Skin infection Flashcards
1
Q
What is impetigo?
A
A superficial, contagious, blistering infection of the skin caused by the bacteria Staphylococcus aureus and Streptococcus pyogene
3
Q
What are the different types of impetigo?
A
- Bullous
- Non-bullous
4
Q
What layer of the skin does impetigo affect?
A
Epidermis
5
Q
What is the most common form of impetigo?
A
Non-bullous impetigo - 70% of cases
7
Q
What is bullous impetigo caused by?
A
Staphylococcus - produces exfoliative toxin
8
Q
How do bullae form in impetigo?
A
Toxin that contains serine proteases acting on desmoglein 1. This process allows S. aureus to spread under the s.corneum in the space formed by the toxin, causing the epidermis to split just below the stratum granulosum.
Large blisters then form in the epidermis with neutrophil and, often, bacterial migration into the bullous cavity. In bullous impetigo, the bullae rupture quickly, causing superficial erosion and a yellow crust
9
Q
What is the following?
A
Impetigo
10
Q
What might you see on examination in someone with impetigo?
A
Erosions that have a yellowish to golden crust on an erythematous base, with patchy distribution, often in the peri-oral and peri-nasal area, although they can occur anywhere on the body.
11
Q
What are the main causative agents of impetigo?
A
- Staphylococcus
- Group A B-haemolytic strep
12
Q
What is erysipelas?
A
A distinct form of superficial cellulitis with notable lymphatic involvement and is raised, sharply demarcating it from uninvolved skin
13
Q
What layer of the skin does erysipelas affect?
A
Dermis
14
Q
What causes non-bullous impetigo?
A
Streptococcus pyogenes
15
Q
What are features of erysipelas?
A
- Painful, red area
- Fever
- Regional lymphadenopathy and lymphangitis
- Distinct elevated borders
16
Q
What is the following?
A
Erysipelas
19
Q
How would you manage someone with impetigo?
A
Topical antibiotics
- Flucloxacillin - 7-10 days
- Fusidic acid
Hygeine advice
20
Q
What layers does cellulitis affect?
A
Dermis and subcut tissue
23
Q
What is the cause of erysipelas?
A
Strep. pyogenes
24
Q
What is the following?
A
Ascending lymphangitis
25
Q
What is the following?
A
Cellulitis
26
Q
How would you treat a mild cellulitis empirically?
A
Oral Flucloxacillin or clarythromycin - 7-14 days
27
Q
How would you treat moderate to severe cellulitis?
A
IV Flucloxacillin, switch to oral fluclox/doxycycline
28
Q
What is folliculitis?
A
Pustular infection of a single hair follicle which can occur in clusters typically on head, back buttocks and extremities
30
Q
What are the features of folliculitis?
A
- Circumscribed, pustular infection of a hair follicle
- Up to 5mm in diameter
- Present as small red papules - Central area of purulence that may rupture and drain
32
Q
Where does erysipelas most commonly affect?
A
The face
33
How would you treat erysipelas?
Benzylpenicillin + Flucloxacillin - consider IV if serious
34
What are features of furunculosis?
* **Single hair follicle-associated inflammatory nodule**
* **Extending into dermis and subcutaneous tissue**
* **May spontaneously drain purulent material**
35
What is cellulitis?
An acute spreading infection of the skin with visually indistinct borders that principally involves the dermis and subcutaneous tissue
36
What are carbuncles?
Large abscess involving multiple adjacent hair follicles, which tend to by multiseptated. These may drain spontaneously
37
What are features of carbuncles?
Infection extends to involve multiple furuncles
* Multiseptated abscesses
* Purulent material expressed from multiple sites
39
What organisms are implicated in cellulitis?
* **B-haemolytic streps**
* **Staph. aureus**
40
What are signs of a cellulitis?
* **Pain**
* **Swelling**
* **Warmth**
* **Erythema** - no distinct borders
* **Systemic upset plus fever**
* **Lymphadenopathy/lymphangitis**
41
Where does cellulitis most commonly affect?
Lower legs
47
What is the cause of folliclitis?
S. Aureus
48
What are signs of necrotising fasciiitis?
* **Crepitus**
* **Haemorrhagic bullae**
* **Skin necrosis**
* **Anaesthesia at site of infection**
50
How would you manage someone with necrotizing fasciitis?
* **ABx** - Fluclox + benpen + Gentamicin + Clindamycin
* **Urgent surgical debridement +/- amputation**
51
Where is folliculitis typically found?
Head, back, buttocks and extremities
52
What is furunculosis?
An inflammatory infection of a single hair follicle that extends deep into dermis and subcutaneous tissue. Usually affecting moist hairy areas of body
53
What is the most common cause of furunculosis?
S. aureus
55
What are risk factors for folliculitis?
* **Obesity**
* **Diabetes mellitus**
* **Atopic dermatitis**
* **Chronic kidney disease**
* **Corticosteroid use**
58
Where are carbuncles most commonly found?
* **Back of neck**
* **Posterior trunk**
* **Thigh**
59
Where are features of septic bursitis?
* **Fever**
* **Pain on movement**
* **Peribursal cellulitis**
* **Swelling**
* **Warmth**
60
How would you treat folliculitis?
Topical antibiotics
61
How would you treat a furuncle?
Topical/oral antibiotics
62
How would you manage someone with a carbuncle?
Hospital admission, surgery and IV Abx
63
What are features of infective tenosynovitis?
* **Erythematous fusiform swelling of finger**
* **Pain with extension of finger**
* **Held in a semiflexed position**
* **Tenderness over the length of the tendon sheath**
64
What is necrotising fasciitis?
A life-threatening subcutaneous soft-tissue infection that may extend to the deep fascia, but not into the underlying muscle. The causal organisms may be aerobic, anaerobic, or mixed flora
65
What is staphylococcal scalded sking syndrome?
An illness characterised by red blistering skin that looks like a burn or scald, hence its name staphylococcal scalded skin syndrome.
The scalded skin syndrome is caused by a toxin-secreting strain of S. aureus.
66
What are the main clinical forms of necrotising fasciitis?
* **Type I** - polymicrobial
* **Type II** - monomicrobial infection with Streptococcus pyogenes (group A streptococci)
67
What organisms are commonly involved in type I necrotising fasciititis?
An aerobe and a facultative anaerobe
* **Streptococci**
* **Staphylococci**
* **Enterococci**
* **Gram negative bacilli**
* **Clostridium**
68
What are the majority of superificial skin infections caused by?
* **S. aureus**
* **S. pyogenes**
69
What layers are involved in necrotizing fasciitis?
Infection extends through the fascia but ***_not into the underlying muscle_***, and ***_tracks along fascial planes_*** extending beyond the area of overlying cellulitis
70
What are symptoms of necrotizing fasciitis?
Rapid onset, sequential development of:
* **Severe, unremitting pain around site**
* **Fever**
* **Delerium**
72
How would you diagnose necrotising fasciitis?
Clinical diagnosis
74
What is the overall mortality associated with necrotising fasciitis?
17-40%
75
What would you trat GAS necrotizing fasciitis?
Benzylpenicillin and clindamycin
76
What is pyomyositis?
A bacterial infection of the skeletal muscles which results in a pus-filled abscess. Pyomyositis is most common in tropical areas but can also occur in temperate zones.
77
Where does pyomyositis most commonly occur?
* **Thigh**
* **Calf**
* **Arms**
* **Gluteal region**
* **Chest wall**
* **Psoas muscle**
78
What are predisposing factors to the development of pyomyositis?
* **Diabetes mellitus**
* **HIV/immunocompromised**
* **Intravenous drug use**
* **Rheumatological diseases**
* **Malignancy**
* **Liver cirrhosis**
79
What are features of pyomyositis?
* **Fever**
* **Pain**
* **Woody induration of affected muscle**
80
How would you investigate suspectedd pyomyositis?
* **Clinical diagnosis**
* **Imaging** - CT/MRI
81
How would you manage someone with pyomyositis?
* **Drainage**
* **Antibiotics**
82
What antibiotics would you use for MRSA infection?
* **Vancomycin**
* **Linezolid**
* **Teicoplanin**
* **Daptomycin**
84
How would you investigate someone with septic arthritis?
* **Clinical diagnosis**
* **Fluid aspiration**
85
What is infective tenosynovitis?
Infection of the synovial sheats that surround tendons
86
What are organisms implicated in infective tenosynovitis?
* **S. aureus**
* **Strep**
* **Mycobacteria**
* **Fungi**
88
How would you manage someone with infective tenosynovitis?
* **Abx**
* **Hand surgeon referral**
90
What toxin is implicated in SSSS?
**Exfoliatin** - causes intra-epidermal cleavage at the level of the stratum corneum leading to the formation of large flaccid blisters that shear readily.
91
Who does SSSS most commonly affect?
Children under the age of 5
92
How would you treat staph scalded skin syndrome?
IV fluids and flucloxacillin
93
What is toxic shock syndrome?
A condition of shock caused by bacterial super antigens
94
What organisms cause toxic shock syndrome?
* Staphylococcus
* Streptococcus
95
What toxin is implicated in TSS?
**TSST-1** - causes cytokine release with abrupt onset of fever and shock, with a diffuse macular rash and desquamation of the palms and soles
96
What are features of TSS?
* **Shock**
* **Confusion**
* **Fever**
* **Rash**
* **Diarrhoea**
* **Myalgia**
* **Desquamation of hands and feet**
97
What can be a cause of TSS in females?
Indwelling tampon
98
What is a class I surgical wound?
Clean wound (respiratory, alimentary, genital or infected urinary systems not entered)
99
What is a class II surgical wound?
Clean-contaminated wound (above tracts entered but no unusual contamination)
100
What is a class III surgical wound?
Contaminated wound (Open, fresh accidental wounds or gross spillage from the gastrointestinal tract)
101
What is a class IV surgical wound?
Infected wound (existing clinical infection, infection present before the operation)
102
What is MRSA?
Methicillin-resistnat staphylococcus aureus
103
Where is MRSA most commonly acquired?
Hospital acquired infection
104
What is MRSA resistant to?
Resistant to penicillin and isolated resistance to other β-lactam antibiotics such as meticillin (now rarely used) and flucloxacillin
105
What is MRSA most commonly found in?
Surgical wounds
106
What type of rash do dermatophytes cause?
Ringworm rash
107
What is the following?
Tinea pedis
108
What is the following?
Tinea cruris
109
What are the 3 main types of dermatophytes which cause skin infection?
* **Epidermophyton**
* **Trichophyton**
* **Microsporum**
110
How would you treat dermatophyte infection?
* **Skin** - terbanifine, imidazole (cream)
* **Scalp** - Griseofulvin, terbinafine PO
* **Nails** - Terbinafine PO
111
How would you treat candida infection of the mouth?
Nystatin (oral suspension)
112
How would you treat vaginal candidiasis?
Imidazole cream +/- pessiary
113
What is the following?
Scabies
114
What is the following caused by?
**Sarcoptes scabiei** - causes itchy red papules in webspaces of finger and toes, palms/soles of feet, around wrist and axilla, male genitalia
115
What is the following?
Viral wart
116
What is the most common cause of the following?
HPV
117
What is the following caused by?
HPV
118
What is the cause of the following?
Herpes simplex
119
Where are the most common places for individuals to get viral warts?
* **Fingers**
* **Toes**
* **Plantar surface**
* **Genital**
120
How would you treat an individual with a herptic rash?
* **Cold Sores** - Aciclovir cream shortens attacks
* **Genital wart** - Oral aciclovir
121
What is the following caused by?
Herpes simplex
122
How would you manage the following?
Admit and IV aciclovir
123
What is the cause of shingles?
Reactivation of VZV
124
What can precede an attack of shingles?
Prodromal phase of tingling or pain, which is followed by a painful and tender blistering eruption
125
How are shingles lesions distributed?
Dermatomal distribution
126
How long does a shingles rash last?
2-4 weeks
127
What are complications of shingles?
* **Post-herpetic neuralgia**
* **Ocular disease**
* **Motor neuropathy**
128
What is the following?
Shingles rash in opthalmic nerve distribution
129
How would you manage someone with acute shingles?
* **Pain relief**
* **Protective ointment for rash**
* **If severe**
* Aciclovir for 1 week, or
* Famciclovir for 1 week
* **Oral abx to protect against secondary infection**
130
How would you manage viral warts?
* **Leave them** - resolve spontaneously (and rapidly) within months/years
* **If troubleseome:**
* Regular keratolytic therapy
* ****Cryotherapy + imiquimod
* Topical 5FU
131
What are features of a common viral wart?
* Papules with a rough, papillomatous and hyperkeratotic surface - from 1 mm to larger than 1 cm.
* Arise most often on the backs of fingers or toes, around the nails—where they can distort nail growth—and on the knees.
132
What are features of plantar warts?
**Verrucas**
Tender inwardly growing and painful ‘myrmecia’ on the sole of the foot, and clusters of less painful mosaic warts.
133
What are features of a plane wart?
Plane warts have a flat surface. The most common sites are the face, hands and shins.
134
What is the following?
**Molluscum contagiosum** - lesions are multiple small (1–3 mm) translucent papules which often look like fluid-filled vesicles but are in fact solid. Individual lesions may have a central depression called a punctum. They exhibit the ***_Köbner phenomenon_***
135
What is the following caused by?
Pox virus
136
How would you manage the following?
Consider:
* **Selenium sulphide shampoo**
* **Imidazole cream**
* **Oral intraconazole** - resistant cases
137
What is the following?
**Pityriasis versicolour** - presents most commonly on the trunk with reddish brown scaly macules, which are asymptomatic. In black-skinned individuals (or in whites who are sun-tanned) it more commonly presents as macular areas of hypopigmentation
138
What is norwegian scabies?
Clinical variant of scabies occuring in immunocompromised individuals where huge numbers of mites are carried in the skin - EXTREMELY INFECITOUS
139
How does norwegian scabies present?
* **Not always itchy**
* **Hyperkeratotic crusted lesions, especially on the hands and feet**
* **Can progress such that the patient has a widespread erythema with irregular crusted plaques**
140
How wouldyou manage scabies?
* **1st line** - Permethrin dermal cream
* **2nd line** - Malthoin
141
What is the pathogenesis of scabies?
The female mite digs burrows and lays eggs which hatch larvae. The itching and red rash is thought to be caused by the mites and their products
142
What is the following?
Headlice eggs
143
What are complications of headlice?
* **Dermatitis**
* **Impetigo**
* **Tender swollen lymph nodes**
144
How would you manage headlice?
At least 2 applications of chemical insecticide and/or physical methods:
* **Neurotoxic agents** - Malathion, Carbaryl, phenothrin
* **Non-irritant options** - Dimeticone
* **Hot air**
* **Meticulous combing**
145
What is the species of lice implicated in head lice?
Pediculus humanus/capitis
