Aim:
To
isolate and identify the Aspergillus sp., from clinical samples.
Introduction:
Aspergillus species are
ubiquitous fungi, commonly occurring in soil, water, and decaying vegetation.
Route of acquiring infection being inhalation of fungal spores. From lungs,
dissemination takes place leading to systemic aspergillosis. Occurrence of Aspergillus
infection in association with chronic lung disease like pulmonary TB, lung
abscess, bronchopneumonia, with residual lung cavity, asthma and lung
malignancy has been documented. Out of 185 species of genus Aspergillus,
only 20 can cause human infection, Some examples are Aspergillus flavus,
Aspergillus fumigates, Aspergillus niger and Aspergillus nidulans.
Fumigatus is the most common species found in human infection all over the
world.
Materials Required:
Clinical sample
Sabouraud dextrose agar
Lacto phenol cotton blue
staining
Procedure:
1. Clinical specimens
were streaked on SDA plate and it was incubated at 37 °C for 5-7 days.
2. Fungal growth was
identified by colony morphology on plate.
3. Microscopic
observations:
Lacto phenol cotton blue staining:
Growth of Fungus were
taken from culture medium on clean grease free sterile microscopic slide and
mixed with 1-2 drops of LPCB stain. Focused the slide first under 10x to find
the area and then under 40x for identification of fungus.
Slide culture technique.
10
mm square block from Potato dextrose agar (PDA) was cut using sterile coverslip
or scalpel. The growth of Fungus were taken from culture medium i.e.
Sabouraud’s dextrose agar (SDA) with the help of L shaped wire and inoculated
into four corner of the block and then a sterile coverslip was kept over the
block. The inoculated side culture was incubated in a wet Petri dish at 25 ±5°C
in Biological Oxygen Demand incubator for 48 to 72 hours. Then the coverslip
was removed and placed over a drop of Lactophenol Cotton Blue (LPCB) stain in
clean sterile glass slide and then focused under 10x to find the area and then
under 40x for identification of fungus.
Result and Interpretation:
Obtained fungal culture from
clinical sample was identified as Aspergillus niger based on Colony
morphology and Microscopic characterization.
Colony
Morphology of Aspergillus species
A. niger:
Colonies consist of a compact white or
yellow basal felt covered by a dense layer of dark-brown to black conidial heads
A. flavus:
Colonies are granular,
flat, often with radial grooves, yellow at first but quickly becoming bright to
dark yellow-green with age.
A. fumigates :
Colonies are typically blue-green with a
suede-like surface consisting of a dense felt of conidiophores.
A. nidulans :
Colonies are typically plain green in
colour with dark red-brown cleistothecia developing within and upon the
conidial layer.
|
Organism
(s)
|
||
|
|
Hyphae
|
Other
features
|
|
A.
fumigatus
|
2.5–8 µm wide, septate, hyaline,
acute angle branching, tree- or fan-like branching. Stipes may resemble
hyphae of zygomycetes
|
Conidial head uniseriate, columnar,
conidia in chains or detached and dispersed. Single or paired conidia may
resemble yeast cells
|
|
A.
niger
|
See A. fumigatus
|
Conidial head biseriate, radiate,
conidia in chains or detached and dispersed. Single or paired conidia may
resemble yeast cells
|
|
A.
terreus
|
See A. fumigatus
|
Small, round, hyaline conidia
(‘accessory’ conidia) attached to the vegetative hyphae
|
Ref:
N. McClenny, Medical Mycology, Volume 43, Issue Supplement_1, 1 January 2005, Pages
S125–S128, https://doi.org/10.1080/13693780500052222.
Raksha et al., Pilot study on
identification of Aspergillus species and its antifungal drug sensitivity
testing by disc diffusion method, Int.J.Curr.Microbiol.App.Sci (2014) 3(12):
555-562.
Shrimal et al., ISOLATION OF
ASPERGILLUS SPECIES FROM SPUTUM SAMPLES: A STUDY CONDUCTED IN A TERTIARY CARE
HOSPITAL, AHMEDABAD, NATIONAL JOURNAL OF MEDICAL RESEARCH, eISSN: 2277 8810, Volume
3│Issue 3│ 2013, 289 – 291.
https://mycology.adelaide.edu.au/descriptions/hyphomycetes/aspergillus/
No comments:
Post a Comment