Skin infections are
either bacterial, fungal or viral. In general the inflammatory response
has different physiological, pathological and biochemical manifestations.
harmful micro-organisms and parasites.
Seals off persistent
stimuli or damaged tissue that cannot be rejected.
in regeneration or repair. Acute inflammatory change is usually followed
by fairly rapid repair. Inflammatory changes vary greatly in intensity and
Regenerated skin however,
unlike liver seldom retains exactly the same physiogical and
histological features as that before the damage.
Repair - is the healing
of wounds resulting in distortion of the original tissues, or in replacing
damaged tissue with elements, e.g. scar tissue. The intensity of the
inflammatory changes, and its duration before subsequent repair depends on:
The type of the
organism and its virulence.
Condition of the skin,
where infection may be more severe in devitalized and lacerated skin.
The body immune
Nature of the
- The severity of the damage.
These chapters summarize
briefly the most common skin infections affecting mainly infants and
Types of Skin Infections
Mycotic Skin Infection
Viral Skin Infection
NORMAL SKIN FLORA
The skin becomes
colonized by normal flora from birth. Colonization of the skin by normal
skin flora is related to different factors:
In infants and children
Micrococci are more prominent than in adult‘s skin. In adults
Propionibacterium are more due to the increased skin lipids.
In old age streptococci
and enterococci become residents of skin especially in moist areas.
Males carry higher
numbers of bacteria than females.
Negroes have less nasal
carriage of Staphylococci than Caucasians.
Type of colonizing
Colonization of one area
of skin by one strain of Staphylococci interferes with colonization by
The skin provides a dry,
mechanical barrier from which contaminating organisms on the surface are
constantly removed by desquamation.
Resident normal skin
flora are found more on moist areas containing abundant sebaceous glands,
while dry skin has less resident normal flora.
Huge number of harmless
normal bacterial flora colonizes the normal skin. These may be resident on
the skin and its appendages or transient flora. When the immune condition
is impaired or the skin is irritated or injured, non-pathogenic organisms
may change their behavior and become pathogenic.
The mechanism of
pathogenicity and even the same strain virulence and ability to cause
inflammation depend mainly on:
The state of the skin
epithelium and its secretions.
The cellular and humoral
Interaction between the
commensal organisms and other organisms.
Permanent eradication of
carriage of Staph. Aureus is not possible, but temporary elimination may
be by oral or topical antibiotics but soon there will be recolonization
after stopping the antibiotics.
RESIDENT NORMAL FLORA
Different species of
micro flora resides normally on the skin surface without causing harmful
effects under the optimum conditions of the skin. Some of this resident
flora may change their behavior and become pathogenic under certain
Normal resident flora of
the skin includes the following species.
Aerobic Gram positive
Micrococci, Gram-positive rods and diphtheroids.
species: in the deeper part of the hair follicles, aerobic cocci and
Pityrosporum sp. yeast present on the surface of the hair follicles and
P. Acnes, P.granulosum
reside on the face and upper trunk at the pubertal age, having a role in
the pathogenesis of acne.
carriers in the throat are about 10% of the normal population, while
carriers in the anterior nares are less.
production by some other members of the throat flora may contribute to
resistance to colonization by Strep. Pyogenes, but carriage is often not
eradicated by therapeutic antibiotics.
There are no
resident bacteria usually in the sweat glands.
The normal flora of
skin has probably a defense mechanism against bacterial infection. P.
Acne and Gram positive cocci cause split of fatty acids into free fatty
acids and triglycerides, which cause skin irritation and inflammation as
the case in Acne.
Sebum alone or the
acidic pH is not the defense mechanism as was previously considered.
Some strains of
normal skin flora can produce antibiotics capable of inhibiting other
creams such as Muperacin cream (Bactroban) can eradicate resident flora
from the nasal carriers and the intertriginous areas for 6 months if
applied twice daily for one week.
BACTERIAL SKIN INFECTIONS
IN NEW BORN AND CHILDREN
Skin infections are
extremely common during the neonatal period. This may be due to changes in
the social and cultural behavior. Most mothers nowadays depend on
housemaids or nurseries to take care of their infants or young children.
This may lead to more exposure to infections and various skin diseases.
Pre-school age group and
young children are more exposed to bacterial infections especially the
contagious ones such as impetigo. Although overcrowding, poor hygiene and
existing skin disease, especially parasitic, predispose to infection, yet
many cases occur in previously healthy subjects with good standard of
from healthy individuals outside epidemics are frequently non-pathogenic
but in epidemics frequently handled materials like gymnasium equipment and
room dust may be important in transmitting diseases.
Biting insects may
transfer the disease, but in addition small non-biting flies of the genus
Hippelates can contribute to the rapid spread of bacterial infections.
A furuncle or boil is an
acute round, tender, circumscribed, perifollicular staphylococcal
inflammation, which generally tends to suppurate.
Furunculosis may become
recurrent and constitute a problem to patients especially in the groin,
nasal cavity, scalp and external auditory canal. The infection may be
associated with constitutional symptoms especially in newborn and
pressure, or hyperhidrosis.
Fig. 23. Furunculosis
Preventive measures are
very important especially to prevent recurrence of infection from nasal
foci, autoinoculation, from perianal or intertriginous areas.
This can be achieved by:
irritation and trauma to the lesions.
Treatment of the
colonized areas and the primary focus as in nostrils.
cream such as Muperacin cream which when applied twice daily in the
nostril for one week will eradicate colonized micro-organism for 6 months.
- Using a suitable anti septic soap as
Cidal or Dial soap may have some good effect.
hyperhidrosis and occlusion of the crural area.
Care of the crural
areas especially in new born and small children by frequent aeration and
changing diapers repeatedly should be taken into consideration.
Washing the hands
especially when blowing the nose and using non perfumed smooth tissue
papers as cotton ones for cleaning the nose.
Care of both the ears and
nostrils is very important and should not be neglected.
Long cotton underwear
is better used and changed daily if possible.
Compresses: hot saline
soaks or compresses can be applied for severe and extensive cases of
Topical antibiotics as
Muperacin (Bactroban cream), Gentamycin (Garamycin cream) or (Sodium
fucidate (Fucidin cream).
(Bactropan cream)applied locally once daily is also very effective and can be
given alone when infection is mild, or in combination with oral
Antibiotic orally and
locally will lead usually to rapid resolution of the lesion.
Oral antibiotics as
(Flucoxacillin, Cephalosporin, and Cephaloridine) are effective in soft
tissue infections. Erythrocin is not effective against all strains of
staphylococci. Co-trimoxazole is another alternative to patients allergic
to other groups.
It is of great importance
not to squeeze or incise the carbuncles when they are acutely inflamed or
those in the dangerous triangle of the face.
If the furuncle becomes
localized and shows definite fluctuation, free incision and drainage can
A carbuncle is a
circumscribed inflammation caused usually by Staph. Aureus complicating
certain diseases such as diabetes or other conditions that lower the body
Carbuncles are composed
of furuncles joined together in the subcutaneous area and when sloughing
shows multiple openings on the surface of the skin. Suppuration is deeply
seated than in the furuncles.
Carbuncle is usually
single and located most frequently on the back and lower side of the neck
and on other hairy areas. The lesions manifest with painful erythema where
later on localize and suppurate discharging the content on the skin
surface. Sloughing leaves an irregular punched-out ulcer, which heal by
Types of Carbuncles
are common and they are characterized by skin redness and multiple
openings on the skin surface. Superficial carbuncles usually do not
leave very deep excavation.
Deep carbuncles are
The skin lesion is brawny
and fixed like a malignant tumor.
Leaves deep cavity after
perforation and sloughing.
Heal by scarring.
The same treatment
applied for furuncles.
Folliculitis is bacterial
infection of skin appendages that originates within the hair follicles.
In infants and young
children, the scalp is the commonest site involved while in adults any
hairy area may be affected.
Fig. 24. Folliculitis
Fig. 25. FOlliculitis
Folliculitis may be
superficial or deep.
This type is also known
as Bockhart impetigo that affects individuals predisposed by maceration
and lack of cleanliness. The lesion begins as a small dom-shaped pustule
where it may rupture, exuding yellowish exudate.
The lesion in deep
folliculitis is spreading deep into the follicles and causing
perifolliculitis. The condition may be extensive involving a wide area
especially the scalp in infants and young children and infiltrating
deep in the
corium causing granulomatous reaction and empetiginized crusted
lesions. Scarring of the area involved and cicatricial alopecia
may be the end stage of deep folliculitis that is known as
Fig. 26. Folliculitis
Impetigo is a contagious
superficial bacterial skin infection most common in children caused by
staphylococci and to a lesser extent by streptococci pyogenes.
Infection is usually
predisposed by different factors mainly:
Impetigo contagiosa may complicate
certain skin diseases such as pediculosis, scabies and eczematous
Fig. 27. Impetigo
Fig. 28. Impetigo
The lesion begins usually
on the face or on other areas presenting with a small reddish macule,
which soon becomes a vesicle and a pustule with a thin roof that ruptures
leaving an oozing abraded skin surface.
Crust is formed when the
lesion becomes dry. Removing of the crust leaves a smooth, moist red and
oozing surface. This represents an important source of infection for
others by auto-infection by the fingers or from fomites used by the patient
Impetigo is highly
contagious especially in infants and this is why satellite lesions appear
near the primary site or on other areas due to autoinfection.
Fig.28b. Impetigo contagiosum
Extensive lesions may
involve wide areas such as the trunk and extremities, which become covered
by numerous, thickly crusted dirty lesions.
Severe cases may show
vegetative lesions with deep ulceration.
changes may occur during the course of the disease. Some areas may show
central healing while the lesions extend peripherally and join together
forming annular, circinate or gyrate patterns. The lesions usually heal
without atrophy or scarring.
Bullous impetigo is
caused by Staphylococci while, the non-bullous form may be caused by
Staph. Aureus, Streptococci, or by both organisms together.
The disease is usually
sporadic but clusters of cases may occur in families and other groups, and
larger outbreaks are occasionally seen in institutions or nurseries.
Bullous impetigo occurs
at all ages. In the newborn bullous impetigo may be especially widespread.
This type was formerly called pemphigus neonatorum .
Minor abrasions and
different skin lesions may predispose to infection if the patient or a
contact carries an appropriate strain of Staphylococcus . An increased
incidence in hospital workers has been noted.
Clinically the disease
begins as painful macule on an erythematous base, which shortly develops
into vesicle or bulla and then pustule, which later on rupture exuding
straw colored, sero-prulent discharge. The exudate dries to form thick
infectious crust, which can cause autoinfection mainly by the fingers to
the adjacent skin or to other areas of the body.
When bullae are a
prominent feature the designation is called ‘Bullous impetigo‘. A
variety of bullous impetigo is impetigo neonatorum that occurs in the
first week after birth. This type is very contagious to the maternity
ward, nurses and other infants.
Bullous impetigo may be
accompanied by severe constitutional symptoms such as fever, diarrhea with
green stool, pneumonia and nephritis. When the bulla becomes larger it
ruptures leaving scalded areas of skin called in some texts as "Lyell‘s
syndrome" or "Epidermal Necrolysis" endangering the life of
Infection can be
transmitted also through fomites used by the patient such as towels or
household utensils or direct contact with the patient. The most common sites
infected are the face, nasal furuncles, lips and scalp.
nephritis: This is uncommon complication of impetigo caused by
Streptococci occurring in children and infants accompanied by edema of
the face and limbs , hematuria , oliguria and with constitutional
symptoms such as fever and diarrhea .
Impetigo due to beta-
hemolytic Streptococci may be complicated by acute glomerulonephritis in
about 2 per cent of infected children.
Scalded skin syndrome
: This is a serious skin problem due to exotoxins of Staph aureus causing
damage to the epidermis which becomes loose and sloughs into sheets
leaving a wide abraded skin surface .
This is a highly
contagious disease of the newborn infants and forms a real problem in
nurseries .The disease usually manifests between the fourth and tenth day
after birth , caused by Staph-aureus. Epidemics of bullous impetigo, in
which some infants may develop staphylococcal scalded skin syndrome, have
occurred in neonates due to transmission of infection in the nursery,
principally via nursing or medical staff.
Impetigo neonatarum is a
serious problem especially when there is an epidemic in nurseries. The
mortality rate is high in neglected and even in treated cases.
The most common sites
involved are the face, perineum, per-umbilical, trunk and extremities.
are common which include: fever, cachexia, diarrhea with green stools
that may lead to severe dehydration. Bacteremia, nephritis, pneumonia,
lung abscess, meningitis are severe and may be fatal complications.
The disease usually
begins in the first or second week of life with the appearance of bullae
on any part of the body, mainly on the face and extremities.
Rapidly enlarging bullae
with thin delicate walls and with a narrow red areola appear. The bulla
has a turbid or pustular fluid. After rupture of the bulla, it leaves a
denuded, oozing crusted surface. The condition may remain localized or
Pemphigus vulgaris: the
bullae appear on normal skin. Nickolsky‘s sign is positive.
Congenital syphilis: The
bullous lesions are on the palms and soles and the presence of other
manifestations of syphilis can help in the differential diagnosis.
Confirmation is by
serological tests for syphilis.
Treatment of impetigo
Preventive measures: are
very important to prevent auto-infection and spread of the infection to
others. Special care and special precautions in nurseries are important in
order to prevent spread of infection.
Drying of the exudate by potassium permanganate 1: 9000 in the form of
wet compresses and application of topical anti bacterial cream such as
Muperacin (Bactropan cream).
Oral antibiotic such as
Flucoxacillin, Amoxicillin, Cephasporin, Cefaclor and Zithromycin
(Zithromax) are effective in curing skin lesions in a short time.
Hospitalized cases having
severe complications should be in isolated rooms and all the precautions
should be considered to prevent spread of the infection to others.
scalded skin syndrome is a rare acute bacterial skin infection of the
newborn usually in breast-fed infants. It is caused by an epidermolytic
toxin elaborated by certain strains of staphylococcus aureus, most
commonly of phage group II,
The organisms reach the
skin, via the circulation, from a distant infective focus, usually in the
middle ear, pharynx, conjunctiva or the site of circumcision or
The symptoms manifest with shooting fever
and the infant is distressed.
Recovery is usually
rapid, even without antibiotic therapy. The mortality rate maybe high in
certain under-developed countries.
The first sign of the
disease is a faint, macular, orange-red, scarlatiniform eruption occurring
in association with purulent conjunctivitis or an upper respiratory tract
infection. Sites of predilection are the central part of the face, the
axillae and the groins.
Tenderness of the skin is
an early and striking feature. The presence of impetiginous crustations
around the nose and mouth is rather characteristic.
The eruption generally
becomes more extensive, and, over the next 24-48 hours, turns to a more
confluent, deep erythema with edema. The surface of the skin then becomes
wrinkled before starting to separate leaving raw, red erosions.
The only real problem
in differential diagnosis of staphylococcal scalded skin syndrome would
be with toxic epidermal necrolysis. Both are clinically similar, while
the latter has a worse prognosis. In the past, Staphylococcal scalded
skin syndrome and toxic epidermal necrolysis were considered the same
disease, but it is now clear that they are entirely distinct entities.
Previous history of drug intake, absence of systemic manifestations such
as fever, and detection of a septic focus may help in the differential
The scalded appearance
of the skin differentiates the disease from bullous impetigo.
The rapid onset with
marked cutaneous tenderness distinguishes the disease from erythroderma
The rarity of bullous disease such as pemphigus in this age and the
clinical manifestations can confirm the diagnosis.
Culture and sensitivity
may be required to detect the most effective and appropriate antibiotics.
Usually Penicillinase-resistant penicillin analogue such as Flucoxacillin
or Methicillin, or an appropriate Cephalosporin or Sodium fucidate are
If the attack is severe,
the drug should initially be given intravenously. Systemic corticosteroids
are absolutely contra-indicated, on the basis of experimental and clinical
evidence that they aggravate the disease.
must be made for heat and fluid losses.
Local treatment of
Antiseptic baths such as
1:9000 Potassium permanganate.
Antibiotic cream is then
applied after drying the lesions with clean gauze.
Bullae should be opened,
drained and after cleaning the area, antibiotic cream and dressing can be
It should be noted that the disease is
contagious, so all dressings or other materials coming in contact with the
lesion should be burnt after use. The medical staff and other attendants
should take all, the possible care and precautions not to get or transmit
Abscess is a circumscribed
bacterial skin infection accompanied by local tissue destruction.
Fig. 29. Pointing
Fig. 30. Abscess
The clinical feature
varies according to the causative organism and the site involved. Abscess
caused by bacteria may involve the skin and internal organs.
Skin and subcutaneous
tissue abscess may involve the gluteal, axillary, scalp or any area of the
skin. The lesion begins as an inflamed erythematous papule that is changed
into a vesicle and to a pustule.
The abscess is usually
encapsulated and this differentiates it from other superficial bacterial
skin infections such as cellulitis. The abscess may localize and has its
opening on the surface of the skin exuding pus.
such as fever, headache, malaise and pain varies according to the size,
site and age of the patient or any accompanying debilitating diseases.
Abscess may localize in
the lungs, kidneys, liver or elsewhere. The accompanying symptoms vary
according to the sites involved.
DIFFERENT TYPES OF
Cold abscess : occurs
with caesating tuberculosis.
This type of abscess
usually involves the gluteal region due I.M injection of certain
medications such as oily injectable preparations, which localize under the
skin causing sterile abscess due to injection superficially or with wrong
These types of abscesses
may be bacterial, amebic abscess or mycotic. An abscess causing different
signs and symptoms may involve the liver, kidney and the lungs.
Treatment of abscess
depends, mainly on the causative organisms. Abscess due to bacterial
infection can be treated by topical and systemic antibacterial.
Opening and drainage of
the abscess contents when it points to the skin.
Other types of abscesses
are treated according to the causative agent.
Cellulitis is a spreading
infection of skin and subcutaneous tissue caused by Staph. Aureus,
Strept.pyogens or Enterocococci. Trauma to the skin is usually a
Fig. 31. Cellulitis
Fig. 32. Cellulitis
The skin becomes red, inflamed, swollen
and tender. The inflammation is diffuse and spread to involve the dermis
and subcutaneous tissue. Ulceration,
lymphadenitis and constitutional symptoms such as pain and fever may
accompany cellulitis. The most common sites for cellulitis are the legs and
cellulitis due to Haemophilus influenza is typically unilateral, and often
is associated with ipsilateral otitis media. The patient presents with
systemic manifestations and the affected cheek or peri-orbital tissue
shows induration and discoloration, occasionally pink but
characteristically purplish blue. A similar violaceous color may occur in
childhood peri-orbital and buccal pneumococcal cellulitis.
Severe cases of spreading
infection associated with severe constitutional symptoms may need
hospitalization especially if there is no response.
Erysipelas is an acute
bacterial infection of the skin and subcutaneous tissues caused by the
group beta-hemolytic Streptococci.
The commonest sites
involved are the face and extremities.
High fever, chills, headache,
vomiting, and pain in the joints usually precede the onset of the
The infection is usually
predisposed by trauma to the skin, ulceration, a small wound or after
vaccination. Unclean tying of the umbilical cord may facilitate the
entrance of the causative streptococci, which can elicit the skin lesion
In the early stage, the
lesion is erythematous red, hot and swollen, later it becomes hard
Fig. 33. Erysipelas
Skin lesions appear as
sharply demarcated, bright red, hot skin that rapidly spread to the
periphery and become pale in the center. The lesion varies from mild
sharply demarcated erythema to severe inflammation and vesiculation or
Degeneration of the
viscera due to bacterial toxins in severe cases.
Serious inflammation of
the internal organs of the meninges, pleura, peritoneum and synovial
bronchopneumonia may be fatal especially in young age groups.
Erysipelas has to be
Other bacterial skin
infection such as cellulitis.
In erysipelas the edge
of the lesion is well demarcated and raised, blistering is common and
there may be superficial hemorrhage into the blisters or in intact skin
especially in elderly people.
In cellulitis it is
diffuse, although some cases present with both types. Severe cellulitis
may show bullae and can progress to dermal necrosis, and uncommonly to
fascitis or myositis. Lymphangitis and lymphadenopathy are frequent.
have a tendency to develop recurrent erysipelas in the same previous
areas involved, which may lead to permanent changes such as
elephantiasis. This will also cause brawny unremitting edema of the
lower limb. Persistent swelling of the lips or cheeks may cause
disfiguring of the areas involved.
as fever and malaise are common.
Local skin gangrene may
complicate some cases of erysipelas where vesicles are formed first on an
erythematous base that become pustular. Later on there is a blackish
discoloration of the skin and severe necrosis.
Severe toxemia, serous
membrane inflammation, septicemia, bronchopneumonia, embolism and even
Topical and systemic
antibiotics can treat mild and localized cases.
Severe cases where there
is an extensive involvement of the skin or if complicated with septicemia
are managed according to the severity of the case and some may need
Ecthyma is a deep
infection of the skin caused by beta hemolytic streptococci affecting
mainly the legs.
The lesion begins as a
vesico-pustule, which ulcerates leaving saucer, shaped ulcer with a raw
base and elevated edges. The lesion takes a long time to heal, it may take
weeks or more leaving a scar.
Treatment is the same as
that applied for impetigo.
Fig. 34. Ecthyma
Listeroses is a bacterial
infectious disease of man and animals. The causative organism is Leisteria
monocytogens, Gram-positive microaerophilic motile bacillus found in water
and soil, which is easily confused with coryneform organisms.
especially milk, cheese and poultry, are the main source of human disease.
Transplacental and birth
canal infections are a well-recognized hazard to the fetus and neonate.
Infection of a baby from
the mother‘s milk has been reported. Some human beings may act as a
carrier of the disease. Newborn infants may be infected from the infected
genital tracts of their mothers.
Fever and septicemia.
Granulomatous lesions may
appear in infants accompanied by systemic symptoms such as carditis,
encephalitis and meningitis, which may be fatal.
In pregnancy, it causes a
rather non-specific and generally mild, influenza-like illness in the
mother, but it may lead to transplacental infection of the fetus.
Severely affected babies
tend to be born prematurely, and there is a high mortality rate.
The most common sites
involved are the back and the mucous membranes of the mouth and the
Miliary skin lesions
appear as scattered, discrete gray or white papules or pustules, about 1-2
mm in diameter, with a red margin, provide a source of organisms for
Purpura and morbilliform
rashes may develop later along the course of the disease.
following blood-borne dissemination of infection may occur.
Postmortem studies reveal
miliary granulomata in many organs.
The late manifestations
of the disease are present with meningitis, occurring a week or two after
Diagnosis is by culturing
the organism from cerebrospinal fluid and food. Biopsy from the skin and
the mucous membranes.
Detection of the organism
in the suspected materials.
Antibiotics according to
the culture and sensitivity results.
Combination of either
Ampicillin or Penicillin and Gentamycin or Kanamycin.
Topical preparations such
as Potassium permanganate compress 1: 9000 and antibacterial cream.
Supportive measures are
Psittacosis is a human
infection which is acquired from parrots (psittacoses) and other birds,
e.g., domestic and sea birds.
Modes of infection
Inhalation of infected
dust contaminated from excreta of infected birds. Air conditions may
facilitate spread of infection from infected birds kept indoors.
Human-to-human infection which may occur due to spread of infected respiratory tract droplets
The manifestations are
very variable. The incubation period is about 2 weeks. The symptoms may
begin with sore throat, cough and headache.
Respiratory symptoms are
the most common manifestations, which vary from mild infection to severe
pneumonia, cyanosis and collapse. Myocardial involvement, jaundice,
encephalitis may be fatal.
occasionally, including a morbilliform eruption.
Rose spots appear in
severe cases resembling the rose spots of typhoid.
Erythema nodosum was
noted in some patients.
antibody, appearing about 10 days from the onset of infection.
Isolation of the organism
is recommended for children.
Tetracycline is the drug of choice in
adults. Early administration is life saving. A dose of 500 mg four to six
times daily usually produces a response in about 48-h and this should be
continued for 10 days.