Fungal Infections Superficial fungal infections and Systemic fungal infections

 

Superficial fungal infections are caused by

• numerousfungi that are capable of superficially invadingthe following:
• ▪ Skin , Nail apparatus▪ ,Mucosal sites, Oropharynx•

• Hair/hair follicles, Anogenitalia, Epidermis,

• These fungi are commensural organisms thatfrequently colonize normal epithelium.
• • Dermatophytes, Candida species, Malassezia species,
• Infections can extend more deeply in the immunocompromisedhost.
• Deeper, chronic cutaneous fungal infections canoccur after cutaneous inoculation.
• ▪ Mycetoma, Chromomycosis, Sporotrichosis

Fungal Infections

 

Systemic fungal infections with cutaneous dissemination;

• these infections occur most often inthe immunocompromised host.
• ▪ Primary lung infection; can disseminate hematogenouslyto multiple organ systems, includingthe skin
• Histoplasmosis.•
• Cryptococcosis
• • North American blastomycosis
• • Coccidioidomycosis
• Disseminated candidiasis commonly arises inthe GI tract.
• • Penicillinosis
• ▪ Primary gastrointestinal (GI) infection; neutropenichost

 

Etiology —

• Three genera of dermatophytes:
• Trichophyton
• M icrosporum
• E pidermophyton .
• • More than 40 species are currently recognized;approximately 10 spp. are commoncauses of human infection.
• • T. rubrum is the most common cause of epidermaldermatophytosis and onychomycosisin industrialized nations.

Under the microscope the fungi appear as rounded or budding forms or hyphae.

• The budding forms are like yeast (round or oval buds).
• The hyphae are molds( elongated rods).
• Yeast-like fungi are Candida and Cryptococcus.
• The mold like fungi are Aspergillus, Rhizopus, Ring worm fungi.

Fungal Infections Dimorphic fungi

 

Fungal Infections Dimorphic fungi (have 2 forms) – are

• histoplasmo­sis,
• blastomycosis,
• sporotrichosis,
• coccidiodomycosis.

Fungal Infections coccidiodomycosis

• They are spherical but grow like molds (hyphae).
• Candida grows like budding yeast called pseudo hyphae.

Fungal Infections Candida grows

• Pneumocystis are also fungi.
• Ring worm, Pityriasis versicolor, and Piedra infect the skin and its appendages.
• Deep mycoses occurs by inhalation.

Fungal Infections Ring worm, Pityriasis versicolor

• Candida albicans is a normal commensal in the mouth but when the mucosa or skin is breached by disease, or surgery, or trauma, then infection occurs.
• Aspergillus and Fusarium infect the host when immu­nologically compromised.

Diagnosis Fungal Infections

• · Microscopic examination of smears or biopsy specimen.
• · Fluorescence microscopy with calcofluor stain­ing is a sensitive technique for sputum, bron­chial lavage fluid, and pus.

India ink smear is used to detect Fungal Infections cryptococci in CSF

• · India ink smear is used to detect cryptococci in CSF.
• · Candida can be seen with Gram-positive stain­ing.
• · Histopathology slides are stained with Gomori methenamine silver staining.
• · Histoplasma is detected by nucleic acid hybrid­ization technique.

ANTIFUNGAL TREATMENT Topical agents

 

Fungal Infections cutaneous Candida, Tinea versicolor (pityri­asis) and ring worm

 

Imidazole and Triazoles

• · Cutaneous applications are clotrimazole, ketoconazole_J miconazole.
• · For cutaneous Candida, Tinea versicolor (pityri­asis) and ring worm any of the above may be used.
• .-1- Va inal formulations are miconazole, cIotrimazole.
• · For vaginal candidiasis clotrimazole may be used.
• For ring worm tolnaftate is used.
• Salicylic acid is used for hyperkeratotic lesions of skin.

Fungal Infections Systemic antifungals

• Prevention
• Apply powder containing imidazoles or tolnaftate to areas prone to fungal infectionafter bathing.

Topical antifungal

• These preparations may be effective for treatment of dermatophytoses of skin butpreparations not for those of hair or nails .
• Preparation is applied bid to involved area optimally for 4 weeks including at least1 week after lesions have cleared.
• Apply at least 3 cm beyond advancing margin of lesion.These topical agents are comparable.
• Differentiated by cost, base, vehicle, andantifungal activity.

Imidazoles

• Econazole (Spectazole)
• Oxiconizole (Oxistat)
• Sulconizole (Exelderm)
• Sertaconazole (Ertaczo)Clotrimazole (Lotrimin, Mycelex)
• Miconazole (Micatin)
• Ketoconazole (Nizoral)

Allylamines

• Naftifine (Naftin)
• Terbinafine (Lamisil)

Naphthionates

• Tolnaftate (Tinactin)
• Substituted pyridone
• Ciclopirox olamine (Loprox)

Systemic antifungal agents

• For infections of keratinized skin :
• use if lesions are extensive or if infection hasfailed to respond to topical preparations.
• Usually required for treatment of tinea capitis and tinea unguium.
• Also may berequired for inflammatory tineas and hyperkeratotic moccasin-type tinea pedis.

Terbinafine

• 250-mg tablet.
• Allylamine.
• Most effective oral antidermophyte antifungal; lowefficacy against other fungi.

Azole/imidazoles

• Itraconazole and ketoconazole
• Itraconazole 100-mg capsules;
• oral solution (10 mg/mL):Intravenous.

Triazole.

• Needs acid gastricpH for dissolution of capsule.
• Raises levels of digoxin and cyclosporine.

Fluconazole

• 100-, 150-, 200-mg tablets;
• oral suspension (10 or 40 mg/mL);
• 400 mg IV.

Ketoconazole

• 200-mg tablets.
• Needs acid gastric pH for dissolution of tablet.
• Take with food orcola beverage; antacids and H2 blockers reduce absorption.
• The mosthepatotoxic of azole drugs; hepatotoxicity occurs in an estimated one of every10,000–15,000 exposed persons

Griseofulvin Micronized:

• 250- or 500-mg tablets;
• 125 mg/teaspoon suspension.
• Ultramicronized :

• 165- or 330-mg tablets. Active only against dermatophytes;less effective than triazoles.

Fungal Infections Systemic antifungals

• Griseofulvin for ring worms.
• Terbinafine 250 mg  for onychomycosis (fun­gal nail infection) and ring worm.
• Treatment is given for 3-6 months.
• The Imidazoles and triazoles may be used for systemic use e.g. fluconazole, itraconazole for blastomycosis, histoplasmosis, aspergillosis.
• Fluconazole penetrates CSF and other body flu­ids.
• · It is useful in oropharyngeal and oesophageal candidiasis in adults.
• Amphotericin B and fluconazole may be used for cryptococcal meningitis, in AIDS, and coccidiodal meningitis.