COCCIDIOIDOMYCOSIS FUNGAL INFECTION FROM DAVIDSON

COCCIDIOIDOMYCOSIS etiology, pathogenesis, clinical features, management

1. COCCIDIOIDOMYCOSIS

2. Etiology
Coccidioidomycosis is caused
by the two species of the
dimorphic soil-dwelling fungus
Coccidioides:
C. immitis and C. posadasii.

3. Epidemiology
Direct exposure to soil harboring
Coccidioides increases risk, but
infection can occur without overt
soil exposure and may be related
to other climatic factors (e.g.,
periods of dryness after rainy
seasons)
It is more common in the United
States

4. Pathogenesis and
Pathology

5. Clinical Features
1. Primary pulmonary infection:
symptomatic in 40% of cases
a. Fever, cough, chest pain,
erythema nodosum, erythema multi
forme, other hypersensitivity
reactions, night sweats, arthralgias
b. Chest x-ray: infiltrate, hilar and
mediastinal adenopathy, pleural
effusion in 10%

6. Clinical Features
c. Occasionally presents as diffuse
reticulonodular pulmonary process
with dyspnea and fever
d. Mild peripheral-blood
eosinophilia
2. Cavitary pulmonary disease:
chronic thin-walled cavities
Symptomatic pts have cough,
hemoptysis, and pleuritic chest
pain.

7. Clinical Features
3. Disseminated infection
a. More likely in pts with cell-mediated
immunosuppression (e.g., Hodgkin’s
disease, HIV infection), pregnant women,
and certain racial and ethnic groups
b. Common sites for dissemination include
bone, skin, joint, soft tissue, and meninges
c. Meningitis: fatal if untreated. Patients
have persistent headache, lethargy, and
confusion.
Examination of CSF reveals lymphocytic
pleocytosis, elevated protein levels,
profound hypoglycorrhachia, and
occasional eosinophilia.

8. Diagnosis
Histopathological Staining
●H and E, PAS or GMS
●Source: Sputum ot tissue
biopsy
●Observation: Spherules which
are large sac like structures
(20-80 mcm), they have thick
double refractile wall and filled
with endospores.

9. Diagnosis
Culture
●On SDA it produces mycelial
growth described as
fragmented hyphae consisting
of Barrel shaped arthrospores
with alternate cells distorted.
●They differ from other
dimorphic fungi as they grow
both at 25 degree C and 37
degree C

10. Diagnosis
Serology
●Antibodies are detected by
immunodiffusion test and CFT
Skin test
●It is done using fungal extracts
●If it produces at least a 5mm
induration within 48 hours after
injection it indicates a past
infection.

11. Treatment
●Focal primary pneumonia:
No therapy except in patients with
underlying cellular immunodeficiency
or prolonged symptoms

●Diffuse pulmonary disease:
Amphotericin B (0.7–1.0 mg/kg daily
or three times a week IV) followed by
itraconazole or fluconazole
(minimum oral dose of 400 mg/d)
after clinical improvement occurs

●Pulmonary cavities: Most do not
require treatment.

12. Treatment
●Chronic pulmonary disease
and disseminated infection:
Prolonged triazole therapy (for
≥1 year)

●Meningitis:
Lifelong therapy with a triazole.
Fluconazole is the drug of
choice (≥400 mg/d). If triazole
therapy fails, intrathecal
Amphotericin B may be used.

13. PARACOCCIDIOIDOMYCOSIS

14. Etiology
Paracoccidioidomycosis (South
American blastomycosis) is
caused by
Paracoccidioides brasiliensis, a
dimorphic fungus acquired by
inhalation from environmental
sources.

15. Pathogenesis Transmission is by
inhalation of spores
which then transform
into the yeast phase in
the lungs.

16. Clinical Features
It occurs as two major forms:
Acute form (juvenile type)
●It affects young adults under the
age of 30 years
●It manifests as disseminated
infection involving multiple
viscera and is refractory to
treatment

17. Clinical Features
Chronic Form (Adult form)
●It accounts for 90% of cases
and predominantly affects
older men.
●It is less severe form
manifested as progressive
pulmonary disease affecting
lower lobes with fibrosis.
●Skin, oral mucosa and cervical
lymphadenopathy are other
features.

18. Diagnosis
Histopathological Examination
●Source: Pus, tissue biopsies or
sputum
●Methanamine silver staining
shows round thick walled yeast
with multiple narrow necked
buds attached
circumferentially giving Pilot
wheel appearance

19. Diagnosis
Culture
●On SDA it yields mycelial form
at 25 degree C which converts
into yeast phase at 37 degree
C
Serology
●Antibodies are detected by
immunodiffusion and ELISA
using gp43 antigen.

20. Treatment Itraconazole is effective
Amphotericin B may be
required for seriously ill
patients.