Development of a Loop-Mediated Isothermal Amplification (LAMP) for the screening of <i>Candida auris</i>

by Woong Sik Jang, Young Lan Choe, Soo Young Yoon, Chae Seung Lim, Min-Chul Cho

Background

Candida auris is an emerging multidrug-resistant yeast associated with invasive infections, healthcare-associated outbreaks, and high mortality, and is often misidentified by conventional diagnostic methods. Rapid, accurate, and scalable screening tools are essential for effective infection control, particularly in high-risk settings.

Materials and methods

We developed a multiplex loop-mediated isothermal amplification (LAMP) assay that combines a broad-range Candida Pan target with a C. auris–specific target in a single isothermal reaction. Assay conditions were optimized for primer ratio and temperature, and analytical sensitivity was evaluated using serial dilutions of culture-derived C. albicans and C. auris DNA, as well as contrived specimens consisting of urine, swab, and whole-blood matrices. Clinical performance was assessed using 35 Candida-positive clinical specimens (blood, urine, ear swabs) and 94 non-infectious controls. Results were compared with Candida Pan qPCR and C. auris qPCR. Cross-reactivity was tested against common bacterial isolates.

Results

Under optimized conditions (1:1 primer ratio, 64 °C), the assay allowed species-level discrimination, with C. auris positive for both Pan and auris channels and C. albicans positive only for the Pan channel. The C. auris-specific LAMP probe detected approximately 10²–10³ cells/mL in culture-derived and contrived specimens, showing a 1–2 log improvement over C. auris qPCR (10⁴–10⁵ cells/mL), while the Pan LAMP channel detected C. auris at around 10⁵ cells/mL. In clinical specimens, Pan LAMP detected Candida spp. in 34/35 cases (97.14%) versus 32/35 (91.14%) for Pan qPCR. All C. auris–positive specimens (9/9) were detected by the multiplex LAMP assay, compared with 6/9 (66.7%) by Pan qPCR. All 94 non-infectious controls and all bacterial isolates tested negative, indicating 100% clinical specificity and absence of cross-reactivity.

Conclusion

The multiplex Candida Pan/auris LAMP assay provides a rapid, highly sensitive, and specific alternative to qPCR for C. auris screening, while preserving broad Candida detection in a single isothermal reaction. Its improved analytical and clinical sensitivity suggests strong potential for use in active surveillance and infection-control programs, particularly in settings where timely identification and containment of C. auris are critical.