Opportunistic Mycoses Lect Seven

8/14/2019 Opportunistic Mycoses Lect Seven

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Candidiosis or Candidiasis

Most commonly encounteredopportunistic mycoses worldwide

Cellular immunity protects againstmucocutaneous candidiasis

Oral , vaginal, skin, neutrophils protect against invasive

candidiasis

Lung, spleen, liver and so on

Normal flora Endogenous inf.


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MOST COMMONLY ISOLATEDCANDIDA SPECIES

C. albicans C. tropicalis C. parapsilosis C. kefyr

C. glabrata Mycology or morphology Macro

Creamy yeast colonies (SDA) Micro Yeast cell reproduce by budding Produce either pseudo or true hyphae Only Candida glabrata produce yeast only Germ tube, fermentation and assimilation

reactions


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PATHOGENICITY

Attachment (Germ tube ismore adhesive than yeastcell)

Adherence to plasticsurfaces (catheter,prosthetic valve..)

Protease

Phospholipase


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Risk factors

Physiological.

Pregnancy, elderly, infancy

Traumatic.

Burn, infection

Haematological. Cellular immune deficiency,

AIDS, chronic granulomatous disease,

aplastic anaemia, leukaemia, lymphoma...

Endocrinological DM, hypoparathyroidism, Addison disease

Iatrogenic.

Oral contraceptives, antibiotics,

steroid, chemotherapy, catheter...


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Clinical manifestations-I

Cutaneous and Subcutaneous Oral

Vaginal

Onychomycosis Dermatitis

Diaper rash

Balanitis


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Clinical forms of candidiasis


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Clinical manifestations-II

Systemic

Esophagitis Peritonitis

Hepatosplenic

Endophthalmitis , Arthritis

Osteomyelitis, Meningitis

Skin lesions, Pulmonary infection

Cystitis, Pyelonephritis

Endocarditis, Myocarditis


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Clinical manifestations-III

Chronic mucocutaneous Candida inf. of skin and mucous

membranes

Verrucose lesions Impaired cellular immunity

Autosomal recessive trait

Hypoparathyroidism, iron deficiency


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Laboratory diagnosis

Direct microscopic examination

Yeast cells, Pseudohyphae, truehyphae

Culture

SDA, routine bacteriological media

Serology

Disseminated candidosis Detection of mannan antigen

(ELISA, RIA, IF, latex agglutination


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Lab Diagnosis refer to lab practical for more details


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Treatment

Cutaneous Topical antifungal

Ketaconazole, Miconazole, nystatin

Systemic Amphotericin B

Fluconazole, itraconazole

Chronic mucocutaneous Amphotericin B Fluconazole, itraconazole

Transfer factor


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Cryptococcosis

Etiologic agent

Cryptococcus neoformans

Mycology

Monomorphic (yeast at 25 and37)

Possess mucoploysaccaride capsule


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Epidemiology and Ecology

World wide

Roosts and droppings of pigeons

Exogenous infection

Four serotypes A-D (most frequently A)

B-C isolated from AIDS patients inAfrica

Underlying cellularimmunodeficiency

(AIDS, lymphoma)


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Pathogenicity factors

Capsule

Diphenol oxidase (+) (Bird seed

agar/caffeic acid medium)

Ability to grow at 37C

Clinical diseases

PULMONARY

Asymptomatic

flu-like/hilar lap/cavitation


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Clinical diseases cont.

Disseminated **Meningitis (acute/chronic) in AIDS Cryptococcoma

Skin lesions

Other

Laboratory Diagnosis

Samples CSF, sputum,

aspiration from skin lesion


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Diagnosis cont.

Direct exam India ink

Culture

SDA, Niger seed agar

Canavanine glycine bromothymolblue

Serology*** Detection of capsule antigen in CSF

and serum by latex agglutination test


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Treatment

Amphotericin B + flucytosine

Life-long fluconazole

prophylaxis following primary

treatment (in AIDS patients)


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Aspergillosis

General characteristic

Purely an opportunistic infection

Infection Depend on host immunity

Cause abortion in sheep and cattle

Pulmonary in birds

Carcinogenic in animals

Aspergillus spp.( most common: A.

fumigatus)


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Risk factors and pathogenesis

Immunosuppression, DM..exogenous inf. (inhalation ofspores)

Inhalation of spores by atopic hostHypersensitivity reactions (allergy)

Ingestion of products contaminatedwithAspergillus toxins

Mycotoxicosis / hepatocellular andcolon carcinoma


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General futures Natural reservoir

air, soil Pathogenicity factors hypha, phospholipase

Infected tissue

vascular invasion, thrombus, infarct,bleeding

Macroscopic powdery mould colonies

(colour of the spores varies from onespecies to other)

Microscopic septate hyphae (dichotomous branching),

vesicula, phialides, microconidia


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Diseases associated withAspergillus

Clinical manifestations-I Mycotoxicoses

Allergic aspergillosis

1.Asthma (Type I)

2. Allergic bronchopulmonaryaspergillosis (Types I, III)

II.Non-invasive local colonization Aspergiloma (Fungus ball) (lungs,

paranasal sinuses) Otomycosis (external otitis)

Onychomycosis

Eye inf. (conjunctival, corneal,

intraocular)


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Clinical manifestations-II

IV. INVASIVE ASPERGILLOSIS

1.Pulmonary

2. Disseminated

GIT, brain, liver

kidney, heart, skin, eye


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Laboratory Diagnosis Samples Sputum, BAL, tissue...

Direct exam Septate hyphae and conidia in sputum;

intravascular hyphae in tissue

Culture SDA (without cycloheximide)

(should grow at least in 2 cultures !)

Serology Allergy (detection of specific IgE in serum--RAST)

Invasive inf. (detection of galaktomannanantigen in serum--ELISA)


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Diagnosis of Aspergillosis

Asp. In the lung

ASPERGILLOMA

Colony appearance of Aspergillus

Structure of Aspergillus


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Treatment

Allergic Steroid

Aspergiloma (if symptomatic) Surgery

amphotericin B

Local and superficial infections

Nystatin

Invasive infection

Surgical debridement Amphotericin B, itraconazole

***High mortality rate


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ZYGOMYCOSIS

Causative agents Rhizopus, Rhizomucor, Mucor...

Natural reservoir

Air, water, soil

Risk factors Diabetic ketoacidosis

immunosuppression

Pathogenesis

Inhalation of sporangiospores Infected tissue

vascular invasion

thrombus, infarct

bleeding


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Laboratory diagnosis

Samples

Sputum, BAL

biopsy of paranasal sinuses..

Direct exam Nonseptate

ribbon-like hyphae which branch atright angles, sporangium

Culture

SDA (cotton candy appearance)


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Clinical and lab diagnosis


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Treatment

Surgical debridement

Amphotericin B

***High mortality rate

Opportunistic Mycoses Lect Seven

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