s3 l25 opportunistic mycoses

8/8/2019 S3 L25 Opportunistic Mycoses

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S3 L24: Opportunistic Mycoses by Dr. Antonio Camacho DDDeeeccceeemmmbbbeeerrr 111999,,, 222000111000

OPPORTUNISTIC MYCOSES

Infections due to fungi of low virulence in patients who are immunologicallycompromised

PATHOGENIC FUNGI

Normal hostoSystemic pathogens - 25 speciesoCutaneous pathogens - 33 speciesoSubcutaneous pathogens - 10 species

Immunocompromised hosto Opportunistic fungi - 300 species

HOST-PATHOGEN EQUILIBRIUM

OPPORTUNISTIC FUNGI

1. Saprophytic - from the environment2. Endogenous a commensal organism

Include many species from:

A (Aspergillus) To Z (Zygomyces)

MOST FREQUENT OPPORTUNISTIC INFECTIONS

Candida species Aspergillus species Mucorspecies Cryptococcus

Candida sp.

Endogenous organismFound in 40-80% of normal human beings present in the mouth, skin, gutand vagina

May be communal or pathogenicFrequently infects skin and mucosa but can also cause pneumonia,septicemia or endocarditis in immunocompromised hosts

MORPHOLOGY AND IDENTIFICATION

In culture or tissue: Oval, budding

yeast cells

Pseudohyphae formation- chains ofelongated cells that are constricted atthe septations between cells

On blood agar, after 24 hours of incubation,moist opaque colonies are seen with yeastyodor

Germ tube ortrue hyphae formationdistinguish Candida albicans from the rest ofCandida sp.

CLINICAL FINDINGS

CUTANEOUS and MUCOSAL CANDIDIASISooral thrushovulvovaginitisocutaneous intertriginous infectionsoonychomycosis

CHRONIC MUCOCUTANEOUS CANDIDIASIS

Chronic mucocutaneous candidiasis (CMC) isthe label given to a group of overlappingsyndromes that have in common a clinicalpattern of persistent, severe, and diffusecutaneous candidal infections.

These infections affect the skin, nails andmucous membranes.

DIAGNOSTIC LABORATORY TESTS

Specimens : swabs and scrapings from superficial lesions, blood, spinalfluid, tissue biopsies, urine, exudates, catheters

Microscopic Examination: using KOH, demonstrate the presence ofpseudohyphae in scrapings or tissue specimens

Culture : 37oC; presence of pseudohyphae

Serology: not useful; lack sensitivity and specificity

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GERM TUBE TEST

rapid screening test where the production of germ tubes by the cells isdiagnostic forCandida albicans

Treatment forCandida

oFor mucocutaneous form: topical nystatin, ketoconazole, fluconazoleoFor systemic infection: Amphotericin B

Aspergillus sp.

Aspergillus is a filamentous mold and is a ubiquitous fungus found in nature(soil, plant debris, and indoor air)

Ubiquitous saprophyteA fumigatus most common human pathogen

Produces abundant conidia easily aerosolized which can be inhaled andinvade the lungs

EPIDEMIOLOGY

Distributed worldwideCommonly found in soil, food, paint, air vents, disinfectants

Aspergillus is the second most commonly recovered fungus in opportunisticmycoses (following Candida spp).

The three principal entities are: allergic bronchopulmonary aspergillosis pulmonary aspergilloma invasive aspergillosis

Nosocomial occurence of aspergillosis due to catheters and other devices isalso frequently observed.


Produce conidial structure: long condiosphores with terminal vesicles

Portal of Entry INHALATION

ASPERGILLOSIS

CLINICAL TYPESAllergicohypersensitivity to the organismo respiratory symptoms may be mild to alveolar fibrosisFungus ball (Aspergilloma)o recognized by x-ray, may be mistaken for TB cavity

oA colony of saprophytic mold growing in preformed cavity usually due toTB or sarcoidosis

oPatients cough up the fungus elementsAggressive tissue invasionoprimarily a pulmonary disease but

aspergillus disseminate to any organomay cause endocarditis, osteomyelitis,

otomycosis, and cutaneous


Specimens : sputum, other respiratory specimens, or lung biopsy

Microscopic Examination: with KOH, presence of hyaline branching septatehyphae

Cultureo require 1-3 weeks for growthoassumes a variety of colorsospecies differentiation is based on spore formation as well as their color,

shape and texture

Serologyo Immunodiffusion test

antibody detection presence of precipitin bands (5) presence of 3 or more bands indicate more severe disease

oEIA to measure galactomannan highly specific (99%) but less sensitive (50%)

TREATMENT-AMPHOTERICIN B

Mucorsp.

Acute inflammation of soft tissue, usually fungal invasion of the blood vessels

Organisms under the order MUCORALES of the class ZYGOMYCETES

1. Rhizopus species

2. Mucorspecies3. Absidia species

EPIDEMIOLOGY

World-wide distributionCommon in soil, food, organic debris, seen on decaying vegetables in therefrigerator and on moldy bread

Rhinocerebral infection major clinical form

Frequently seen in the uncontrolled diabetic

MUCORMYCOSIS

CLINICAL FINDING

Rhinocerebral infection:o results from germination of spores in nasal

passages and invasion of the hyphae intothe blood vessels causing thrombosis,infarction, and necrosis.

oblood vessels and nerves are damaged,facial edema, bloody nasal exudate, orbitalcellulitis


Culture: Grow rapidly on lab media producing abundant cottony colonies.


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Direct examination: broad hyphae withuneven thickness, irregular branching andsparse septations

TREATMENT

Surgical debridement

Rapid administration of amphotericin B

Control of underlying disease

Crytococcus neoformans

Yeast with a thick polysaccharide capsule

Occurs worldwide in nature

Found in very large numbers in dry pigeon and chicken droppings


Spherical cells that produce buds

Polysaccharide capsule surrounds theorganismCapsule may suppress T-cell function virulence factor

Phenoloxidase (melanin) also avirulent factor

PATHOGENESIS

INHALATION OF YEAST CELLS (AEROSOLIZED)

PRIMARY PULMONARY INFECTION(asymptomatic or flu-like illness)

In immunocompromised, may disseminate to

other organs preferentially to the CNS (meningoencephalitis)

CLINICAL FINDINGS

Meningoencephalitisoprolonged clinical course: begin with visual problems; headache, neck

stiffness, coma, death

Skin and lung infectionso formation of a granulomatous reaction with giant cellsoCryptococcoma: mass in the mediastinum


o Specimens: spinal fluid, exudates, blood, urine, sputumo LACCASE PRODUCTION: (catalyzes formation of melanin)

differentiates C. neoformans and gattiifrom nonpathogenicCryptococcus

o INDIA INK TEST-demonstrates capsule of thisyeast

o Latex Agglutination test for antigen decreasing titer indicates a good prognosis


LABORATORY FINDINGS

Cryptococcus neoformans in sputum,Wright Stain

Cryptococcus neoformans in bloodculture, Gram stain

TREATMENT

AMPHOTERICIN B + FLUOCYTOSINE: Standard for cryptococcalmeningitis

PREDISPOSING FACTORS

MalignanciesoLeukemiasoLymphomasoHodgkins DiseaseDrug therapiesoAnti-neoplasticsoSteroidso Immunosuppressive drugs

AntibioticsoOver-use or inappropriate use of antibiotics alter the normal flora allowing

fungal overgrowth

Therapeutic proceduresoSolid organ or bone marrow transplantoOpen heart surgeryo Indwelling cathetersoArtificial heart valvesoRadiation therapyOther FactorsoSevere burnsoDiabetesoTuberculosiso IV Drug use

AIDS


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SOME COMMON ASSOCIATIONS BETWEEN FUNGAL ORGANISMSAND DISEASE CONDITIONS

Cryptococcus Candida Aspergillus Zygomycetes

Diabetes melllitus

tuberculosis

lymphoma

Hodgkins disease

steroid therapy

immunosuppression

prolonged antibiotictherapy

prolonged IV catheter

prolonged urinarycatheter

corticosteroid therapy

Diabetes mellitus

hyperalimentationimmunosuppression

leukemia

corticosteroid

therapy

tuberculosis

immunosuppression

IV drug use

diabetes mellitus

leukemia

steroid therapy

IV therapy

severe burns

IMPROVING TREATMENT

New Drugs

New therapeutic regimen

Aggressive therapy

Conjunctive therapy

NEW DRUGS

EchinocandinsThird generation azoles

New classes of antifungal agents

NEW THERAPEUTIC REGIMENCombination Therapy1.Simultaneously administering two drugs2.Sequential Tx with two or more drugs3.Alternate Administration of two or moreAGGRESSIVE THERAPY FOR IMMUNOCOMPROMISED PATIENTS1.Prophylactic Anti-fungal agents at, or near, the time of chemotherapy2.Empirical Start therapy when patient at risk, i.e., fever and/or infiltrate

without response to anti-bacterials.

3.Pre-emptiveWhen there is some additional evidence of fungal infection(serology, isolate, etc.)

CONJUNCTIVE THERAPY FOR IMMUNOCOMPROMISED PATIENTSThe use of anti-fungal agents with immunotherapy (interferon, colony stimulatingfactors, interleukin

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s3 l25 opportunistic mycoses

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