Transcript SSSS (Cont`d)

Bacterial
infections
Dr Qassim S. Al-Chalabi
F.A.B.H.S
Bacterial infections
The normal skin flora
•
Protects the skin from bacterial infections through bacterial
interference.
•
The resident skin flora consists of:

Staphylococcus species, e.g. S. hominis & S. epidermidis. Staph.
aureus isn’t a member of resident skin flora except in anterior nares
or perineum (in 20% of individuals) & in lesional skin of atopic
dermatitis (90% of pts).

- Micrococcus species.
- Aerobic coryneforms.

- Anaerobic propionibacterium species, e.g. P. acnes. commonly
inhabit the sebaceous hair follicles.

- Yeasts: pityrosporum.
Impetigo contagiosum
•
Acute contagious superficial pyogenic infection of the skin.
•
Staph. Aureus and Streptococcus Pyogens are the most
common cause of skin infections.
•
Impetigo occurs most frequently in early childhood,
although all ages may be affected. It occurs in the temperate
zone, mostly during the summer in hot, humid weather.
Predisposing factors for pyoderma
• Common sources of infection for children are pets, dirty
fingernails, and other children in schools, daycare
centers, or crowded housing areas; for adults, common
sources include infected children and self-inoculation
from nasal or perineal carriage.
• Impetigo often complicates pediculosis capitis, scabies,
herpes simplex, insect bites, eczema, and other itching
skin diseases.
IMP
1- Non-bullous impetigo
•
Staph. aureus or group A stretp. or both “mixed
infections”.
•
May arise as 1ry inf. or as 2ry inf. of pre-existing
dermatoses, e.g. pediculosis, scabies & eczemas.
•
An intact st. corneum is probably the most
important defense against invasion of pathogenic
bacteria.
Clinical feature
•
A thin-walled vesicle on erythematous base, that soon
ruptures & the exuding serum dries to form golden-yellowish
(honey-color) crusts that dry & separate leaving erythema
which fades without scarring.
•
Regional adenitis with fever may occur in severe cases.
•
Sites: face & 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
Non-bullous impetigo – varieties (Cont’d)
•
Ecthyma
(ulcerative
impetigo):
adherent
crusts, beneath which purulent superficial
saucer-shaped ulcer occur. Healing occurs
after few wks, with scarring.
Site: more on distal extremities (thighs & legs).
SSSS (Cont’d)
Treatment of impetigo
1. Treatment of predisposing causes, e.g. pediculosis
& scabies.
2. Remove the crusts: by olive oil or hydrogen
peroxide or soap and water.
3. Topical
antibiotic
ointment,
e.g.
tetracycline,
bacitracin, mupiracin (Bactroban®), Fusidic acid
(Fucidin®).
SSSS – treatment (Cont’d)
4. 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 caps 500 mg daily for 3 days in
adults.
•
In erythromycin-resistant S. aureus: amoxicillin +
clavulanic a. (Augmentin®) 25 mg/kg/day.
2- Bullous impetigo
•
Staph. aureus through staphylococcal toxin (exfoliatin).
•
Age: all ages, but more common in childhood & newborn.
•
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.
•
Site: face is often affected, but the lesions may occur
anywhere, including palms & soles.
Syndromes caused by staph. exotoxins
Staph. Scalded Skin Syndrome “SSSS” (Ritter’s dis.)
•
It occurs mainly in infancy & childhood or rarely in adults
with renal failure or immunological incompetence.
•
The condition is usually caused by a toxin produced by
staphylococcal
infection
elsewhere
(e.g.
impetigo
or
conjunctivitis). Staph. aureus of phage group II, mostly type
71, which elaborates two exotoxins, epidermo-lytic toxins A
& B (ET-A & ET-B).
SSSS (Cont’d)
Clinically
•
it begins suddenly with diffuse, tender, red skin
simulating “scald”. Large flaccid bullae occur 
rupture immediately. Large sheets of superficial
epidermis separate & exfoliate. Healing occurs
usually within 7-14 days with or without
treatment. Usually good prognosis.
SSSS – clinically (Cont’d)
Treatment (good prognosis)
•
Systemic & topical
secondary infection.
•
Supportive
treatment:
disturbance.
antibacterial
iv
fluid,
agent:to

electrolyte
Erysipelas
It’s due to infection of the dermis & upper subcutaneous
tissue by group A streptococci.
The organism reaches the dermis through a wound or small
abrasion.
Site : Leg & face.
It begins with high fever & rigors. There is a well-demarcated
erythematous, hot, tender swelling of the skin. The surface
may
show
vesicles
or
lymphadenopathy are frequent.
bullae.
Lymphangitis
&
Erysipelas (Cont’d)
Complications
•
Recurrences may lead to lymphedema.
•
Subcutaneous abscess.
•
Septicemia.
•
Nephritis.
Cellulitis
•
It is an acute inflammation of subcutaneous
tissue. Currently, erysipelas is regarded as a
form of cellulitis rather than a distinct entity.
•
Cellulitis is usually caused by gp A strept.,
but staph. aureus may be implicated.
Cellulitis (Cont’d)
•
Clinically: the edge is diffuse with indurated, red, tender area
of the skin.
•
Recurrent strept. cellulitis or erysipelas is due to lymphatic
damage & venous insufficiency.
•
Treatment of erysipelas & cellulitis :
•
Systemic
antibiotics,
especially
penicillin,
penicillin 600-1200 mg IV/6 hrs or erythromycin.
•
Rest, analgesics
e.g.
benzyl
Folliculitis
= inflammatory disease of the hair follicles, which may be
infectious or non-infectious.
Superficial folliculitis
It isn’t always infective in origin, physical or chemical injury or
adhesive plasters may be associated with folliculitis,
usually sterile.
Superficial folliculitis (Cont’d)
1. Follicular impetigo of Bockhart: a domeshaped pustule at the orifice of a hair follicle
that heals within 7-10 days. Topical steroids
are a common predisposing factor.
2. Pseudofolliculitis
of
the
beard:
from
penetration into the skin of sharp tips of
shaved hairs.
Deep folliculitis
1. Sychosis “Folliculitis barbae”
•
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 later will be
scaring and hair loss.
•
DD: pseudofolliculitis of the beard, Tinea barae.
Deep folliculitis (Cont’d)
2. Furunculosis “Boils”
•
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
predliction is the back of the neck.
Other causes of folliculitis
•
Gram negative folliculitis with antibiotic treatment
of Acne Vulgaris.
•
Pityrosporum folliculitis.
•
Eosinophilic folliculitis in HIV infections.
•
Pseud. aeruginosa folliculitis.
Hidradenitis suppurativa “Apocrinitis”
•
is a chronic disease characterized by recurrent abscess
formation, primarily within the folded areas of skin that
contain both terminal hairs and apocrine glands.
•
It begins after puberty, commonly in females.
•
Sites: axillary & anogenital regions where apocrine glands
are present. There is small red, tender, subcutaneous
nodules that become fluctuant, becomes chronic & indolent
due
to
subcutaneous
extension.
Rupture
&
sinuses
discharging pus occur. Healing occurs with scar formation.
Hidradenitis suppurativa (Cont’d)
Treatment
•
Appropriate antibiotics for 2 wks, e.g. erythromycin and
metronidazole or clindamycin or long term of tetracyclines.
•
•
Systemic corticosteroids, e.g. prednisolone 60 mg daily.
Oral contraception containing 50 mg ethyl estradiol may be
useful.
•
Isotretinoin for 4 months .
•
Surgery in refractory resistant cases.
Erythrasma
•
It is chronic, localized superficial infection of skin by
Corynebacterium Minutissimum
•
There is 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.
•
It gives coral-red fluorescence under Wood’s light.
•
Topical treatment with antifungal agents for 2 weeks or
topical fusidic acid.
•
Erythromycin orally.
Trichomycosis axillaris
• Causative organism: Corynebacterium tenuis
• Characteristic features: Yellowish brown concretions on
axillary hair shafts
• Treatment: Shaving; topical erythromycin.
Pitted keratolysis
The combination of unusually sweaty feet and
occlusive shoes encourages the growth of organisms
that can digest keratin. The result is a cribriform
pattern of fine punched-out depressions on the
plantar surface, coupled with an unpleasant smell.
Anthrax (Malignant Pustule)
• Acute disease in humans and animals caused by
Bacillus anthracis , a Gram-positive sporeforming rod.
• Primarily caused by contact with infected wild or
domestic animals, or their products (e.g., wool,
goat, animal hides, bones, etc.)
Clinical picture
• Clinical forms: cutaneous, pulmonary, and GI.
• IP= ultra short 1-5 days patients may experience
low-grade fever and malaise
• Primary lesion is a “malignant pustule,” which
begins as a painless papule, evolves into a
hemorrhagic bulla with surrounding nonpitting
edema, and ultimately forms a characteristic black
eschar surrounded by vesicles.
• Regional lymph glands become tender an
enlarged, and frequently suppurate.
Treatment:
• (i) Bioterrorism associated: ciprofloxacin or
doxycycline
• (ii) Conventional anthrax: Penicillin