respi 2 tranx

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OPPORTUNISTIC MYCOSES

Portal of entry: respiratory, mucocutaneous Infectious particles: conidia, mycelia Agents:

o Widely distributed (as saprophytes,normal flora)

o Invade only in the presence of someunderlying predispositions and mainly

immunocompromised individuals

I. Candidiasisa. Considered the most common

systemic/ opportunistic fungal infection

worldwide

b. Mostly endogenous; occasionallyexogenously acquired (hospital setting)

c. Clinical spectrum extremely diverse(from skin irritation to life-threatening

infections)d. Leading fungal infection in patients with

HIV-AIDS

e. Occurs as:i. Cutaneous and subcutaneous

(diseases of the skin and

mucosal surfaces)

ii. Systemic/ disseminated/invasive

1. Candidemia (e.g.catheter related)

2.

Acute/ chronicdisseminate candidiasis

3. Deep organ candidiasisf. Host factors predisposing to

candidiasis:

i. Physiological (pregnancy, age)ii. Trauma (burns, infection)

iii. Hematological (neutropenia,cellular immunodeficiency)

iv. Endocrinological (DM,hypothyroidism, Addisons

disease)v. Iatrogenic (chemotherapeutics,

corticosteroids, oral

contraceptives, catheters, etc.)

vi. Others (IV drug addiction,malnutrition)

g. Caused by Candida spp.:i. C. albicans- most common

agent, most pathogenic

ii. Normal flora of skin, vagina,mucous membrane, stool, GIT(

major colonizing habitat)

iii. Ascomyceteiv. Dimorphic, reproduce by

budding

v. Infectious particles: yeast cells,pseudohyphae

h. Laboratory Diagnosis:i. Gram Stain/ KOH/ histopath

exam:

- small budding yeast cells (4-5

um) and psuedohyphae

ii. Culture at room temp/ 37OC :-pseudohyphae with clusters of

round blastoconidia

-chlamydospores, yeast cellsand pseudohyphae on

Chlamydospore/ Cornmeal Agar

iii. Germ tube test (for C. albicans)iv. Others:

1. Assimilation tests2. Biotyping3. Immunofluorescence4. Immunohistochemistry5. DNA probes, PCR6. Mannan antigen

detection (RIA, ELISA,LAT)

v. Treatment and prevention1. Cutaneous- topical

nystatin, ketoconazole,

fluconazole

2. Systemic- ketoconazole,fluconazole,

Subject: Microbiology and ParasitologyTopic:Lecturer: Dr. Eleanor P. PadlaDate of Lecture: Sept 1, 2011Transcriptionists:pinkyred :)Editor: pinkyredPages: 4

SY

2011-2012


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itraconazole,

flucystosine, ampho B

3. Avoid disturbing thenormal balance of

microbial flora and

intact host defense

II. Aspergillosis

a. Acquired following inhalation ofinfectious conidia

b. Occurs as:i. Allergic form (allergic

bronchopulmonary aspergillosis

or ABPA)

ii. Colonizing form/ pulmonary(aspergilloma)

iii. Invasive/ disseminatediv. Mycotoxicosisv. Caused byAspergillus spp.:

1. Most common cause-A. fumigates, A. flavus

2. Ascomycetes3. Natural reservoir- soil,

air

4. Ubiquitous, frequentlaboratory

contaminants

vi. Laboratory Diagnosis:1. KOH/ HIstopath

-wide, septate,

dichotomously

branching(45O) hyphae,

conidial heads may be

seen

2. Culture:

-conidiophore supports

swollen vesicle covered

with rows of phialides

bearing radial chains of

conidia3. ID of cultures

-depends on difference

of conidial heads

4. Others:

-serology

-immunohistochemisrty

- glactomannan antigen

detection in serum

vii. treatment and prevention

- Allergic form- itraconazole,corticosteroids

- Aspergilloma- surgery,Ampho B

- Disseminated- itraconazole,fluconazole, ampho B

- Avoid/ minimize exposureto conidia- Prophylactic low-dose

Ampho B or itraconazole

III. Cryptococcosis

a. Aka Busse- Buschkes disease/Torulosis

b. Believed to be acquired followinginhalation of non-encapsulated/

minimally encapsulated yeast, or

Basidiospores

c. Primary site of infection: lungsd. One of the most common life-

threatening infections in patients withAIDS

e. Occurs as:i. Pulmonary (acute, chronic)

ii. Disseminated1. Meningitis- most

frequently diagnosed

form

iii. Neurotropism related tophenoloxidase activity

iv. Cutaneous form: raref. Caused by basidiomycete yeasts:i. Cryptococcus neoformans


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ii. Cryptococcus gattiig. Encapsulated yeastsh. replicate by buddingi. Do not produce hyphae/ psuedohyphaej. Cryptococcus neoformans (Filobasidiella

neoformans)i. common in temperate climate

ii. affects immunocompromisedpatients

iii. environmental reservoir:pigeon droppings

iv. infectious particles:unencapsulated yeast,

basidiospores

v. includes serotypres A, D, ADhybrid

1. C. neoformans var.neoformans (Serotype

D)

2. C. neoformans var.grubii(serotype A)

vi. Clinical disease: meningitisk. C. gattii (Filobasidiella bacilliospora)

i. In tropical/ subtropical climatesii. Effects immunocompetent

individuals

iii. Environmental reservoir:Eucalyptus trees

iv. Infectious particles:basidiospores

v. Includes: Serotypes B, Cvi. Clinical disease: pneumonia

l. Virulence factors:i. Capsule

1. Wide capsule2. Antiphagocytic3. 5 Serotypes: A,B,C,D,AD

ii.

Production of phenoloxidase1. Converts phenoliccompounds to melanin

2. Survival mechanismwithin phagocytes

m. Laboratory Diagnosisi. KOH/ India ink/ histopath

1. Yeast cells with widecapsule

ii. Culture (37oC)1. Creamy, mucoid yeast

colonies

2. Brown to black colonieson Niger/Bird Seed Agar

iii. ID of cultures1. Biochemical tests (e.g.

urease production)

2. Caffeic acid test-phenoloxidase

production

3. Growth on L-canavarine-glycine-

bromthymol blue (CBG)

n. Treatmenti. Ampho B. ampho B-5 FC

combination

ii. Fluconazole prophylaxisfollowing primary treatment (in

AIDS patients)

IV. Zygomycosisa. Aka mucormycosis/phycomycosisb. Acquired following exposure to

sporangiospores

c. Risk factors: diabetic acidosis,immunosuppression

d. Occurs as:i. Rhinocerebral (most frequent

form)

ii. Pulmonaryiii. Cutaneousiv. Gastrointestinalv. Disseminated- aggressively

angio-incvasive, predominantly

infarctive

e. Caused by filamentous fungi (e.g.Rhizopus, Mucor, Absidia)

i. Belong to order Mucorales,Class Zygomycetes

ii. Natural reservoir: soil, air,water

iii. Ubiquitous, frequentlyencountered as contaminantsf. Laboratory Diagnosis:

i. KOH/Histopath1. Wide (ribbon-like),

aseptate hyphae

branching at right

angles

ii. Culture at RT


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1. Cotton-candyappearance of colonies

2. Morphologic featuresidentify species

3. Caution in interpretingresults

g. Treatment and preventioni. Amphotericin Bii. Surgical debridement

iii. Control of predisposing factors(e.g. Diabetes/ underlying

disease

V. Table 1. Characteristics of Species causingZygomycosis

CHARACTER-

ISTICS

Rhizopus Mucor Absidia

Sporangia Round Round PyriformSporangiosp

ores

Unbranched,

nodal

Branched,

internodal

Branched,

internodal

Columellae Hemi-

spherical

Round to

oval

Conical

Rhizoids Well

developed

Absent Rudiment-

ary

Collarettes None

remains

when

sporangial

wall is

dissolved

Present

when

sporangial

wall is

dissolved

Rhizopus

Absidia

_______END OF TRANX__________

Hi to reych, arabels, anabels, eloh, jez, and to gempot!

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din to Cuz! And to my dear roommate maanto

Hannah, and rr! ^_^

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