Microbiology

Question 1

Which colour do gram-positive bacteria stain?

Answer 1

Purple/blue

Question 2

Which colour do gram-negative bacteria stain?

Answer 2

Pink

Question 3

Is staphylococcus gram-positive or negative?

Answer 3

Gram-positive

Question 4

Which staphylococcus bacteria is coagulase positive?

Answer 4

Staph. aureus

golden border in petri dish

Question 5

Which antibiotic is used against staph. aureus?

Answer 5

Flucloxacillin

Question 6

Which toxins can be produced by staph. aureus?

Answer 6

Enterotoxin

SSSST

PVL

Question 7

What is osteomyelitis?

Answer 7

Inflammation of the bone and medullary cavity, usually located in one of the long bones?

Question 8

Which bacteria commonly cause osteomyelitis in newborns and children?

Answer 8

Staph. aureus

Group B strep

Question 9

Which bacteria commonly causes osteomyelitis in adults?

Answer 9

Staph. aureus

Question 10

What is the gold standard investigation for osteomyelitis?

Answer 10

Bone biopsy

Question 11

Which classification system is used in osteomyelitis?

Answer 11

Gustilo Classification

Question 12

Which investigations are used for diabetic foot ulcers?

Answer 12

Plain radiograph

MRI

Question 13

What is the treatment for diabetic foot?

Answer 13

Debridement

Antimicrobials

Question 14

Which antibiotic is used in diabetic foot ulcer?

Answer 14

Flucloxacillin (IV)

MRSA cases = Doxycycline in mild and Vancomycin in moderate-severe cases

Severe cases - Flucloxacillin + Metronidazole

Question 15

Why is oral doxycycline used instead of oral flucloxacillin when switching from IV to oral medication is osteomyelitis?

Answer 15

Flucloxacillin has poor bone penetration

Question 16

Who is at risk of haematogeneous osteomyelitis?

Answer 16

Prepubertal children

PWID

Patients with central lines/dialysis

Elderly

Special conditions (e.g. sickle cell disease)

Question 17

Which bone does Gaucher’s disease typically affect?

Answer 17

Tibia

Question 18

What are the signs and symptoms of vertebral osteomyelitis?

Answer 18

Insidious pain and tenderness

Fever

Raised inflammatory markers

Question 19

How is vertebral osteomyelitis treated?

Answer 19

Drain large paravertebral/epidural abscesses

Antimicrobials for 6 weeks minimum

Question 20

What is Pott’s disease?

Answer 20

Vertebral tuberculosis

Question 21

Is vertebral TB infectious?

Answer 21

No

Question 22

What are some risk factors for infection in prosthetic joints?

Answer 22

Presence of comorbidities (e.g. rheumatoid arthritis, diabetics mellitus, malignancy)

Use of corticosteroids, TNF inhibitors

Prior arthroplasty or prior infection at the surgical site

Prolonged duration of surgery

Postoperative complications (e.g. haemato,a)

Question 23

What is a biofilm?

Answer 23

A microbe-derived sessile community

Characterised by cells that are attached to a substratum, interface or each other.

The cells are embedded in a matrix of extracellular polymeric substance and exhibit an altered phenotype.

Question 24

Which bacteria are msot commonly involved in prosethetic joint infections?

Answer 24

Staph. aureus

Staph. epidermidis

Cuttibacterium acnes (upper limb)

E. coli

pseudomonas aeruginosa

Question 25

How are prosthetic joint infectios diagnosed?

Answer 25

Culture - perioperative tissue Blood culture CRP Radiology

Question 26

How is prosthetic joint infection treated?

Answer 26

Debridement Antibiotics Irrigation Retention of the prosthesis

Question 27

How is septic arthritis treated?

Answer 27

Flucloxacillin (high doses) Less than 5 years old - add Ceftriaxone (for H. influenzae cover)

Question 28

Which bacteria causes septic arthritis?

Answer 28

Staph. aureus

Question 29

Which bacteria commonly causes pyomyositis?

Answer 29

Staphylococcal bacteria

Question 30

What are some risk factors for pyomyositis?

Answer 30

IDU Diabetes Mellitus Contaminated wounds

Question 31

What is pyomyositis?

Answer 31

A primary skeletal muscle abscess. Associated with fever, muscle swelling and pain. More common in tropical and sub-tropical regions.

Question 32

What is myonecrosis?

Answer 32

Acute invasion of healthy tissue that can occur spontaneously or as a result of traumatic injury.

Question 33

What is the treatment for myonecrosis?

Answer 33

Treatment surgery AND Antibiotics ( clindamycin + penicillin for clostridium)

Question 34

Which bacteria causes tetanus?

Answer 34

Clostridium tetani

Question 35

Which type of bacteria are clostridium tetani?

Answer 35

Gram-positive anaerobic rods Spores found in soil, gardens etc.

Question 36

What are the signs/symptoms of tetanus?

Answer 36

Lock jaw Trismus Risus sardonicus Muscle spasm

Question 37

What causes spastic paralysis in tetanus infection?

Answer 37

Neurotoxin release

Question 38

Which investigations are used to diagnose tetanus?

Answer 38

Serum and urine toxin assays

Question 39

How is tetanus treated?

Answer 39

Surgical debridement Antitoxin Supportive measures Antibiotics for 7-10 days ( Penicillin, Metronidazole) Booster vaccination