Cutaneous infection & infestation (1) Flashcards
(50 cards)
1
Q
What are commensal bacteria on the skin?
Give examples
A
Commensal bacteria → present on the skin but not causing a disease
- staphylococci
- micrococci
- corynebacteria
- propionibacteria
2
Q
Is Staphylococcus Aureus pathogenic or commensal?
A
Staph Aureus
- always regarded as pathogenic
- may be commensal
- disease associated with: direct invasion of the epidermis, hair follicle, production of toxin
3
Q
Is Streptococcus Pyogens pathogenic or commensal?
A
Streptococcus Pyogens
- group A streptococcus
- always pathogenic
- acute onset and rapid spread
- may co-infect with staphylococcus
4
Q
Spot diagnosis
A
Impetigo
- a superficial bacterial skin infection usually caused by either Staphylcoccus aureus or Streptococcus pyogenes
- It can be a primary infection or a complication of an existing skin condition such as eczema (in this case), scabies or insect bites
- common in children, particularly during warm weather
5
Q
Location of the lesions in impetigo
A
The infection can develop anywhere on the body but lesions tend to occur on the face, flexures and limbs not covered by clothing
6
Q
Spread of impetigo
A
Spread is:
- by direct contact with discharges from the scabs of an infected person
- The bacteria invade skin through minor abrasions and then spread to other sites by scratching
- Infection is spread mainly by the hands, but indirect spread via toys, clothing, equipment and the environment may occur
- incubation period is between 4 to 10 days
7
Q
Spot diagnosis
A
Impetigo
8
Q
Features of impetigo
A
- ‘golden’, crusted skin lesions typically found around the mouth
- very contagious
9
Q
Management of impetigo
A
Limited, localised disease
- topical fusidic acid is first-line
- topical retapamulin is used second-line if fusidic acid has been ineffective or is not tolerated
- MRSA is not susceptible to either fusidic acid or retapamulin. Topical mupirocin (Bactroban) should, therefore, be used in this situation
Extensive disease
- oral flucloxacillin
- oral erythromycin if penicillin-allergic
- children should be excluded from school until the lesions are crusted and healed or 48 hours after commencing antibiotic treatment
10
Q
Antibiotics to cover streptococcus and staphylococcus
A
- Penicillins: Flucloxacillin
- macrolides: erythromycin, clarithromycin
- Trimethoprim
- Tetracycline
11
Q
Sore, itchy arms
Diagnosis?
A
Impentigenous eczema
(infected eczema with impetigo)
- Treat eczema + infection together
- Treat with steroids + antibiotics (Flucloxacillin)
12
Q
Spot diagnosis
A
Folliculitis
13
Q
Spot diagnosis
A
Folliculitis
- due to staph aureus
14
Q
Management of folliculitis
A
Management:
- Short course: Flucloxacillin or clarithromycin
- Chronic: longer course (3-months) of tetracycline antibiotics e.g. doxycycline, lymecycline
15
Q
Spot diagnosis
A
Ecthyma
- a skin infection → stapho-strep
- crusted sores beneath which ulcers form
- it’s a deep form of impetigo, as the same bacteria causing the infection are involved
Management: 3-weeks of clarithromycin
16
Q
Spot diagnosis
A
Ecthyma
(staph-strep infection)
17
Q
Spot diagnosis
A
Cellulitis
18
Q
What’s cellulitis? (pathophysiology)
A
Cellulitis is a term used to describe an inflammation of the skin and subcutaneous tissues, typically due to infection by Streptococcus pyogenes or Staphylcoccus aureus.
19
Q
Features of cellulitis
A
- commonly occurs on the shins
- erythema, pain, swelling
- there may be some associated systemic upset such as fever
20
Q
Criteria for admission of a patient with cellulitis
A
Eron classification → to guide who needs to be admitted
Admit for IV antibiotics the following patients:
- Has Eron Class III or Class IV cellulitis
- Has severe or rapidly deteriorating cellulitis (for example extensive areas of skin)
- Is very young (under 1 year of age) or frail
- Is immunocompromized
- Has significant lymphoedema
- Has facial cellulitis (unless very mild) or periorbital cellulitis
The following is recommend regarding Eron Class II cellulitis:
Admission may not be necessary if the facilities and expertise are available in the community to give intravenous antibiotics and monitor the person
21
Q
Management of cellulitis
A
- flucloxacillin as first-line for mild/moderate cellulitis
*Clarithromycin, erythromycin (in pregnancy) or doxycyline is recommended in patients allergic to penicillin
severe cellulitis → co-amoxiclav, cefuroxime, clindamycin or ceftriaxone
22
Q
Is cellulitis bilateral or unilateral?
A
Almost always unilateral
23
Q
Spot diagnosis?
A
Erysipelas
- streptococcal cellulitis
- tends to be unilatera/on the face
- pt may be systemically unwell
- Management: antibiotics
24
Q
Spot diagnosis
A
Staphylococcal scalded skin syndrome
25
What's ***SSSS***?
**Staphylococcal scalded skin syndrome** (SSSS)
* serious skin infection
* caused by the **Staphylococcus** aureus
* toxins from staph (exfoliating)
* usually in children
**Management:** IV antibiotics + fluids + analgesia
\*doesn't scar
\* usually outcome is good if treated
26
Conditions associated with sensitivity to streptococcal antigen
* erythema nodosum
* guttate psoriasis
* vasculitis (Henoch-Schonlein Purpura)
* glumerulonephritis
27
Hx:
* Pt brought in by ambulance
* Low BP, temperature unwell
* septic shock-like picture
What's the diagnosis?
Necrotising fascitis
28
Classification of ***nerotising fascitis***
It can be classified according to the causative organism:
* **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***
29
Features of ***necrotising fascitis***
* acute onset
* painful, erythematous lesion develops
* often presents as rapidly worsening cellulitis with pain out of keeping with physical features
* extremely tender over infected tissue
30
Management of necrotising fascitis
* urgent surgical referral debridement
* intravenous antibiotics
31
Spot diagnosis
Herpes simplex virus (cold sore)
Caused by: ***HSV-1***
Management: ***topical aciclovir***
32
Spot diagnosis
Eczema Herpeticum
33
What's ***Eczema Herpeticum***?
It's management
***Eczema herpeticum***
* severe primary infection of the skin by herpes simplex virus 1 or 2
* more commonly seen in children with atopic eczema
* often presents as a rapidly progressing painful rash
**Management:** As it is potentially life-threatening children should be admitted for IV aciclovir
\*sometimes antibiotics are required if also infected with bacteria
34
Describe lesion in eczema herpeticum
* monomorphic punched-out erosions (circular, depressed, ulcerated lesions)
* usually 1–3 mm in diameter
35
Spot diagnosis
Varicella-Zoster - chicken pox
**Chickenpox** is caused by primary infection with varicella zoster virus
\*Shingles is a reactivation of the dormant virus in dorsal root ganglion
36
Spread and infectivity of chicken-pox
* Chickenpox is highly infectious
* spread via the respiratory route
* can be caught from someone with shingles
* infectivity = 4 days before rash, until 5 days after the rash first appeared
* incubation period = 10-21 days
37
Clinical features of chickenpox
* tend to be more severe in older children/adults
* fever initially
* itchy, rash starting on head/trunk before spreading. Initially macular then papular then vesicular
* systemic upset is usually mild
38
Management of chickenpox
Management is supportive
* keep cool, trim nails
* ***calamine lotion***
* immunocompromised patients and newborns with peripartum exposure should receive **varicella zoster immunoglobulin (VZIG)**. If chickenpox develops then **IV aciclovir** should be considered
39
School excision in chickenpox
NICE:
* *Advise that the most infectious period is 1–2 days before the rash appears, but infectivity continues until all the lesions are dry and have crusted over (usually about 5 days after the onset of the rash).*
40
Potential complications of chicken pox
A common complication is secondary bacterial infection of the lesions
* NSAIDs may increase this risk
* whilst this commonly may manifest as a single infected lesion/small area of cellulitis, in a small number of patients invasive group A streptococcal soft tissue infections may occur resulting in necrotizing fasciitis
Rare complications include
* pneumonia
* encephalitis (cerebellar involvement may be seen)
* disseminated haemorrhagic chickenpox
* arthritis, nephritis and pancreatitis may very rarely be seen
41
Spot diagnosis and management
Shingles
* Shingles is an acute, unilateral, painful blistering rash caused by reactivation of the Varicella Zoster Virus (VZV)
* **Oral aciclovir** is first-line.
* One of the main benefits of treatment is a reduction in the incidence of post-herpetic neuralgia.
42
Shingles vaccine
Vaccine to boost the immunity of elderly people against herpes zoster. Some important points about the vaccine:
* offered to all patients aged 70-79 years
* is live-attenuated and given sub-cutaneously
\*As it is a live-attenuated vaccine the main contraindications are immunosuppression
Side-effects
* injection site reactions
* less than 1 in 10,000 individuals will develop chickenpox
43
Foetal varicella-zoster syndrome
- timeframe in pregnancy
- features
Fetal varicella syndrome (FVS)
* risk of FVS following maternal varicella exposure is around 1% if occurs before 20 weeks gestation
* very small number of cases occurring between 20-28 weeks gestation and none following 28 weeks
* features of FVS include skin scarring, eye defects (microphthalmia), limb hypoplasia, microcephaly and learning disabilities
44
Other (apart from foetal varicella-zoster) risks to foetus
Other risks to the fetus
* shingles in infancy: 1-2% risk if maternal exposure in the second or third trimester
* severe neonatal varicella: if the mother develops rash between 5 days before and 2 days after birth there is a risk of neonatal varicella, which may be fatal to the newborn child in around 20% of cases
45
Management of chickenpox exposure in pregnancy
* if there is any doubt about the mother previously having chickenpox maternal blood should be urgently **checked for varicella antibodies**
* if the pregnant woman is not immune to varicella she should be given **varicella-zoster immunoglobulin (VZIG)** as soon as possible. RCOG and Greenbook guidelines (effective up to 10 days post exposure)
* **oral aciclovir** should be given if pregnant women with chickenpox present within 24 hours of onset of the rash
46
What's *Herpes Zoster Opthalmicus*? (what happens in it?)
**Herpes zoster ophthalmicus (HZO)**
* reactivation of the varicella-zoster virus in the area supplied by the ophthalmic division of the trigeminal nerve
* accounts for around 10% of case of shingles
47
Features of Herpes Zoster Opthalmicus
* vesicular rash around the eye, which may or may not involve the actual eye itself
* ***Hutchinson's sign***: rash on the tip or side of the nose. Indicates nasociliary involvement and is a strong risk factor for ocular involvement → this is due to naso-cilliary n. involvement - call for ophthalmologist!!!
48
Management of Herpes Zoster Opthalmicus
* **oral antiviral** treatment for 7-10 days
* ideally started within 72 hours
* **intravenous antivirals** may be given for very severe infection or if the patient is immunocompromised
* **topical corticosteroids** may be used to treat any secondary inflammation of the eye
* ocular involvement requires **urgent ophthalmology** review
49
Possible complications of *Herpes Zoster Opthalmicus*
* ocular: conjunctivitis, keratitis, episcleritis, anterior uveitis
* ptosis
* post-herpetic neuralgia
50
Spot diagnosis
Warts
| (caused by Human Papilloma Virus)
