Lecture 38: Antimicrobial Resistance - Fungal Infections (PDF)

ANTIMICROBIAL RESISTANCE by Dr. Daniel Czyż FUNGAL INFECTIONS, PART I Lecture 37 Today’s lecture will cover: Lecture 37: Fungal infections Lecture 38: Antifungal treatment Mechanisms of resistance After completion of this lecture, students should be able to: Recognize...

ANTIMICROBIAL RESISTANCE by Dr. Daniel Czyż FUNGAL INFECTIONS, PART I Lecture 37 Today’s lecture will cover: Lecture 37: Fungal infections Lecture 38: Antifungal treatment Mechanisms of resistance After completion of this lecture, students should be able to: Recognize different types of fungi and virulence mechanisms Be familiar with different types of mycoses and yeast (Candida) infections  Good vs C  Good vs bad C Types of fungi Yeast Mold (mycelium) Single cell Hyphae (branching filaments) Can be pathogenic Can be pathogenic Dimorphic Temperature-mediated fungal dimorphism Pathogenic fungi can be dimorphic Switch from mycelial to yeast form is temperature- dependent Dimorphism is use for rapid identification of infections Romani 2004  Fungal virulence mechanisms Allergic immune responses (hypersensitivity) Environmental fungi Asthma Toxin production Aflatoxins (produced by Aspergillus flavus) Mycoses Host infection  Types of mycoses Superficial mycoses: Skin layer Hair Nails Subcutaneous: Deep tissue Systemic: Internal organs Primary Secondary (opportunistic) Pearson Superficial mycoses Most common & easily transmissible Recurrent & persistent Not a serious health threat Treated with topical anti-fungal agents (often OTC) WebMD Subcutaneous mycoses High among specific occupations that are in contact with soil (agricultural workers, miners, gardeners, etc) Sporotrichosis (Sporothrix schenckii) aka Rose-gardener’s disease Treated with oral anti-fungal Azoles (i.e. ketoconazole or fluconazole) Subcutaneous mycosis case study Who: A 32-year-old pig farmer Symptoms: Fever, night sweats, weight loss of 10 kg over 3 months, coughing up blood, skin ulcers Diagnostics: Chest scans revealed internal cavities. HIV negative. Rufino et al. 2013 Sporothrix schenckii positive Treatment & outcome: Amphotericin B. Full recovery  Systemic Mycoses Most often acquired from the environment (i.e. breathing in airborne spores) Three major systemic mycoses are: Histoplasmosis Spores often found in bird and bat droppings Common in the Mississippi and Ohio River valleys Healthy individuals do not get infected Effective treatments are available, but fatal if not treated Coccidioidomycosis (Valley Fever) Spores are found in soil (most common in the SW of the US) Impossible to prevent infection in areas of high risk Healthy individuals do not get infected Blastomycosis Spores are ubiquitously found in moist soil and on decomposing wood and leaves Healthy individual do not get infected Human mycobiota Underhill & Iliev 2014 Human mycobiota Candida is the most abundant fungi in the human body Candida is the most common cause of hospital-acquired bloodstream infections Hallen-Adams & Suhr 2017 Candida auris: emerging pathogen Lone & Ahmad, 2019 Candida spp. CDC closely monitors C. auris infections Candida auris Emerging MDR yeast (some strains pan-resistant) High mortality Can indefinitely colonize patients’ skin Can survive in the environment for extended periods Resistant to certain disinfectants Easily disseminated Associated with extended hospital stays and recent use of antibiotics/antivirals Question?