Microbiology

Question 1

define osteomyelitis

Answer 1

inflammation of bone and medullary cavity, usually located in one of the long bones, unusual sites include pubic symphysis and clavicle

Question 2

presentation of osteomyelitis

Answer 2

five features of inflammation

Question 3

diagnosis of osteomyelitis

Answer 3

• bone biopsy (GOLD standard)
• wound swabs/blood cultures are not always diagnostic
• cross sectional imaging may be helpful e.g. CT, MRI

Question 4

management of osteomyelitis

Answer 4

await lab results, do not treat empirically (UNLESS SEPSIS)

surgery to remove infected tissue, drain and debride (takes 6 weeks to be covered by vascularised tissue)

Question 5

causes of osteomyelitis

Answer 5

open fractures
diabetes
vascular insufficiency
haematogenous spread
prosthetic join infection

Question 6

common organism in open fracture osteomyelitis

Answer 6

staph aureus

Question 7

organisms in PWID osteomyelitis

Answer 7

staph
strep
unusual pathogens e.g. pseudomonas, candida

Question 8

why is dialysis a cause of osteomyelitis?

Answer 8

line high risk of staph colonisation

often co-morbidities including peripheral vascular disease and diabetes

Question 9

what is vertebral osteomyelitis associated with?

Answer 9

epidural or psoas abscess

Question 10

presentation fo vertebral osteomyelitis

Answer 10

insidious pain

tenderness

Question 11

management of vertebral osteomyelitis

Answer 11

drainage

anti-microbial for 6 weeks minimum

Question 12

risk factors for prosthetic joint infection include

Answer 12

RA
diabetes
malnutrition
obesity

Question 13

how can prosthetic joint infections occur?

Answer 13

direct inoculation at surgery

seeding of joint at a later time

Question 14

diagnosis of prosthetic joint infection

Answer 14

multiple perioperative tissues and if the same organism grows from multiple samples this increases significance
blood culture
CRP
radiology

Question 15

what is frequently picked up in perioperative tissue samples in prosthetic joint infection?

Answer 15

staph epidermidis (coagulase negative staph) but are low virulence so are not causative

Question 16

management of prosthetic joint infection

Answer 16

removal of prosthesis

re-implantation after aggressive antibiotic therapy

Question 17

unusual patient groups

Answer 17

• sickle cell osteomyelitis
• Gaucher’s disease
• SAPHO (adults) and CRMO (kids)

Question 18

causative organisms in sickle cell osteomyelitis

Answer 18

staph aureus

salmonella

Question 19

drug of choice for staph aureus

Answer 19

flucloxacillin IV (oral has poor bone penetration- when switching to oral use doxycycline)

Question 20

what to use against staph aureus if penicillin allergic

Answer 20

vancomycin

Question 21

drug of choice for staph epidermidis

Answer 21

vancomycin

Question 22

drug of choice for strep pyogenes

Answer 22

doxycycline

Question 23

drug of choice for gram negatives

Answer 23

clindamycin

Question 24

drug of choice for anaerobes

Answer 24

metronidazole

Question 25

how can septic arthritis be caused?

Answer 25

spread by direct invasion through penetrating wound, other infections e.g. cellulitis), spread from osteomyelitis or haematogenous spread

Question 26

define septic arthritis

Answer 26

inflammation of a joint space caused by infection

Question 27

bacterial causes of septic arthritis

Answer 27

``` staph aureus strep coagulase negative staph (prosthetic joints) neisseria gonorrhoea in sexually active haemophilus influenza in pre-school ```

Question 28

diagnosis of septic arthritis

Answer 28

joint fluid for microscopy, culture and sensitivity blood culture if pyrexial exclude crystals

Question 29

management of septic arthritis

Answer 29

antibodies | surgery

Question 30

viral arthritis causes

Answer 30

alphavirus hep B parvovirus B19 rubella virus

Question 31

define pyomyositis

Answer 31

bacterial infection of skeletal muscle

Question 32

causative organisms of pyomyositis

Answer 32

staph immunocompromised= pseudomonas, beta haemolytic strep and enterococcus clostridial infection possible in contaminated wounds

Question 33

define myositis

Answer 33

diffuse viral infection of muscles

Question 34

causes of myositis

Answer 34

``` HIV, HTLV CMV rabies chikungunya other arboviruses can also be fungal and parasites ```

Question 35

define tetanus

Answer 35

neurotoxin causes spastic paralysis (binds to inhibitory neurones, preventing release of neurotransmitters)

Question 36

cause of tetanus

Answer 36

clostridium tetani (gram +ve anaerobic rods that produce spores- found in soil and gardens)

Question 37

incubation of tetanus

Answer 37

4 days-several weeks

Question 38

presentation of tetanus

Answer 38

locked jaw | muscle spasms

Question 39

diagnosis of tetanus

Answer 39

culture (anaerobic gram +ve and spore is drumstick shaped) | serum and urine toxin assay

Question 40

management of tetanus

Answer 40

surgical debridement antitoxin (preventative vaccine at 2, 3 and 4 months) antibiotics (penicillin and metronidazole) booster vaccine