Text of 1. Direct infection of skin : impetigo, ecthyma, folliculitis, furunculosis, carbuncle, sycosis. 2....
1. Direct infection of skin : impetigo, ecthyma, folliculitis,
furunculosis, carbuncle, sycosis. 2. Secondary infection: eczema,
infestations, ulcers, etc. 3. Effect of bacterial toxin:
staph.-associated scalded skin syndrome (SSSS), toxic shock
Direct inf. of skin or subcut. tissue: Impetigo, ecthyma,
cellulitis, vulvovaginitis, perianal inf., strepto. ulcers,
blistering distal dactylitis, necrotizing fasciitis. 2 ry inf.:
eczema, infestations, ulcers, etc.
Tissue damage from circulating toxin: scarlet fever, toxic
shock-like syndrome. Skin lesions attributed to allergic hyper-
sensitivity to strepto. antigens: erythema nodosum, vasculitis.
Skin dis. provoked or influenced by strepto. inf.: psoriasis
especially guttate forms.
Mechanical disruption (inflammations, abrasions) Prolonged use
of steroids, topical or systemic Presence of systemic illnesses
(DM, malignancy) Immunosuppression Malnutrition Anaemia
Acute contagious skin infection caused mostly by staph. Aureus
and strept. Affects children mainly esp. in summer times.
1- Non-bullous impetigo: Caused by staph., strept. or both
organisms. 2- Bullous impetigo: Caused by staph aureus.
Staph. aureus or gp A stretp. (GAS) or both mixed infections.
May arise as 1 ry inf. or as 2 ry inf. of pre-existing dermatoses,
e.g. pediculosis, scabies & eczemas. An intact st. corneum is
probably the most important defense against invasion of pathogenic
A thin-walled vesicle on erythematous base, that soon ruptures
& the exuding serum dries to form yellowish-brown (honey-color)
crusts that dry & separate leaving erythema which fades without
scarring. Regional adenitis with fever may occur in severe
Sites: Exposed parts eg. face & extremities. Scalp (in
pediculosis). Any part could be affected except palms & soles.
Complications: Post- streptococcal acute glomerulo-nephritis AGN
especially in cases due to strepto. pyogenes M. type 49.
Circinate impetigo: with peripheral extension of lesion &
healing in the center.
Crusted impetigo: on the scalp complicating pediculosis.
Occipital & cervical LNs are usually enlarged &
Ecthyma (ulcerative impetigo): adherent crusts, beneath which
purulent irregular ulcers occur. Healing occurs after few wks, with
Site: more on distal extremities (thighs & legs).
Age: all ages, but commoner in childhood & newborn
(impetigo neonatorum). Site: face is often affected, but the
lesions may occur anywhere, including palms & soles.
The bullae are less rapidly ruptured (persist for 2-3 days)
& become much larger. The contents are at first clear, later
cloudy. After rupture, thin, brownish crusts are formed.
Treatment of predisposing causes: e.g. pediculosis &
scabies. Remove the crusts: by hydrogen peroxide. Topical
antibiotic: e.g. tetracycline, bacitracin, gentamycin, mupiracin
(Bactroban ), Fusidic acid (Fucidin ).
Systemic antibiotics are indicated especially in the presence
of fever or lymphadenopathy, in extensive infections involving
scalp, ears, eyelids or if a nephritogenic strain is suspected,
e.g. penicillin, erythromycin & cloxacillin. Azithromycin
(Zithromax ) 2 caps 500 mg daily for 3 days in adults. In
erythromycin-resistant S. aureus: amoxicillin + clavulanic a.
(Augmentin ) 25 mg/kg/day.
inflammatory disease of the hair follicles, which may be
infectious or non-infectious.
Superficial Folliculitis (Bockharts Impetigo)
a dome-shaped pustule at the orifice of a hair follicle that
heals within 7-10 days.
Caused by staph aureus and affects mainly extremities and
scalp. Topical steroids are a common predisposing factor.
Recurrent red follicular papules or pustules centered on a
hair, usually remain discrete over the beard or upper lip, but may
coalesce to produce raised plaques studded with pustules. DD:
pseudofolliculitis of the beard, T. barae.
from penetration into the skin of sharp tips of shaved
It is a staphylococcal infection similar to, but deeper than
folliculitis & invades the deep parts of the hair folliculitis.
Occasionally several closely grouped boils will combine to form a
carbuncle. The carbuncle usually occurs in diabetic cases. The site
of election is the back of the neck.
Cellulitis is an infection of subcutaneous tissues. Ersipelas:
Its due to infection of the dermis & upper subcutaneous tissue
by gp A streptococci. The organism reaches the dermis through a
wound or small abrasion. It is regarded as a superficial dermal
form of cut. cellulitis.
Erythema, heat, swelling and pain or tenderness. Fever and
malaise which is more severe in erysipelas. In erysipelas:
blistering and hemorrhage. Lymphangitis and lymphadenopathy are
Edge of the lesion: well demarcated and raised in erysipelas
and diffuse in cellulitis.
Recurrences may lead to lymphedema. Subcutaneous abscess.
Systemic antibiotics, especially penicillin, e.g. benzyl
penicillin 600-1200 mg IV/6 hrs or cephalosporines. Rest,
It is mild, chronic, localized superficial infection of skin by
Coryn. Minutissimum. Clinically: sharply- defined but irregular
brown, scaly patches
usually localized to groins, axillae, toe clefts or may cover
extensive areas of trunk & limbs. Obesity & DM may coexist.
Coral red fluorescence under woods light.
Topical treatment with azole antifungal agents for 2 weeks or
topical fucidin. Erythromycin orally.
A mother brings 5 yr old Johnny to surgery. He has developed
this rash, which is weeping and crusting.
What is the diagnosis?
A highly infectious skin disease, which commonly occurs in
What is the likely causative organism?
The causative organism is usually Staphylococcus Aureus or can
be strep pyogenes.
What is the treatment?
Treatment: Mild localised cases - use topical antibiotic
Polyfax Widespread or more severe infections use systemic
antibiotics, such as flucloxacillin (or erythromycin if penicillin
A: He does not have to be excluded from school so long as he is
on antibiotics B: He has to remain off of school for 5 days from
the onset of the lesions C: He must remain off of school until the
lesions have crusted or healed D: He must remain off of school
until he has completed the antibiotic course.
A 27 year old business man attends surgery complaining of pain
and itching in the beard area. You examine him and see the
What is the Diagnosis?
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.
What is the causative organism?
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)
What is the 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 2 Gram negative trimethoprim
What is the most common causative organsism?
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
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
Painful red nodule
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