rajan s cleveland clinic journal of medicine 2012;79:57-66

Skin, and Soft Tissue

Infections

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ImpetigoImpetigo is a common skin infection caused

by streptococcus group A or staphylococcus bacteriaoMRSA is becoming a common cause.

Most common in children, particularly those in unhealthy living conditions.

In adults, it may follow other skin or upper respiratory infection.

SymptomsA single or multiple blisters filled with pus with a

reddish raw base (in infants). Itchy or painful blister: yellow or honey colored

fluid oozes and the lesion become crusty. It may spread to other areas and other persons.Affected sites: face, arms, or legs. It may cause

local lymphadenopathy.

Diagnosis Based mainly on the appearance of the skin

lesion.A culture of the skin or lesion usually grows the

bacteria Streptococcus pyogenes or Staphylococcus spp.

The culture can help determine if MRSAis the cause.

Prognosis & Complications

The sores of impetigo heal slowly and seldom scar.

Complications: opost-streptococcal glomerulonephritis.ocondition often recur in young childrenoSpread to other parts of the body (common)oPermanent skin damage and scarring (very rare).

Bullous impetigoMainly seen in children younger than 2 years.Involves painless, fluid-filled blistersomostly on the arms, legs, and trunk.osurrounded by red and itchy (but no sores) skin.

The blisters may be large or small.After they break they form yellow scabs.Caused by S. aureus toxins that separate the

dermis from epidermis.

EcthymaEcthyma is a skin infection similar to impetigo but

more sever because it invade deeper "deep impetigo”.Most often caused by Streptococcus sp.The infection start in skin that has been injured due to

a scratch or insect bite.It often develops on the legs.Small blister or pustule with a red border which later

erodes and form an ulcers.Diagnosis: clinically or analysis of aspirated fluid or

biopsy in the laboratory.

Acne vulgarisAcne vulgaris or cystic acne or simply acne.Acne affects mostly skin with a greater number

sebaceous follicles: the face, the upper part of the chest, and the back.

A common human skin diseaseSymptoms: scaly red skin, blackheads and

whiteheads, seborrhea (increased sebum secretion), papules, pustules, nodules (large papules), and possibly scarring.

Causes:Hormonal: androgens (testosterone,)Genetic.Psychological.Diet.Infectious Agent

Propionibacterium acnes.Staphylococcus epidermidis.

Pathogenesis:Acne develops as a result of blockages in the follicles by hyper keratinization. Enlargement of sebaceous glands and increase sebum production. In these conditions, the commensal bacterium Propionibacterium acnes can cause infection, leading to inflammatory lesions (papules, pustules, or nodules) in the dermis, which results in redness and may result in scarring or hyperpigmentation.

Boils and carbunclesBoils and carbuncles are painful, pus-filled

bumps (microabscesses around the hair follicles).Boils (furuncles) usually start as red, tender lumps

full of pus which grow larger and more painful until they rupture and drain.

A carbuncle is a cluster of boils.Common sites: face, neck, armpits*, buttocks or

thighs (hair-bearing areas are more likely to sweat).

The causative organism is S. aureus.

Staphylococci enter through a cut or scratch into skin then neutrophils rush to the site.

A painful, red bump appear with red, swollen skin around it. The bump increase in the size over a few days as it fills with pus (cloud reach the size of a golf ball) with yellow-white tip that eventually ruptures and allows the pus to drain out.

Once the boil drains, the pain usually subsides.Small boils usually heal without scarring but a

large boil may leave a scar.

A carbuncle is a cluster of boils that often occurs on the back of the neck, shoulders or thighs.

Carbuncles are deeper and more severe and more likely to leave a scar.

Risk factors: Although anyone can develop boils or carbuncles but the following factors can increase the risk.

o Close contact with staph infection patients.o Diabetes.o Other skin conditions.o Compromised immunity.

Complications of boils and carbuncles:oBlood poisoning, oMRSA.oSkin abscess.

Diagnosis:

Culture in these situations:orecurring infections.oNo response to standard treatment.oweakened immune system.

Treatment: For larger boils and carbunclesodraining the boil with an incisionoAntibiotics in certain situations.oBoils & carbuncles should never be

squeezed; risk of blood dissemination.oTreatment must be initiated if the lesions

became extremely painful or high fever developed.

Skin abscessA skin abscess is collection of pus in the skin.Pus: dead neutrophils + dead bacteria+ dead tissues.It is a defensive reaction of the tissue to prevent the

spread of infectious.Skin abscesses may occur after:

oA bacterial infection (often staphylococcus; boils and folliculitis)

oA minor wound or injury.oForeign material.

It may occur anywhere on the body and affects people of all ages.

Symptoms may include:oFever & chills.oLocal swelling, redness, tenderness & warmth.oHard tissue (induration)oOpen or closed sore, or domed nodule. fluid drainage.

• Complications: oUsually cure with proper treatment.o Infections caused by MRSA are do not respond to

regular antibiotics and need special medicines.oSpread to the blood and throughout the body.oTissue death (gangrene).

CellulitisCellulitis is inflammation of the subcutaneous

tissues.Caused by S. pyogenes and S. aureus .Cellulitis appears as a swollen red area of skin,

feels hot and tender, and it may spread rapidly.Skin on lower legs is most commonly affected.Cellulitis may affect only skin's surface or can

spread to lymph nodes and bloodstream.The spreading infection may rapidly turn life-

threatening, if left untreated

Symptoms and Signs:

Redness, swelling, tenderness, pain, warmth, fever. The borders are indistinct.

Risk factors include:Lymphedema.History of cellulitis.Intravenous drug use.Obesity.Weakened immune system.Skin conditions.

Complications:The bacteria can spread rapidly throughout the

lymph nodes and bloodstream.Recurrent episodes of cellulitis:

may damage the lymphatic drainage system leading to chronic swelling of the affected extremity

In rare casesinfection spread to the fascia (necrotizing

fasciitis)

Cellulitis is usually a superficial infection of the skin. But if severe or if left untreated, it can spread into lymph nodes and bloodstream. Pictured here is mild cellulitis (left) and severe cellulitis (right).

Necrotizing fasciitisA rapidly progressive inflammatory infection of

the fascia, with secondary necrosis of the subcutaneous tissues.

Risk factors:diabetes mellitus, vascular insufficiencies and

cancer.Group A beta-hemolytic Streptococcus a major

cause. However, other pathogens may be present, including:Clostridium, Enterobacteriaceae (e.g.

Escherichia coli), Pseudomonas and Klebsiella

Signs and symptomsRapid progression of severe pain with fever.Swelling , redness, hotness, blister, gangrene and

necrosis. Gas crepitus under the skin. Mortality as high as 73 % if untreatedSurvivors may have a shorter life span owing to

infectious causes such as pneumonia, cholecystitis, urinary tract infections, and sepsis.

Complications:Scarring with cosmetic deformity & limb loss.Septic shock with cardiovascular collapse (Toxic

shock syndrome)Organ failure including renal failure.

Diagnosis:WBC , differential , ESR, blood urea. Microbiology

Culture &Gram's stain (blood, tissue)Susceptibility tests

Treatment:Intravenous antibiotic therapy. combination of

penicillin G, aminoglycoside and clindamycin.Surgery to remove dead tissue and amputations of

affected limbs, in some cases.Hyperbaric oxygen to preserve healthy tissue.