BIO205 Lecture Exam 3 study guide

Define hyphae

Long, thread-like filaments of mold

Define spores

Reproductive cells that fungi use to spread (like seeds)

Define budding

The process of asexual reproduction in yeast; new cell grows off parents cell

Define saprophytic

Feeds on dead/decaying organic matter

Define chitin

Material that makes up fungal cell walls

Define thallus

The body of a mold (made up of hyphae)

Define septate hyphae

Hyphae with cross-walls (sections)

Define aseptate hyphae

Hyphae without cross walls; one continuous tube

Define dimorphic

Fungi that can switch between yeast (in the body) and mold (in the environment) depending on temperature

Define mycelium

A mass of hyphae (visible mold growth)

Define sporangium

A sac-like structure inside a sporangium (the sac)

Define sporangiospores

Spores formed inside a sporangium (in a sac)

Define conidiospores

Spores formed at the tip of a hyphae (outside of sac)

Define mycoses

Fungal infections

Define dermatophytes

Fungi that infect hair, skin, nails (ringworm/tinea)

Define true fungal pathogens

Fungi that can infect healthy individuals

Define opportunistic infections

Fungi that only affects weakened immune systems

Define superficial

On the surface of hair/skin

Define systemic

Spread throughout the body; usually start by inhaling spores into lunch’s

Define cutaneous

In deeper epidermis

What are the three clinical manifestations of fungal diseases

Allergic reactions, mycoses, and fungal toxicoses

What are factors that predispose people to opportunistic infections

Being immunocompromised, cancer chemotherapy, long-term antibiotics, diabetes, and organ transplant

Define the importance of patient history

Travel history helps point clues to certain fungi

How is Sabouraud dextrose agar used

Used as a selective medium that fungi grows best on

What is KOH prep

Dissolves the tissue and leaves fungal cells under the microscope

What is a GMS stain

A special stain that highlights only fungi black/green if they turn black/green

What are two reasons fungal infections are hard to treat

Antifungals can be toxic to humans and fungi are eukaryotes, which means they are limited unique drug targets

What are two targets for anti-fungal therapy

Cell membrane and cell wall synthesis

How does amphotericin B work

It binds to ergosterol, which creates pores that make fungal cells leak and die

How do azole drugs work

It blocks ergosterol synthesis which weakens fungal membrane

How are immunocompromised patients treated

They are treated with a combination of amphotericin B and azoles, often long term

What are the four true fungal pathogens

Blastomyces, coccidioides, histoplasma, and paracoccidioides

What is the significance of the Mississippi River/Great Lakes to fungal pathogens

Where the fungal pathogen blastomycosis is found

What is the significance of the desert Southwest to fungal pathogens

It is where coccidioidomycosis is found (valley fever)

What is the significance of Mexico and Central America to fungal infections

Where paracoccidioidomycosis is found

What is the importance of spherule to fungal infections

Unique structural form that helps identify specific fungi (cocci)

What are the importance of bird/bat droppings to fungal infections

Contributes to histoplasmosis, it is where the fungi is found

What is the importance of steering wheel formation to fungal infections

It is a distinctive microscopic shape (steering wheel shape)

What disease does aspergillus cause

It causes aspergillosis

How is aspergillus transmitted

Transmitted through the inhalation of fungal spores

How is aspergillus diagnosed

Diagnosed through microscopy or culture

How is aspergillus treated

Treated with amphotericin B or azole

Where is candida found

Found on the skin and mucous membranes

How is candida transmitted

Transmitted between individuals

What type of disease does candida cause

Causes thrush, vaginal candidiasis, and invasive candidiasis

How is candida treated

Treated with azole

How do dermatophytes cause superficial fungal infections and tinea lesions

They lie beneath the surface of the skin

How are dermatophytes diagnosed

Diagnosed through a physical exam

Where are microbiota found

Found all over the body that have openings to the outside world

When/how are microbiota acquired

Begins during childbirth and established through rest of life

What conditions allow microbiota to become opportunistic infections

Poor immune systems or immune suppression

Define infection

A condition in which pathogenic microbes penetrate host defenses, enter the tissue and multiply

Define disease

Alteration of an organs’ normal function

Define sign

Manifestations of a disease that can be observed or measured (fever, rash)

Define symptom

Characteristics of a disease that can be felt by the patient alone

Define pathogenicity

An organism’s potential to cause infection and disease

Define virulence

The relative severity of the disease

Define virulence factor

Relative severity of the disease

Define infectious dose

The minimum # of microbes for an infection

Define asymptomatic

Lack symptoms

Define syndrome

A group of symptoms or signs that collectively characterize a particular disease or condition

What are the 5 steps to establishing an infection

1. Portals of entry

2. Attaching to host

3. Surviving host defenses

4. Causing disease

5. Portals of exit

What virulence factors are important in establishing an infection

Adhesion factors

What are the 4 primary routes of entry

Food, water, air, wounds

What are the 5 categories of virulence factors

1. Adhesion factors

2. Biofilms

3. Anti phagocytic factors

4. Extracellular enzymes

5. Toxins

Define fimbriae

Specialized adhesion structure

Define glycocalyx

Specialized adhesion structure

Define attachment proteins

Found on viruses and many bacteria

Define adhesions

Ability to bind to one another or host tissue

Define capsule

Composed of chemicals found in body; can be slippery which makes it difficult for phagocytes to engulf bacteria

Define leukocidin

Destroy phagocytic white blood cells

Define phagocyte

Phagocytic cells

Define exoenzyme

Enzymes secreted by the pathogen

Define phagocytosis

Process of WBC’s engulfing pathogens

Define hyaluronidase

Digests hyaluronic acid

Define collagenase

Digests collagen

Define coagulase

Coagulates blood proteins

Define kinase

Digests clots

Define exotoxin

Secreted by a living bacterial cell

Define endotoxin

Not actively secreted; shed from outer membrane

Define enterotoxin

Toxin that specifically targets the intestines

Define neurotoxin

Type of exotoxin

What is the difference between exotoxin and endotoxin

Exotoxin is secreted by a living cell, endotoxin is not actively secreted

What are the portals of exit for a pathogen

Respiratory infection, skin infection, intestinal parasites, urogenital tract, and blood

What are the 5 general stages of disease

Incubation period, prodromal period, illness, decline, convalescence

What is a resevoir

Site where pathogens are maintained as source of infection

What are the three types of reservoirs

Animal reservoir, human carrier, nonliving reservoir

What are zoonoses

Animal reservoir; direct contact with animals or its waste, eating animals, bloodsucking arthropods

How do zoonoses relate to reservoirs

Zoonotic diseases

What are the 3 ways zoonotic diseases infect humans

What are 5 categories of human carriers

Asymptomatic, incubating, convalescent, convalescent, chronic, passive

What are 3 modes of transmission

Contact, vehicle, or vector transmission

What is a fomite

What is epidemiology

Study of where and when diseases occur and how they are transmitted within populations

Define incidence

Number of new cases of a disease in a given area during a period of time

Define prevalence

Number of total cases of a disease in a given area during a given period of time

Define endemic

Define epidemic

Define pandemic

What are nosocomial infections

Infections acquired while in a health care facility