First appeared on Cleveland Clinic
Bacterial infections
Humans are natural hosts for many bacterial species that
colonize the skin as normal flora. Staphylococcus aureus and Streptococcus
pyogenes are infrequent resident flora, but they account for a wide variety of
bacterial pyodermas. Predisposing factors to infection include minor trauma,
preexisting skin disease, poor hygiene, and, rarely, impaired host immunity.
Impetigo
Definition and
Etiology
Impetigo is a superficial skin infection usually caused by
S. aureus and occasionally by S. pyogenes.
Prevalence and Risk
Factors
Impetigo affects approximately 1% of children.
Pathophysiology and
Natural History
S. aureus produces a number of cellular and extracellular
products, including exotoxins and coagulase, that contribute to the
pathogenicity of impetigo, especially when coupled with preexisting tissue
injury. Impetigo commonly occurs on the face (especially around the nares) or
extremities after trauma.
Signs and Symptoms
Two clinical types of impetigo exist: nonbullous and
bullous. The nonbullous type is more common and typically occurs on the face
and extremities, initially with vesicles or pustules on reddened skin. The
vesicles or pustules eventually rupture to leave the characteristic
honey-colored (yellow-brown) crust. Bullous impetigo, almost exclusively caused
by S. aureus, exhibits flaccid bullae with clear yellow fluid that rupture and
leave a golden-yellow crust.
Diagnosis
Diagnosis is by clinical presentation and confirmation by
culture.
Treatment
For most patients with impetigo, topical treatment is
adequate, either with bacitracin (Polysporin) or mupirocin (Bactroban), applied
twice daily for 7 to 10 days. Systemic therapy may be necessary for patients
with extensive disease.
Folliculitis,
Furunculosis, and Carbunculosis
Definition and
Etiology
Folliculitis is a superficial infection of the hair
follicles characterized by erythematous, follicular-based papules and pustules.
Furuncles are deeper infections of the hair follicle characterized by
inflammatory nodules with pustular drainage, which can coalesce to form larger
draining nodules (carbuncles).
Pathophysiology and
Natural History
S. aureus is the usual pathogen, although exposure to
Pseudomonas aeruginosa in hot tubs or swimming pools can lead to folliculitis.
In general, folliculitis is a self-limited entity. Occasionally, a pustule
enlarges to form a tender, red nodule (furuncle) that becomes painful and
fluctuant after several days. Rupture often occurs, with discharge of pus and
necrotic material. With rupture, the pain subsides and the redness and edema
diminish.
Signs and Symptoms
Folliculitis is generally asymptomatic, but it may be
pruritic or even painful. Commonly affected areas are the beard, posterior
neck, occipital scalp, and axillae. Often a continuum of folliculitis,
furunculosis (furuncles), arises in hair-bearing areas as tender, erythematous,
fluctuant nodules that rupture with purulent discharge. Carbuncles are larger
and deeper inflammatory nodules, often with purulent drainage, and commonly
occur on the nape of the neck, back, or thighs. Carbuncles are often tender and
painful and occasionally accompanied by fever and malaise.
Diagnosis
Diagnosis is by clinical presentation and confirmation by
culture.
Treatment
Topical treatment with clindamycin 1% or erythromycin 2%,
applied two or three times a day to affected areas, coupled with an
antibacterial wash or soap, is adequate for most patients with folliculitis.
Systemic antistaphylococcal antibiotics are usually necessary for furuncles and
carbuncles, especially when cellulitis or constitutional symptoms are present.2
Small furuncles can be treated with warm compresses three or four times a day
for 15 to 20 minutes, but larger furuncles and carbuncles often warrant
incision and drainage. If methicillin-resistant S. aureus (MRSA) is implicated
or suspected, vancomycin (1-2 g IV daily in divided doses) is indicated coupled
with culture confirmation. Antimicrobial therapy should be continued until
inflammation has regressed or altered depending on culture results.
Ecthyma
Definition and
Etiology
Ecthyma is a cutaneous infection characterized by thickly
crusted erosions or ulcerations. Ecthyma is usually a consequence of neglected
impetigo and often follows impetigo occluded by footwear or clothing.
Prevalence and Risk
Factors
Ecthyma typically occurs in homeless persons and soldiers based
in hot and humid climates.
Pathophysiology and
Natural History
S. aureus or S. pyogenes is the usual pathogen of ecthyma.
Untreated staphylococcal or streptococcal impetigo can extend more deeply,
penetrating the dermis, producing a shallow crusted ulcer. Ecthyma can evolve
from a primary pyoderma, in a pre-existing dermatosis, or at the site of
trauma.
Signs and Symptoms
Infection begins with vesicles and bullae that progress to
punched-out ulcerations with an adherent crust, which heals with scarring. The
most common site of infection is the legs.
Diagnosis
Diagnosis is by clinical presentation and confirmation by
culture.
Erysipelas and
Cellulitis
Definition and
Etiology
Erysipelas is a superficial cutaneous infection of the skin
involving dermal lymphatic vessels. Cellulitis is a deeper process that extends
to the subcutis.
Prevalence and Risk
Factors
Erysipelas has a predilection for young children and the
elderly. Lymphedema, venous stasis, web intertrigo, diabetes mellitus, trauma,
alcoholism, and obesity are risk factors in the adult patient.
Pathophysiology and
Natural History
Group A ?-hemolytic streptococcus is the most common
pathogen responsible for erysipelas, and S. aureus is by far the most common
pathogen for cellulitis. S. pyogenes produces enzymes that promote infection
with systemic manifestations, such as fever and chills, tachycardia, and
hypotension. Left untreated, cellulitic skin can become bullous and necrotic,
and an abscess or fasciitis, or both, can occur.
Signs and Symptoms
Classically, erysipelas is a tender, well-defined,
erythematous, indurated plaque on the face or legs. Cellulitis is a warm,
tender, erythematous, and edematous plaque with ill-defined borders that
expands rapidly. Cellulitis is often accompanied by constitutional symptoms,
regional lymphadenopathy, and occasionally bacteremia.
Diagnosis
Diagnosis is by clinical presentation and confirmation by
culture (if clinically indicated, ie., bullae or abscess formation).
Treatment
Penicillin (250-500 mg, qid × 7-10 days) is the treatment of
choice for erysipelas; parenteral therapy may be necessary for extensive or
facial disease. An oral antistaphylococcal antibiotic is the treatment of
choice for cellulitis; parenteral therapy is warranted for patients with extensive
disease or with systemic symptoms as well as for immunocompromised patients.
Good hygiene, warm compresses three or four times a day for 15 to 20 minutes,
and elevation of the affected limb help to expedite healing.
Necrotizing Fasciitis
Definition and
Etiology
Necrotizing fasciitis is a rare infection of the
subcutaneous tissues and fascia that eventually leads to necrosis. Predisposing
factors include injuries to soft tissues, such as abdominal surgery, abrasions,
surgical incisions, diabetes, alcoholism, cirrhosis, and intravenous drug
abuse.
Pathophysiology and
Natural History
S. pyogenes can be the sole pathogen responsible for
necrotizing fasciitis, but most patients have a mixed infection with other
aerobes (groups B and C streptococci, MRSA) and anaerobes (Clostridium spp).
Signs and Symptoms
Infection begins with warm, tender, reddened skin and
inflammation that rapidly extends horizontally and vertically. Necrotizing
fasciitis commonly occurs on the extremities, abdomen, or perineum or at operative
wounds. Within 48 to 72 hours, affected skin becomes dusky, and bullae form,
followed by necrosis and gangrene, often with crepitus. Without prompt
treatment, fever, systemic toxicity, organ failure, and shock can occur, often
followed by death. Computed tomography (CT) or magnetic resonance imaging (MRI)
can help to delineate the extent of infection. Biopsy for histology, Gram
stain, and tissue culture help to identify the causative organism(s).
Diagnosis
Diagnosis is by clinical presentation; CT or MRI; skin
biopsy for pathology, Gram stain, and tissue culture; culture of fluid from
bullae or fluctuant plaques; and blood cultures.
Treatment
Necrotizing fasciitis is a surgical emergency requiring
prompt surgical debridement, fasciotomy, and, occasionally, amputation of the
affected extremity to prevent progression to myonecrosis. Treatment with
parenteral antibiotics (usually gentamicin and clindamycin) is mandatory. Even
with treatment, mortality approaches 70%.
Fungal and yeast infections
Dermatophytosis
Definition and
Etiology
Dermatophytosis implies infection with fungi, organisms with
high affinity for keratinized tissue, such as the skin, nails, and hair.
Trichophyton rubrum is the most common dermatophyte worldwide. This is similar to
Ringworm.
Pathophysiology and
Natural History
Three fungal genera—Trichophyton, Microsporum, and
Epidermophyton—account for the vast majority of infections. Fungal reservoirs
for these organisms include soil, animals, and infected humans.
Signs and Symptoms
Tinea pedis (athlete's foot) is the most common fungal
infection in humans in North America and Europe. Affected skin is usually
pruritic, with scaling plaques on the soles, extending to the lateral aspects
of the feet and interdigital spaces, often with maceration.
Tinea cruris (jock itch) occurs in the groin and on the
upper, inner thighs and buttocks as scaling annular plaques; disease is more
common in men and typically spares the scrotum.
A
Ringworm treatment can
help with uncomfortable symptoms.
Tinea capitis, or fungal infection of the scalp, is most
common in children. It is characterized by scaly, erythematous skin, often with
hair loss. Tinea capitis can resemble seborrheic dermatitis. Kerion celsi is an
inflammatory form of tinea capitis, characterized by boggy nodules, usually
with hair loss and regional lymphadenopathy.
Tinea corporis (body), faciei (face), and manuum (hands)
represent infections of different sites, each invariably with annular scaly
plaques. Tinea unguium (onychomycosis) is fungal nail disease, characterized by
thickened yellow nails and subungual debris.
Potassium hydroxide preparation or culture help to establish
the diagnosis for all forms of fungal infections.
Diagnosis
Diagnosis is by clinical presentation, KOH examination, and
fungal culture.
Treatment
For most patients, topical treatment with terbinafine
(Lamisil), clotrimazole (Lotrimin, Mycelex), or econazole (Spectazole) cream is
adequate when applied twice daily for 6 to 8 weeks. For onychomycosis, tinea
capitis, and extensive dermatophyte disease, systemic treatment is often necessary:
itraconazole (Sporanox) or terbinafine (Lamisil) for nail disease, and
griseofulvin or fluconazole for scalp or extensive dermatophyte disease. Some patients use a
Ringworm cure to work with symptoms.
Candidiasis
Definition and
Etiology
Candidiasis refers to a diverse group of infections caused
by Candida albicans or by other members of the genus Candida. These organisms
typically infect the skin, nails, mucous membranes, and gastrointestinal tract,
but they also cause systemic disease.
Prevalence and Risk
Factors
Infection is common in immunocompromised patients,
diabetics, the elderly, and patients receiving antibiotics.
Pathophysiology and
Natural History
Candida albicans accounts for 70% to 80% of all candidal
infections. C. albicans commonly resides on skin and mucosal surfaces.
Alterations in the host environment can lead to its proliferation and
subsequent skin disease.
Signs and Symptoms
Candidal intertrigo is a specific infection of the skin
folds (axillae, groin), characterized by reddened plaques, often with satellite
pustules. Thrush is oropharyngeal candidiasis, characterized by white
nonadherent plaques on the tongue and buccal mucosa. Paronychia is an acute or
chronic infection of the nail characterized by tender, edematous, and
erythematous nail folds, often with purulent discharge; this disease is common
in diabetics. Angular cheilitis is the presence of fissures and reddened scaly
skin at the corner of the mouth, which often occurs in diabetics and in those
who drool or chronically lick their lips.
Candidal vulvovaginitis is an acute inflammation of the
perineum characterized by itchy, reddish, scaly skin and mucosa; creamy
discharge; and peripheral pustules. The counterpart in men is balanitis,
characterized by shiny reddish plaques on the glans penis, which can affect the
scrotum. Balanitis occurs almost exclusively in uncircumcised men.
Diagnosis
Diagnosis is by clinical presentation, KOH examination, and
fungal culture.
Treatment
For candidal intertrigo and balanitis, topical antifungal
agents such as clotrimazole, terbinafine, or econazole cream, applied twice
daily for 6 to 8 weeks, is usually curative when coupled with aeration and compresses.
For thrush, the treatment is nystatin suspension or clotrimazole troches four
to six times daily until symptoms resolve. Systemic antifungal drugs, such as
fluconazole 100 to 200 mg/day or itraconazole 100 to 200 mg/day, for 5 to 10
days may be necessary for severe or extensive disease. For paronychia,
treatment consists of aeration and a topical antifungal agent such as
terbinafine, clotrimazole, or econazole for 2 to 3 months; occasionally, oral
antistaphylococcal antibiotics are needed, coupled with incision and drainage
for secondary bacterial infection. Cheilitis resolves with aeration,
application of a topical antifungal agent, and discontinuation of any
aggravating factors. A single 150-mg dose of fluconazole, coupled with
aeration, is usually effective for vulvovaginitis.
Tinea (Pityriasis)
Versicolor
Definition and
Etiology
Tinea versicolor is a common opportunistic superficial
infection of the skin caused by the ubiquitous yeast Malassezia furfur. This is similar to
Ringworm.
Prevalence and Risk
Factors
Prevalence is high in hot, humid climates. Purported risk
factors include oral contraceptive use, heredity, systemic corticosteroid use,
Cushing's disease, immunosuppression, hyperhidrosis, and malnutrition.
Pathophysiology and
Natural History
M. furfur may filter the rays of the sun and also produces
phenolic compounds that inhibit tyrosinase, which can produce hypopigmentation
in many patients.
Signs and Symptoms
Infection produces discrete and confluent, fine scaly,
well-demarcated, hypopigmented or hyperpigmented plaques on the chest, back,
arms, and neck. Pruritus is mild or absent.
These symptoms can be generally alleviated with a
Ringworm cure.
Diagnosis
Diagnosis is by clinical presentation. Potassium hydroxide
preparation exhibits short hyphae and spores with a spaghetti-and-meatballs
appearance.
Treatment
Selenium sulfide shampoo (2.5%) or ketoconazole shampoo is
the mainstay of treatment, applied to the affected areas and the scalp daily
for 3 to 5 days, then once a month thereafter. Alternatively, a variety of
topical antifungal agents, including terbinafine, clotrimazole, or econazole
cream, applied twice daily for 6 to 8 weeks, constitute adequate treatment,
especially for limited disease. Systemic therapy may be necessary for patients
with extensive disease or frequent recurrences, or for whom topical agents have
failed.
Ringworm treatment can be
helpful with certain symptoms.
Viral infections
Herpes Simplex
Definition and
Etiology
Herpes simplex virus (HSV) infection is a painful,
self-limited, often recurrent dermatitis, characterized by small grouped
vesicles on an erythematous base. Disease is often mucocutaneous. HSV type 1 is
usually associated with orofacial disease, and HSV type 2 is usually associated
with genital infection.
Prevalence and Risk
Factors
Eighty-five percent of the population has antibody evidence
of HSV type 1 infection. HSV type 2 infection is responsible for 20% to 50% of
genital ulcerations in sexually active persons.
Pathophysiology and
Natural History
Disease follows implantation of the virus via direct contact
at mucosal surfaces or on sites of abraded skin. After primary infection, the
virus travels to the adjacent dorsal ganglia, where it remains dormant unless
it is reactivated by psychological or physical stress, illness, trauma, menses,
or sunlight.
Signs and Symptoms
Primary infection occurs most often in children, exhibiting
vesicles and erosions on reddened buccal mucosa, the palate, tongue, or lips
(acute herpetic gingivostomatitis). It is occasionally associated with fever,
malaise, myalgias, and cervical adenopathy. Herpes labialis (fever blisters or
cold sores) appears as grouped vesicles on red denuded skin, usually the
vermilion border of the lip; infection represents reactivated HSV. Primary
genital infection is an erosive dermatitis on the external genitalia that
occurs about 7 to 10 days after exposure; intact vesicles are rare. Recurrent
genital disease is common (approximately 40% of affected patients). Prodromal
symptoms of pain, burning, or itching can precede herpes labialis and genital
herpes infections.
Diagnosis
Viral culture helps to confirm the diagnosis; direct
fluorescent antibody (DFA) is a helpful but less-specific test. Serology is
helpful only for primary infection. The Tzanck smear can be helpful in the
rapid diagnosis of herpesviruses infections, but it is less sensitive than
culture and DFA.
Treatment
Acyclovir remains the treatment of choice for HSV infection;
newer antivirals, such as famciclovir and valacyclovir, are also effective. For
recurrent infection (more than six episodes per year), suppressive treatment is
warranted. Primary infection in immunosuppressed patients requires treatment
with acyclovir 10 mg/kg every 8 hours for 7 days.
Herpes Zoster
Definition and
Etiology
Herpes zoster (shingles) is an acute, painful dermatomal
dermatitis that affects approximately 10% to 20% of adults, often in the
presence of immunosuppression.
Pathophysiology and
Natural History
During the course of varicella, the virus travels from the
skin and mucosal surfaces to the sensory ganglia, where it lies dormant for a
patient's lifetime. Reactivation often follows immunosuppression, emotional
stress, trauma, and irradiation or surgical manipulation of the spine, producing
a dermatomal dermatitis.
Signs and Symptoms
Herpes zoster is primarily a disease of adults and typically
begins with pain and paresthesia in a dermatomal or bandlike pattern followed
by grouped vesicles within the dermatome several days later. Occasionally,
fever and malaise occur. The thoracic area accounts for more than half of all
reported cases. When zoster involves the tip and side of the nose (cranial
nerve V) nasociliary nerve involvement can occur (30%-40%). Most patients with
zoster do well with only symptomatic treatment, but postherpetic neuralgia
(continued dysthesias and pain after resolution of skin disease) is common in
the elderly. Disseminated zoster is uncommon and occurs primarily in
immunocompromised patients.
Diagnosis
Diagnosis is by clinical presentation, viral culture, or
direct fluorescent antibody.
Treatment
Zoster deserves treatment, with rest, analgesics, compresses
applied to affected areas, and antiviral therapy, if possible, within 24 to 72
hours of disease onset. Disseminated and ophthalmic zoster warrants treatment
with acyclovir 10 mg/kg intravenously every 8 hours for 7 days.
Warts
Definition and
Etiology
Warts are common and benign epithelial growths caused by
human papillomavirus (HPV).
Prevalence and Risk
Factors
Warts affect approximately 10% of the population. Anogenital
warts are a sexually transmitted infection, and partners can transfer the virus
with high efficiency. Immunosuppressed patients are at increased risk for
developing persistent HPV infection.
Pathophysiology and
Natural History
HPV infection follows inoculation of the virus into the
epidermis through direct contact, usually facilitated by a break in the skin.
Maceration of the skin is an important predisposing factor, as suggested by the
increased incidence of plantar warts in swimmers. After inoculation, a wart
usually appears within 2 to 9 months. The rough surface of a wart can disrupt
adjacent skin and enable inoculation of virus into adjacent sites, leading to
the development and spread of new warts.
Signs and Symptoms
The common wart is the most common type: It is a
hyperkeratotic, flesh-colored papule or plaque studded with small black dots
(thrombosed capillaries). Other types of warts include flat warts (verruca
plana), plantar warts, and condyloma acuminatum (venereal warts).
Diagnosis
The clinical appearance alone should suggest the diagnosis.
Skin biopsy may be performed, if warranted.
Treatment
Therapy is variable and often challenging. Most modalities
are destructive: cryosurgery, electrodesiccation, curettage, and application of
various topical products such as trichloroacetic acid, salicylic acid, topical
5-fluorouracil, podophyllin, and canthacur. For stubborn warts, laser therapy
or injection with candida antigen may be helpful. The immunomodulator imiquimod
cream (Aldara) is a novel topical agent recently approved for treating
condyloma acuminatum, and it might help with common warts as well, usually as
adjunctive therapy. Sexual partners of patients with condyloma warrant
examination, and women require gynecologic examination.
Prevention and
Screening
For common warts, no approaches have been documented to
prevent transmission. For genital warts (condyloma), the risk correlates with
the number of sexual partners. A quadrivalent HPV vaccine (Gardasil) has been
available since 2006, and this represents the newest approach to preventing
genital HPV infection and ultimately cervical cancer in women. The vaccine is
safe and 100% effective and is recommended for girls and women ages 9 to 26
years.
Molluscum Contagiosum
Definition and
Etiology
Molluscum contagiosum is an infectious viral disease of the
skin caused by the poxvirus.
Prevalence and Risk
Factors
The prevalence is less than 5% in the United States.
Infection is common in children, especially those with atopic dermatitis,
sexually active adults, and patients with human immunodeficiency virus (HIV)
infection. Transmission can occur via direct skin or mucous membrane contact,
or via fomites.
Pathophysiology and
Natural History
The disease follows direct contact with the virus, which
replicates in the cytoplasm of cells and induces hyperplasia.
Signs and Symptoms
Molluscum are smooth pink, or flesh-colored, dome-shaped,
umbilicated papules with a central keratotic plug. Most patients have many
papules, often in intertriginous sites, such as the axillae, popliteal fossae,
and groin. They usually resolve spontaneously, but they often persist in
immunocompromised patients.
Diagnosis
Diagnosis is by clinical presentation and by skin biopsy, if
warranted.
Treatment
Treatment might not be necessary because the disease often
resolves spontaneously in children. Treatment is comparable to the modalities
outlined for warts; cryosurgery and curettage are perhaps the easiest and most
definitive approaches. In children, canthacur, applied topically then washed off
2 to 6 hours later, is well tolerated, and is very effective.
Summary
- Impetigo is a superficial skin infection usually
caused by Staphylococcus aureus and occasionally by Streptococcus pyogenes.
- Folliculitis is a superficial infection of the
hair follicles characterized by erythematous, follicular-based papules and
pustules.
- Ecthyma is a deep infection of the skin that
resembles impetigo. Ecthyma is somewhat common in patients with poor hygiene or
malnutrition.
- Erysipelas is a superficial streptococcal infection
of the skin.
- Necrotizing fasciitis is a rare infection of the
subcutaneous tissues and fascia that eventually leads to necrosis.
- Dermatophytosis implies infection with fungi,
organisms with high affinity for keratinized tissue, such as the skin, nails,
and hair. Trichophyton rubrum is the most common dermatophyte worldwide.
- Cutaneous candidiasis is a yeast infection
caused primarily by Candida albicans.
- Tinea versicolor is a common superficial
infection of the skin caused by the ubiquitous yeast Malassezia furfur. This can be helped with certain kinds of Ringworm cure.
- Herpes simplex virus infection is a painful,
self-limited, often recurrent dermatitis, characterized by small grouped vesicles
on an erythematous base.
- Herpes zoster (shingles) is an acute, painful
dermatomal dermatitis that affects approximately 10% to 20% of adults, often in
the presence of immunosuppression.
- Warts are common and benign epithelial growths
caused by human papillomavirus.
- Molluscum contagiosum is an infectious viral
disease caused by the poxvirus.