Skin infection pdf - د.عمر

Fifth stage

Dermatology

Lec-4

Dr.Omar

24/10/2016

Skin Infections

I. Bacterial skin infections

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???



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

Impetigo

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

 The causative organism is usually Staphylococcus Aureus (>90% cases

), 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.

 Usually on the face around the mouth, but any area could be affected.

Treatment:

 Mild localised cases - use topical antibiotic Polyfax
 Widespread or more severe infections – use systemic antibiotics, such as flucloxacillin

(or erythromycin if penicillin allergic)

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.A



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)

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 – ciprofloxacin
  Gram negative – trimethoprim

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

Cellulitis Erysipelas

 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)

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

Orbital cellulitis – refer urgently

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

 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

 Complications include hypothermia, dehydration and secondary infection.

 Treatment: ABC, refer urgently for IV antibiotics and fluids, may need referral to

tertiary burns centre

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

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.

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

fluorescence.

Viral Skin Infections

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

Molluscum contagiosum

  Caused by DNA pox 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

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

Shingles treatment

• Aciclovir 800mg 5 times daily, for 7 days

• Rest, analgesia

Complications include:

 Post herpetic neuralgia

 Secondary infection

 Guillain Barre Syndrome

 Occular disease

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

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

Genital herpes

Herpes Simplex Keratitis

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

A.L.Y