Background and Purpose

Invasive candidiasis (IC) is a life-threatening fungal infection predominantly affecting critically ill and immunocompromised patients. Its diagnosis remains challenging because clinical features are nonspecific and conventional culture methods often show low sensitivity and delayed positivity. Consequently, there is a growing need for rapid, reliable, and non-culture-based diagnostic tools. The Candida mannan IgM antibody assay has recently emerged as a potential biomarker for early detection of IC. This study aimed to assess the diagnostic performance of the Candida mannan IgM antibody test in comparison with, and as an adjunct to, fungal culture for the detection of invasive candidiasis in patients with septicaemia admitted to a tertiary care hospital in New Delhi, India.

Materials and Methods

A prospective observational study was conducted from October 2023 to August 2024, enrolling 100 patients with clinical suspicion of IC. Blood, urine, and tracheal aspirate samples were obtained for fungal culture, and corresponding serum samples were tested for Candida mannan IgM antibodies using the FungiXpert® Candida Mannan IgM Antibody Detection K-Set. Culture was considered the reference standard. Diagnostic indices like sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. The association between antibody detection and culture results was analyzed using the chi-square test, with a p-value <0.05 considered statistically significant.

Results

Among the 100 patients evaluated, 58% were culture positive for Candida species. The Candida mannan IgM antibody test demonstrated a sensitivity of 31% (95% CI: 21.4–42.6%), specificity of 83.3% (95% CI: 69.2–91.6%), PPV of 72% (95% CI: 52.4–85.7%), and NPV of 46.6% (95% CI: 36.4–57.0%). A significant association was observed between antibody positivity and culture positivity (p = 0.037).

Conclusion

The Candida mannan IgM antibody assay, while limited in sensitivity, exhibited high specificity and a significant correlation with culture results. These findings indicate that the test may serve as a valuable adjunct to conventional fungal culture for diagnosing invasive candidiasis, particularly in septic patients where early identification is critical. Incorporating serological testing alongside culture could enhance diagnostic accuracy and facilitate timely antifungal intervention in resource-constrained healthcare settings.