Quiz 1 Flashcards
What are some species of fungi associated with humans
Molds and yeasts
Meaning of Saprophytic
able to live on dead or decaying organic matter
How fungi acquire food and reproduce
acquire food by absorption, can reproduce sexually and/or asexually
What is a mold
Multicellular, filamentous form of fungi cosisting of thread-like filaments to form fuzzy colonies
What is a yeast
unicellular; produce circular, restricted, pasty or mucoid colonies
What does dimorphic mean
exhibit either a yeast or mold phase (may be temperature dependent)
What is a hyphae
Microscopic filaments (as in mold)
What is a mycelium
Network of hyphae; colony
Difference between Aerial mycelium and Vegatative mycelium
aerial mycelium grows above the substrate while vegitative mycelium grows within/below the substrate
What is a filamentous fungi
Mold
Types of septate seen in mold
septate and sparsely septate (frequent perpendicular cross-walls and infrequent perpendicular cross-walls)
difference between hyaline and dematiaceous pigmentation
Hyaline (nonpigmented hyphae) vs Dematiaceous (dark and pigmented hyphae; due to presence of melanin in the cell wall)
How Unicellular yeast reproduces
asexually (budding and binary fission) and sexually
What is Conidia
asexual spores
Role of conidia
Means of dispersal, or survival (dormant state)
How conidia can vary
vary in size, shape, and color; Unicellular or multicellular
What is the spectrum of mycotic disease
superficial, cutaneous, mucosal, systemic
How fungi are classified
traditionally botanic taxonomy or clinical microbiology groupings
Clinical microbiology groupings of fungal diseases (mycoses)
superficial, cutaneous, systemic, opportunistic
Superficial mycoses
confined to the outermost “dead” layer of the skin or hair
cutaneous mycoses
affects the keratinized layer of the skin,hair or nails
systemic mycoses
affects the intenal organs or deep tissues of the body
opportunistic mycoses
found primarily in immunocompromised persons; infections of a great variety of tissues
How do opportunistic mycoses pose a significant diagnostic challenge
complexity of the patient population at risk and increasing array of fungi that can infect these individuals
Superficial / cutaneous mode of transmission
person to person or from animal to human contact
Subcutaneous mode of transmission
through the skin (trauma to the skin)
Deep mycoses mode of transmission
Opportunistic growth in immunocompromised; inhalation of spores or in presence of intravenous devices
Lab values to support bacterial pathogen
Increased WBC count, Neutrophils, marked increase in total protein, Marked decrease in glucose, CSF Lactate > 35 mg/dl
Lab values to support viral pathogen
Increased WBC count, Lymphocytes, moderate increase in total protein, normal glucose, Lactate normal
lab values to support fungal pathogen
Increased WBC, Lymphocytes and monocytes, mod-marked increase in total protein, normal to low glucose, lactate >25 mg/dl
How specimens should be handled when processing
Specimens should be processed under a biological safety cabinet
How saprobes can affect a specimen in the lab
They can be found in the air generally and can be transmitted to growing/testing mediums
Spectrum of antifungal agents (broad v narrow)
Antifungal agents act on a spectrum of activity. Broad spectrum agents can be more broadly effective against many different organisms. Narrow spectrum agents are more specific and can be less intense
difference between fungistatic and fungicidal
Both describe the activity of antifungal agents. One kills organisms while the other inhibits the growth of an organism (cidal, static)
Fungistatic
Level of antifungal activity that inhibits the growth of an organism
Fungicidal
the ability of antifungal agent to kill an organism in vitro or in vivo
What would happen if you use 2 antifungal agents?
synergism or anagonism can occur. The antifungal agents can work together to beat the organism or they can inhibit the effectiveness of the agents
What are systemically active agents
Systemically active agents work through the whole whole body to fight off the organism
Polyene
Binds to ergosterol to destroy the integrity of the fungal cell membrane
Azole
inhibits fungal enzyme lanosterol 14-α-demethylase, cell membrane synthesis of fungal cell
Echinocandins
inhibits synthesis of 1,3 beta-glucans (constituent of fungal cell wall)
Flucytosine
interferes with the synthesis of DNA,RNA and proteins (fluorouracil)
Allyamines
inhibit enzyme squalene epoxidase, leads to a toxic amount of squalene in the fungal cell membrane
difference between topical and systemic active agents
topical agents are used in the treatment of superficial, cutaneous and mucosal infections. Systemic is a more thorough infection of the body. Topical vs systemic therapy is dependent on status of host, type and extent of the infection, and location of the infection
Development of antifungal resistance is due to
emergence of intrinsically resistant species or a gradual stepwise alteration of cellular strucutres or functions
Mechanisms of antifungal resistance
Efflux pumps (reduces accumulation of drug), target alterations, overexpression of target
Primary systemic pathogens
pathogens capable of initiating infection in a normal, apparently immunocompetent host
Opportunistic pathogens
pathogens that only cause infection when there are disruptions in the protective barriers of the skin and mucous membranes or when defects in the host immune system allows them to penetrate, colonize and reproduce in the host (most fungi)
Pathogenesis of Fungal disease
ability of pathogens to effect the body, primary systemic pathogens vs opportunitsic pathogens
Saprobic phase
pathogens are found in soil or decaying vegetation which leads to the next phase that forms infectious airborne cells
Parasitic phase
the pathogen has adapted ot growth at 37C and reproduces in host respiratory mucosa
