What laboratory test is indicated for a suspected vaginal candidiasis (yeast infection)?

From the Guidelines

To diagnose a yeast infection, the most appropriate lab test to order is a polymerase chain reaction (PCR) for the Candida group, which has high clinical accuracy and can identify the specific Candida species involved 1. This test is preferred over traditional methods such as microscopy and clinical suspicion, which have drawbacks and limitations.

• Microscopy has poor sensitivity, while yeast cultures can lead to a delay in diagnosis and treatment.
• Clinical diagnosis may result in misdiagnosis and unnecessary treatment. In contrast, PCR has been shown to have high sensitivity (90.9%) and specificity (94.1%) for diagnosing vulvovaginal candidiasis, making it a more reliable option 1. Additionally, PCR can identify the specific Candida species involved, which is important for guiding treatment, as some species may be resistant to certain antifungal medications. For example, C. glabrata is often resistant to azole therapy, and treatment with boric acid or nystatin may be necessary 1. Overall, ordering a PCR test for the Candida group is the most appropriate choice for diagnosing yeast infections, as it provides accurate and reliable results that can guide effective treatment.
• Other tests, such as vaginal wet mount with potassium hydroxide (KOH) preparation and microscopic examination, may also be used, but they have lower sensitivity and specificity compared to PCR 1.
• Vaginal pH testing may also be performed, but it is not a definitive diagnostic test, as yeast infections typically have a normal vaginal pH of 4.0-4.5 1.

From the Research

Diagnosis of Yeast Infection

To diagnose a yeast infection, the following lab tests can be ordered:

• Microscopic examination (KOH preparation) 2, 3
• Fungal culture for pathogen determination 3
• Gram stain showing yeast 4
• Saline microscopy, potassium hydroxide, and methylene blue 4
• Molecular tests, such as PCR, can also be used to aid in the diagnosis of yeast infections 5

Lab Tests for Yeast Infection

The following lab tests can be used to diagnose a yeast infection:

• Vaginal wet mount 3
• Vaginal culture 3
• Yeast DNA detection by PCR 5
• Fungal susceptibility testing 6

Interpretation of Lab Results

The interpretation of lab results for yeast infection diagnosis includes:

• Positive yeast culture results 2, 3, 4
• Presence of yeast on microscopic examination 2, 3, 4
• Detection of yeast DNA by PCR 5
• Fungal susceptibility testing results 6