Common cutaneous bacterial infections

Faghihi. G.Dermatology professor

Isfahan University of Med.

Normal skin is a barrier against microbial pathogens

Predisposing factors to Bacterial Skin Infections :

• Neutropenia• HIV infection• IV Drug ABUSE• Diabetes• Parasitic Infestations • Wounds,burns,abrasions• Atopic disease• Alcoholism

MRSA Abscess and Surrounding Cellulitis in Arm of Patient with HIV Infection

Some other conditions as risk factors for bacterial cut. Infections

For example :

poor hygienefriction and wearing

tight clothingseborrhea

Common important bacterial skin infections

Include:• Impetigo• folliculitis• furuncles • carbuncles• cellulitis • erysipelas

Impetigo pustules or bullae that rupture and become crusted usually appears on the face, especially around nose and mouth

mainly affects infants and children

• The infection is spread by direct contact with lesions or with nasal carriers.

• The incubation period is 1–3 days after exposure to Streptococcus and 4–10 days for Staphylococcus

The most common pathogen

Both bullous and nonbullous are primarily caused by Staphylococcus aureus

with Streptococcus also commonly being involved in the nonbullous form.

Risk factors for Impetigo

Atopic dermatitis parasitosisTraumaBurns minor abrasionsSports(direct

contact)

Diagnosis usually clinicallysmear and culture definitely

• Leucocytosis ….. About 50 % patients

Children who get impetigo: should not attend school or daycare. They should not have close contact, with other children

limited uncomplicated impetigoTreatment(topical):

• Ointment mupirocin• Ointment retapamulin• Cream fusidic acid

Equally as effective as oral Ab.

Extensive or accompanied systemic symptoms or lymphangitis(systemic Ab.)• Penicillins( dicloxacillin, flucloxacillin or

Alternatively amoxicillin combined with clavulanate

• Cephalosporins• Clindamycin• MacrolidsIn cases of severely ill/ immunocompromised

• IV ceftriaxone• Iv ampicillin/sulbactam/cefuroxime

One major complication of impetigo:

• Post Strep GN

Efficacy of treatment of strep.impetigo

In eradication acute P-S-G-N

is not known.

MRSA decolonization

Impetigo Bockhart

superifical staphyloccocal folliculitis

a superifical staphyloccocal folliculitis with thin-walled pustules

at the folliclular openings.

Streptococcal intertrigo

is a cutaneous condition seen in infants and young children, characterized by a fiery-red erythema and maceration in the neck, axillae or inguinal folds

a distinctive foul odor and an absence of satellite

lesions.

Treatment strep.intertrigo

eliminate friction, heat, and maceration by keeping folds cool and dry

Compresses with Burow solution 1:40

Treatment with penicillin V-K suspension, 125 mg orally 3 times a day 10 days

Bacterial folliculitis

The bacterial agent often responsible for folliculitis is Staphylococcus aureus

The infection (hair follicles)can be shallow

or deep

can even lead to formation of

inflammatory nodules or pustules

which will surround the hair follicle.

• superficial folliculitis (the most common form)

• Deep folliculitis (sycosis)

Folliculitis most commonly occurs://• Beard area in men• Scalp• Upper trunk (chest, under

breasts, in armpits)• Buttocks• Thighs• Groin

Pseudomonas aeruginosafolliculitis

• hot tub folliculitis• The infection is typically found in

areas of the body, which are soaked under an improperly chlorinated hot tub or wirlpools.

• The typical body parts affected ::are buttocks, hips, legs and thighs ,face and neck are spared.

It is self limited(7-14 Days)• Sometimes for widespread

infection or immunosuppressed or febrile ,ill patients:

oral quinolone/topical gentamycin

Folliculitis Treatment

• Superficial folliculitis may heal on its own within 1 to 2 weeksApplying antibiotic ointments like Bacitracin, (bacitracin + neomycin + polymyxin B), or (mupirocin), washing with antibacterial soaps may help in more resistant cases

• In a deep folliculitis and recurrent cases, oral antibiotics (dicloxacillin, cephalosporins) may be needed.

• Folliculitis caused by MRSA requires treatment by antibiotics chosen on the basis of antibiotic sensitivity test (1).

• S. aureus carriers may be treated with mupirocin ointment in the nasal vestibule as previously said...

Family members may be also treated by mupirocin to eliminate the carrier state and prevent re-infection

(boil ) furuncle

Furuncles are skin abscesses caused by staphylococcal infection, which involve a hair follicle and surrounding tissue.

A carbuncle

is a coalescence of several inflamed follicles into a single inflammatory mass with purulent drainage from multiple follicles. Constitutional symptoms, including fever and malaise, are commonly associated with these lesions but are rarely found with furuncles.

Diff Dx furuncles or carbuncles

• Ruptured epidermal cysts or pilar cysts• Acne conglobata• Hidradenitis suppur.

Patients with recurrent furunculosis

should be evaluated:predisposing factors such as

obesity, diabetes, occupational or industrial exposure to inciting factors, nasal carriage of Staphylococcus aureus or ,/methicillin-resistant S. aureus (MRSA) colonization.

• Treatment with warm compresses antiseptic sol./ or incision and drainage

• Systemic antibiotics:(multiple furuncles,severe illness, systemic signs, immunosuppresed , cellulitis around lesions , Areas like nose, Ear canal ,face and genitalia and acral parts:

• Cloxacillin,dicloxacillin,CA-MRSA: (Cotrimoxazole , doxy, clinda )

Furuncles treat./

Bacterial cellulitis

Cellulitis is a deep infection of the skin, (dermis/ subcutis) usually accompanied by generalized (systemic) symptoms such as

fever and chills.

streptococci , Staphylococcus and H.influenza, are the most common

causes of cellulitis.

Cellulitis causes the affected area of skin to turn red, painful, hot and swollen

Risk factors for cellulitis

• a skin condition such as eczema or a fungal infection of the foot or toenails (athlete’s foot) can cause small breaks to develop in the surface of the skin.

• having a weakened immune system (as a result of health conditions such as HIV or diabetes, or as a side effect of a treatment such as chemotherapy

• lymphoedema – a condition that causes swelling of the arms and legs, which can sometimes occur spontaneously or may develop after surgery for some types of cancer

• Venous insufficiency• intravenous drug abuse (injecting drugs such as heroin)

Cellulitis secondary to tinea infection.

Venous Insufficiency With Supra-Imposed Ulceration and Severe Cellulitis

In healthy adults

isolation of an etiologic agent is difficult and unnecessary.

If the patient has: diabetes, an immunocompromising disease, or

persistent inflammation: blood cultures or aspiration of the area of maximal inflammation may be useful.

Indications for IV antibiotics in cellulitis

• Severely ill patients • those whose condition is unresponsive to

standard oral antibiotic therapy • Immunosuppressed patients• Patients with facial cellulitis• Any patient with a clinically significant

concurrent condition, including lymphedema and cardiac, hepatic, or renal failure

• Individuals with newly elevated creatinine, creatine phosphokinase, and/or low serum bicarbonate levels or marked left-shift polymorphonuclear neutrophils

In cases of cellulitis without draining wounds or abscess, • streptococci continue to be the likely etiology,and beta-lactam antibiotics are appropriate therapy, as noted in the following:

In mild cases of cellulitis treated on an outpatient basis, dicloxacillin, amoxicillin, and cephalexin are all reasonable choices

Clindamycin or a macrolide (clarithromycin or azithromycin) are reasonable alternatives in patients who are allergic to penicillinfluoroquinolones are best reserved for gram-negative organisms with sensitivity demonstrated by culture

Some clinicians prefer an initial dose of parenteral antibiotic with a long half-life (eg, ceftriaxone followed by an oral agent)

In otherwise healthy adults

empiric treatment with a penicillinase-resistant penicillin, first-generation cephalosporin, amoxicillin-clavulanate (Augmentin), macrolide, or fluoroquinolone (adults only) is appropriate.

Antibiotics should be maintained for at least three days after the resolution of acute

inflammation

Adjunctive therapy includes:• cool compresses;• appropriate analgesics for pain;• tetanus immunization; and • immobilization and elevation of the affected

extremity

more severe cases that require parenteral antibiotics to cover MRSA

• , vancomycin, • daptomycin, • tigecycline, • ceftaroline, and • linezolid are appropriate choices.

However, vancomycin continues to be the drug of choice because of its overall excellent tolerability profile, efficacy, and cost

Erysipelas

an acute streptococcus bacterial infection of the upper dermis and

superficial lymphatics.

Historically, the face was most affected; today the legs

are affected most oftenThe erythematous skin lesion

enlarges rapidly and has a

sharply demarcated raised edge.

It appears as a red, swollen, warm, hardened and painful rash, similar in consistency to an orange peel. More severe infections can result in vesicles, bullae, and petechiae, with possible skin necrosis.

Blood cultures are unreliable for diagnosis of the disease, but may be used to test for sepsis. Elevation of (ASO) titer occurs after around 10 days of illness.

Erysipelas must be differentiated from: herpes zoster, angioedema, contact dermatitis, and diffuse inflammatory carcinoma of the breast.

ERYSIPELOID

Acute cut,. infection with Erysipelothrix

rhusiopathiae.

This type of bacteria is found in

fish, birds, mammals, and shellfish.

It usually affects people who work with

these animals (such asfishermen , farmers

or butchers).

Symptomswarmth, tenderness, and redness (non purulant cellulitis)on the skin

TreatmentAntibiotics, especially

penicillin, are used to treatalternatives:erythromycincephalosporinetetracyclinesThe infection rarely spreads. It may be self limited.

ERYTHRASMA

Chronic superficial bacterial skin infection Corynebacterium Minutissimum

inside startum corneum

Wood light examination of erythrasma

The patches of erythrasma are initially pink, but progress quickly to become brown and scaly (as skin starts to shed), which are classically sharply demarcated.

Erythrasmic patches are typically found in intertriginous areas (skin fold areas - e.g. armpit, groin, under breast) - with the toe web-spaces being most commonly involved. The patient is commonly otherwise asymptomatic. The diagnosis can be made on the clinical picture alone.

It is prevalent among diabetics and the obese, and in warm climates; it is worsened by wearing occlusive clothes.

Treatment of erythrasma

Aluminium chloride 20%

improved hygienetopical azoles

topical fusidic acid

oint. whitefield(SA +Bezoic acid)

oral erythromycin or tetracyclines

erythrasma

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