Skin and soft tissue infections Flashcards

1
Q

What us impetigo?

A

Superficial highly infectious skin infection

Multiple vesicular lesions on an erythematous base

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2
Q

What is highly suggestive of impetigo?

A

Golden crust

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3
Q

What are the causative organisms of impetigo?

A

Most common= staph aureus

Less commonly= strep pyogens

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4
Q

Where does impetigo occur?

A

Exposed areas e.g. face, extremities, scalp

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5
Q

What are the predisposing factors of impetigo?

A

Skin abrasions
Minor trauma or burns
Por hygiene

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6
Q

What is the treatment of impetigo?

A

Small areas= topical antibiotics

Large areas= topical treatment an oral antibiotics

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7
Q

What is erysipelas?

A

Infection of upper dermis

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8
Q

What are the clinical features of erysipelas?

A

Painful red area, no central clearing
Associated fever
Regional lymphadenopathy and lymphangitis
Distinct elevated borders

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9
Q

What is the commonest cause of erysipelas?

A

Strep pyogenes

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10
Q

Where is erysipelas most often seen?

A

Legs

Areas of existing lymphedema, venous stasis, obesity, paraparesis, diabetes mellitus

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11
Q

What is the treatment of erysipelas?

A

Combination of anti-staph and anti-strep antibiotics

IV antibiotics if severe

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12
Q

What is cellulitis?

A

Diffuse skin infection involving deep dermis and subcutaneous fat

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13
Q

What are the clinical features of cellulitis?

A

Spreading erythematous area with no distinct borders
Fever
Regional lymphadenopathy and lymphangitis

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14
Q

What are the most common causative organisms of cellulitis?

A

strep pyogenes

staph aureus

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15
Q

What are the predisposing factors for cellulitis?

A

DM
Tinea pedis
Lymphoedema

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16
Q

What is the treatment of cellulitis?

A

Combination of anti-staph and anti-strep antibiotics

IV antibiotics if severe

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17
Q

What are the hair associated infections?

A

Folliculitis
Furuncles
Carbuncles

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18
Q

What are the clinical features of folliculitis?

A

Circumscribed pustular infection of hair follicle
Up to 5mm in diameter
Small red papule
Central area of purulence that may rupture and drain

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19
Q

Where is folliculitis found?

A

Head
Back
Buttocks and extremities

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20
Q

What is the most common causative organisation of folliculitis?

A

Staph aureus

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21
Q

What is the treatment of folliculitis?

A

None or topical antibiotics

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22
Q

What are furuncles commonly referred to as?

A

Boils

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23
Q

What are the clinical features of furuncles?

A

Single hair follicle associated with inflammatory nodule

Extending to dermis and subcutaneous tissue

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24
Q

Where do furuncles occur?

A

Moist, hairy, friction prone areas

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25
Q

What is the most common causative organism of furuncles?

A

Staph aureus

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26
Q

What are the risk factors for furuncles?

A

Obesity
DM
CKD

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27
Q

What is the treatment of furuncles?

A

None
Topical antibiotics
If not improving, oral antibiotics

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28
Q

When do carbuncles occur?

A

Infection extends to involve multiple follicles

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29
Q

Where do carbuncles often occur?

A

Back of neck, posterior trunk or thigh

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30
Q

What are the clinical features of carbuncles?

A

Multiseptated abscesses

Purulent material may be expressed

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31
Q

What is the treatment of carbuncles?

A

Often require hospital admission, surgery and IV antibiotics

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32
Q

What are the predisposing factors for necrotising fasciitis?

A

DM
Surgery, trauma
Peripheral vascular disease
Skin popping

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33
Q

What are the types of necrotising fasciitis?

A

Type I- missed infection, typically strep, staph or enterococci
Type II- mono microbial, associated with strep pyogenes

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34
Q

What are the clinical features of necrotising fasciitis?

A

Rapid onset
Sequential development of erythema, extensive oedema and severe pain
Haemorrhagic bullae, skin necrosis and crepitus may develop
Anaesthesia at site highly suggestive

35
Q

What are the systemic features associated with necrotising fasciitis?

A
Fever
Hypotension
Tachycardia
Delirium
Multiorgan failure
36
Q

What is the treatment of necrotising fasciitis?

A

Surgical review mandatory

Broad spectrum antibiotics- flucloxacillin, gentamicin, vancomycin

37
Q

What is pyomyositis?

A

Purulent infection deep within striated muscle, often manifesting as an abscess

38
Q

What are the common sites for pyomyositis?

A
Thigh, calf
Arms
Gluteal region
Chest wall
Psoas muscle
39
Q

What are the clinical features of pyomyositis?

A

Fever
Pain
Woody induration of affected muscle

40
Q

What can untreated pyomyositis lead to?

A

Septic shock and death

41
Q

What are the predisposing factors for pyomyositis?

A

DM
Immunocompromised
IV drug abuse
Malignancy

42
Q

What is the most common causative organism of pyomyositis?

A

Staph aureus

43
Q

What are the possible causative organisms for pyomyositis?

A

Gram + and -
TB
Fungi

44
Q

What investigations are done for pyomyositis?

A

CT/MRI

45
Q

What is the treatment of pyomyositis?

A

Grainage

Antibiotics

46
Q

What is septic bursitis?

A

Small bursae- small sac like cavities containing fluid and lined by synovial membrane
Located subcutaneously between bony prominences or tendons

47
Q

Where is septic bursitis most often found?

A

Patellar or olecranon regions

48
Q

What are the predisposing factors for septic bursitis?

A

DM
IV drug abuse
Immunosuppression
Alcoholism

49
Q

What are the clinical features of septic bursitis?

A

Peribursal cellulitis, swelling, warmth
Fever
Pain on movement

50
Q

How is septic bursitis diagnosed?

A

Aspirate fluid- not always done

51
Q

What is the most common causative organism of septic bursitis?

A

Staph aureus

52
Q

What are the possible causative organisms of septic bursitis?

A

Staph aureus
Gram -
Mycobacteria
Brucella

53
Q

What is the treatment of septic bursitis?

A

Antibiotics

54
Q

What is infectious tenosynovitis?

A

Infection of synovial sheets surrounding tendons

55
Q

What are the most common locations for infectious tenosynovitis?

A

Flexor muscle associated tendons

Tendon sheets of the hand

56
Q

What is the most common inciting event for infectious tenosynovitis?

A

Trauma

57
Q

What are the causative organisms of infectious tenosynovitis?

A

Staph aureus and strep most common

Chronic due to mycobacteria or fungi

58
Q

What are the clinical features of infectious tenosynovitis?

A

Erythematous fusiform swelling of the finger
Held in semiflexed position
Tenderness over length pf tendon sheet and pain with extension are classic

59
Q

What is the treatment of infectious tenosynovitis?

A

Empiric antibiotics

Hand surgeon to review

60
Q

What are toxin mediated syndromes often due to and why?

A

Superantigens- they can bypass normal immune system and attach directly to T cell receptors

61
Q

What are the most common causative organisms of toxin mediated syndromes?

A

Staph aureus

Strep pyogens

62
Q

What are the causes of toxic shock syndrome?

A

High absorbency tampons- most common
Staph aureus skin infection
Strep

63
Q

What are the diagnostic criteria for staph aureus toxic shock syndrome?

A
Fevere
Hypotension
Diffuse macular rash
At least 3 organs involved
Isolation of staph aureys
64
Q

What is strep in toxic shock syndrome associated with?

A

Deep seated infections and high mortality

65
Q

What is the treatment of strep causing toxic shock syndrome?

A

Urgent surgical debridement of infected tissues

66
Q

What is the treatment of toxic shock syndrome?

A
Remove offensive agent
IV fluids
Inotropes
Antibiotics- v high dose
IV immunoglobulins
67
Q

What causes staphylococcal scalded skin syndrome?

A

Particular strain of staph aureus producing exfoliative toxin A or B

68
Q

What are the clinical features of staphylococcal scalded skin syndrome?

A

Widespread bullar and skin exfoliation

Usually in children

69
Q

What is the treatment of staph scalded skin syndrome?

A

IV fluids and antimicrobials

70
Q

What is Panton-Valentin leucocidin toxin?

A

Toxin that can be transferred from one strain of staph aureus to another
Can cause haemorrhagic pneumonia

71
Q

What are the clinical features of Panton-Valentin leucocidin toxin?

A

Tends to affect children and young adults

Recurrent boils which are difficult to treat

72
Q

What is the usual progression of IV catheter associated infections?

A

Local inflammation

Progress to cellulitis and even necrosis

73
Q

What is commonly associated wth IV catheter associated infections?

A

Bacteraemia

74
Q

What are the risk factors for IV catheter associated infections?

A

Cannula in situ >72 hours

Cannula in lover limb

75
Q

What is the causative organisms of IV catheter associated infections?

A

Staph aureus

76
Q

How are IV catheter associated infections diagnosed?

A

Clinical or positive blood diagnosis

Echo for complications

77
Q

What is the treatment of IV catheter associated infections?

A

Remove cannula

14 days antibiotics

78
Q

What are the types of surgical site infection?

A

Class I= clean wound, systems not entered
Class II= clean contaminated wound, no unusual contamination
Class III= Contaminated wound
Class IV= infected wound

79
Q

What are the possible causative bacteria of a surgical site infection?

A
Staph aureus
Staph, strep and enterococci
Fungi
Anaerobes
E. coli
Pseudomonas aeruginosa
80
Q

What are the personal risk factors for surgical site infection?

A
DM
Smoking
Obesity or malnutrition
Steroid use
Staph aureus colonisation
81
Q

What are the procedural risk factors for surgical site infection?

A

Shaving site prior evening
Improper pre-op skin prep
Improper antimicrobial prophylaxis
Break in sterile technique

82
Q

How is surgical site infection diagnosed?

A

Pus/tissue culture- deep if possible

83
Q

What is the treatment of surgical site infection?

A

Antibiotics