6 weeks

I.e. 6 weeks of treatment

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What are the principles of surgery?

Remove infected tissue
Drain
Debride

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Where does infection of the bone tend to happen?

Prosthetic joints - Co-Ag negative staph (epidermidis)
Vertebral osteomyelitis
Post-Traumatic infection
Diabetic foot infection

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When does Coag -ve staph become a problem?

Any patient with a metal/plastic prosthetic

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What are appropriate cultures for osteomyelitis?

Percutaneous aspirate

Deep surgical cultures

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Who is likely get osteomyelitis?

Open fractures
Diabetes/Vascular insufficiency
Haematogenous osteomyelitis
Vertebral osteomyelitis
Prosthetic joint infection
Specific hosts and pathogens

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What is early managent of open fracture infections?

Aggressive debridement

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When is a diabetic wound more likely to get infected?

> 2cm for >2months

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In diabetic osteomyelitis is it usually one or multiple organisms?

Many

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What is the type of investigation for diabetic osteomyelitis?

Probe to bone (90% specific)

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Can an X-ray show changes of osteomyelitis?

Yes but only if its been there a long time

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What is the best imaging for osteomyelitis?

MRI

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What is the treatment for sever diiabetic foot ulcer?

Gentamicin
Flucloxacillin (vancomycin if Penicillin allergic)
Metronidazole

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What is the time frame for Mild, moderate and severe diabetic foot ulcer?

7 days
7 days
7-10 days

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How long is the treatment for osteomyelitis?

6 weeks

What are antibiotics for Gram +ve organisms?

Flucloxacillin Vancomycin Doxycycline (oral switch)

What are gram -ve antibiotics organisms?

Gentamicin/Aztreonam IV | Oral Cotrimoxazole/Doxycyline (oral switch)

What is the treatment for anaerobes?

Metronidazole

Why is oral switch important?

Some antibiotics are not absorbed the same when switched from IV to Oral (vancomycin) IV antibiotics are expensive and time consuming

When is a psuedomonas culture likely to be treated as a causitive organism?

The context Bone biopsy, blood or sputume - yes Sinus fluid or skin swab - No

What organsims are never really ignored?

Staph aureus | Group A,B,C or G strep

What kind of people get Haematogenous osteomyelitis?

Prepubertal children PWID Central Lines Elderly

With Haematogenous osteomyelitis is sepsis more or less likely than in osteomyelitis?

Yes

Where is the most common place for Haematogenous osteomyelitis to occur?

Femur

If staph aureus is present what should be taken out if present?

IV line

What should be checked for in staph aureus infection?

Endocarditis

What types of osteomyelitis can PWID contract?

Contiguous Haematogenous Direct inoculation

Where do PWID get osteomyelitis?

Unusual site SCJ SChoJ Pubic Symphusis

What kind of osteomyelitis is occurs in patients with sickle cell?

Acute long bone osteomyelitis

What is gauchers disease?

Lysosomal storage disese

Where does bone infection usually occur in gauchers?

Tibia

What type of osteomyelitis is vertebral and what is it associated with?

``` Haematogenous May be associated with epidural or psoas absess PWID IV infections GU infections SSTI ```

What percentage of patients with osteomyelitis have a fever?

50%

What percentage of patients with osteomyelitis have insidious pain and tenderness?

95%

What comes first, biopsy or antibiotics?

Biopsy

Do antibiotics get into pus?

When is MRI repeated?

Unexplained increase in inflammatory markers Increasing pain New anatomincally related signs and symptoms

Why is MRI repeat not always accurate?

Lags behind | Resolution is occuring but not shown until after

What is the name of vertebral TB?

Potts disease

Is Potts disease infection and does it have systemic symptoms?

What should be checked in kids and Adults in TB?

Kids - INF-y R1, IL12 beta 1 | Adults - HIV

What are risk factors in prosthetic joint infection?

Rheumatoid arthritis Diabetes Malnutrition Obesity

Why were the obese prophylaxis treatments changed?

Set for 70kg | To stop people from getting inadequate dosing

What is the mechanism of prosthetic joint infection?

Direct inoculation at time of surgery Manipulation of joint at time of surgery Seeding of joint at later time

What are the classifications for early and late prosthetic joint infections?

Early < Month | Late > Month

What is biofilm?

Community of bacteria that are very difficult to penetrate with antibiotics That grow slowly covering the prosthetic joint

What are the pathogens common in prosthetic joint infection?

``` Staph aureus Staph epidermidis Propionibacterium acnes (upper limb) E.coli Pseudomonas ```

How are prosthetic joint infections diagnosed?

Multuple cultures of perioperative tissue (if same organism is present this increases significance) Blood cultures can also be useful CRP Radiology

What is the treatment of prosthetic joint infections?

Removal of prosthetic and cement 6 week therapy Re-implantation of the joint after aggressive antibiotic therapy (Depends on the patient context)

What is the treatment of prosthetic joint infections?

Removal of prosthetic and cement 6 week therapy Re-implantation of the joint after aggressive antibiotic therapy (Depends on the patient context)

How is PVL noticed?

More sick than you expect | Necrotising bacteriaema

What causes pyomyositis?

90% staphylococcal | Can be tropical

What are the 3 types of myositis?

Viral - HIV, HTLV, Influenza, CMW, Rabies, Chikungunya and other arboviruses Fungal Parasites

What is the most common infective cause of seizures?

Taenia (when it cysts in the brain)

What is the causitive organism of tetanus and what is its characteristics?

Clostridium tetani Gram +ve anaerobic rods Spore forming

What does clostridium tetani produce?

Neurotoxin causes spastic paralysis

What is the incubation period for clostridium tetani?

4 days - several weeks

What is shown on culture of clostridium tetani?

Anaerobic gram +ve Terminal drumstick shaped sors Serum and urine toxin assays

What is the treatment of tetanus?

``` Surgical debridement Antitoxin Supportive measures - early intubatiions, beta blockers Antibiotics for 7 to 10 days Penicillin/Metroniadazole Booster Vaccination ```

MSK microbiology 03/10/18 Flashcards

(69 cards)