Fungal Qualitative Determination

Group 6

Carolino, Mildred Joy D.

Rosario, Leslie Deniel F.

Dooc, Grace Joy

Ildefonso, John Rave

Signo, Reign Venice

Definition of Terms

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● Antigen Detection - This involves using antibodies to detect the presence of specific
fungal antigens in a sample. This can be a rapid and sensitive method, but it is only able
to detect certain types of fungi.
● Aspergillosis - is a fungal disease caused by molds of the genus Aspergillus. Primary
cutaneous aspergillosis enters through a break in the skin, such as the site of an injury
or a surgical wound; it is a common hospital-acquired infection. In secondary cutaneous
aspergillosis, the fungus enters via the respiratory system and disseminates
systemically, manifesting in lesions on the skin.
● Aspergillus - any of a genus (Aspergillus) of ascomycetous fungi with branched radiate
sporophores including many common molds.
● Blastomyces Dermatitidis - is a dimorphic fungus that grows in a mycelial form at room
temperature, and as a yeast at 37°C. An organism responsible for blastomycosis. B.
dermatitidis is a budding yeast that primarily exists in the soil and is acquired via
inhalation.It is thought to enter the lung, subsequently producing a widespread
pyogranulomatous infection through hematogenous spread involving the lungs, skin,
bone, and genitourinary tract.
● Candida - any of a genus (Candida) of parasitic fungi that resemble yeasts, occur
especially in the mouth, vagina, and intestinal tract where they are usually benign but
can become pathogenic, and have been grouped with the imperfect fungi but are now
often placed with the ascomycetes.
● Culture - This involves growing the fungi from a sample on a special medium that allows
them to grow and reproduce. This can be more time-consuming than direct microscopy,
but it can be more accurate in identifying the specific type of fungus present.
● Cutaneous Mycoses - Mycoses that cause superficial infections of the epidermis, hair,
and nails.
● Dermatophytes - a fungus parasitic on the skin or skin derivatives (such as hair or
nails).
● Dermatophytosis - a disease (as athlete's foot) of the skin or skin derivatives that is
caused by a dermatophyte
● Direct microscopy - This involves examining a sample of the material under a
microscope to look for fungal structures such as hyphae (filaments) and spores.
● Dimorphic Fungi - capable of changing their growth to either mycelial or yeast yeast
phase, depending on the growth conditions.
● Fungal Qualitative Determination - The process of identifying the presence or absence
of fungi in a sample, without necessarily quantifying the amount present.
● Fungi - A fascinating and diverse group of organisms often overlooked in the shadow of
plants and animals. They are eukaryotic organisms that include microorganisms such as
yeasts, molds and mushrooms. These organisms are classified under kingdom fungi.
The organisms found in Kingdom fungi contain a cell wall and are omnipresent.
● Histoplasma Capsulatum - is a dimorphic fungus that remains in a mycelial form at
ambient temperatures and grows as yeast at body temperature in mammals. Infection
causes histoplasmosis.

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 ● Malassezia furfur - a genus of lipophilic typically nonpathogenic yeastlike imperfect
fungi. A skin commensal, can cause an infection of the skin called pityriasis versicolor.
● Molds - (multicellular filamentous fungi) are microscopic fungi that live on plant or animal
matter. They can be found indoors and outdoors and are part of our natural environment.
They play an important role in the environment by breaking down and digesting organic
material. Molds can multiply by producing microscopic spores similar to the seeds
produced by plants. Many spores are so small they easily float through the air and can
be carried for great distances by even the gentlest breezes.
● PCR (polymerase chain reaction) - This involves using DNA amplification to detect the
presence of specific fungal DNA in a sample. This is a very sensitive and specific
method, but it can be expensive and time-consuming.
● Polysaccharides - are the most abundant carbohydrates found in food. They are
long-chain polymeric carbohydrates composed of monosaccharide units bound together
by glycosidic linkages.
● Serology - Antibody serology tests check for the presence or level of specific antibodies
in the blood. Antibodies are proteins that your immune system makes to fight foreign
substances. These substances are often pathogens, (disease-causing germs) such as
viruses and bacteria. When you have an infection, your body makes antibodies that are
targeted to those pathogens.
● Subcutaneous Mycoses - Mycoses that penetrate the epidermis and the dermis to
infect deeper tissues.
● Systemic Mycoses - Mycoses that spread throughout the body.
● Yeasts - are predominantly unicellular and oval or round in shape. Most propagate by an
asexual process called budding in which the cell develops a protuberance, which
enlarges and eventually separates from the parent cell. Yeasts are neither a natural nor
a formal taxonomic group,but are a growth shown by a wide range of unrelated fungi.

● Yeast Infection - affects the skin, nail and mucous membranes of the mouth, vagina,
and are usually caused by commensal Candida species, notable c. albicans. Infection is
generally endogenous in origin, but genital infection can be transmitted sexually.
● Zygomycota - this fungus produces typical sporangia on long sporangiophores, but
complex branching structures arise from the sporangiophore and terminate in small,
few-spored sporangioles.

DISCUSSION OF TOPIC

Key Points:
● Most infections are caused by fungi that grow as saprophytes in the environment.
Superficial, subcutaneous and systemic patterns of infection are recognised.

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 ● Fungi take the form of yeasts, which grow by budding; moulds, which grow as
filamentous extensions called hyphae, forming a mycelium; or dimorphic fungi, which
can grow as yeast or mould forms.
● Pathogenic fungi can establish an infection in all exposed individuals; others are
opportunistic pathogens that cause disease only in a compromised host.
● Many fungal diseases have a global distribution, but some are endemic to specific
geographical regions.
● Subcutaneous fungal infections are acquired by traumatic implantation; systemic
infections are usually acquired by inhalation.
● Only dermatophytosis, a common superficial infection of the skin, nails and scalp hair, is
truly contagious.
● Some yeasts are human commensals and cause endogenous infection when there is
some imbalance in the host.
● The most frequently encountered fungal agents in the United Kingdom are Candida spp.,
dermatophytes, Aspergillus spp., Cryptococcus spp. and Pneumocystis jirovecii.
● Diagnosis of fungal infections is based on a combination of clinical observation and
laboratory investigation, which may include direct microscopy. histology, culture, PCR
and serology. Early recognition of systemic infections in immunocompromised persons is
a major challenge.

Fungi are a unique group of organisms, different from all others in their behavior and cellular
organization. Fungi also have an enormous range of activities as pathogens of crop plants or
humans, as decomposer organisms, as experimental "model organisms" for investigating
genetics and cell biology, and as producers of many important metabolites. The uniqueness of
fungi is a prominent feature of this book, which adopts a functional approach, focusing on topics
of inherent interest and broad significance in fungal biology. The uniqueness of fungi is reflected
in the fact that they have the status of a kingdom, equivalent to the plant and animal kingdoms.
So, fungi represent one of the three major evolutionary branches of multicellular organisms.
Fungi are the most important causes of crop dis- eases, responsible for billions of dollars worth
of damage each year, and for periodic devastating disease epidemics. Fungi are the main
decomposers and recyclers of organic matter, including the degradation of cellu- lose and wood
by the specialized enzyme systems unique to fungi. Fungi produce some of the most toxic
known metabolites, including the carcinogenic aflatoxins and other mycotoxins in human foods
and animal feedstuffs. With the advance of the acquired immune deficiency syndrome (AIDS)
and the increasing role of transplant surgery, fungi are becoming one of the most significant
causes of death of immuno- compromised and immunosuppressed patients. Fungal diseases
that were once extremely rare are now commonplace in this sector of the population. Fungi
have an enormous range of biochemical activities that are exploited commercially - notably the
production of antibiotics (e.g.penicillins), steroids (for contraceptives),ciclosporina (used as
immunosuppressants in transplant surgery), and enzymes for food processing and for the soft
drinks industry. Fungi are major sources of food. They are used for bread-making, for mushroom
production, in several traditional fermented foods, for the production of Quorn™ mycoprotein
now widely available in supermarkets and the only survivor of the many "single-cell protein"
ventures of the late 1900s - and, of course, for the production of alcoholic drinks. Fungi can be

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used as "cellular factories" for producing heterologous (foreign) gene products. The first
genetically engineered vaccine approved for human use was produced by engineering the gene
for hepatitis B surface antigen into the yeast (Saccharomyces cerevisiae) genome. In this way
the antigen can be produced and exported from the cells, then purified from the growth
medium.The genome sequences of several fungi have now been determined, and in several
cases the genes of fungi are found to be homologous (equivalent) to the genes of humans. So,
fungi can be used to investigate many fundamental cell-biological processes, including the
control of cell division and differentiation relevant to biomedical research. Fungi are increasingly
being used as commercial biological control agents, providing alternatives to chemical
pesticides for combating insect pests, nematodes, and plant-pathogenic fungi.

The true fungi (Kingdom Mycota)

● Chytridiomycota

The Chytridiomycota, commonly termed chytrids, number about 1000 species (Barr 1990) and
are con- sidered to be the earliest branch of the true fungi, dating back to about 1 billion years
ago. They have cell walls composed mainly of chitin and glucans (poly- mers of glucose) and
many other features typical of fungi. But they are unique in one respect, because they are the
only true fungi that produce motile, flagellate zoospores. Typically, the zoospore has a single,
posterior whiplash flagellum, but some of the chytrids that grow in the rumen of animals have
several flagella, and some other chytrids (e.g. Basidiobolus ranarum, recently transferred to the
Chytridiomycota based on SSU rDNA analysis), have no flagella. This provides a good example
of the value of DNA sequencing in determining the true phylogenetic relationships of organisms.

● Glomeromycota

Fungal fossils resembling the common and economically important arbuscular mycorrhizal (AM)
fungi were associated with plants in the Rhynie chert deposits of the Devonian era about 400
million years ago (mya). They probably played a vital role in the establishment of the land flora.
Recent detailed analysis of these fungi, based on SSU rDNA sequences, has shown
convincingly that they are distinct from all other major fungal groups, so they have been
assigned to a new phylum, the Glomeromycota (Schuessler et al. 2001).

● Zygomycota

Five major features serve to characterize the phylum Zygomycota:

1. Cell walls composed of a mixture of chitin, chitosan (a poorly or non-acetylated

form of chitin) and polyglucuronic acid;
2. Hyphae that typically lack cross walls, so all the nuclei are contained within a
common cytoplasm (a coenocytic mycelium);
3. The production of a thick-walled resting spore the zygospore - which if formed by
a sexual process involving the fusion of two gametangia

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 4. The production of asexual spores by cytoplasmic cleavage within a sporangium;
5. A haploid genome.
6.
● Ascomycota

The phylum Ascomycota contains about 75% of all the fungi that have been described to date. It
is not only the most important phylum, but also the most diverse, and many of the relationships
within this group have yet to be resolved by modern molecular methods.

● Basidiomycota

According to Kirk et al. (2001), the Basidiomycota contains about 30,000 described species,
which is 37% of the described species of true fungi. Although the most familiar examples of this
group are the mushrooms and toadstools, there is an enormous diversity of species, including
basidiomycetous yeasts, many important plant pathogens, and some serious human pathogens.
The one single feature that characterizes the group is the basidium in which meiosis occurs,
leading to the production of sexual spores (basidiospores) that usu- ally are produced externally
on short stalks termed sterigmata.

● Mitosporic fungi

Finally, among the true fungi, we consider the large number of ascomycetous fungi that produce
conidia, but whose sexual stages are absent, rare or unknown. In the past, these fungi have
variously been termed "Deuteromycota" (Deuteromycotina) or "Fungi Imperfecti" but the more
appropriate term is mitosporic fungi, indicating that the spores are produced only by mitotic
nuclear division. The majority of these fungi are likely to be assigned to genera of the
Ascomycota by gene sequence comparisons. But at present, the genera and species with no
known sexual stage are given provisional generic names, termed "form genera." When a sexual
stage is discovered the fungus must be renamed, and described according to the features of its
sexual.

Fungal parasites of plants

A large number of fungi are adapted to grow as plants, obtaining some or all of their nutrients
from the living tissues of their host. Many of these associations are quite specific because the
fungus infects only one type of bost, and sometimes it is so specific that the fungus cannot grow
at all in laboratory culture- it is an obligate parasite that can grow only in the host tissues. Many
examples of this are found among the rust fungi and powdery mildew fungi while other
examples are found in the fungus-like downy mildews, and the plasmodiophorids. These
host-specific fungi are termed biotrophic parasites (bios = life: trophy = feeding) because they
feed from living host cells without killing them, often by producing special nutrient absorbing
structures to tap the host's reserves. At the other end of the spectrum are many common fungi
that aggressively attack plant tissues. They are termed necrotrophic parasites (necros death)

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because they kill the host tissues as part of the feeding process - for example by producing
toxins or degradative enzymes.

Fungal symbionts of plants

Many fungi form symbiotic associations with plants, in which both of the partners are likely to
benefit. The two most important examples are lichens and mycorrhizas. Lichens are intimate
associations between two organisms: a photosynthetic partner (a green alga or a
cyanobacterium) and a fungus which together produce a thallus that can withstand some of the
most inhospitable environments on Earth. Typically, the fungus encases and protects the
photosynthetic cells, and also absorbs mineral nutrients from trace levels in the environment,
while the photosynthetic partner provides the fungus with carbon nutrients. There are about
13,500 lichen species across the globe, and they play essential roles as pioneer colonizers of
habitats where no other organisms can grow, including rock surfaces and unstable, arid mineral
soils.

Fungal pathogens of humans

In contrast to the many fungal parasites of plants, there are only some 200 fungi that infect
humans or other warm-blooded animals. In fact, humans have a high degree of innate immunity
to fungi, with the excер- tion of the dermatophytic fungi which commonly cause infections of the
skin, nails, and hair. However, the situation changes drastically when the immune system is
compromised, and this is becoming common in patients with AIDS, transplant patients whose
immune system is purposefully suppressed, patients suffering from cancer or advanced
diabetes, and patients undergoing prolonged corticosteroid therapy. In any of these
circumstances there is a significant chance of infec- tion from fungi that pose no serious threat
to healthy people.

Fungi in biotechnology

Fungi have many traditional roles in biotechnology, but also some novel roles, and there is
major scope for their future commercial development (Wainwright 1992).Fungi are used to
produce several traditional foods and beverages, including alcoholic drinks (ethanol from the
yeast Saccharomyces cerevisiae) and bread, where the yeast produces CO₂ for raising the
dough. Penicillium roqueforti is used in the later stages of pro. duction of the blue-veined
cheeses such as Stilton and Roquefort, to which it imparts a characteristic flavor P. camemberti
is used to produce the soft cheeses such as Camembert and bries; it grows on the cheese sur-
face, forming a "crust," and produces proteases which progressively degrade the cheese to give
the soft con. sistency. Less well known but equally significant is the role of fungi in the
fermentation of traditional foods around the world. For example, Rhizopus oligosporus used to
convert cooked soybean "grits" to a nutritious staple food, called tempeh.

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Fungal Diseases

Valley Fever (Coccidioidomycosis)

Valley fever, also known as coccidioidomycosis, stems from an infection triggered by the fungus
Coccidioides. This fungus typically resides in the soil across the southwestern United States, as
well as portions of Mexico and Central and South America. Recently, it has been identified in
south-central Washington as well. Inhalation of the microscopic fungal spores from the air can
lead to contracting Valley fever, though most individuals exposed to these spores remain
unaffected. Typically, those who do fall ill with Valley fever will recuperate naturally within weeks
to months, while others may require antifungal medication. Certain demographic groups face a
heightened risk of experiencing severe illness. While it's challenging to entirely prevent
exposure to

Fungal Eye Infections

Fungal eye infections are highly uncommon, yet they pose significant risks. The primary route
for contracting such infections typically stems from ocular injuries, especially those inflicted by
plant matter like sticks or thorns. Keratitis, characterized by inflammation or infection of the
cornea, and endophthalmitis, affecting the inner eye, are the two main manifestations. Various
fungal species can trigger these infections, underscoring the diverse nature of the pathogens
involved.

Though fungal eye infections are infrequent, their gravity cannot be overstated. These infections
commonly arise from ocular injuries, especially those involving plant debris such as sticks or
thorns. Keratitis and endophthalmitis, affecting the cornea and interior eye, respectively, denote
the inflammation or infection at play. The broad array of fungal agents underscores the
complexity and severity of these ocular conditions.

Fungal Nail Infection

Fungal nail infections stem from a variety of fungi present in the environment. These fungi
exploit minor openings in the nails or nearby skin, gaining entry to induce infection. The
susceptibility to such infections arises from the interaction between the fungi and the
compromised integrity of the nail structure or the surrounding skin. Essentially, these infections
thrive in environments conducive to their growth, capitalizing on vulnerabilities within the nail or
skin barrier to establish themselves and cause harm.

Ringworm

1. Contracting ringworm is possible through direct contact with an infected individual,

necessitating precautions to prevent its transmission. Those afflicted should refrain from
sharing personal items such as clothing, towels, or combs to curb the spread of the
infection to others.
2. Interacting with animals carrying ringworm poses a similar risk of transmission to
humans. Various animals, notably dogs and cats, particularly young ones, can transmit

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 ringworm upon contact. Additionally, livestock like cows, goats, pigs, and horses also
have the potential to spread the infection to humans. Hence, caution is essential when
handling such animals to avoid contracting ringworm.
3. The transmission of ringworm from both human and animal sources underscores the
importance of maintaining hygiene practices and minimizing direct contact with
potentially infected individuals or animals. Implementing preventative measures, such as
regular handwashing and avoiding sharing personal items, can mitigate the risk of
contracting this fungal infection.

Treatment

There aren't many useful medicines for fungal infections compared to the many options we have
for bacterial infections, and this difference becomes especially noticeable when examining the
treatment choices available in the field of infectious diseases. Because both fungi and humans
are eukaryotes, many drugs that kill fungi can also be harmful to the human body. The
effectiveness of anti-itch medications varies widely. Most of them rely on the differences in
sterols in fungal and mammalian cell membranes, but some drugs like echinocandins
(anidulafungin, caspofungin, and micafungin) interfere with ß-glucan synthesis in the fungal cell
wall. Most anti-itch drugs are applied externally. Only a few can be taken orally.

● Amphotericin B and the echinocandins (anidulafungin, caspofungin, micafungin) are

given parenterally because of poor absorption from the gastrointestinal tract.
● The azoles (fluconazole, itraconazole, posaconazole, voriconazole, isavuconazole) and
flucytosine are available for oral and/or parenteral administration.
● Terbinafine and griseofulvin are usually administered orally.
● Amphotericin B is the historical treatment of choice in life-threatening disease, despite its
toxicity, liposomal and lipid complex formulations are less toxic but much more
expensive.
● A combination of amphotericin B and flucytosine reduces the likelihood of the
emergence of resistance to flucytosine. Combinations of azole drugs and amphotericin B
are seldom used therapeutically.
● New antifungals are being evaluated for use in systemic mycoses. Posaconazole or
isavuconazole is used as step-down therapy in invasive aspergillosis and mucormycosis
for patients who have responded to amphotericin B or as salvage therapy for patients
who do not respond or cannot tolerate amphotericin B.
● Antifungal prophylaxis is often used to help prevent opportunistic infections in patients
undergoing solid organ or stem cell transplants and in those with hematological
malignancies. Oral or topical antifungals are also used to prevent recurrent vaginal
candidiasis.

Antifungal drugs facing resistance haven't become a big issue overall. However, sometimes it
happens, particularly after prolonged therapy for invasive candidiasis using azoles or
echinocandins. Recently, there's a growing concern about Azole-resistant Aspergillus fumigatus
infection, which is acquired from the environment due to unintended consequences of
agricultural fungicide use. This issue has been identified in various countries globally. As a

9
result, there's a common practice of conducting susceptibility testing for any drug that doesn't
deliver the expected therapeutic response. This helps in understanding and addressing potential
challenges related to antifungal resistance.

REFERENCES

Johnson, E. Fungal Diseases: Understanding, Diagnosis, and Treatment.

Barer,M., Irving, W., Perera, N., Swann, A., (2019)”Medical Microbiology: A guide to microbial
infections: Pathogenesis, Immunity, Laboratory Investigation and Control”

Deacon, J. W., (2006)”Fungal Biology”, Blackwell publishing

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Date and Time of entering the library: February 22,2024 11:00 am

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