Candida albicans and

Aspergilus species

Aguilar, Princess AlenBumagat, Giane Carla

Fernandez, JarlathSidocon, Erisia Shorouk

Candida albicansMorphology

Methods of IdentificationPathogenicity

ViabilityMode of transmissionPrevention & Control

Candida albicans Gen. Characteristics

Agent of yeast infectionsPremier cause of yeast infection in the

worldOval yeast with a single budThin walled, reproduce by budding or fissionNormal flora

◦Upper respiratory, gastrointestinal, female genital tracts, mucosa, skin, and digestive tract

In tissues, appear as budding yeasts or as elongated budding “pseudohyphae”

Candida albicans. Notice the spherical chlamydoconidla (resting bodies formed from hyphal cells) and the smaller blastoconidia (asexual spores produced by budding).

Microscopic features-almost complete sexual budding

C. albicans in mycelial or tissue phase with blastoconidia budding from the pseudohyphae.

Microscopic morphology of C. albicans showing budding spherical to ovoid blastoconidia.

Methods of IdentificationGerm Tube Test (+) w/ capsule

◦ A rapid screening test for Candida albicans and Candida dubliniensis.

◦ 0.5 mL of serum, containing 0.5% glucose, is lightly inoculated with the test organism and incubated at 37°C for 2-3 hours.

On microscopy, the production of germ tubes by the cells is diagnostic for Candida albicans.

sugar assimilation profile distinctive green colour on

CHROMagar. production of chlamydospores

(corn meal agar @ 20°C)

Production of germ tubes by C. albicans

Methods of Identification

CHROMagar Candida plate showing chromogenic colour change for C. albicans (green), C. tropicalis (blue), C. parapsilosis (white) and C. glabrata (pink).

Pathogenicity:Candidiasis is an acute-to-chronic

fungal infection that can involve the mouth, vagina, skin, nails, bronchi, lungs, alimentary tract, bloodstream, or urinary tract.

Most widely recognized manifestation of C. albicans is THRUSH, an infection of oral mucosa which is also an indication of immunosuppression.

Candidiasis Oral thrush

- is a yeast infection that forms white curd-like patches on the oral mucocutaneous membranes.

Vulvovaginitis/ vagina thrush

- as a thick yellow-white discharge.

- Diabetes, antibiotic therapy, oral contraceptives, and pregnancy predispose the patient to this condition.

- Due to loss of lactobacilli the C. albicans flourishes

Cutaneous candidiasis

- Occurs in chronically moist areas of skin and in burn patients.- Onychomycosis and paronychia-Chronic mucocutaneous candidiasis

Cadidemias- occur in patients who have indwelling catheters.

Viability: DRUG SUSCEPTIBILITY

- Sensitive to nystatin, miconazole, clotrimazole, ketoconazole, fluconazole, amphotericin B for invasive candidiasis

DRUG RESISTANCE- Resistant strains have been described for all the above antifungal drugs

SUSCEPTIBILITY TO DISINFECTANTS- Sensitive to 1% sodium hypochlorite, 2% glutaraldehyde, formaldehyde; only moderately sensitive to 70% ethanol (phenolic may be substituted)

PHYSICAL INACTIVATION- Inactivated by moist heat (121°C for at least 15 min)

SURVIVAL OUTSIDE HOST- Survives outside of host, especially in moist, dark areas

Mode of transmission: Normal flora of oral cavity, genitalia,

large intestine or skin of 20% of humans

80% of nosocomial fungal infectionsEndogenous spread (part of normal

human flora); by contact with excretions of mouth, skin, and feces from patients or carriers; from mother to infant during childbirth; disseminated candidiasis may originate from mucosal lesions, unsterile narcotic injections, catheters.

Prevention & Control: Keeping your skin clean and dry, by

using antibiotics only as your doctor directs, and by following a healthy lifestyle, including proper nutrition. 

People with diabetes should try to keep their blood sugar under tight control.

HIV or another cause of recurrent episodes of thrush, then antifungal drugs such as clotrimazole (Lotrimin, Mycelex) can help to minimize flare-ups.

For local infection, removal of the cause (eg. Moisture) & administration of antimicrobial agents are effective.

Tropical cream (eg. Nystatin & miconazole)

For systemic infection- oral ketoconazole can control mucocutaneous candidiasis.

For disseminated candidiasis- intravenous amphotericin B, oral flucytosine or oral ketoconazole can be effective if cellular immunity.

Aspergillus speciesexist only as molds

MorphologyMethods of Identification

Pathogenicity:Viability:

Mode of transmission: Prevention & Control:

GENERAL CHARACTERISTICS2nd most common isolated fungus after

CandidaA. fumigatus is the specie most commonly

isolatedPathogenic species are A. flavus, .A. terreus,

& A. nigerFast growing fungusNot dimorphic and producing septate hyphaeSpores are constantly present in the airDoes not cause disease, except for

immunocompromised person w/ 90% mortality

MorphologyMay be either uniseriate or

biseriateArise from a “foot cell”, a

vegetative hyphaeUniseriate

◦Phialides attached to the vesicle at the end of conidiophore

MorphologyBiseriate

◦Posses a supporting structure called metula

◦Metulae attached directly to the vesicle, & attached to each metula are phialides then eventually conidia are produced.

MorphologyColor of the fungus comes from the conidia,

asexual spore.Colors are black, white, yellow, brown, tan,

green, gray, beige, pink, but most pathogens are green to tan colored.

“Fungus balls” in the lungs of agricultural workers who routinely are in contact w/ fungal conidia from environmental sources. This can be seen through X-ray and can be removed through surgery.

Erect conidiophore arising from a foot cellConidia can be aligned in very straight,

parallel columns or in radiant pattern around the vesicle and it can be rough or smooth.

Aspergillus fumigatusMost important pathogenCan colonize and later invade

abraded skin, wounds, burns, the cornea, the external ear, or paranasal sinuses.

may grow at temp. range of 20-50°C, best grow at 40-45°C◦Produces conidial heads w/

numerous conidia◦Hyphae are septate

w/ dichotomous branching

Aspergillus flavusGrowing on cereals or nuts

produces aflatoxins that may be carcinogenic or acutely toxic especially in the liver

• Uniserate or biserate or both w/ phialides covering the entire spherical vesicle

• Conidia are globose to subglobose (3-6 um in diameter), pale green and conspicuously echinulate. Some strains produce brownish sclerotia.

Aspergillus nigerBeano™ is an enzyme

preparation from A. niger that breaks down CHO typically found in beans, Cabbage, broccoli and other high fiber foods which are tending to produce flatulence as a result of microbial action in the intestines.

Biserate w/ phialides covering the entire surface of the spherical vesicle; conidia are black

Microscopic featuresSPECIES CONIDIOPHORE PHIALIDES VESICLE

A. clavatus Long, smooth Uniseriate Huge, clavate-shaped

A. flavus Colorless, rough Uni-/biseriate Round, radiate head

A. fumigatus

Short (<300 µm), smooth, colorless or greenish Uniseriate Round, columnar

head

A. glaucus group

Variable length, smooth, colorless Uniseriate

Round, radiate to very loosely columnar head

A. nidulans Short (<250 µm), smooth, brown

Biseriate, short

Round, columnar head

A. niger Long, smooth, colorless or brown Biseriate Round, radiate

head

A. terreus Short (<250 µm), smooth, colorless Biseriate Round, compactly

columnar head

A. versicolor Long, smooth, colorless Biseriate Round, loosely

radiate head

Colony IdentificationSPECIES SURFACE REVERSE

A. clavatus Blue-green White, brownish with age

A. flavus Yellow-green Goldish to red brown

A. fumigatus Blue-green to gray White to tan

A. glaucus group Green with yellow areas

Yellowish to brown

A. nidulans Green, buff to yellow Purplish red to olive

A. niger Black White to yellow

A. terreus Cinnamon to brown White to brown

A. versicolor

White at the beginning, turns to yellow, tan, pale green or pink

White to yellow or purplish red

IdentificationGrowth is rapid to moderately

rapid (colonies may be seen in 4 days)

Powdery in textureA. nidulans and A. glaucus slowly

grows, in 7 days reaching 0.5 -1cm at 25°C

A. clavatus

A. flavus

A. glaucus

A. fumigatus

A. nidulans

A. niger

A. terreus

Pathogenecity=Aspergillosis

Invasive aspergilloma◦ Neutropenia is the single most predictive factor for

developing this Dse.◦ The Px has sinusitis, & dissemination throughout the

body◦ There may be high titers of galactomannan Ag in

serumAspergillus spp. Are the frequent cause of disease

in the bone marrow transplant recipient in addition to other cancer transplant Px.

Allergic aspergillosis◦ High titer or IgE Ab against Aspergillus is detected◦ Infection is initiated as the fungal conidia were inhaled,

thus airborne In the lung air spaces, conidia begin to germinate and

invade tissue

PathogenecityConidia in the earwax can lead to

a painful ear Dse known as Otomycosis

Common to people with Asthma or cystic fibrosis

Invasive type only affects immunocompromised patients

Can cause multiple organ involvement- brain, liver, heart, and bone producing hemoptysis and granulomas

Symptomsw/in the few days, Px

develops a severe fever that fails to response to anti-fungal therapy

Pneumonia like symptoms are possible

Wheezing (as in asthma)CoughingChest painShortness of breathAspergilloma/ “Fungus

balls”

Fungus balls

TreatmentVoriconazole -first-line treatment for

invasive aspergillosis. Amphotericin B for invasive aspergillosisItraconazoleLipid Amphotericin FormulationsCaspofunginMicafunginPosaconazole**immunosuppressive medications should be discontinued or decreased.

PreventionWear an N95 mask when near or in a dusty

environment such as construction sitesAvoid activities that involve close contact to

soil or dust, such as yard work or gardeningUse air quality improvement measures such

as HEPA filtersTake prophylactic antifungal medication if

deemed necessary by your healthcare provider

Clean skin injuries well with soap and water, especially if the injury has been exposed to soil or dust

Thank you for listening!