Introduction to Mycology Nov. 30, 2015 Bob Slinger, MD, Division of Infectious Disease, CHEO

Objectives 231 Recognize the morphological characteristics of yeasts and filamentous fungal pathogens 232 Recognize the clinical classification, common etiology and impact of human mycoses including superficial, cutaneous, sub‐cutaneous and disseminated infections. 233 Discuss the available treatment options and mechanisms of action of anti‐fungal agents including amphotericin B, the azoles, and echinocandins.

Fungi: eukaryotic= nuclear membrane Rigid cell wall

Fungal Morphology 1 2 basic morphological forms: yeasts and filaments (hyphae) Yeasts- unicellular, round to oval, reproduce by budding Hyphae: multi-cellular, groups of hyphae called molds (produce infectious round or oval spores called conidia, these are not yeast) Dimorphism: fungus can exhibit either the yeast form or the filamentous form (e.g. histoplasmosis)

Hyphae Conidia (Spores) Yeasts bsite/Lects/Fungi.htm

Hyphae Intracellular yeasts.

Who is at risk for Fungal Infections? Some fungi able to affect healthy persons Those with impaired innate immunity: eg change in Normal bacterial flora caused by antibiotic therapy Those with impaired cellular immunity due to diseases or medications eg neutropenia caused by leukemia or chemotherapy for cancer Those with impaired cell mediated immunity eg due to steroid use ( asthmatics receiving inhaled steroids) or due to diseases that affect T cells eg HIV

Classification of Fungal Infections Anatomically, based on depth of invasion superficial cutaneous subcutaneous systemic Host Factors Called opportunistic/ non-opportunistic = Healthy host vs non- healthy host)

Superficial Mycoses infections limited to the outermost layers of the skin and hair no invasion of deeper tissues, so no inflammation and no symptoms E.g Tinea versicolor: Malassezia species hypopigmented macules, “spaghetti and meatballs" appearance of organism in skin scrapings Hyphae and conidia

Tinea versicolor case: Patient complains of white patches on back, not itchy or painful

Case: Child with multiple pink circular lesions, itchy, scaly borders, lives on farm, no tick bites

What is diagnosis? A) Lyme disease B) Blastomycosis C) Ring worm D) Candidiasis

Cutaneous Mycoses: Dermatophytes extend deeper into epidermis, or into hair and nails cellular immune responses may occur inflammation and symptoms (itching, burning) caused by diseases are referred to as ringworm identified by appearance +/- microscopic exam and culture

Tinea capitis

Tinea unguium

Tinea pedis (Athlete’s foot)

Case: Patient reports development of redness and swelling on back of hand. Is an avid rose gardener and recalls rose thorn injury in this area weeks ago.

What is diagnosis? A) Coccidioidomycosis B) Aspergillosis C) Tinea manus D) Sporotrichosis

Fungal culture from biospy of skin nodule: Sporotrichosis Conidiophores and conidia of the fungus Sporothrix schenckii

Subcutaneous Fungal Infections e.g. Sporotrichosis involve the dermis, subcutaneous tissues, muscle and fascia most infections are chronic initiated after organism is implanted in skin by trauma spread by lymphatic system difficult to treat, surgical excision e.g. Sporotrichosis: Sporothrix schenckii, from plant thorns, nodules and ulcers along lymphatics at site of inoculation

. Case: 18 -year-old otherwise healthy male with a 3-month history of progressive pneumonia despite antibacterial therapy. Consolidation involving the left lower lobe and early cavitation. Lives near Lake of the Woods in Northern Ontario, active outdoors, has a dog with a chronic cough, patient and dog are non-smokers. Also has skin lesion on elbow.

Sputum sample

What is diagnosis? A) Bartonellosis B) Histoplasmosis C) Anaplasmosis D) Blastomycosis

Systemic Fungal Infection Blastomyces dermatitidis: Manitoba, Northern Ontario usually lung, rare cases of localised skin or bone lesions

Blastomycosis in Northern Ontario

Systemic Fungal Infection agents are inherently virulent, able to evade host defences primary focus of infection is the lung secondary infection may occur elsewhere in the body Blasto, histo, coccidioidomycosis are top 3 May also referred to as “dimorphic” or “geographic” fungi

Systemic: Dimorphic Grow as hyphae in environment, but as yeast in humans Pathogenicity: ability to survive and multiply within phagocytic cells e.g. Blastomycosis, histoplasmosis Histoplasmosis: bird or bat droppings and soil central Canada, St. Lawrence valley localised lung disease in most patients disseminated disease may occur in immunosuppressed patients

Case: Patient with Leukemia A 4 year old boy with leukemia develops prolonged fever and neutropenia Later complains of difficulty eating, and then blurring of vision Physical exam shows pharynx on right CT scan of abdomen and photo of fundus are abnormal

CT of abdomen showing multiple lesions. Endoscopic view on right. N Engl J Med 2007; 356:e4January 25, 2007DOI: /NEJMicm040112

Fundus Exam What fungal infection do you suspect? A) Aspergillosis B) Blastomycosis C) Candidiasis D) Leptospirosis

Opportunistic Infections: Candida Candida infections occur with physiological normal flora disruptions e.g. vaginal candidiasis as a result of antibiotic therapy disrupting normal flora e.g. Pharyngeal Thrush in neutropenic patients – disseminated candidiasis

Opportunistic Infections Can be yeasts ( Candida) or hyphae (molds) infections in patients with immune deficiencies, or impaired host defences HIV Alteration of normal flora Diabetes mellitus Immunosuppressive therapy Malignancy Newborns/infants

Infant with cutaneous candidiasis Satellite lesions

Opportunistic Molds: Aspergillus ubiquitous in environment, particularly spreads during building renovations invasive disease in patients with neutropenia, post- transplant patients other manifestations: allergic (Allergic Bronchopulmonary Aspergillosis)

Aspergillosis Pneumonia

Aspergillosis: Angioinvasion Hyphae in blood vessel wall, leads to infarction

Opportunistic Molds: Mucormycosis,similar to Aspergillus, leads to severe disease in neutropenic patients

Antifungal Agents Amphotericin B, Lipid Amphotericins bind to ergosterol in the cell membrane, causing leakage Azoles : block ergosterol synthesis e.g. fluconazole, voriconazole, posaconazole Echinocandins (e.g. caspofungin): block glucan synthesis in cell wall

Echinocandins Azoles and Amphotericin

Lab Diagnosis of Fungal Infections Specify on requisition when fungal cultures required; put down names of suspected agents if possible Lab will look for fungal elements hyphae and yeast Bacterial gram stain will show yeast (Candida) as well Culture on special media (some will grow on media used for bacteria e.g. candida) Antigen and antibody tests in some cases: send out to Provincial Lab or to USA for special tests ( can discuss these with Infectious Diseases )

Fungal Infection: Treatment and Prevention Sanford Guide to Antimicrobial Therapy - recommended for treatment information Prevention: antifungal medications given to some high risk patients e.g. some leukemia and transplant patients on fluconazole infection control measures used in hospital to prevent aspergillus inhalation, masks to prevent high risk environmental exposure Thank you