MYCOLOGY MICROSCOPIC APPEARANCE OF MOULDS

- Genetic and biochemical properties Antler Hyphae Have swollen and

- Danger branching tips that
- Study of fungi resembles moose antlers
- Use to humans Racquet Hyphae Contains enlarged, club-
- Taxonomy shape areas
Spiral Hyphae Tightly coiled
FUNGI Rhizoid Rootlike structures
- Eukaryotic Zygomycetes
- Fungal cell wall are made of chitin
- Grows at best neutral pH
- Moisture are necessary for growth but spores HYALINE VS. DEMATIACEOUS
and conidia survive in dry conditions HYALINE DEMATIACEOUS
- Can cause mild infection and trigger allergic (Moniliaceous_ Hyphae
reaction Hyphae
- Immunocompromised patients are at risk Characteristics Either non Darkly
- Fungi are classified as either MOLD or YEAST pigmented ot pigmented
lightly
MOLDS VS. YEAST pigmented
MOLDS YEAST Fontana mason Pink to red Brown
Definition Multiple Contain only single stain
identical nuclei
nuclei DIMORPHISM AND POLYMORPHISM
Grows in DIMORPHISM
the form of - Include mold phase and either yeast or sperule
hyphae phase.
Appearance Fuzzy White and thread  Yeast or tisse state: grown in 37degrees Celsius
appearance Oval shape with increase CO2
Can be  Mold phase: grown at room tempt. (22 to 25
found in degrees Celsius) in ambient air.
several
shapes and POLYMORPHISM
color - Have both yeast and mould forms in the same
Habitat Found in Very common culture.
dump, dark Can found on fruits
or steam- and berries REPRODUCTION
filled areas Can be isolate in ASEXUAL REPRODUCTION
stomach and skin of - Results in the formation of conidia
mammals - Carried out by specialized fruiting structures
Reproduction Reproduce Reporoduce asexually known as CONDIOGENOUS.
through through mitosis.
small spores Most common form 2 CONDIGENOUS CELLS
Can either called budding. 1. PHIALIDE: vase-like structure that produce
be sexual or Phialoconidia.
asexual 2. ANNELIDE: ringed structures that produce
Health Allergic Can cause infection in Anneloconidia.
Hazard reaction immunocompromised
and individuals.
respiratory
problem
SEXUAL REPRODUCTION: Teleomorph  Scelotium – hardened mass of mycelium that
- Anamorph teleomorph reproduce asexually generally serves as an overwintering stage.
- Synanamorphs: more than 1 anamorph is  Multicellular – such as mycelial cords,
present in for the same teleomorph. rhizomorphs and fruit bodies (mushrooms)

Example of Teleomorph HETEROTROPHY– other food

 Pseudallescheria boydii which has two  Saprophytes or saprobes – feed on dead tissues
anamorphs: Scedodporium or organic waste()decomposers)
apiospernum and Graphium sp.  Symbionts – mutually beneficial relationship
between a fungus and another organism
ZYGOMYCOTA  Parasites – feeding on living tissue of a host.
- Organism found in soil o Parasites that cause disease are called
- Produce profuse gray to white Pathogen.
- Aerial mycelium characterized by presence of
sporangiophore and sporangiospores. HETEROTROPHIC BY ABSORPTION
- Mucor, Absidia and Rhizopus - Fungi get carbon from organic sources
- Hyphal tips release enzymes
ASCOMYCOTA - Enzymatic breakdown of substrate
- Production of sexual spores known as ascospore - Products diffuse back into hyphae
- Ascospores are formed within saclike structures
known as Ascus. FUNGAL STRUCTURES
HYPAHE
BASIDIOMYCOTA - Long, branching filaments that come together
- The only known major pathogen is Filibasidiella to form the Mycelium.
neoformans. The perfect form of Cryptococcus Septate hyphae – with separation or cross walls
neoformans var. neoformans. Aseptate or Sparsely septate –
- Presence of clamp connections Pseudohyphae – chain of cells formed by
budding.
MYCOLOGY TERMS VEGETATIVE HYPHAE
MOULDS - Functions as food absorption and are the
Multicellular fungi portion that extends below the agar surface.
YEAST AERIAL HYPHAE
- Single-cell fungi - Extends above the agar forming conidia.
MYCOSIS
- Fungal infection CONIDIA
SYSTEMIC MYCOSIS - Conidial morphology is important in fungal
- Multi-organ infection caused by fungi identification.
OPPORTUNISTIC MYCOSIS - Microconidia – small
- Fungal disease that occurs primarily in - Macroconidia – large
immunocompromised patients
DIMORPHIC FUNGI TYPES OF CONIDIA
- Fungi that shows both a non-mould and mould  Arthroconidia – resulting from the
phase fragmentation of hyphae into individual cells.
SAPROBE  Balstoconidia – conidia formed as the result of
- Organism capable of living on decaying organic budding.
material  Chlamydoconidia – terminal cells in the hyphae
enlarge and have thick walls.
CHARACTERISTICS OF FUNGI  Poroconidia – formed by being pushed through
BODY FORM a small pore.
 Unicellular  Phialoconidia – tube shaped that can be
 Filamentous (tube-like strands called hypha- branched.
singular or hyphae-plural)  Annelloconidia – vase shaped conidia.
 Mycelium – aggregate of hyphae
SEXUAL REPRODUCTION  Papanicolaou Stain - good for initial
- Fungal nuclei are normally haploid, with the differentiation of dimorphic fungi. Works well
exception of transient diploid stages formed on sputum smears.
during the sexual life cycles.  Gram Stain - generally fungi are gram positive;
- Sexual reproduction requires the fusion of Actinomyces and Nocardia are gram variable.
hyphae from different mating types.  Modified Acid-Fast Stain - used to differentiate
- Fungi use sexual signalling molecules called the acid-fast Nocardia from other aerobic
pheromones to communicate their mating type. Actinomyces.
- Plasmogamy – is the union of cytoplasm from  Giemsa Stain - used for blood and bone marrow
two parent mycelia. specimens.
- In most fungi, the haploid nuclei from each  India Ink - demonstrates the capsule of
parent do not fuse right away; they coexist in Cryptococcus neoformans in CSF specimens.
the mycelium, called a herekokaryon.
- In some fungi, the haploid nuclei pair off two to FUNGAL CULTURING
a cell; such a mycelium is said to be dikaryotic.  Generally tube media is used rather than plated
- Hours, days, or even centuries may pass before media because:
the occurrence of karyogamy, nuclear fusion - there is less chance for spore release into the
- During karyogamy, the haploid nuclei fuse, environment.
producing diploid cells. - less chance for dehydration
- The diploid phase is short-lives and undergoes - easie of storage.
meiosis, producing haploid spores.
- The paired processed of karyogamy and meiosis  The agar in a tube is inoculated in a straight
produce genetic varation. line. Preliminary identification is based on
differential growth patterns on various media
ASEXUAL REPRODCUTION
- In addition to sexual reproduction, many fungi MEDIA
can reproduce asexually  Sabouraud's dextrose agar (Sab-Dex) - classic
- Mold produce haploid spores by mitosis and medium, recommended for most studies.
form visible mycelia.  Sabouraud's dextrose agar with
chloramphenicol - chloramphenicol inhibits
bacterial growth.
FUNGAL SPECIES IDENTIFICATION METHODS
 Brain heart infusion slant (BHI) - more enriched
STAINS USED:
than Sab-Dex. Used in recovery of H.
 Lactophenol Cotton Blue (LPCB) - very popular capsulatum.
for quick evaluation of fungal structures; will
 Potato-dextrose agar (PDA) and Corn-meal
stain the chitin in cell walls of fungi.
agar - are used in slide cultures; as they induce
 Periodic Acid - Schiff Stain (PAS) - stains certain spore formation, which greatly aids in
polysaccharide in the cell walls of fungi. Fungi identification.
stain pink-red with blue nuclei.
 Mycosel agar - commercially produced agar
 Gomori Methenamine Silver Stain - silver containing chloramphenicol to inhibit bacterial
nitrate outlines fungi in black due to the silver growth, and cycloheximide to inhibit
precipitating on the fungi cell wall. The internal saprophytic fungi and some yeasts (including C.
parts of hyphae are deep rose to black, and the neoformans).
background is light green. o Aspergillus and Scopulariopsis
 Gridley Stain - Hyphae and yeast stain dark blue (saprophytes) are opportunistic
or rose. Tissues stain deep blue and background pathogens.
is yellow. o Cycloheximide will prevent their
 Mayer Mucicarmine Stain - will stain capsules growth.
of Cryptococcus neoformans deep rose. o Cryptococcus neoformans is also
 Fluorescent Antibody Stain - simple, sensitive, inhibited.
and extremely specific method of detecting o Bacteria-like fungi (such as
fungi in tissues or fluids. Applications for many Actinomycetes) are inhibited by
different fungal organisms. chloramphenicol.
SPECIAL APPLICATION AGAR MICROSCOPIC EVALUATION
 Caffeic Acid Agar - Cryptococcus neoformans METHODS:
will produce melanin resulting in black colonies.  Teased Preparation
(protect media from light)  Slide Culture Techniques - best as it gives
 Birdseed Agar - used to isolate Cryptococcus undisturbed microscopic morphology.
neoformans from contaminated cultures.  Transparent Tape Preparation
 KT Medium & Kelley Agar - used to convert
dimorphic fungus Blastomycetes dermatitidis
from mycelial to yeast form.
 Modified Converse Liquid Medium (Levine's) -
used to promote spherule production by
Coccidioides immitis.

FUNGAL GROWTH REQUIREMENTS

Temperature - Room temperature (25-30 C ) for most
fungi. Notes:
- Nocardia sp. and some dimorphic organisms
grow best at 37 degrees C.
- Any fungus capable of growing at 37 C, should
be considered potentially pathogenic.

Atmosphere - True fungi are aerobic; there are a few

anaerobes among the bacteria-like fungi.
Time - Some yeasts grow overnight. Saprophytes are
fast growers (several days). Generally cultures are held
at least 4 weeks.
- Exceptions: Paracoccidioides brasiliensis may
require 4-5 weeks, & 10 weeks are
recommended if Histoplasma capsulatum is
suspected.

COLONY MORPHOLOGY (Macroscopic features)

 Surface topography - Some fungal colonies may
be free growing, covering the entire surface of
agar in a particular manner; others grow in a
restricted manner.
 Surface texture -examples: cottony or wooly
(floccose), granular, chalky, velvety, powdery,
silky, glabrous (smooth, creamy), waxy, etc.
 Pigmentation - Fungi may be colorless or
brightly colored. Color may be on fungus itself,
on its sporulating apparatus, on the agar, or on
the bottom of the colony (reverse
pigmentation). Pigment color is due to the color
of the sporulating apparatus. The pigment can
be diffused into the agar. It is important to note
the top pigment (obverse) and the discoloration
of the agar medium (reverse). See
Dematiaceous in definitions.
 Mycelium
a. Vegetative mycelium - provides nutrition
b. Aerial mycelium – reproductive