U6 LEC: OPPORTUNISTIC MYCOSES Flashcards
Infections in patients with immune deficiencies who would otherwise not be infected.
Opportunistic Mycoses
Opportunistic mycoses are seen in those people with impaired host defenses such as?
- AIDS
- Alteration of Normal Flora
- Diabetes Mellitus
- Immunosuppressive therapy
- Malignancy
Part of a normal human flora
Endogenous
Examples of Endogenous Mycoses
- Candida spp.
- Pneumocystis jirovecii
Most common endogenous mycoses, indicator of weak immune system
thrush (Candida spp.)
Fungus does not normally live in/on human body
Exogenous
Examples of Exogenous Mycoses
- Cryptococcus neoformans
- Aspergillus (different species)
- Zygomycetes
- Many Other Fungi
Causative agent of Candidiasis or Moniliasis
Candida albicans and other Candida spp.
Candida albicans causes?
Candidiasis or Moniliasis
Candidiasis
oval, buddying yeast that produces?
pseudohyphae
T/F: Candida albicans causes the most frequent opportunistic fungal infections.
True
Candidiasis
harmless inhabitants of the?
skin and mucous membranes (RT, GIT, Female Genital Tract)
T/F: Normal immune system keeps Candida on body surfaces.
True
Other Candida species
- C. tropicalis
- C. krusei
- C. parapsilosis
- C. glabrata
- C. gullermondii
- C. lusitaniae
- C. kefyr
Candidiasis
Main Defense Mechanisms
- skin and mucous membranes integrity
- presence of normal bacterial flora
- phagocytosis
- killing (most in PMNs, less in macrophages)
- T cells (CD4)
Candidiasis
Important Risk Factors
- Neutropenia
- Diabetes mellitus
- AIDS
- SCID
- Myeloperoxidase defects
- Broad-spectrum antibiotics
- Indwelling catheters
- Major surgery
- Organ transplantation
- Neonates
- Severity of an illness
- Intravenous drug addicts
Candidiasis
Clinical Forms
- Cutaneous and Mucosal
- Invasive
Candidiasis
Manifestations under Cutaneous and Mucosal Candidiasis
- Oral thrush
- Oezophagitis
- Vulvovaginal infection
- Cutaneous candidiasis (skin trauma, burn patients)
- Onchomycosis
- Mucocutaneous candidiasis (SCID patients)
Invasive Candidiasis also refers to?
Systemic, Disseminated, Hematogenous Candidiasis
Invasive Candidiasis
begins with?
candidemia (only 50% can be proven)
Invasive Candidiasis
If phagocytic system is normal?
invasive infection stops here (destroyed by phagocytes)
Invasive Candidiasis
If phagocytic system is compromised?
infection spreads to many organs (causes focal infection)
Invasive Candidiasis
Mortality of candidemia
30-40%
Candidiasis
Specimen
- Swabs or scrappings from lesions
- Sputum
- CSF
- Exudates
Candidiasis
Microscopic
Gram (+) oval, budding yeast/elongated budding cells in chain (pseudohyphae)
Candidiasis
SDA
soft, cream-colored colonies with yeasty odor, surface growth consists of oval budding cells
Candidiasis
Ferments?
glucose and maltose producing acid and gas
Candidiasis
Serological test
Precipitation tests
This agar is used to differentiate Candida based on?
color
CHROM agar
Green
C. albicans
CHROM agar
Pink
C. krusei
CHROM agar
Metallic blue
C. tropicalis
CHROM agar
White to mauve
Other species
This is done for Candida albicans in presence of high protein content.
Germ tube
Germ Tube
specimen
plasma or serum
Germ Tube
(+) result
presence of germ tube
Germ Tube
What Candida spp. is present if there is (+) result?
Candida dubliniensis
Chlamydoconidia is present in?
C. albicans and C. dubliniensis
Candidiasis
Epidemiology
- Endogenous
- Cross infections (ICU patients)
Candidiasis
Treatment
Neutropenic patients: Amphotericin B
Non neutropenic patients:
Nystatin, Caspofungin
Candidiasis
This treatment suppresses intestinal and vaginal candidiasis
Nystatin
Causative agent of Pneumocystis Pneumonia
Pneumocystis jirovecii
Pneumocystis jirovecii causes?
Pneumocystis Pneumonia
Pneumocystis jirovecii is formerly called?
P. carinii
Pneumocystis
previously classified as?
protozoa
Pneumocystis
considered as fungus based on?
nucleic acid and biochemical analysis
Pneumocystis
Present in?
lung of many mammals
Pneumocystis
Infection in humans
persistent but harmless
Pneumocystis
Main Risk Factors
- AIDS
- Transplantation
- Corticosteroid
- Antineoplastic therapy
Pneumocystis
Main defense mechanism
T-cell mediated
Pneumocystis
Causes what in immunocompromised patients?
Interstitial pneumonitis
Pneumocystis
Specimens can be?
sputum, bronchoalveolar lavage
Pneumocystis
Treatment and Prevention
Co-trimoxazole or Pentamidine
Causative agent of Cryptococcosis or Torulosis
Cryptococcus neoformans
This causes Cryptococcosis
Cryptococcus neoformans
Other term for Cryptococcosis
Torulosis
Cryptococcosis
causes an acute or chronic infection that involves the brain, called?
meningitis
Cryptococcosis
occurs worldwide in?
soil and in bird droppings
Cryptococcosis
Prominent feature
thick polysaccharide capsule
Cryptococcosis
Infection is via?
respiratory tract
Cryptococcosis
Symptoms associated with?
nonspecific pulmonary signs and symptoms
Cryptococcosis
May disseminate in other organs like?
brain (cryptococcal meningitis)
Cryptococcosis
Clinical manifestation
slowly developing chronic meningitis that resembles a brain tumor, brain abscess, degenerative CNS disease
Cryptococcosis
Specimen
CSF, Exudate, Sputum, Urine
Cryptococcosis
Microscopic
round or ovoid, often budding with thick capsule
Cryptococcosis
SDA
cream, shiny, mucoid colonies
Cryptococcosis
Serological tests
Cryptococcal polysaccharide capsular antigen test, latex agglutination test
Cryptococcosis
Treatment
Combination of chemotherapy of Amphotericin B and Flucytosine
Cryptococcosis
Main Risk Factors
- T cell deficiency (AIDS)
- Corticosteroid therapy
- Organ transplantation
- Hematological malignancy
Cryptococcosis
Main Defense Mechanism
T cells
Cryptococcosis
Treatment
Amphotericin B +
- Flucytosine
Cryptococcosis
Recurrence Prevention
Fluconazole
Cryptococcosis
Epidemiology
Exogenous, not transmitted from human to human
Cryptococcosis
This agar is used to detect the enzyme, phenol oxidase
Niger Seed Agar (Bird Seed Agar)
Causative agent of Aspergillosis
Aspergillus spp.
Aspergillus spp. causes?
Aspergillosis
Aspergillosis
Worldwide occurring saprophytes, living in?
soil and plants (small conidia that form aerosols)
Aspergillosis
Most common
Aspergillus fumigatus
Aspergillosis
Other species
- A. flavus
- A. niger
- A. terreus
- A. nidulans
Aspergillosis
Produces aflatoxins in food
A. flavus
Aspergillosis
Specimen
Tissue biopsy
Aspergillosis
Microscopic
hyphal fragments (using methenamine silver)
Aspergillosis
Cultivation in SDA
gray to green colonies
Aspergillosis
Main Defense Mechanisms
Phagocytosis
Aspergillosis
Treatment
- Amphotericin B
- Itraconazole
- Flucytosine
- Surgery
Aspergillosis
Prevention
Avoid exposure to conidia (new buildings)
Aspergillosis
Main Risk Factors
- Hematological malignancy
- Bone marrow transplantation
- Corticosteroid therapy
Causative agent of Zygomycosis
- Mucor
- Rhizopus
- Absidia
- Rhizomucor
Zygomycosis is also called as?
Mucormycosis
Phycomycosis
Zygomycosis
invasive disease caused by?
Zygomycetes (Mucor, Rhizopus, Rhizomucor, Absidia)
Zygomycosis
These fungi are?
ubiquitous thermotolerant saprophyte
Zygomycosis
spores are present in?
air and dust
Obsolete polyphyletic taxon, forms coenocytic hyphae and reproduce asexually by producing sporangiophores within which develops sporangiospores
Class Phycomycetes
Rhizopus
Mycelium, 3 types of hyphae
- Stolon
- Rhizoid
- Sporangiophores
Mucor
Mycelium
1 type only: Sporangiophores
Rhizoids
R: Present
M: not present
Food
R: absorbed by rhizoids
M: absorbed by entire mycelial surface
Sporangiophores
R: occurs in tufts from the stolons opposite the rhizoids
M: occur singly from any point on the mycelium
Spores
R: easily disseminated by the wind
M: remain adhered to the columella, not easily disseminated
Absidia
Difference from Rhizopus
Rhizoids in between Sporangiosphores
Absidia
Difference from Mucor
Mucor have no rhizoids
Rhizomucor
Difference from Mucor
have rhizoids and stolons, grow at 50-55C
Rhizomucor
Difference from Absidia
have globose sporangia, sporangiophores are not swollen where they merge with the columella
Zygomycosis
Risk Factors
- Acidosis
- Leukemias
- Lymphoma
- Corticosteroid treatment
- Severe burns
- Immunodeficiencies
Zygomycosis
Clinical Manifestations
- Rhinocerebral Mucormycosis
- Thoracic Mucormycosis
- Other sites of invasion
This disease can progress rapidly with invasion of the sinuses, eyes, cranial bones and brain
Rhinocerebral Mucormycosis
Rhinocerebral Mucormycosis
Results from germination of?
sporangiospores in nasal passages
Rhinocerebral Mucormycosis
Invasion of?
hyphae into blood vessels
Rhinocerebral Mucormycosis
Invasion of hyphae causes?
- Thrombosis
- Infarction
- Necrosis
Rhinocerebral Mucormycosis
Patients develop?
- edema of involved facial area
- bloody nasal exudate
- orbital cellulitis
Rhinocerebral Mucormycosis
Almost invariably associated with?
- acute diabetes mellitus
- debilitating disease (leukemia, lymphoma)
Thoracic Mucormycosis
Follows inhalation of sporangiospores with?
invasion of lung parenchyma and vasculature
Thoracic Mucormycosis
In both locations, this causes massive tissue destruction
ischemic necrosis
Other Sites of Invasion
Skin infections following burns or surgery
Primary cutaneous infections
Other Sites of Invasion
These are also reported
Subcutaneous zygomycosis
Zygomycosis
Specimen
Nasal discharge, sputum, biopsy
Zygomycosis
Microsopic (KOH)
broad and aseptate, branched mycelium, sometimes distorted hyphae, clearly stained by Methenamine silver stain
Zygomycosis
SDA
Abundant and cottony
Zygomycosis
Treatment
Amphotericin B
Causative agent of Penicilliosis / Talaromycosis
Talaromyces marneffei
Talaromyces marneffei causes?
Penicilliosis
Other term for Penicilliosis
Talaromycosis
Talaromyces marneffei is formerly known as?
Penicillium
T/F: There are more than 100 Penicillium species.
False
more than 150
Penicilliosis
Form
thermally dimorphic
Penicilliosis
Present in?
environment (saprophytes), grow on various substrates (bread, jam, fruit, cheese)
Penicilliosis
Important opportunistic pathogen in?
HIV infected
Penicilliosis
Causes?
disseminated infection with multiple organ involvement
Penicilliosis
Common in?
Southeast Asia
Penicilliosis
Risk Factors
- Adult-onset immunodeficiency syndrome
- Cancer
- HIV/AIDS
- Organ transplant
Penicilliosis
These can also get Talaromycosis.
Bamboo rats (no evidence of spread from rats to people)
T/F: Penicilliosis has no person to person spread.
True
Penicilliosis
Specimen
Bone marrow, blood, lung fluids, lymph nodes, skin
Penicilliosis
Microscopic
yeast are small, oval, 2-4um in diameter
Penicilliosis
SDA
yellow green colonies with characteristic soluble red pigment
Penicilliosis
Molecular techniques
PCR
Penicilliosis
Treatment
Amphotericin B, Oral Itraconazole