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Year 3 Medicine Block > INFECTIOUS DISEASES: Skin and joint infections > Flashcards

INFECTIOUS DISEASES: Skin and joint infections Flashcards

1
Q
A
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2
Q

What is osteomyelitis?

A

Inflammation of bone and bone marrow, usually caused by bacterial infections

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3
Q

Most common bacteria causing osteomyelitis?

A

Staphylococcus aureus

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4
Q

Risk factors for developing osteomyelitis?

A

Open fractures
Orthopaedic operations - esp w prosthetic joints
DM - esp w diabetic foot ulcers
Peripheral arterial disease
IV drug use
Immunosuppression

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5
Q

Presentation of osteomyelitis?

A

Fever

Gangrene
Pain and tenderness
Erythema
Swelling

Non-specific - w fever, lethargy, nausea and muscle aches

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6
Q

Investigations to do for suspected osteomyelitis?

A

MRI - best for establishing dx

XR - not good in early disease. Signs on XR = periosteal reaction, localised osteopenia, destruction of bone

FBC - raised WCC,
CRP, ESR

Blood cultures - causative organism and find abx sensitivity.

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7
Q

Management for osteomyelitis?

A

Surgical debridement of infected bone and tissues
ABx therapy- 4-6 weeks or 3-6 months in chronic osteomyselitis
If in prosthetic joint = prosthetic replacement surgery.

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8
Q

BNF recommendation for abx therapy of acute osteomyelitis?

A

6 weeks flucloxacillin +/- Rifampicin or fusidic acid for first 2 weeks

Alternative of flucloxacillin = Clindamycin. If MRSA related = vancomycin or teicoplanin

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9
Q

When is staph aureus likely to cause pneumonia?

A

After influenza

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10
Q

What causes diabetic foot disease?

A

secondary to neuropathy and peripheral artery disease

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11
Q

Why is diabetes a RF for peripheal arterial disease?

A

diabetes is RF for both microvascular and macrovascular ischaemia

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12
Q

Presentation of diabetic foot infection?

A

Neuropathy: loss of sensation

Ischaemia: lack of foot pulses, reduced ABPI, intermittent claudication

Complications: calluses, ulceration, cellulits, gangrene, osteomyelitis

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13
Q

What is low risk for diabetic foot disease?

A

No deformity, just calluses alone

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14
Q

What is moderate risk for diabetic foot disease?

A

deformity or
• neuropathy or
• non-critical limb ischaemia

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15
Q

What is high risk for diabetic foot disease?

A
  • Previous ulceration,
  • previous amputation,
  • on RRT,
  • neuropathy + non-critical limb ischaemia,
  • neuropathy + callus AND/OR defomity,
  • non-critical limb ischaemia + callus AND/OR deformity
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16
Q

What is ankle brachial pressure index?

A

ratio of systolic BP in the lower legs to arms

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17
Q

What are the interpretations of ABPI?

A

> 1.2: may indicate calcified, stiff arteries. This may be seen with advanced age or PAD

  1. 0 - 1.2: normal
  2. 9 - 1.0: acceptable

< 0.9: likely PAD. Values < 0.5 indicate severe disease which should be referred urgently

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18
Q

What is charcots arthropathy?

A

Bones in the foot become weak–> dislocations and fractures–> changes shape of foot/ ankle

Presents with 6Ds- destruction, deformity, degeneration, dislocation, dense bones and debris)

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19
Q

Define Cellulitis

A

Infection of subcutaeneous tissues and dermis

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20
Q

If cellulitis extends over a joint worry there might be___1____

___2____( ortho infection) may present as cellulitis

A

If cellulitis extends over a joint worry there might be___septic arthritis____

__Osteomyelitis___(ortho infection) may present as cellulitis

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21
Q

Key in cellulitis is a __1___ in the skins barrier for pathogens to enter.

A

1 Breakdown

bacteria need a point of entry

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22
Q

Give examples of how skin barrier may be broken to allow bacteria to enter and cause cellulitis

A

IV drug ucer infection around venepuncture

skin trauma

eczematous skin

fungal nail infections / athletes foot (cracks between toes)

ulcers

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23
Q

Who is susceptible to get cellulitis?

A
  • DM - hyperglyacemia
  • DM with Peripheral neuropathy - cant feel trauma
  • Obesity - pressure sores/immobility
  • IV drug users - infection / abscess around point of injection
  • PAD - poor blood flow for healing and tendancy to ulcerate
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24
Q

What systemic features might point to bacteraemia rather than local infection in cellulitis?

A

fevers

sweats

rigors

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25
How does cellulitis present ? (to look at)
Erythema (red discolouration) Warm or hot to touch Tense Thickened Oedematous Bullae (fluid-filled blisters) A golden-yellow crust can be present and indicate a staphylococcus aureus infection
26
Who is susceptible to MRSA cellulitis infection?
Recent hopsital admission and length of their stay Ask: has MRSA screening been done? results please
27
What are the bacteria causes of cellulitis ?
Staphylococcus aureus Group A Streptococcus (mainly streptococcus pyogenes) Group C Streptococcus (mainly Streptococcus dysgalactiae) MRSA
28
Compare the gram stain morphology of Staphylococcus and Streptococcus
Staph - clusters of gram +ve cocci Strep - chains of gram +ve cocci
29
Cellulitis - if there is a hx of trauma with skin penetratio what immunisation status must be checked?
Tetanus consider immunisation
30
If cellulitis errythema extends over a joint what do you need to assess?
* Range of movement of joint * Septic Arthritis -pain restricts * Osteomyelitis LL - weight bearing reduced * Time course * start on joint or spread to joint? * Prosthics * metalwork / recent arthroscopy
31
1. What is a lifethreatening complication of cellulitis? 2. What would you seen on plain Xray for the above?
1. Necrotising fascitis 2. Xray - may see gas bubbles within tissues
32
1. What are two differencials for an errythematous, swollen LL? 2. Can they co-exist?
1. Cellulitis / DVT 2. Yes - think elderly immobile woman with infected venous ulcers
33
What bedside investigation would you do for pt with suspected cellulitis and why?
Diabetic: BM - hyperglycaemia Non Diabetics: fasting glucose ASK : Is sliding scale of insulin needed for better glycaemic control?
34
Cellulitis - how should you examine the skin?
Note distribution and extent of errythema Draw around at admission - judge extent Broken skin? check between toes Temperature difference palpate local lymphadenopathy
35
If cellulitis includes joint - how examine?
Palpate for bony tenderness Feel for effusioon Assess passive and active range of movement
36
Cellulitis - if ulcers present how to examine?
Is any bone visible ? Describe ulcer (slough, exudate, necrotic tissue, margins, depth) Metal probe to see if can reach bone - indication of bony involvement
37
What lab investigations for suspected cellulitis and why?
Blood * FBC - raised WCC (neutrophilia in bacterial) * CRP * Blood cultures - organism and sensitivities Other * Abscess I&D aspiration - bacterial cause * Joint fluid aspiration - microscopy and culture - organism * Deep bone biopsy - debridement see if osteomyelitis * Wound swab
38
What imaging for suspected cellulitis?
Plain Xray / MRI - look for joint destruction in septic arthritis and changes associated with osteomyelitis
39
Treatment for cellulitis?
1st line - IV / oral flucloxacillin Allergy: IV clarithromycin or erythromycin if pregnant
40
What is the classification for severity of cellulitis?
Eron Classification
41
Outline Eron classification for cellulitis
Class 1 – no systemic toxicity or comorbidity Class 2 – systemic toxicity or comorbidity Class 3 – significant systemic toxicity or significant comorbidity Class 4 – sepsis or life-threatening
42
What are some differencials for cellulitis ( BMJ best practice)
**Necrotising fascitis** - pain ++ / necrotic bulous changes/ crepitus **Thrombophlebitis** (superficial) - tender palpable cord along vein (recent catheter) **DVT**- previous DVT/ hypercoag/immobile **Gout** - urate, knee, 1st metatarsopharangeal **Lyme disease** - ticks **Dermamtitis -** demarcated/pruritis/ Hx **Fixed drug eruption -** Hx rxn, well demarcated, itching burning, lips/genitals involved
43
At which stages of Eron classification would you admit for IV AB?
1. If Eron stage 3 or 4 (toxic, co-morbidities ++, septic) 2. frail, very young or immunocompromised patients.
44
Causative organism(s) in Type 1 necrotising fasciitis?
Mixed organisms - aerobes and anaerobes.
45
Pts with _______ what condition? _____ most commonly get type 1 necrotising fasciitis post surgery?
Pts with diabetes most commonly get type 1 necrotising fasciitis post surgery
46
Difference between Cellulitis and Erysepilas in terms of where it affects the body?
Erysipelas - more superfical - epidermis and dermis Cellulitis - dermis and subcut tissue
47
Necrotising fasciitis can be classified according to the causative organism: Type 1 is caused by ____________ (often occurs post-surgery in diabetics). This is the most common type Type 2 is caused by \_\_\_\_\_\_\_\_\_\_
Type 1 is caused by mixed anaerobes and aerobes (often occurs post-surgery in diabetics). This is the most common type Type 2 is caused by Streptococcus pyogenes
48
Which organism most commonly causes erysipelas ? compare to celluitis
**Erysipelas** - Streptoccous pyogenes (group A beta -haemolytic) **Cellulitis** - Staphloccoccus aureus is most common
49
Risk factors for necrotising fasciitis?
IV drug use Immunosupression Diabetes mellitus - especially if being treated with SGLT-2 inhbitors Skin factors: recent trauma, burns or soft tissue infections
50
Where does Erysipelas commonly occur and who does it usually affect ?
**Where?** Most commonly on face - cheeks and periorbitally **Who?** often children / elderly / immunocompromised
51
Presentation of necrotizing fasciitis?
Acute onset Pain at affected site on skin - pain out of proportion to physical features Swelling at affected site Erythema at afected site Rapidly worsening cellulitis Tenderness over infected tissue - even with light touch Skin necrosis, gas gangreen, dusky - late signs Fever and tachycardia - late signs or absent
52
Management of necrotising fasciitis?
Urgent surgial referral debridement IV abx (broad spec e.g meropenem).
53
Define necrotising fasciitis
Necrotizing fasciitis — a destructive and rapidly progressive soft tissue infection that involves the deep subcutaneous tissues and fascia (and occasionally muscles), which is characterized by extensive necrosis and gangrene of the skin and underlying structures (from NICE)
54
What is Septic Arthritis ?
Infection of the joint and synovial fluid
55
What organsims cause septic arthritis?
Staphloccus aureus (most common cellulitis) Strep pyogenes Haemophilus influenzae type B (\<5yrs / non working spleen) Strep pneumoniae (no spleen / hyposplensim) Mycobaterium tuberculosis (immunosuppressed TB in body)
56
Briefly outline the pathophsyiology of septic arthritis
Results from either direct bacterial invasion from overlying cellutlis or osteomyelitis. Can also result from haemotoligcal spread from bacteraemia. Cabn occur following surgery e..g total hip replacement
57
What are the clincial features of septic arthritis?
Hot Swollen Tender joint Reduced rang of movement (active and passive) due to pain Fever (more likely with haematological spread) (NOTE: TB septic arthtirits can get COLD joint!)
58
What are some RF for septic arthritis (BMJ BP)
OA / RA low socioeconomic status Prosthetic Joint \>80 yrs Immunosuppressed (HIV/diabetes/ alcohol misuse) concurrent infection ulcers recent joint surgery interarticular injections
59
What investigations would you do for septic arthritis?
Joint aspiration microscopy, sensitivity and culutre WCC count of aspirate Blood cultures CRP / ESR / WCC U&Es LFTs
60
How treat septic arthritis
THINK SEPSIS - start sepsis 6 Flucloxacillin Penicillin allergic - Clindamycin refer to Ortho for surgical washout if severe/ prosthetic joint removal
61
What are some complications of septic arthritis
Damange to synovium and cartilage - osteomyelitis and arthritis sepsis death

Year 3 Medicine Block (56 decks)

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