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D4249-83 – Standard Test Method Technical Guide
🧪 Summary of Test Method for Candida albicans
This test method is designed for the detection and enumeration of Candida albicans in raw sewage, waste waters, and natural waters. The procedure involves filtering sample volumes through 1.2-µm retentive porosity gridded membrane filters and placing them on the surface of mCA selective medium. Incubation is carried out at 37°C for 2 to 4 days, after which typical colonies are counted using a dissecting microscope. For confirmation, suspect colonies are transferred to bovine (calf) serum and incubated for 2 to 3 hours. The presence of germ tubes, which are elongated extensions 3 to 4 µm wide and up to 20 µm long with no constriction at the base, confirms C. albicans.
📊 Key Technical Specifications
The following table summarizes the critical parameters for the enumeration procedure:
| 🟦 Parameter | 📏 Specification |
|---|---|
| Membrane Filter Porosity | 1.2 µm |
| Incubation Temperature | 37°C |
| Incubation Duration | 2–4 days |
| Confirmation Medium | Bovine (calf) serum |
| Confirmation Incubation | 2–3 hours |
| Germ Tube Width | 3–4 µm |
| Germ Tube Length | Up to 20 µm |
| Reference Standard | ASTM D 1129 |
🔬 Significance and Use in Water Quality
Candida albicans is a commensal yeast in the gastrointestinal, genitourinary, and alimentary tracts of healthy humans and animals and is a serious opportunistic pathogen. It is found in raw sewage and natural waters receiving human and animal wastes. The yeast can survive in seawater for at least six days, and in vitro survival in distilled and lake water has been demonstrated. This test method is useful for monitoring treatment processes for efficiency in removing pathogens and as a potential indicator of recreational water quality. Public health and sanitary engineering interests should be aware of its presence in wastewater and the potential for disease in contiguous waters.
❓ Frequently Asked Questions
🔍 What is the scope of this test method?
It covers the detection and enumeration of Candida albicans in raw sewage, waste waters, and natural waters. The analyst must determine if it yields satisfactory results in other water matrices.
💡 How is C. albicans confirmed?
Suspect colonies are picked to bovine serum, incubated for 2–3 hours, and examined for germ tubes. True germ tubes have no constriction at the point of origin, distinguishing them from pseudohyphae.
⚡ What are the incubation conditions?