CRYPTOCOCCUS

@Cryptococcus neoformans causes cryptococcal meningitis.

Properties:

@ C neoformans is an oval, budding yeast surrounded by a wide polysaccharide capsule . It is not dimorphic.

Transmission:

@ It occurs widely in nature and found

in soil containing pigeon droppings.

@ Birds are not infected.

@ Human infection results from

inhalation of the organism.

@ No human to human transmission.

Diseases:

@ Lung infection is often asymptomatic

or may produce pneumonia.

@ Disease is common in AIDS patients,

and the organism disseminates to

C.N.S. (meningitis) and other organs.

Laboratory Diagnosis:

@ In CSF mixed with India ink, the wide, unstained capsule is seen

@ Culture of CSF and other specimens.

@ Serologic tests can be done for both antibody and antigen.

@ In CSF, capsular antigen is detected by latex particle agglutination test.

Treatment & Prevention

@ Cryptococcal infection is treated by amphotericin B, flucytosine, or fluconazole

@ No means of prevention.

ASPERGILLUS

@ Aspergillus fumigatus. cause infections of skin, eyes, ears, and other organs .

@ It causes "fungus ball" in lungs; and bronchial asthma Properties:

@ Aspergillus exist only as molds; it is not dimorphic.

@ Has septate hyphae & conidia with radiating chains

Transmission:

@ Widely distributed in nature, & live

on decaying vegetation, producing

chains of conidia.

@ Transmission is by conidia shed in the

air.

Diseases:

@ Asp. fumigatus invades lungs causing

hemoptysis, granulomata, and asthma

@ It invades pulmonary cavities & causes

aspergilloma ("fungus ball"),

@ Aspergillus flavus contaminates cereals

& nuts to produce aflatoxin that causes

liver toxicicity and cancer.

Laboratory Diagnosis:

@ Biopsy show septate, branching hyphae

@ Cultures show colonies with radiating chains of conidia.

@ High levels of IgE are detected in patients with Aspergillus asthma.

@ IgG precipitins antibodies are detected by serology.

Treatment & Prevention:

@ For aspergillosis give amphotericin B

@ Fungus ball can be removed surgically.

@ For aspergillosis asthma give steroids

@ No specific means of prevention.

MUCOR & RHIZOPUS

@ The disease zygomycosis is caused by the saprophytic molds: Mucor and Rhizopus.

@ They are not dimorphic.

@ Transmitted from the environment by asexual spores from the air

@ Causes infarction & necrosis nasal sinuses, lungs, eyes, and gut.

Lab. diagnosis:

@ Culture: shows colonies with spores inside sporangium.

@ Biopsy: to detect hyphae with irregular walls and branches.

Treatment:

@ Give amphotercin B and remove necrotic tissue surgically.