Detecting Candida albicans via feminine hygiene products

The method manipulates the properties of multifilament cotton threads in the form of microfluidic-thread-based analytical devices (μTADs) to render a simple color change in positive cases.

"Can we leverage frequently used items and discardable materials, such as sanitary napkins and hydrogels, to detect the presence of pathogens in urine and vaginal fluid?” proposed Naresh Mani, PhD, an associate professor of biotechnology at the Manipal Institute of Technology in India, whose research focuses on developing frugal sensors or systems using off-the-shelf items.

Mani is also the corresponding author of a review article on knitting thread devices to detect Candida albicans in ACS Omega, a peer-reviewed journal from the American Chemical Society.

“In low-income communities, women who are at high risk of developing yeast infections are normally burdened by the direct and indirect cost of diagnosis,” Mani told Contemporary OB/GYN®. “Diagnosis necessitates frequent hospital visits, which involve sample collection and a follow-up with the physician.”

The alternative of a home-detection kit to ascertain the presence of a pathogen could be provided by health centers and non-governmental organizations, according to Mani. “This approach asserts the importance of frugal and hygiene product-based detection systems, which can enhance the quality of life of women in the least developed countries,” he said.

The frugal microbial identification assay targets all age groups, but primarily women aged 36 and older.

“The goal is mercerization of threads to boost their absorption efficiency and imbibing suitable substrates specific to pathogens,” Mani said.

The facile mercerization method uses a heptane wash to bolster reagent absorption and penetration, which has been shown to be more robust than other existing conventional mercerization methods.

Compared to an untreated thread, a heptane-treated thread showed better results for lower concentrations of C. albicans and comparable results for higher concentrations.

In addition, the twisted mercerized fibers are drop-cast with media consisting of L-proline beat-naphthylamide, which undergoes hydrolysis by the enzyme L-proline aminopeptidase secreted by C. albicans, thus signaling the presence of the pathogen via color change, with a detection limit of 0.58 × 106 cfu/mL.

When the flexible and easily disposable thread-based detection device is integrated with menstrual hygiene products, the detection time is 10 minutes for spiked vaginal discharge.

“Our method also has a long shelf life and high stability, making it a discreet detection device for testing, while providing new vistas for self-testing multiple diseases that are considered taboo in certain societies,” Mani said.

Mani and his fellow researchers have performed the test on simulated vaginal fluid. “We have yet to determine the sensitivity and specificity of the proposed test,” Mani said. “Still, a chair-side or point-of-care test which can qualitatively provide an answer could be a breakthrough for clinicians.”

Meanwhile, integrating this approach for detecting, colorimetrically, myriads of pathogens will be a daunting task, according to Mani, noting that artificial intelligence and machine learning might provide a better solution.

The cost of a single test is likely to cost the consumer less than $1.

“Our microfluidics, sensors and diagnosis laboratory welcomes other research groups and companies for possible collaboration,” Mani said.

Reference

1. Prabhu A, Singhal H, Nandagopal MSG, et al. Knitting thread devices: detecting Candida albicans using napkins and tampons. ACS Omega. 2021. 6, 19; 12667–12675. doi:org/10.1021/acsomega.1c00806