What lab test is used for diagnosing Candida infections?

From the Guidelines

The primary lab test used for diagnosing Candida infections is the combined detection of mannan antigen and anti-mannan antibodies, which has shown higher sensitivity and specificity when used together 1. This approach is supported by a meta-analysis of 14 studies, which found that the combined assay had a sensitivity of 83% and specificity of 86% for diagnosing invasive candidiasis 1. The use of mannan antigen and anti-mannan antibodies is a non-invasive, non-culture-based method that can help confirm or exclude the diagnosis of an invasive fungal disease 1. Some key points to consider when diagnosing Candida infections include:

• The importance of early and proper specimen collection to ensure diagnostic accuracy 1
• The use of multiple testing methods, such as fungal culture, microscopic examination, and molecular tests, to confirm the diagnosis 1
• The consideration of clinical prediction rules and risk factors, such as Candida colonization and severity of illness, to identify patients at high risk of candidiasis 1
• The potential use of empirical antifungal therapy in critically ill patients with risk factors for invasive candidiasis and no other known cause of fever 1

From the Research

Lab Tests for Candida

• The following lab tests are used for diagnosing Candida infections:
  • Polymerase Chain Reaction (PCR) 2, 3, 4, 5
  • Blood cultures 2, 4, 5, 6
  • Immunomagnetic separation (IMS) with solid-phase cytometry (SPC) 6
  • 1,3-β-d-glucan (BDG) 4, 5
  • Mannan and anti-mannan antibody 4, 5
  • T2Candida nanodiagnostic panel 4
  • Candida albicans germ tube antibody (CAGTA) 4, 5

Sensitivity and Specificity of Lab Tests

• PCR: sensitivity ~90%, specificity ~90% 4
• Blood cultures: positive in < 50% of invasive candidiasis cases 4, 5
• IMS/SPC: sensitive and specific, with a low detection limit (1 cell/ml of blood) 6
• BDG: sensitivity ~80%, specificity ~80% 4
• Mannan and anti-mannan antibody: sensitivity ~80%, specificity ~80% 4
• T2Candida: sensitivity ~90%, specificity ~98% 4

Clinical Application of Lab Tests

• Non-culture tests can be useful in diagnosing invasive candidiasis, especially in cases where blood cultures are negative 4, 5
• Clinicians must understand the pretest likelihood of invasive candidiasis and test performance to use non-culture tests effectively 4, 5
• Lab tests can help identify the species of Candida, which can inform treatment decisions 2, 3