This document provides an introduction to medical mycology for nurses. It discusses the basic characteristics of fungi, including their cell structure, modes of growth, and reproduction. It then covers various types of fungal infections like cutaneous, subcutaneous, opportunistic, and systemic mycoses. Specific opportunistic infections like candidiasis, cryptococcosis, aspergillosis, and mucormycosis are explained in terms of their causative agents and clinical presentations. The document emphasizes that immunosuppressed patients are more susceptible to deep and opportunistic fungal infections.

1. Medical
Mycology
Introduction
to
Basics
for nurses
WALTER WASWA,
BSC.MLS
5/18/2017 WALTER WASWA 1

2. Reference books
• Brooks, Geo. F. etal, (2007):Medical
microbiology, 24ed. The McGraw-Hill
Companies, Inc. New York.-----an e book in the
library.
• Other books on microbiology in the library.
5/18/2017 WALTER WASWA 2

3. Introduction
• Mycology is the study of fungi
• The study of fungi is known as mycology and
scientist who study fungi is known is a
mycologist.
• Fungal infections are termed as mycoses
• Fungi are differ from bacteria and other
prokaryotes.
1. Cell walls containing chitin (rigidity & support), mannan &
other polysaccharides
2. Cytoplasmic membrane contains ergosterols
3. Possess true nuclei with nuclear membrane & paired5/18/2017 WALTER WASWA 3

4. Characteristics of Fungus
• Diverse group of chemo heterotrophs
– > 90,000 known species
• Saprophytes
– Digest dead organic matter
• Parasites
– Obtain nutrients from tissues of organisms
• Molds & mushrooms are multicellular
• Yeasts are unicellular
5/18/2017 WALTER WASWA 4

5. CHARACTERISTICS OF FUNGI (Continued)
Dimorphic Fungi
Can exist as both multicellular fungi (molds) and yeasts.
Many pathogenic species.
– Mold form produces aerial and vegetative hyphae.
– Yeast form reproduces by budding.
Dimorphism in pathogenic fungi typically depends on
temperature:
– At 37oC: Yeast form.
– At 25oC: Mold form.
Dimorphism in nonpathogenic fungi may depend on other
factors: Carbon dioxide concentration.
5/18/2017 WALTER WASWA 5

6. Understanding the Structure of
Fungi
• Yeasts and molds have different structural and
reproductive characteristics
– Yeast are unicellular, nucleated rounded fungi while
molds are multicellular, filamentous fungi
– Yeast reproduce by a process called budding while
molds produce spores to reproduce
– Some yeast are opportunistic pathogens in that they
cause disease in immuno-compromised individuals
– Yeast are used in the preparation in the variety of
foods
5/18/2017 WALTER WASWA 6

7. Predisposing factors to fungal
infection
1.Use of
Antibiotics,
2.Use of
steroids,
3.Immunosuppressive
conditions
5/18/2017 WALTER WASWA 7

8. Fungal Diseases
• Mycosis- fungal infection
–< 100 cause human disease
–Not highly contagious
–Humans acquire from nature
• Groups based on degree on tissue
involvement and mode of entry
• Cutaneous mycoses-dermatophytes
–Epidermis, hair & nails
–Contagious-direct or indirect contact
–Secrete keratinase that degrades keratin
5/18/2017 WALTER WASWA 8

9. CLASSIFICATION
• Depending on cell morphology
1. Yeasts
2. Yeast like fungi
3. Molds
4. Dimorphic fungi
5/18/2017 WALTER WASWA 9

10. 1.Yeasts
• Unicellular fungi
which reproduce
by budding
• On culture -
produce smooth,
creamy colonies
e. g Cryptococcus
neoformans
(capsulated yeast)
5/18/2017 WALTER WASWA 10

11. 2.Yeast like fungi
• Grow partly as yeasts and partly as
elongated cells resembling hyphae which
are called pseudo hyphae. e.g. Candida
albicans
5/18/2017 WALTER WASWA 11

12. 3.Molds/ Filamentous
fungi
• Form true mycelia &
reproduce by formation
of different types of
spores.
• Vegetative/ aerial
hyphae
e.g. Rhizopus, Mucor
5/18/2017 WALTER WASWA 12

13. 4. Dimorphic fungi
• Occur in 2 forms
Molds (Filaments) – 25C (soil)
Yeasts – 37C (in host tissue)
Most fungi causing systemic infections are
dimorphic:
– Histoplasma capsulatum
– Blastomyces dermatidis
– Paracoccidioides brasiliensis
– Coccidioides immitis
– Penicillium marneffei
– Sporothrix schenkii
5/18/2017 WALTER WASWA 13

14. Reproduction in fungi
• Sexual - formation of Zygospore, ascospores
or basidiospores
• Asexual reproduction – budding or
fission
• Asexual spores are formed on or in specialized
structures.
• Vary in size, shape & colour but these
characteristics are constant for a particular
species.
5/18/2017 WALTER WASWA 14

15. conidia-asexual reproductive
structure –can be inhaled
• Micro conidia
- Small, single
celled
• Macro conidia
– Large, single or
many celled
• Seeds
5/18/2017 WALTER WASWA 15

16. Structure
• The main body of most fungi is made up of fine,
branching, usually colourless threads called
hyphae
• Several of these these hyphae, all intertwining to
make up a tangled web called the mycelium
• Most fungi are multinucleate and multicellular
organisms with cross wall called septa or aseptate
(coenocytic)
• Yeasts are unicellular
• One major difference is that most fungi have cell
walls that contain chitin, unlike the cell walls of
plants, which contain cellulose

17. Single Hyphae

18. Reproduction
• Life cycle involves the fusion of hyphae from two
individuals (Male & Feamle
• Each parent hyphae has haploid nuclei
• The fusion of hyphae is called plasmogamy.
• The fused hyphae containing haploid nuclei from
two individuals is heterokaryotic.
• In some cases, plasmogamy results in cells with
one nucleus from each individual. This condition
is called dikaryotic.
• Two nuclei that originated from different
individuals fuse to form a diploid zygote.
• Meiosis then produces either four haploid nuclei
or four haploid cells.

19. YEASTS AND MOLDS
•Molds - multicellular
•Yeasts - unicellular
•The simplest form of growth is budding.
•Buds are called blastoconidia.
•Seen in yeasts.

20. ..Reproduction in yeast
• Reproduce by budding.

21. Microbiology: A Clinical Approach © Garland Science
YEASTS
© CDC/ Dr. Edwin P. Ewing, Jr.

22. .
The life cycle of Rhizopus stolonifera ( bread
mold).

23. Fungal Infections/ Mycoses
• superficial
• CUTANEOUS MYCOSES
• SUBCUTANEOUS MYCOSES
• SYSTEMIC
• OPPORTUNISTIC
• FUNGAL TOXINS AND ALLERGIES
5/18/2017 WALTER WASWA 23

24. SUPERFICIAL MYCOSES
Fungal infections that do not involve a tissue
response:

25. …SUPERFICIAL MYCOSES
•Pityriasis Versicolor. chronic mild superficial
infection of the stratum corneum caused by
Malassezia globosa,
•M restricta,
•M furfur complex.
• Invasion of the cornified skin and the host
responses are both minimal.

26. SUPERFICIAL MYCOSES
• Tinea Nigra- is a superficial chronic and
asymptomatic infection of the stratum
corneum caused by the dematiaceous fungus
Hortaea (Exophiala) werneckii
• This condition is more prevalent in warm
coastal regions and among young women.
5/18/2017 WALTER WASWA 26

27. SUPERFICIAL MYCOSES
• Piedra
• Black piedra is a nodular infection of the hair
shaft caused by Piedraia hortai.
• White piedra, due to infection with
Trichosporon species, presents as larger,
softer, yellowish nodules on the hairs.
5/18/2017 WALTER WASWA 27

28. CUTANEOUS
•caused by fungi that infect only the
superficial keratinized tissue (skin, hair, and
nails)/cannot grow at 37degrees
•Dermatophytes eg
microsporon/trichophyton/epidermophyton
•Sometimes reffered as Ringworm – skin lesions
characterized by red margins, scales and itching
•Image?

29. …CUTANEOUS MYCOSES
•Classified based on location of infection
a) Tinea pedis – on the feet or between the toes
b) Tinea corporis – between the fingers, in wrinkles
on the palms
c) Tinea cruses – lesions on the hairy skin around
the genitalia
d) Tinea capitis – scalp and eyebrows
e) Onychomycosis – chronic
infection of the nail bed
•Commonly seen in toes
•Hyperkeratosis – extended scaly areas on the hands
and feet

30. Microbiology: A Clinical Approach © Garland Science
..CUTANEOUS
www.doctorfungus.org

31. Mucocutaneous …
•MUCOCUTANEOUS MYCOSES colonization of
the mucous membranes
•Caused by the yeast Candida albicans
•Often associated with a loss of
immunocompetence
•Thrush – fungal growth in the oral cavity
•An indicator of immunodeficiency.
•Vulvovaginitis – fungal growth in the vaginal
canal
•Can be associated with a hormonal
imbalance

32. SUBCUTANEOUS MYCOSES
•Agent –from the soil /vegetable
•Entry-through trauma
•localized primary infections of
subcutaneous tissue:
•Can cause the development of cysts and
granulomas.
•Provoke an innate immune response -
eosinophilia.

33. SUBCUTANEOUS MYCOSES
There are several types:
•Sporotrichosis – traumatic implantation of fungal
organisms
•Paranasal conidiobolae mycoses– infection of the
paranasal sinuses
•Causes the formation of granulomas.
•Zygomatic rhinitis– fungus invades tissue through
arteries
•Causes thrombosis.
•Can involve the CNS.

34. SUBCUTANEOUS MYCOSES
• At ambient environmental temp-mould
• At 35-37degrees grow as budding yeast
• Sporothrix schenckii -Sporotrichosis
• Phialophora verrucosa, Fonsecaea pedrosoi,
others - Chromoblastomycosis
• Pseudallescheria boydii, Madurella
mycetomatis, others - Mycetoma
• Exophiala, Bipolaris, Exserohilum, and others -
Phaeohyphomycosis
5/18/2017 WALTER WASWA 34

35. DEEP/systemic MYCOSES
Deep mycoses Usually seen in immunosuppressed
patients with:
•AIDS
•Cancer
•Diabetes
•Can be acquired by:
•Inhalation of fungi or fungal spores
•Use of contaminated medical equipment
•Deep mycoses can cause a systemic infection –
disseminated mycoses
•Can spread to the skin

36. Common examples
• Coccidioides immitis, C posadasii -
Coccidioidomycosis
• Histoplasma capsulatum- Histoplasmosis
Blastomyces dermatitidis -Blastomycosis
• Paracoccidioides brasiliensis -
Paracoccidioidomycosis
5/18/2017 WALTER WASWA 36

37. Microbiology: A Clinical Approach © Garland Science
..DEEP MYCOSES
www.doctorfungus.org

38. ..DEEP MYCOSES
Coccidiomycoses – caused by genus Coccidioides
•Primary respiratory infection
•Leads to fever, erythremia, and bronchial
pneumonia
•Usually resolves spontaneously due to immune
defense
•Some cases are fatal

39. …DEEP MYCOSES
Histoplasmosis – caused by Histoplasma
capsulatum
•Often associated with immunodeficiency
•Causes the formation of granulomas
•Can necrotize and become calcified
•If disseminated, histoplasmosis can be fatal.

40. Microbiology: A Clinical Approach © Garland Science
..DEEP MYCOSES
© CDC/Susan Lindsley, VD

41. …DEEP MYCOSES
Aspergillosis – caused by several species of
Aspergillus
•Associated with immunodeficiency
•Can be invasive and disseminate to the blood
and lungs
•Causes acute pneumonia
•Mortality is very high.
•Death can occur in a matter of weeks.

42. opportunistic mycoses eg.
1. Candida albicans and other Candida species -
Systemic candidiasis
2. Cryptococcus neoformans- Cryptococcosis
3. Aspergillus fumigatus and other Aspergillus
species -Aspergillosis
4. Species of Rhizopus, Absidia, Mucor, and other
zygomycetes - Mucormycosis (zygomycosis)
5. Penicillium marneffei- Penicilliosis

43. Candidiasis
Cause: Candida albicans
–Dimorphic fungus of the class
Deuteromycetes
–Grows as yeast or pseudohyphae
–Spread by contact; often part of normal flora
–Opportunistic infections common
–Vulvovaginitis
–Oral candidiasis (thrush)
–Intestinal candidiasis

44. Candidiasis
Cutaneous
Thrush
Vaginal candidiasis is the most common
clinical infection. Local factors such as pH
and glucose concentration (under
hormonal control) are of prime
importance in the occurrence of vaginal
candidiasis. In mouth: normal saliva
reduces adhesion (lactoferrin is also
protective).

45. Chronic mucocutaneous
candidiasis
Chronic mucocutaneous
candidiasis (CMC) is the label
given to a group of overlapping
syndromes that have in common
a clinical pattern of persistent,
severe, and diffuse cutaneous
candidal infections. These
infections affect the skin, nails
and mucous membranes.
Immunologic studies of patients with
CMC often reveal defects related to
cell-mediated immunity, but the
defects themselves vary widely.

46. Mucutaneous candidiasis: response to
fluconazole
Transfusion of a Candida-specific transfer factor has
been reported to be very successful (remission for > 10
years) when combined with antifungal therapy. The
availability of effective oral agents, especially the azole
antimicotics, has dramatically changed the life of
patients living with CMC.

47. Cryptococcosis
Respiratory Fungal Infection
–Cryptococcus neoformans
–A yeast of class Basidiomycetes
–Soil; esp. contaminated with bird droppings
–Airborne to humans
–Gelatinous capsules resist phagocytosis
–Respiratory tract infections
–Occasional systemic infections involving brain

48. Opportunistic Mycoses
•Opportunistic mycoses are fungal infections that do not
normally cause disease in healthy people, but do cause
disease in people with weakened immune defenses.
•The most common infections are:
•Candidiasis
•Aspergillosis
•Cryptococcosis
•Zygomycosis
•Pneumocystis carinii

49. Cryptococcus neoformans
• Primary infection in lungs
• Cryptococcal meningitis is most common disseminated
manifestation
• Can spread to skin, bone and prostate
Organism is ubiquitous and infections
occur worldwide
C. neoformans recovered in large
amounts in pigeon poop
Does not cause disease in birds

50. Diagnosis
• Lumbar puncture and microscopic
examination of cerebrospinal fluid
is diagnostic.
• (India ink staining)
Cyrptococcal antigens in CSF and
serum.
Immune response
Phagocytosis by neutrophils is inhibited by the presence of a capsule.
However, activated neutrophils have an increased capacity to
phagocytize C. neoformans.
Cell mediated immunity primary defense
About 30% of cryptococcus infections occur in patients with lymphoma
(CNS)
Therapy
Amphotericin B & 5FC
Fluconazole also effective

51. Aspergillosis
• Genus occurs worldwide and
contains hundreds of species.
• These species constitute the most
commonly found fungi in any
environment
Major portal of entry is the
respiratory tract. Dissemination
can occur from the lungs and
involve other areas of the lung,
the brain, GI tract, and kidney.
CNS and nasal-orbital cavities
can also occur without lung
involvement. Risk factors for
invasive disease are

52. Aspergillosis
• Aspergillosis is the most common fatal infection seen in patients with chronic
granulomatous disease of childhood.
• Patients with this condition are unable to form toxic oxygen radicals after
phagocytosis.
• Progressive and disseminated disease can complicate neoplastic diseases,
especially acute leukemia, bone marrow and organ transplantation (not
necessarily AIDS).
In immunosuppressed hosts:
invasive pulmonary infection, usually
with fever, cough, and chest pain.
May disseminate to other organs,
including brain, skin and bone. In
immunocompetent hosts: localized
pulmonary infection in persons with
underlying lung disease. Also causes
allergic sinusitis and allergic
bronchopulmonary disease.
Agent: Aspergillus fumigatus, A. flavus.

53. Environmental species kill neutropenic
patients.
• Zygomycosis. Zygomycosis due to Rhizopus, Rhizomucor, Absidia, Mucor species,
or other members of the class of Zygomycetes, also causes invasive
sinopulmonary infections. An especially life-threatening form of zygomycosis
(also known as mucormycosis), is known as the rhinocerebral syndrome, which
occurs in diabetics with ketoacidosis. In addition to diabetic ketoacidosis,
neutropenia and corticosteroids are other major risk factors for zygomycosis.
• Phaeohyphomycosis. Phaeohyphomycosis is an infection by brown to black
pigmented fungi of the cutaneous, superficial, and deep tissues, especially brain.
These infections are uncommon, life-threatening, and occur in various
immunocompromised states.
• Hyalohyphomycosis. Hyalohyphomycosis is an opportunistic fungal infection
caused by any of a variety of normally saprophytic fungi with hyaline hyphal
elements. For example, Fusarium spp. infect neutropenic patients to cause
pneumonia, fungemia, and disseminated infection with cutaneous lesions.

54. …. Respiratory Fungal Infections
Histoplasmosis
–Histoplasma capsulatum, an ascomycete
–Airborne infection
–Transmitted by inhalation of spores in
contaminated spores
–Associated with chicken & bat droppings
–Respiratory tract symptoms; fever, headache,
cough, chest pains

55. ….Respiratory Fungal Infections
Blastomycosis
–Blastomyces dermatitidis, an ascomycete
–Associated with dusty soil & bird droppings
–Skin transmission: via cuts & abrasions
–Raised, wart-like lesions
–Airborne transmission: via inhalation of
spores
–Respiratory tract symptoms
–Occasional internal infections with high
fatality rate

56. Aflatoxin are a small group of mycotoxins
produced by the fungi from the genus
Aspergillus, Aspergillus flavus and
Aspergillus parasiticus , produces a natural
occurring human carcinogen, bis-
furanocumarin that is found in aflatoxin,

57. . Aflatoxins are known contaminants on
corn, peanuts, tree nuts, cottonseed
and certain meats and hypoallergenic
milks

58. Useful Properties of Fungi
5/18/2017 WALTER WASWA 58
Source of food
e.g. mushrooms
Fermentation - Production of
alcohol, bread, cheese
e.g. Sacchromyces spps
Antibiotic production
e.g. Penicillin from
Penicillium notatum

59. Useful Properties of Fungi
5/18/2017 WALTER WASWA 59
Ergot from Claviceps
purpurea, used to induce
uterine contractions
Vaccines for Hepatitis B –
Sacchromyces cerevisiae

60. Diagnosis/Treatment
1. Grown in medium that selects for fungal
growth
-Grow at 25 C and 37 C
2. KOH preparations of skin biopsies
-Dissolves keratin in skin scrapings or biopsies
-Leaves only fungal cells
3. Therapy- amphotericin B or ketoconazole
-Toxic to humans
5/18/2017 WALTER WASWA 60

61. The end
5/18/2017 WALTER WASWA 61