A performance evaluation of an immuno-latex chromatography card for the rapid detection of Candida spp

This report evaluates the performance and species specificity of an immuno-latex chromatography card (ICC) for rapid detection of Candida spp. Double-manipulator single-blind Gram staining smear examination (GSSE) and ICC were used to analyze 354 vaginal discharge specimens (VDS) (including 98 tested as positive by GSSE) from women with suspected candidal vaginitis, simulated specimens with a concentration gradient, and vaginitis causing organism suspensions (0.9% NaCl) of 22 species from nine genera. Limit of detection, semi-quantitative detection performance, total detection performance and species specificity were determined for ICC, and the results were compared with those of the GSSE method. The limits of detection of ICC for Candida spp. in organism suspensions with 0.9% NaCl and simulated specimens were 7 × 10⁶ cells/L and 7 × 10⁸ cells/L respectively. For species specificity, the results were positive for six Candida spp. (C. albicans, C. glabrata, C. parapsilosis, C. tropicalis, C. krusei and C. guilliermondii) and negative for the remaining 16 species (C. lusitaniae, Saccharomyces cerevisiae; three Gram-positive coccus species, four Gram-negative bacillus species, three Gram-negative coccus species and four common microbes causing vaginal infection) from eight genera. The overall sensitivity, specificity, accuracy, positive predictive value and negative predictive value of ICC for VDS were 93.81%, 99.10%, 97.31, 98.14% and 96.90%, respectively. The above indicators in the 98 VDS evaluated as positive were 84.39%, 92.86%, 86.74%, 96.72% and 70.27%, respectively. In summary, ICC offered better specificity, sensitivity, positive predictive value and negative predictive value for the detection of Candida spp. in VDS.