Difference Between Systemic and Opportunistic Mycoses

The key difference between systemic and opportunistic mycoses is that systemic mycoses are fungal infections caused due to primary and opportunistic fungal pathogens, while opportunistic mycoses are caused due to opportunistic fungal pathogens.

Mycoses are fungal infections in animals, including humans. Mycosis mainly occurs as a result of the inhalation of fungal spores or localized colonization of the skin. Immunocompromised people, very young and old people and patients suffering from cancers, diabetes, etc., are at a higher risk of fungal infections. The immune status and infectious dose from environmental exposure are critical factors for fungal infections. There are different types of mycoses as superficial, cutaneous, subcutaneous, or systemic, depending on the type and degree of tissue involvement and the host response to the pathogen. Systemic mycoses are deep infections that affect internal organs, including lungs, abdominal viscera, bones and or central nervous system. Systemic mycoses may arise due to primary pathogens as well as opportunistic pathogens.

CONTENTS

1. Overview and Key Difference
2. What are Systemic Mycoses
3. What are Opportunistic Mycoses
4. Similarities Between Systemic and Opportunistic Mycoses
5. Side by Side Comparison – Systemic vs Opportunistic Mycoses in Tabular Form
6. Summary

What are Systemic Mycoses?

Systemic mycoses are fungal infections that affect internal organs. Fungi enter our body via lungs, gut, paranasal sinuses or skin. Then they spread into different organs through the bloodstream. Once they invade organs, organs fail to function, leading to serious problems. Immunocompromised patients such as AIDS patients, patients with low white blood counts, organ transplant recipients, cancer patients and very old and very young people, etc., are more susceptible to systemic mycoses. However, healthy individuals are also subject to systemic mycoses. Generally, systemic mycoses belong to a group of diseases that are difficult to diagnose and treat. In certain regions in the world, system mycoses are responsible for high rates of morbidity and mortality.

Clinical features vary among individuals. They can also vary from asymptomatic to disseminated fatal diseases. Moreover, clinical features depend on the specific type of infection and the type of organ affected. General symptoms include fever, cough and loss of appetite. There are two types of systemic mycoses as endemic or opportunistic. Histoplasmosis, coccidioidomycosis, blastomycosis, and sporotrichosis are several types of endemic mycoses. Aspergillosis, mucormycosis, mycetoma, blastomycosis. paracoccidioidomycosis, candidiasis, chromoblastomycosis, sporotrichosis are several opportunistic fungal infections. Opportunistic mycoses are described in the below section.

What are Opportunistic Mycoses?

Opportunistic mycoses are fungal infections caused due to opportunistic fungi that are normal resident flora (commensal). They are common in all environments. Normal fungi in the body become pathogenic when the host immune system weakens. Host immune defences may be altered due to immunosuppressive therapy or chronic diseases or during antibacterial therapy. Therefore, opportunistic fungi cannot cause diseases in immunocompetent people.

Candida, Cryptococcus, Aspergillus, Mucor, and Rhizopus are five medically important opportunistic fungi. Examples of opportunistic mycoses include aspergillosis, mucormycosis, mycetoma, blastomycosis. paracoccidioidomycosis, candidiasis, chromoblastomycosis and sporotrichosis.

What are the Similarities Between Systemic and Opportunistic Mycoses?

• Opportunistic mycoses are one of the two types of systemic mycoses.
• Internal organs fail to function due to both systemic and opportunistic mycoses.
• Fungi gain access to the host mainly via the respiratory tract.

What is the Difference Between Systemic and Opportunistic Mycoses?

Systemic mycoses are fungal infections affecting internal organs, while opportunistic mycoses are a type of systemic mycoses. Systemic mycoses can be caused due to both primary pathogens and opportunistic pathogens, while opportunistic mycoses are solely due to opportunistic fungal pathogens which are normal flora. So, this is the key difference between systemic and opportunistic mycoses. Moreover, systemic mycoses are possible in immunologically normal hosts by primary pathogens while opportunistic mycoses occur in immunocompromised people who suffer from cancer, organ transplantation, surgery, and AIDS. Thus, this is another significant difference between systemic and opportunistic mycoses.

Below is a summary of the difference between systemic and opportunistic mycoses in tabular form.

Summary – Systemic vs Opportunistic Mycoses

Systemic mycoses are fungal infections that affect internal organs, including lungs, abdominal viscera, bones and central nervous system. These deep mycoses are due to primary fungal pathogens or opportunistic fungal pathogens. Therefore, opportunistic mycoses are systemic mycoses caused by opportunistic fungal pathogens. Thus, this summarizes the difference between systemic and opportunistic mycoses.

Reference:

1. Knott, Dr Laurence. “Systemic Mycoses. Learn about Systemic Mycoses.” Patient.info, 27 Oct. 2014, Available here.
2. Walsh, Thomas J. “Spectrum of Mycoses.” Medical Microbiology. 4th Edition., U.S. National Library of Medicine, 1 Jan. 1996, Available here.

Image Courtesy:

1. “Histoplasmosis capsulatum” By CDC/Dr. Libero Ajello – This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL) (Public Domain) via Commons Wikimedia

2. “The oral fungal pathogen Candida albicans (red) produce hyphae that allow attachment of another fungus Candida glabrata (green)” By NIH Image Gallery (CC BY-NC 2.0) via Flickr