L-8 Clinical Approaches to dermatological infections

Clinical Approaches to Dermatologic Infections

• Merrick D. Elias, DO, FAOCD, FAAD from Elias Dermatology, LLC is the author of the presentation.
• Images presented are courtesy of ETAS (Educational Testing and Assessment Systems) in 2014 and Dermatology by Bolognia, Jorizzo and Rapini, and other online sources.
• There are no reported conflicts of interest in the presentation.

Bacterial Infections: Actinomycosis

• Causative organism is Actinomyces israelii, an anaerobic gram-positive rod.
• Characteristics include chronic suppurative nodules and sinus tracts with exudate containing "sulfur granules."
• Most commonly involves the cervicofacial region, especially near the mandible, known as "lumpy jaw."
• Could also involve the abdomen and thoracic region.
• The infection's source is "endogenous" such as oral flora.
• Its risk factors consist of poor oral hygiene, penetrating foreign bodies, and dental procedures.

Pitted Keratolysis

• Causative organism is Kytococus sedentarius, formerly Micrococcus sedentarius.
• Characteristics include shallow 1-3 mm pits on the plantar surface of feet; malodor and hyperhidrosis are common.
• Treatment involves topical erythromycin, clindamycin, or benzoyl peroxide.

Staphyloccocal Infections

• Phage group II S. aureus exotoxins are able to produce bullous or exfoliative skin lesions and syndromes.
• These syndromes include toxic shock syndrome (TSS), staphylococcal scalded skin syndrome, bullous impetigo, and scarlatiniform eruption (staphylococcal scarlet fever).
• Other Staphylococcal Infections include: Impetigo (non-bullous), Folliculitis/Furunculosis, Sycosis barbae, Ecthyma, Cellulitis, Botryomycosis, Acute paronychia, Felon (staphylococcal whitlow), Purpura fulminans, and Endocarditis.

Trichomycosis Axillaris

• Causative organism is Corynebacterium tenuis
• Characteristics include yellowish-brown concretions on axillary hair shafts
• Treatment includes shaving, benzoyl peroxide gel, and topical erythromycin or clindamycin

M. Marinum – Swimming Pool/Aquarium Granuloma

• Begins as a small papule at the site of inoculation and evolves into a nodule or granulomatous plaque, potentially with a verrucous surface
• Sporotrichoid spread can occur
• Treatment is Minocycline

Superficial Mycoses

• Superficial mycoses are generally limited to the outer layers of the hair, skin, and mucosal surfaces
• They rarely invade the cells below

Pityriasis Versicolor (Tinea Versicolor)

• Current nomenclature: Malassezia furfur, M. pachydermatis, M. dermatis, M. obtuse, M. restrica, M. sympodialis, M. slooffiae
• Refers to sun spots, found worldwide, and prefers a humid, moist, warm environment with increased CO2 tension
• Appears as round to oval yeast forms on normal skin in sebum-rich areas
• Conversion to hyphae and spore referred to as spaghetti and meatballs
• Mild, chronic, sharply demarcated hyper or hypopigmented macules with fine scaling
• Lesions are often seen on the neck, shoulders, chest, back, upper arms, and abdomen
• Woods lamp (+) shows pale yellow fluorescence
• Implicated in folliculitis (Pityrosporum folliculitis), seborrheic dermatitis, atopic dermatitis, invasive infections, and onychomycosis
• KOH: Curved septate hyphae with short chains or clusters of budding thick-walled yeast cells, may see only hyphae or only yeast cells
• Topical treatment: Selenium sulfide, ketoconazole shampoo, topical “azoles,” ciclopirox
• Systemic treatment: Ketoconazole, itraconazole, fluconazole

Other Superficial Mycoses

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

The Dermatophytes

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

Common Dermatophyte Infections

• Factors favoring Dermatophyte Infection:
  • Large inoculum size
  • Suitable environment: Hydration, friction, maceration, heat, darkness, occlusion
  • Growth rate of fungus must be greater than epidermal turnover

Tinea Capitis

• Dermatophyte infection of the scalp and hair, generally seen in childhood

• Ectothrix: -Arthroconidia coat the outside of the hair, cuticle destroyed -Fluorescent (Woods light, 366 nm, mercury lamp with a nickel chromium oxide filter, fluorescence is due to pteridine production) -Nonfluorescent: T. mentagrophytes, T. rubrum, T. verrucosum, T. megninii, M. gypseum, M. nanum

• Endothrix Black Dot Ringworm

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

• Favus

  • Chronic infection of the scalp begins in childhood and may extend into adulthood
  • Scutula: 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 -Treatment is Griseofulvin, itraconazole, terbinafine, and selenium sulfide or ketoconazole or cicloprox shampoo

• Kerion

  • Boggy, oozing inflammatory reaction to fungus
  • Regional lymphadenopathy and scarring alopecia may result
  • Most frequently due to M. canis, T. tonsurans, T. verrucosum, T. mentagrophytes
  • Differential Diagnosis will include seborrheic dermatitis, impetigo, folliculitis, lupus, psoriasis, and alopecia areata

Tinea Corporis or Ringworm

• Any of the dermatophytes can cause tinea corporis; the most frequently recovered organisms include T. rubrum, T. mentagrophytes, M. canis, and T. tonsurans
• Transmitted directly from individuals, animals, or fomites
• Organisms invade stratum corneum; generally causing an annular lesion with an erythematous raised, scaly advancing border; the center of the lesion may show clearing -Tinea Imbricata: T. concentricum endemic to South Pacific, S. & C. America, and Far East -Manifested as Polycyclic scaly noninflammatory lesions -Tinea Profunda: Verrucous inflammatory response patients may have defective cellular immunity -Majocchi’s Granuloma: Granulomatous lesion of hair follicle, generally associated with T. rubrum; requires biopsy for diagnosis and oral antifungal -Differential Diagnosis will include seborrheic, atopic or contact dermatitis, psoriasis, impetigo, lichen simplex, nummular eczema, and tertiary syphilis

Tinea Barbae

• In men, the bearded area of the face and neck, generally inflammatory
• Associated with exposure to animals
• Requires oral antifungal

Tinea Variations

• Tinea Cruris: Mainly seen in males, involves the groin, perineal and perianal skin through direct or indirect contact
  • E. floccosum, T. rubrum, T. mentagrophytes are possible causes
• Tinea Faciei: Most frequently impacts females and children on the upper lip and chin, possibly related to animal exposure
  • T. rubrum, T. mentagrophytes, T. concentricum, and M. canis are possible causes
• Tinea Manuum: Palmar/interdigital areas of the hands almost always associated with T. pedis
  • T. rubrum, T. mentagrophytes, E. floccosum are possible causes
• Tinea Pedis: Moccasin, interdigital, and vesicular types exist -E. floccosum and T. mentagrophytes are possible causes -Interweb infections will often involve fungi, yeast, gram-negative and gram-positive bacteria

Tinea Unguium

• Dermatophyte infection of the nails
• Onychomycosis is a fungal infection of the nails due to dermatophyte, yeast, or nondermatophyte
  • Distal Lateral Subungual Onychomycosis: Begins distally and involves the nail bed, nail plate, and lateral nail fold; thick nail with debris, loose, or cracked nail plate, with T. rubrum as a likely cause
  • Proximal White Subungual Onychomycosis: Rarest form of onychomycosis and an AIDS marker, it's when organisms enter the cuticle and infect the proximal part of the nail bed causing white islands that slowly invade the nail plate with T. rubrum as the most frequently recovered cause
  • White Superficial Onychomycosis: Organism invades the surface of the nail plate of toenails only and causes Irregular white chalky opaque patches on the nail -T. mentagrophytes is the most frequent cause, also Aspergillus species esp. terreus, Acremonium (formerly Cephalosporium), Fusarium, and Scopulariopsis -In HIV population, generally caused by T. rubrum

A Common Diagnostic Error: Tinea Incognito

• Corticosteroid use can cause an atypical appearing lesion
• Needs to be treated with antifungal medications and not topical or systemic steroids
• Avoid combination drugs with antifungal plus steroid or clotrimazole/betamethasone cream
• Referral to a board-certified dermatologist is advised if: the diagnosis is uncertain or unable to confirm diagnosis with KOH or other means

Dermatophytids

• Eczematous allergic reaction to dermatophyte infection elsewhere on the skin with sterile lesions
• Reaction clears after fungus has been eradicated
• Alternate names: Id reaction, DermatophytID reaction

Lacaziosis (Keloidal Blastomycosis, Lobomycosis, Lobo’s Disease)

• Lacazia loboi, formerly Loboa loboi
• Associated with Brazil and the Caribbean, specifically bottle-nosed dolphins
• Can cause Painless keloids, nodules, occasionally ulcers, verrucose lesions on the face and upper extremities
• Presents No inflammatory reaction around skin
• Biopsy: 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) -Stains with Fontana Masson stain
• Organism is not culturable
• Treatment: Surgical excision (antifungals ineffective)

Candidiasis

• Causes include Candida albicans, C. glabrata, C. parapsilosis, C. tropicalis, C. krusei, C. dubliniensis, C. kefyr
• Most common fungal opportunistic infection C. albicans and C. glabrata most often isolated from patients with invasive candidiasis
• Cutaneous and mucocutaneous candidiasis affects all ages, most common in very young and elderly, both sexes with mucosal prevalent in HIV positive individuals
• Manifestations include thrush, perleche, vulvovaginitis, balanitis, paronychia, onychomycosis, intertrigo, folliculitis, congenital and neonatal candidiasis, systemic dissemination to any organ
• Cutaneous lesions include papulonectrotic eschars, purpura
• Biopsy: Budding yeast, pseudohyphae, some species produce true hyphae

Treatment: -Topical: topical -azoles, nystatin, terbinafine, naftine -Systemic: Amphotericin B, ketoconazole, fluconazole, itraconazole, voriconazole, caspofungin

• Species: -C. albicans is the most common species (50%-60% of candida infections) and presents as true and pseudohyphae -C. glabrata accounts for 15%-20% of candida infections and has Fluconazole resistance -C. parapsilosis causes chronic paronychia and systemic infections -C. tropicalis makes up 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 is most frequently implicated in cases of recurrent infection following antifungal drug treatment

Miscellaneous Organisms Causing Fungus-Like Infections

• Rhinosporidiosis:
  • Rhinosporidium seeberi, an aquatic protozoan previously considered a fungus. Rare in USA.
• Protothecosis:
  • Prototheca wickerhamii, which causes rare cutaneous, subcutaneous, systemic infections by achloric algae
  • Worldwide habitat: Stagnant water
  • Skin lesions are generally seen in immunosuppressed patients after trauma through papules, plaques,vesicles, cellulitis, eczematoid dermatitis, and verrucous nodules
  • Can cause olecrenon bursitis 1/3 cases
  • Treatment includes surgical excision, amphotericin B +/- tetracycline, and ketoconazole