Infections

Question 1

What is necortising fascitis

Answer 1

Rpaid destruction of the tissue in limb/genitalia/perineum (fourniers gangrene)

Question 2

Which organisms cause necrotising fascitis

Answer 2

Clostridium pefringens - causes gangrene - if area of inflammation is smoothed –> Crepitus
Group A staphylococci - v aggressive inflammation

Vibrio vulcuficus

Question 3

How does necrotising fascitis present

Answer 3

Redness of limb/perineum/genitalia 
Pain will be disproportionate to spread of erythema
May have areas of localised abscesses 
Skin bullae
cutaneous gangrene 
swelling 
Oedema
Massive discolouration

Question 4

What is going on underneath the skin

Answer 4

Necrosis of muscle tissue

Accumulation of pus - dishwater pus

Question 5

How can it be investigated

Answer 5

Diagnosis should not be delayed - based on clinical suspicion
Tissue biopsy/wound swab - culture and fin abx sensitives of causative organism

Question 6

How is necrotising fascitis treated

Answer 6

Radical surgical debridement - cut any red skin and any browned necrotic muscle tissue
May be better to amputate - shown to have better function - need the opinion of two surgeons
Hyperbaric oxygen chamber - eliminate anaerobic organisms
Broad spectrum abx
Empirical treatment: penicillin, clindamycin, metronidazole and an aminoglycoside e.g. gentamycin
Clostridum -> fluclox/clindamycin
Step series -> benzylpenicillin/clindamycin

Question 7

What is osetomyelitis

Answer 7

infection of bone marrow leading to destruction of bone and necrosis

Question 8

How is the infection able to spread in osetomyelitis

Answer 8

spreads to the cortex and periosteum via haversian canals

once periosteum infected bone undergoes necrosis

Question 9

Which organisms cause osteomyelitis

Answer 9

Staph aureus
H influenzae
Streptococcus species

Question 10

what are the risk factors for osteomyelitis

Answer 10

trauma - open fracture or surgery 
Prosthetics 
Diabetes - ulcer formation 
IV drug use 
Immunosuppression 
TB 
sickle cell anaemia

Question 11

What do x rays show in osteomyelitis

Answer 11

Patchy areas of osteopenia (lytic lesions) and soft tissue swellings
Periosteal reaction and necrosis (7-10 days)
Sequestrum - dead bone
Involucrum - new layer of bone growth outside normal bone, growing out of stripped periosteum

Question 12

What is the definitive test for osetomyelitis

Answer 12

Bone biopsy

Question 13

How is osetomyelitis treated

Answer 13

Debride infected area and wash out with saline
Remove any prosthesis present - biofilm
bone graft to fill hole left by infection or antibiotic implants
4-6 weeks follow up with oral abx - ceftriaxone or penicillins
vanc for MRSA
Hyperbaric o2 therapy for recurrent osteomyelitis

Question 14

Which organisms often cause septic arthritis

Answer 14

Staph aureus

MRSA is on the rise

Question 15

Which abx would you give for septic arthritis

Answer 15

staph - clindamycin or flucloxacillin

Question 16

What happens to the cartilage in septic arthritis if not treated

Answer 16

Pus erodes cartilage

Question 17

How may bacteria get into the joint

Answer 17

Direct means - through injury
Via blood stream - synovial membrane is vascularised
Most often in knee or hip

Question 18

Other than antibiotics how else would you treat septic arthritis

Answer 18

Surgical washout

- flush joint with saline until all pus washed out and no more pus accumulates

Question 19

What is the criteria used to when suspecting septic arthritis in children

Answer 19

Kochers criteria

• inability to weight bear on affected side
• ESR >40
• WCC >12,000 cells/mm3
• Temperature >38.5

1=3%
2= 40%
3=93%
4=99%