Microbiology

Question 1

Treatments of choice for osteomyelitis (2)

Answer 1

• Aggressive debridement

- Antimicrobials (IV)

Question 2

Which % of all open fractures become infected?

Answer 2

Between 3-25%

Question 3

Non-union and poor wound healing can indicate which condition?

Answer 3

Osteomyelitis

Question 4

Common isolate in osteomyelitis

Answer 4

S. aureus

Question 5

Osteomyelitis is only ever spread by direct inoculation. True/false?

Answer 5

False - can be haematogenous.

Question 6

Needle-licking PWID are likely to develop which isolate?

Answer 6

Eikenella corrodens

Question 7

Which % of dialysis patients develop infection?

Answer 7

7%

Question 8

Most common pathogen in dialysis patients’ osteomyelitis?

Answer 8

S. aureus

Question 9

Sickle Cell disease can predispose to osteomyelitis. True/false?

Answer 9

True

Question 10

“A lysosomal storage disorder which can mimic bone crisis” is likely to describe which disease?

Answer 10

Gaucher’s Disease

Question 11

Gaucher’s disease often affects which bone?

Answer 11

Tibia

Question 12

Diabetic / vascular osteomyelitis is often polymicrobial. True/false?

Answer 12

True

Question 13

The first-line investigation for a deep ulcer you suspect to cause osteomyelitis?

Answer 13

Probe-to-bone test + inflammatory markers

Question 14

If there’s a positive probe to bone test in a deep ulcer, what is the next step in diagnosis of osteomyelitis?

Answer 14

Plain radiograph

Question 15

In a deep ulcer which is an osteomyelitis concern, you check radiographs (2nd stage investigation) to find there’s no evidence of osteomyelitis. What’s the next step?

Answer 15

Osteomyelitis unlikely, consider soft tissue infection (2 weeks treatment)

Question 16

If a radiograph is consistent with osteomyelitis, BUT not characteristic, what’s the next line of studies?

Answer 16

MRI

Question 17

What is the definitive/ final investigation for diagnosis of osteomyelitis?

Answer 17

Bone biopsy

Question 18

Haematogenous osteomyelitis presents in which 3 groups?

Answer 18

• Prepubertal children
• PWID
• Central lines/ dialysis patients

Question 19

Urogynae procedures can predispose to which form of osteomyelitis?

Answer 19

Osteitis pubis

Question 20

Neck surgery can predispose to which form of osteomyelitis?

Answer 20

Clavicle osteo

Question 21

Which pathogens are common in sickle cell osteomyelitis? (2)

Answer 21

• Salmonella

- S. aureus

Question 22

Gaucher’s disease is always infectious.

Answer 22

False

Question 23

Plain X-rays are useful in diagnosing bone infection. True/false?

Answer 23

False

Question 24

Which imaging modality could be useful in diagnosing bone infection?

Answer 24

Technetium bone scan (detects osteoblast activity)

Question 25

Most common cause of acute osteomyelitis (1)

Answer 25

-Post trauma or open ounds

Question 26

Most common organism causing acute osteomyelitis (2)

Answer 26

1) S. aureus | 2) May also be haemophillus in children

Question 27

Does vertebral OM always present with fever?

Answer 27

No, only 50% of cases do

Question 28

What makes SAPHO/CRMO different from regular OM?

Answer 28

They are multifocal

Question 29

SAPHO is adults/kids?

Answer 29

Adults

Question 30

In OM, empiric antibiotics should be used ASAP. T/F?

Answer 30

False, wait until suggestive results

Question 31

How is vertebral OM treated? (4)

Answer 31

1) Drain abscess 2) Antibiotics for 6 weeks 3) Monitor ESR (should decrease by >50%) 4) Repeat MRI if ESR raises, pain increases or new symptom

Question 32

Skeletal TB is AKA

Answer 32

Pott's Disease

Question 33

Skeletal TB is often symptomatic, T/F?

Answer 33

False - often asymptomatic

Question 34

Do skeletal TB / Pott's Disease patients commonly have pulmonary TB?

Answer 34

Less than 50% have pulmonary TB

Question 35

If prosthetic OM develops <1 month from insertion of prosthesis, what was the likely source?

Answer 35

Wound sepsis

Question 36

If prosthetic OM develops >1 month from insertion of prothesis, what is the likely source?

Answer 36

Intraoperative

Question 37

PVL treatment

Answer 37

Fluclox

Question 38

What is a S. epidermidis virulence factor in OM?

Answer 38

Slime

Question 39

Pyomyositis describes what kind of infection

Answer 39

Pus-forming muscle infection

Question 40

Septic arthritis common cause

Answer 40

S. aureus

Question 41

How is septic arthritis diagnosed? (3)

Answer 41

1) Joint aspirate 2) C&S 3) Blood cultures if pyrexial (30-60% sensitive)

Question 42

What's the standard treatment choices & route for acute OM or septic arthritis?

Answer 42

Flucloxacillin IV 2g QDS for 2 weeks, PO antibiotics for maximum 4 weeks

Question 43

What's the antibiotic treatment & route for chronic OM?

Answer 43

PO flucloxacillin

Question 44

What's the antibiotic treatment & route for MRSA-OM?

Answer 44

IV vancomycin

Question 45

Tetanus gram stain profile & growth condition

Answer 45

Gram positive rod, strict anaerobe

Question 46

"Drumstick shaped bacteria" is code for

Answer 46

C. tetani

Question 47

Treatment of tetanus (4)

Answer 47

1) Antitoxin 2) Surgical debridement 3) Supportive antibiotics (penicillin, metronidazole) 4) Booster toxoid vaccine

Question 48

Is the tetanus vaccine live?

Answer 48

No, it's a toxoid

Question 49

Which book is recommended for vaccine advice in children?

Answer 49

The Green Book

Question 50

Children with skeletal TB should be offered which test? What should adults be offered?

Answer 50

Children -> IFNgamma assay | Adults -> HIV test

Question 51

What are the cardinal signs of inflammation?

Answer 51

``` Rubor (redness) Calor (heat) Dolor (pain) Tumour (swelling) Functio lasea (loss of function) ```

Question 52

What bloods are useful in OM diagnosis?

Answer 52

CRP, PV, WBC count, blood cultures, ESR

Question 53

Technetium bone scan shows what kind of activity?

Answer 53

Osteoblastic

Question 54

What organism causes OM in children?

Answer 54

Haemophillus

Question 55

How is pus in OM treated?

Answer 55

Lancing, drainage

Question 56

What is a Brodie's abscess?

Answer 56

An abscess that develops within bone due to a deep OM. The outer bone dies and acts as sequestrum, protecting the infection.

Question 57

What is a complication of Brodie's abscess?

Answer 57

Involucrum formation.

Question 58

What is involucrum?

Answer 58

A layer of bone which forms external to the periosteum of a bone with a deep OM

Question 59

Are blood tests useful in diagnosis of COM?

Answer 59

No

Question 60

Cellulitis common causative organisms?

Answer 60

Staphs & streps

Question 61

How is cellulitis treated? (NHST antibiotic man)

Answer 61

Flucloxacillin 1g QDS, IV/PO for 7 days

Question 62

"Bony sinus" is a keyword for what

Answer 62

A DEEP bone infection

Question 63

2-step surgery is how successful in controlling infection in OM?

Answer 63

80-90%