(Section D: Other Infectious Agents) Lecture 30 Flashcards
Mycoses
Fungal infections caused by a fungus (yeast or mold)
How many fungi are reported to cause diseases of humans and other warm-blooded animals?
About 200-300 fungi
Mycotoxins
Toxi chemical compounds produced by certain fungi that grow on food crops and other organic materials
What can airborne spores cause?
Asthma, allergies, or cause occupational diseases
List major health risks posed by fungi
- Mycoses
- Mycotoxins
- Airborne spores
How many people are affected by fungal disease? How many deaths are attributed to fungal diseases?
- Over a billion people affected by fungal disease
- ~1.5 million deaths are attributable to fungi annually
Are fungal infections noticeable?
No
* Transient exposure to fungi or fungal colonization occurs without the knowledge of the affected individual
How virulent are fungi?
Most fungi have low virulence
Is it easy to diagnose fungal infections?
No, it is difficult to diagnostically distinguish between presence and infection
How are mycoses classified?
- Site of infection
- Route of acquisition
- Type of virulence
Site of infection classifications
- Superficial: Only on the epidermis, usually clears up on its own
- Cutaneous: Goes into the dermis
- Subcutaneous: Goes into the subcutaneous layer, cause by wounds
- Systemic: Dissemination through bloodstream, infects other organs
Route of acquisition classifications
- Exogenous: External sources such as aerosols and direct contact
- Endogenous: Happens in immunocompromised individuals
Type of virulence classifications
- Primary mycoses: Can infect healthy individuals
- Opportunistic mycoses: Usually affect immunocompromised individuals, hard to affect healthy individuals
Dermatophytic fungi
* Site of infection
* Species
- Most are superficial and cutaneous
- Trichophyton, Microsporum, and Epidermophyton
What are Trichophyton, Microsporum, and Epidermophyton fungi classified as?
Molds
Are dermatophytic fungi very good at spreading?
No, they are usually self-limiting and generally have no cellular immune response
Opportunistic Systemic Mycoses
* Mechanism
* Species
- Expoit the imbalance between the host and the pathogen that occurs in immunocompromised individuals
- Candida, Aspergillus
What type of fungi are Candida?
Yeasts
What type of fungi are Aspergillus?
Molds
What are risk factors that are associated with getting fungal infections?
(10)
- HIV infection and AIDS
- Solid-organ transplantation
- Anticancer chemotherapy
- Granulocytopenia
- Premature birth
- Old age
- Use of corticosteroids
- Use of broad-spectrum antibiotics
- Central vascular catheters
- Gastrointestinal surgery
- Colonization with fungus
True or False:
Candida species always cause infections when they infect humans
False, a large proportion of humans innocuously carry several Candida species on epithelial surfaces
What species of Candida is most frequently associated with Candidiasis?
Candida albicans
What types of superficial candidiasis infections are there?
- Oropharyngeal candidiasis
- Denture stomatitis
- Vulvovaginal candidiasis
- Chronic mucocutaneous candidiasis
Virulence Factors of Candida
- Adhesins (bind and stick)
- Dimorphism (budding and hyphae forms)
- Phenotypic switching (change genetic expression proteins)
- Extracellular hydrolases
How does invasive Candidiasis work?
- Adhesion and Colonization
- Change morphology
- Migrate through tissues
- Budding allows travel in bloodstream
- Can form biofilms
Symptoms of Candidiasis
- Fever and chills
- Low blood pressure
- Muscle aches
- Skin rash
- Weakness or fatigue
How is Candidiasis diagnosed?
- Selective media cultures
- Detection of anti-Candida antibodies and Candida antigens in blood samples
How is epidemiology of Candida evaluated?
- DNA fingerprinting
- Microarrays
- PCR
