Dermatologic Infections: Clinical Approaches

Clinical Approaches to Dermatologic Infections Slides

• The Powerpoint covers clinical approaches to dermatologic infections
• Merrick D. Elias, DO, FAOCD, FAAD, from Elias Dermatology, LLC, created the presentation
• Images are courtesy of ETAS (Educational Testing and Assessment Systems) – 2014 and Dermatology by Bolognia, Jorizzo and Rapini and other online sources

Bacterial Infections

Actinomycosis

• The causative organism is Actinomyces israelii, an anaerobic gram-positive rod
• Chronic suppurative nodules and sinus tracts with "sulfur granules" are characteristic features
• This commonly involves the cervicofacial region near the mandible, producing "lumpy jaw"
• It can also involve the abdomen and thoracic region
• The source of infection is endogenous, such as oral flora
• Poor oral hygiene, penetrating foreign bodies, and dental procedures are risk factors

Pitted Keratolysis

• Kytococus sedentarius (formerly Micrococcus sedentarius) is the causative organism
• Shallow 1-3 mm pits on the feet's plantar surface is a characteristic
• Malodor and hyperhidrosis are common occurrences
• Treatments include topical erythromycin, clindamycin, or benzoyl peroxide

Staphylococcal Infections

• Phage group II S. aureus produce exotoxins, which can cause bullous or exfoliative skin lesions and syndromes

Bullous or Exfoliative Skin Lesions and Syndromes

• Toxic Shock Syndrome (TSS)
• Staphylococcal Scalded Skin Syndrome
• Bullous Impetigo
• Scarlatiniform Eruption (Staphylococcal Scarlet Fever)

Other Staphylococcal Infections

• Impetigo (non-bullous)
• Folliculitis/Furunculosis
• Sycosis barbae
• Ecthyma occurs uncommonly and is largely caused by Group A streptococcus.
• Cellulitis
• Botryomycosis
• Acute paronychia
• Felon (staphylococcal whitlow)
• Purpura fulminans
• Endocarditis
• Note that Erysipelas is not equal to Staph Aureus

Trichomycosis Axillaris

• Corynebacterium tenuis is the causative organism
• Yellowish brown concretions appear on axillary hair shafts
• Treatment consists of shaving, benzoyl peroxide gel, topical erythromycin, or clindamycin

M. Marinum – Swimming Pool/Aquarium Granuloma

• It starts as a small papule at the inoculation site then evolves into a nodule or granulomatous plaque with a verrucous surface
• Sporotrichoid spread can occur
• Minocycline is a treatment option

Fungal Infections of the Skin

Superficial Mycoses

• Superficial mycoses are confined to the outer layers of the skin, hair, and mucosal layers and rarely invade the cells below

Pityriasis Versicolor (Tinea Versicolor)

• Most current nomenclature: Malassezia furfur, M. pachydermatis, M. dermatis, M. obtuse, M. restrica, M. sympodialis, M. slooffiae
• Called "Sun Spots"
• It is found worldwide because it prefers humid, moist, warm environments and increased CO2 tension
• This appears as round to oval yeast forms on normal skin in sebum-rich areas
• Conversion to hyphae and spore appear as “spaghetti and meatballs"
• Mild, chronic, sharply demarcated hyper/hypopigmented macules appear with fine scaling
• Most often seen on the neck, shoulders, chest, back, upper arms, and abdomen
• Wood's lamp yields a (+) pale yellow fluorescence
• Implicated in other diseases include: folliculitis (Pityrosporum folliculitis), seborrheic dermatitis, atopic dermatitis, invasive infections, onychomycosis)
• KOH shows curved septate hyphae with short chains or clusters of budding thick-walled yeast cells, and only hyphae or only yeast cells
• Topical treatments include: Selenium sulfide, ketoconazole shampoo, topical “azoles,” ciclopirox
• Systemic treatments include: Ketoconazole, itraconazole, fluconazole

Other Superficial Mycoses

• Tinea Nigra Palmaris, or Superficial phaeohyphomycosis, new name: Hortaea werneckii
• Piedras is limited to the hair shaft, characterized by firm, irregular nodules of fungal elements
• White Piedra appears as tan to white soft, nonadherent small concretions ~1mm, on the scalp, beard, moustache, and pubic areas, and hairs may fluoresce
• New nomenclature is Trichosporon ovoides and T. inkin, formerly Trichosporon beigelii, which are found in Keratinophilic soil, water and sewage organisms, seen in temperate regions
• Black Piedra is black, firm, adherent concretions 1 mm in diameter, most common on the scalp, and also found in the pubic area, beard and mustache known as Piedraia hortae found in soil and water in humid, tropical areas

The Dermatophytes

• Dermatophyte: Group of closely related filamentous fungi that colonize keratin such as the stratum corneum, hair, nails, and feathers of animals
• Dermatophytosis: Cutaneous infections of keratinized tissue by the dermatophyte genera of fungi such as Trichophyton, Microsporum, and Epidermophyton
• Dermatomycosis: Organisms other than the dermatophytes cause deep fungal or systemic infections with cutaneous manifestations

Common Dermatophyte Infections

• Large inoculum size
• Suitable environment with hydration, friction, maceration, heat, darkness, occlusion
• Growth rate of the fungus must be greater than epidermal turnover

Tinea Capitis

• Dermatophyte infection of the scalp and hair, generally seen in childhood
• With Ectothrix, Arthroconidia coat the outside of the hair, and the cuticle is destroyed
• Lesions fluoresce under Woods light (366 nm mercury lamp with a nickel chromium oxide filter), and fluorescence is due to pteridine production
• Nonfluorescent: T. mentagrophytes, T. rubrum, T. verrucosum, T. megninii, M. gypseum, and M. nanum

Endothrix “Black Dot Ringworm”

• Arthroconidia invade the interior of the hair shaft
• Black dots are remnants of brittle hair broken at the surface of the scalp with cuticle intact
• Species examples: T. rubrum, T. gourvilli, T. yaounde, T. tonsurans, T. soudanense, T. violaceum
• KOH prep reveals Arthroconidia within the hair shaft

Favus

• This chronic infection of the scalp begins in childhood and may extend into adulthood
• Scutula appear as Yellowish cup shaped crusts made up of hyphae and keratinous debris, may have a single hair piercing through the center
• Primarily T. schoenleinii, occasionally T. violaceum, M. gypseum
• KOH prep: Hyphae and airspaces within hair shaft
• Treatments consist of Griseofulvin, itraconazole, terbinafine, and selenium sulfide or ketoconazole or cicloprox shampoo

Kerion

• Boggy, oozing inflammatory reaction to fungus
• Regional lymphadenopathy
• Scarring alopecia may result
• Most frequently caused by M. canis, T. tonsurans, T. verrucosum, T. mentagrophytes
• Differential diagnosis includes Seborrheic dermatitis, impetigo, folliculitis, lupus, psoriasis, and alopecia areata

Tinea Corporis ("Ringworm")

• Any dermatophytes can cause tinea corporis; the most frequently recovered organisms include: T. rubrum, T. mentagrophytes, M. canis,T. tonsurans
• Transmission happens directly from individuals, animals, or fomites
• Organisms invade the stratum corneum, generally causing an annular lesion with an erythematous raised, scaly advancing border, and the center of the lesion may show clearing
• Tinea Imbricata is caused by T. concentricum, endemic to South Pacific, S. & C. America and Far East. This is a polycyclic scaly noninflammatory lesion
• Tinea Profunda produces a verrucous inflammatory response, and those with defective cellular immunity are susceptible
• Majocchi's Granuloma, a granulomatous lesion of the hair follicle, is generally associated with T. rubrum and requires biopsy for dx and oral antifungal
• Differential Diagnosis includes seborrheic, atopic or contact dermatitis, psoriasis, impetigo, lichen simplex, nummular eczema, tertiary syphilis

Tinea Barbae

• In men, this inflammatory condition affects the bearded area of the face and neck
• Often associated with exposure to animals
• Requires oral antifungal

Tinea Infections

• Tinea Cruris mainly affects males andinvolves the groin, perineal and perianal skin directly or indirectly through E. floccosum, T. rubrum, and T. mentagrophytes
• Tinea Faciei affects females and children most frequently on the upper lip and chin and may have a history of animal exposure caused by T. rubrum, T. mentagrophytes, T. concentricum, and M. canis
• Tinea Manuum is on the palmar/interdigital areas of the hands and is often associated with T. pedis caused by T. rubrum, T. mentagrophytes, and E. floccosum
• Tinea Pedis includes Moccasin type from E. floccosum and T. rubrum, Interdigital type from E. floccosum and T. mentagrophytes, and Vesicular type with T. mentagrophytes
• Interweb infections often involve fungi, yeast, and gram-negative and positive bacteria

Tinea Unguium

• This is a dermatophyte infection of the nails called Onychomycosis, which is a fungal infection of the nails caused by dermatophytes, yeast, or nondermatophytes
• Distal Lateral Subungual Onychomycosis: the infection begins distally and involves the nail bed, nail plate and lateral nail fold; with a thick nail with debris, loose or cracked nail plate caused by T. rubrum
• Proximal White Subungual Onychomycosis: a rare form of onychomycosis which is an AIDS marker
• Organisms enter the cuticle and infect the proximal part of the nail bed, causing white islands that slowly invade the nail plate caused by T. rubrum and also T. megninii, T. schoenleinii, T. tonsurans, T. mentagrophytes, and E. floccosum
• White Superficial Onychomycosis occurs when an organism invades the surface of the nail plate of toenails only, and there are irregular white chalky opaque patches on the nail
• Most frequent are T. mentagrophytes, also Aspergillus species esp. terreus, Acremonium (formerly Cephalosporium), Fusarium, and Scopulariopsis with T. rubrum generally causing the infection in the HIV population

A common diagnostic error: Tinea Incognito

• The use of corticosteroids can cause an atypically appearing lesion
• Tinea needs to be treated with antifungal medications only and not topical or systemic steroids

Tinea (Summary Chart)

• Tinea faciei presents as itchy spots on the cheeks with edges of the spots raised and may include bumps, blisters, or scabs
• Tinea barbae presents as crusting and swelling on the facial hair area with facial hair easily pulled out
• Tinea corporis presents as red, scaly, and itchy patches on the torso, body, and legs, patches are more prominent in body folds, and kerion may develop
• Tinea Unguium presents as white or yellow streaks on the toe/fingernails as a crumbly nail that may lift up easily as flaky white patches on top of the nail plate, and in severe cases, the nail may be damaged
• Tinea incognito may develop in any ringworm-affected area and present as bruised blood vessels, rashes may become raised and scaly, and the skin also pustular and irritable
• Tinea Capitis : Round, itchy and scaly spots and dry scaling similar to dandruff, with bald spots due to hair loss, Kerion (a pus-filled lump) and Favus (more severe form of tinea capitis) may also develop
• Tinea manuum indicates blistering rashes with a sticky fluid that may appear in crops on your hand, the edges of the spots may be raised, and skin discoloration
• Tinea cruris are itchy reddish-brown rashes on the groin, and the spots may reach to the buttocks
• Tinea pedis presents as round, dry patches on top of the foot, with clusters of blisters on the side of the foot, moist, peeling and irritable skin between the toes, and the entire sole, heel, and sides of the foot may become dry but not inflamed

Dermatophytids

• Dermatophytids are eczematous allergic reactions to dermatophyte infection elsewhere on the skin, with sterile lesions, whose reaction clears after the fungus has been eradicated
• Alternate names: Id reaction, DermatophytID reaction

Lacaziosis (Keloidal Blastomycosis, Lobomycosis, or Lobo's Disease)

• Lacazia loboi formerly Loboa loboi is associated with bottle-nosed dolphins in Brazil and the Caribbean
• Painless keloids, nodules, occasional ulcers, and verrucose lesions occur on the face and upper extremities without inflammatory reaction around skin
• Biopsy reveals Single or multiple budding thick-walled cells 9-10µm, appear to be attached by a bridge, found free or phagocitized in a granulomatous reaction "chain of coins” or “brass knuckles," which stains with Fontana Masson stain
• The organism cannot be cultured
• Treatment: Surgical excision (antifungals ineffective)

Candidiasis

• Species: Candida albicans, C. glabrata, C. parapsilosis, C. tropicalis, C. krusei, C. dubliniensis, and C. kefyr
• This is the most common fungal opportunistic infection
• C. albicans and C. glabrata are most often isolated from patients with invasive candidiasis
• Cutaneous and mucocutaneous candidiasis affects all ages but is most common in very young and elderly of both sexes, while mucosal candidiasis is more prevalent in HIV positive patients
• Clinical manifestations include Thrush, perleche, vulvovaginitis, balanitis, paronychia, onychomycosis, intertrigo, folliculitis, congenital and neonatal candidiasis, and systemic dissemination to any organ
• Cutaneous lesions: Papulonectrotic eschars and purpura
• Biopsy reveals budding yeast, pseudohyphae, and some species produce true hyphae

Candidiasis Treatments

• Topical treatments: Topical -azoles, nystatin, terbinafine, and naftine
• Systemic treatment: Amphotericin B, ketoconazole, fluconazole, itraconazole, voriconazole, and caspofungin

Candida Species

• C. Albicans accounts for 50-60% and results in true and pseudohyphae
• C. Glabrata accounts for 15-20% and Fluconazole resistance
• C. Parapsilosis results in chronic paronychia and systemic infections
• C. Tropicalis accounts for 6-12% and frequently causes dissemination to skin and is a major cause of septicemia and disseminated candidiasis especially in patients with leukemia, lymphoma, and diabetes
• C. Dubliniensis is implicated in oropharyngeal Candidiasis in HIV-infected patients and most frequently implicated in cases of recurrent infection following antifungal drug treatment

Factors contributing to Candida Infection

• Impaired epithelial cell barrier
• Systemic illness
• Neutrophil and macrophage disorders
• Immune disorders
• Therapeutic agents
• Congenital or acquired endocrine disorders
• Malignancies
• Indwelling catheters
• Hyperalimentation
• Heat, humidity and friction

Miscellaneous Organisms Causing Fungus-Like Infections

• Rhinosporidiosis is caused by Rhinosporidium seeberi, an aquatic protozoan previously considered a fungus found to be rare in the USA
• Protothecosis is caused by Prototheca wickerhamii, and is a rare cutaneous, subcutaneous, systemic infection by achloric algae found with a worldwide habitat: Stagnant water
• Skin lesions are generally seen in immunosuppressed patients after trauma: papules, plaques, vesicles, cellulitis, eczematoid dermatitis, and verrucous nodules, accounting for of olecrenon bursitis in 1/3 of cases
• Treatment: Surgical excision, Amphotericin B +/- tetracycline, and ketoconazole