1. Skin Infections
د.هيثم

2. Bacterial skin infections
Viral skin infections
Fungal skin infections

3. Bacterial skin infections

4. Why does skin get infected?
There are multiple types of bacteria which are normally present on the skin.
For example: Staphylococcus epidermidis and yeasts
The presence of bacteria does not automatically lead to a skin infection
What is the difference between colonisation and infections???

5. Colonisation: Bacteria are present, but causing no harm
Infection: Bacteria are present and causing harm.
A break in the epidermal integrity can allow organisms to enter and become pathogenic. This can occur as a result of trauma, ulceration, fungal infection, skin disease such as eczema
The stratum corneum of the epidermis is important in maintaining a barrier against skin infections

6. Impetigo
A highly infectious skin disease, which commonly occurs in children.

7. The causative organism is usually Staphylococcus Aureus (>90% cases1), but less often can be strep pyogenes.
Begins as a vesicle, which may enlarge into a bulla.
Weeping, exudative area with characteristic honey coloured or golden, gummy crusts, which leave denuded red areas when removed.
May present as macules, vesicles, bullae or pustules
Bullae are more prominent in staphylococcal infection and in infants

8. Impetigo
Treatment:
Mild localised cases - use topical antibiotic Polyfax
Widespread or more severe infections – use systemic antibiotics, such as flucloxacillin (or erythromycin if penicillin allergic)
Up to 10 days if needed. NB if the primary skin problem is not treated, the infection may not settle eg underlying eczema needs treating as well

9. Folliculitis Inflammation of the hair follicle.
Presents as itchy or tender papules and pustules at the follicular openings.
Complications include abscess formation and cavernous sinus thrombosis if upper lip, nose or eye affected.
Sycosis Barbae is a variant which occurs in the beard area, ofen spread by shaving. Pseudofollicultis is not an infection, but an inflammatory condition caused by ingrowing hairs.

10. Most common cause is Staph Aureus.
Other organisms to consider include:
Gram negative bacteria – usually in patients with acne who are on broad spec antibiotics
Pseudomonas (“Hot tub folliculitis”)
Yeasts (candida and pityrosporum)
Hot tub – typically occurs 1-4 days after bathing in unchlorinated contaminated water

11. Folliculitis treatment
Topical antiseptics such as Chlorhexidine
Topical antibiotics, such as Fusidic acid or Mupirocin
More resistant cases may need oral antibioics such as Flucloxacillin
Hot tub folliculitis – ciprofloxacin2
Gram negative – trimethoprim

12. Cellulitis Infection of the deep subcutaneous layer of the skin
Presents as a hot, tender area of confluent erythema of the skin
Can cause systemic infection with fever, headache and vomiting.
Erysipelas is more superficial and has a more well demarcated border
Treatement same and can coexist

13. Erysipelas

14. Cellulitis Streptococcus – Group A Strep Pyogenes.
Others include Group B, C, D strep, Staphylococcus Aureus, haemophilus influenzae (children) and anaerobic bacteria (e.g Pasteurella spp. After animal bites)

15. Treatment of cellulitis
Oral Flucloxacillin or erythromycin if allergic
Co-amoxiclav in facial cellulitis
If severe systemic upset, may require admission for IV antibiotics.
After the acute attack has settled, especially in recurrent episodes – consider the underlying cause

16. Orbital cellulitis – refer urgently

17. Staphylococcal Scalded Skin Syndrome
A superficial blistering condition caused by exfoliative toxins of certain strains of Staph Aureus
Usually in children less than 5 yrs old
Characterised by blistering and desquamation of the skin and Nikolsky's sign (shearing of the epidermis with gentle pressure), even in areas that are not obviously affected
Does not involve mucos membranes like TENs or SJS do

18. begins with a prodrome of pyrexia and malaise, often with signs and symptoms of an upper respiratory tract infection
discrete erythematous areas then develop and rapidly enlarge and coalesce, leading to generalised erythema - often worse in the flexures with sparing of the mucous membranes
large, fragile bullae form in the erythematous areas and then rupture

19. Complications include hypothermia, dehydration and secondary infection.
Treatment: ABC, refer urgently for IV antibiotics and fluids, may need referral to tertiary burns centre

20. What is the diagnosis?
Painful red nodule

21. Furunculosis (boils) and carbuncles
Deeper Staphylococcal abscess of the hair follicle
Coalescence of boils leads to the formation of a carbuncle
Treatment is with systemic antibiotics and may need incision and drainage.
Consider looking for underlying causes, such as diabetes

22. Erythrasma
Colonisation of axillae or groin with Corynebacterium Minutissimum.
Presents as a fine, reddish brown rash in the flexures, which is sharply marginated.
Often misdiagnosed as a fungal infection
Woods light illumination produces a characteristic coral-pink fluorescence.
Treatment is with topical fusidin cream.

24. When you use the Wood’s light, the skin lesion shows a dramatic coral pink fluorescence.

25. Viral Skin Infections

26. Viral warts and verrucas
Caused by human papilloma virus
Main types, common, plane and plantar
Very common
Disappear spontaneously eventually
If treatment is needed, options include:
Salicylic acid topically – needs daily treatment and can take months
Cryotherapy
Imiquimod cream

29. Molluscum contagiosum
Caused by MC virus
Common in children, but can occur at any age
Spread by direct contact
Presents as multiple small, pearly, dome-shaped papules with central umbilication
Can occur at any site
Usually resolve spontaneously in 6-18 months
Resolution is heralded by the development of erythema around the lesions.
Treatment is not usually necessary – simple reassurance and advice about reducing transmission.
If treatment is necessary, options include:
Piercing the lesion with an orange stick tipped with iodine
Curretage
imiquimod cream

31. Herpes Zoster (Shingles )
Caused by reactivation of the chickenpox virus which has lain dormant in the dorsal root or cranial nerve ganglia
Rash is preceded by a prodromal phase of up to 5 days of tingling or pain
Then develop painful grouped vesicles/pustules on a red base in a dermatomal distribution.
Most common in thoracic and trigeminal areas
Lesions become purulent, then crusted
Healing takes place in 3-4 weeks

33. Shingles treatment Aciclovir 800mg 5 times daily, for 7 days
Rest, analgesia usually gabapentine.
Complications include:
Post herpetic neuralgia
Secondary infection
Guillain Barre Syndrome
Occular disease
Reduces duration of rasha nd reduces pain. Should be started within 72 hours of onset. Id opthalmic nerve involved. Need opthalmic opionin in trigeminal, esp if lesions on the side and tip of the nose.

34. Post-herpetic Neuralgia
Pain lasting longer than 3 months after the rash.
The followings are risk factors for developing post-herpetic neuralgia?
A: Older age
B: More severe pain during the eruption
C: Severely inflamed rash
D: Prodromal pain in dermatome
Risk reduced by antgi-viral agents at the start of the rash. Treatments include amitriptyline, pregabalin as per NICe guidelines on neuropathic pain management

35. Herpes Simplex Virus
A highly contagious infection spread by direct contact
HSV 1 : also commonly called “coldsore”
HSV 2 usually presents on the genitalia
Primary infection is usually asymptomatic.
Recuurent infection presents as acute, painful gingivo-stomatitis with multiple small intra/peri-oral ulcers (but any site could be affected). Associated with fever, malaise and lymphadenopathy.
NB orogential contact can result in HSV 1 in the genital area.

36. Genital herpes
Herpes Simplex Keratitis
Herpetic Whitlow

37. Clinically: Grouped umbilicated vesicles/pustules on erythematous base.
Treatment:
Topical aciclovir can be used: 5 times daily for 5 days. Reduces duration of attack and duration of viral shedding.
The correct dose of aciclovir for HSV is 200mg 5 times daily for 5 days

38. Thank you