Sputum for fungi (Fungus, Yeast and Molds)
Sputum for fungi
Sample for Sputum for fungi
- The sputum sample is needed to find the presence of the fungus.
- Advise patient to get deep cough sputum.
- The sample can be refrigerated for up to 24 hours.
- Sputum may be stable at room temperature for 72 hours.
- Do not freeze the sample.
- Store it at room temperature.
Precautions of Sputum for fungi
- Sputum should be examined as fresh as possible because Histoplasma capsulatum dies rapidly at room temperature.
- The saprophytic fungi like candida and commensal bacteria rapidly multiply if kept at room temperature and it will interfere in the separation of pathogenic fungi.
- Try to minimize contamination with the saliva.
- Stop aspirin, ibuprofen, naproxen, and warfarin which will thin the bronchial secretion.
Method to collect a good sample of Sputum for fungi
- Brush your teeth and rinse your mouth (don’t use antiseptic mouthwash).
- Take a couple of long, deep breaths.
- Breathe in deeply again and cough hard until sputum comes up.
- Spit out the sputum into the sample cup.
- Keep coughing up sputum until there is approximately 1 teaspoon.
Indications for Sputum for fungi
- This is done for the diagnosis of respiratory fungal infection.
- In the case of :
- shortness of breath
- A cough that is, most of the time, dry.
- Muscle aches and pains.
Microbiology of Fungi
- Fungi are microorganisms. The majority are nonpathogenic.
- Fungi are eukaryotic organisms and are divided broadly into three main groups:
- These are single-celled. These are facultative anaerobes.
- Candida e.g. C.albicans
- Cryptococcus e.g. C. neoformans.
- These are filamentous fungi (hyphae). These are aerobic.
- These fungal hyphae form mycelium.
- Mycelium has two functions:
- The vegetative mycelium penetrates into the medium and absorbs nutrients.
- Aerial mycelium has reproductive structures for the spread of molds.
- This exists in both the above forms.
- Blastomyces dermatidis causing North American blastomycosis.
- Histoplasma capsulatum causing Histoplasmosis.
- Histoplasma duboisii causing African histoplasmosis.
- Sporothrix schenckii causing Sporotrichosis.
- Some of the fungi that exist in either form are called dimorphic fungi.
- The cell wall of the fungi is thick and composed of polysaccharides.
- Fungi are not motile.
- Most of these fungal diseases are opportunistic and need some predisposing factor; these are called Mycosis.
- Predisposing factors are:
- Immune deficiency syndrome.
- The sputum fungal smear is one of the best ways to find out if your respiratory illness is caused by a fungus.
- A positive smear for fungus indicates a fungal infection.
- The following types of fungal infections may be seen in the respiratory system:
- Pneumocystis carinii.
Normal Sputum for fungi
- A normal (negative) result means no fungus was seen in the test sample.
- When sputum is positive for fungal infection.
Procedure for Sputum for fungi
- The smear can be stained.
- Wet preparation:
- Take skin scraping, hair, nail clipping, vaginal swab, sputum, or body fluids.
- Make a thin sputum smear and mix it with KOH (10%).
- Then smear is examined under the microscope.
- Gram stain (invented by Hans Christian Gram).
- Make a sputum smear on the slide.
- Fix it with heat.
- Stain with Gram’s stain.
- See under the microscope.
- Wet preparation:
- Culture on the Saubourads dextrose agar medium (SDAM).
- Candida albicans show raised creamy smooth colonies after 72 hours on SDAM.
- Another media used is nutrient agar media.
- Fungi grow slowly, and it may take several weeks to grow fungi.
- C. neoformans form white, granular, or wrinkled first and later on moist, shiny, and mucoid colonies on SDAM.
- Serology may be helpful in some of the fungal infections like histoplasmosis, coccidioidomycosis, and South American blastomycosis.