Download - respi 2 TRANX
-
8/4/2019 respi 2 TRANX
1/4
1
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
-
8/4/2019 respi 2 TRANX
2/4
2
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
-
8/4/2019 respi 2 TRANX
3/4
3
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
-
8/4/2019 respi 2 TRANX
4/4
4
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!
Happy birthday to Quen! And to Ramone, hehehehi
din to Cuz! And to my dear roommate maanto
Hannah, and rr! ^_^
Happy studying!