Clinical Spectrum of some Mycotic Agents.
MOLDS
YEAST
-Candida
-Cryptococcus
-Malassezia
furfur
-Aspergillus
-Mucorales
-Dermotophytes
DIMORPHIC
FUNGI
-Sporothrix shenckii
(Sporotrichosis)
-Histoplasma
capsulatum
(histoplasmosis)
-Coccidioides
immitis
(coccidioidomycosis
)
Candida
Gram positive, oval, budding yeast.
Opportunistic pathogen
Types:
C. tropicalis
C. parapsilosis
C. glabata
Principal pathogen: Candida albicans
Predisposing factor:
1. At extreme of age
2. During pregnancy
3. Debilitated/immunosuppressed patients
4. Diabetes Mellitus
5. Use of broad spectrum antibiotics
6. Treatment with steroids (include inhale steroids)
Infections:
Superficial infections
Deep infections
Lab Diagnosis:
Specimens: According to the site of infections
M.V: Yeast cells appear as oval gram positive budding yeast with pseudohyphae
Culture:
SDA (Sabouraud Dextrose Agar)
inhibit bacterial growth
Some specialized (chromogenic) agars: for easy differentiation.
Biochemical Reaction:
Germ tube formation: Most true C. albicans produce true hyphae when
incubated for 2-3h in human serum.
Chlamydospores formation on cornmeal agar
Sugar fermentation & assimilation
Treatment:
Topical antifungal (superficial infections)
Oral/Parentral= immunosuppressed patients
Cryptococcus neoformans
From: Cryptococcus
Opportunistic pathogens
Most infections occur @ IMMUNOCOMPRIMISED patients <HIV patients mostly>
Encapsulated yeast
Widely in nature:
Dried pigeon droppings
Soil contaminated with bird droppings
Pathogenesis:
Fungus was inhaled & the lungs are principal portal of entry
Meningitis (acute/chronic): Clinical manifestation
Lab Diagnosis:
Specimens: CSF, blood, sputum
M.V:
CSF: Mounted in India Ink encapsulated budding yeasts appear
surrounded by large gelatinous capsule
Culture:
SDA: gives mucoid colonies of typical capsulated yeast.
Also give diagnostic brown pigments on bird seed (Niger seed) media
Biochemical Reaction:
Urease: Positve
Serological reaction:
Detection of cryptococcal capsular antigen in CSF/serum using
anticapsular antibodies <latex agglutination>
Treatment:
𝐴𝑚𝑝ℎ𝑜𝑡𝑒𝑟𝑖𝑐𝑖𝑛 𝐵 𝑜𝑟 𝑓𝑙𝑢𝑛𝑎𝑧𝑜𝑙𝑒 + 𝐹𝑙𝑢𝑐𝑦𝑡𝑜𝑠𝑖𝑛𝑒
-antifungal
*can pass BBB*
Malassezia furfur
Lipophillic yeast (part of normal flora)
Cause common, mild superficial infections: Pityriasis versicolor
Potentially disfiguring skin condition
Development of numerous brown scaly patches, hypopigmentation of skin
Treatment: (sorry…tak sempat salin from lecturer)
Aspergillus
 Species:
A. fumigatus
A. niger
A. flavus
 Pathogenesis:
Opportunistic organism
Risk factors: (…sorry tak sempat salin…)
Allergic aspergillosis
Hypersensitivity reaction to the inhalation of Aspergillus spores
Asthma-like symptoms
Formation of mucus plug which may contain Aspergillus mycelium
Aspergilloma
Fungus ball that usually occurs in patients with pre-existing lung
cavities
Invasive pulmonary aspergillosis
Rapidly & progressive & life threatening infection
 Lab diagnosis:
a. Specimen: Sputum
b. M.V:
Long branching hyphal strands dichotomously branch) may be seen in
sputum (direct examination)
After digestion with 10% KOH
Allergic aspergillosis
Invasive aspergillosis: result is negative
*need lung biopsy and it’s important*
c. Culture:
Grows steadily on routine culture media
<SDA without cycloheximide…why did they use that? Because the
cycloheximide will inhibit the aspergillus>
d. Serological reaction:
Detection of high level of Asperfillosis Antibodies in serum
*it will increase with aspergillomas*
e. Radiological: invasive aspergillus
f. Histologically: made by deep tissue biopsies/sterile body
 Treatment:
Pulmonary aspergillosis: Steroids
Aspergillomas: surgical excision (manage hemoptysis)
Invasive: high-dose systemic antifungal therapy
Dermotophytes
Filamentous fungi that cause superficial infection of keratinized structures
3 types:
a) Trichophyton
b) Epidermophyton
c) Microsporum
Natural reservoir:
Humans: anthropophilic
Animals: zoophilic
Soil: geophilic
Human infections:
E. floccosum
T. rubrum
T. mentagrophytes
T. tonsurans (anthropophilic)
M. canis (zoophilic)
Pathogenesis:
Clinical picture: ring worm/tinea
According (anatomically) to site
Lab diagnosis
a. Specimen: skin scales, nail/hair covered with 10% KOH
b. MV: branching hypha & spores
c. Culture: Dermatophytes
grow readily on routine media
*SDA + Cycloheximide & Chloraphenicole
Treatment:
Difficult & long courses
Antifungal drugs (orally)
I.
Griseofulvin
II.
Itraconazole
Sporotricosis
Infection on subcutaneous tissue
Occurs within 3 months of a contaminated inoculation injury
(arms/hands)
Painless nodules develops at site injury
Further lesions develop along lymphatic channels
Treatment:
Oral itraconazole
Saturated potassium iodide solution
Histoplasmosis
Species: Histoplasma capsulatum: Dimorphic fungus
Causes:
Asymptomatic infection/only mild self-limiting chest infection
More pulmonary infection occurs <resembles TB>
Treatment: Amphotericin B/Itraconazole
Coccidioidomycosis
Species: Coccidioides immitis
Found: soil in SW of USA & some parts of Central & SA
Infection occur:
Inhalation of airborn spores (anthroconidia) from environment
Endospores: Patient sputum (highly infectious)
Similar to Histoplasmosis
*no yeast form
*it is highly infectious