CEDT Journal

Foot odour (bromodosis) is a distressing condition, both socially and medically, was found to be derived from isovaleric acid, which is produced when Staphylococcus epidermidis, a resident species of the normal cutaneous microbial flora, degrades leucine present in sweat. In addition, Bacillus subtilis was detected in the plantar skin of subjects with strong foot odour, and this species was shown to be closely associated with increased foot odour [1].

There appears to be a constant concern with regards to body hygiene and malodour, making the use of agents such as fragrant deodorants and antiperspirants one of the largest cosmetic sellers globally (estimated to be worth about US$ 74.55 billion in 2019) [2]. One of the most important personal care products is deodorant witch contain antimicrobial agents that prevent body odor.

Current active ingredients in deodorants, such as triclosan and benzalkonium chloride, are small molecules (<600Da) that microorganisms can develop resistance against after repeated long-term use and may penetrate the skin, causing irritation and sensitisation. To address such issues, polyionenes, which are largemolecular membrane-disrupting polymers that contain quaternary ammoniums and varying hydrophobic components, has been synthesized [3].

Polyquaterium-117 is a cationic amphiphilic polyionene biopolymer that enables killing the microbes through a unique functional mechanism. This polymer will first attach onto the cell membrane of the microbe through strong multivalent ionic interactions between the cationic charges in the polymer and anionic phosphate groups on the microbial membrane. Thereafter, the hydrophobic components in the polymer insert into the lipid domain of the microbial membrane, leading to membrane disruption, membrane lysis, and eventually microbial cell death. Due to the nature of multivalent interaction and physical membrane disruption, the risk of development of antimicrobial resistance is very low [4,5].

We formulated a spray solution containing Polyquaterium-117 0.5%w/v as an active antimicrobial ingredient, together with isopropyl alcohol which is synergistically antimicrobial (unpublished data) and allows evaporation of the spray solution. The aim of this study was to preliminarily evaluate the efficacy and safety of this Polyquaterium-117-containing hydroalcoholic solution in healthy individuals and individuals affected by bromodosis in a single-center, open-label, pre-post intervention study.

We randomly recruited 70 subjects (age 37.59 ± 10.24; 49 females). The patients were to use the foot odour spray for 3 weeks, once or twice daily as tolerated, and then undergo a questionnaire evaluation.

Before using the product, 52 participants (74.29%) were troubled by foot odor, while after using the product, only 13 participants (18.57%) still experienced foot odor. The incidence of foot odor was significantly reduced after the product use (P < 0.001, McNemar test). The usage details of the product among the 52 participants who had foot odor before using the product are shown in Table 1.

Out of the 70 participants, 5 (7.14%) reported adverse reactions: 3 experienced dryness, 1 had cracked heels and peeling skin, and 1 reported itching without any lesions after one week of use and subsequently stopped using the product. We posit these being the side effects of the isopropyl alcohol.

Table 1: Demographics, apply practices of the participants with foot odour and effects of treatment on the spray.

Interestingly, about three quarters of the randomly selected study population report and are troubled by foot odour, though most cases were relatively mild. This could be related to conducting the study in a tropical region like Singapore. More than 80% of participants found the spray to be effective and were satisfied with its results.

In conclusion, results from this study suggest that the 0.5% Polyquaterium-117 hydroalcoholic spray solution can be effective and safe in reducing foot odour.

Author Contributions

HLT and WH conducted the study, analyzed the data and wrote the manuscript.

Acknowledgments

The authors acknowledge the funding support of Trisafe Healthtech Pte Ltd. Hong Liang Tey is supported by the Clinician Scientist Award (CSAINV20nov-0003) from the National Medical Research Council of Singapore.

Funding Information

This study was supported by Trisafe Healthtech Pte Ltd.

Conflict Of Interest Statement

HLT formulated the spray solution. WH has no conflict of interest to disclose.

Ethics Statement

All procedures performed involving human participants were in accordance with the 1964 Helsinki Declaration and its later amendments. Informed consent was obtained from all individual participants.

References

1. Ara K, Hama M, Akiba S, Koike K, Okisaka K, et al. (2006) Foot odor due to microbial metabolism and its control. Can J Microbiol 52: 357364.
2. Statista (2024) Size of the global antiperspirant and deodorant market 2012-2025.
3. Liu S, Ono RJ, Wu H, Teo JY, Liang ZC, et al. (2017) Highly potent antimicrobial polyionenes with rapid killing kinetics, skin biocompatibility and in vivo bactericidal activity. Biomaterials 127: 36-48.
4. Leong J, Shi D, Tan JPK, Yang C, Yang S, et al. (2022) Potent Antiviral and Antimicrobial Polymers as Safe and Effective Disinfectants for the Prevention of Infections. Adv Healthc Mater 11: e2101898.
5. Qiu Q, Yang C, Wang Y, Alexander CA, Yi G, et al. (2022) Silanefunctionalized polyionenes-coated cotton fabrics with potentantimicrobial and antiviral activities. Biomaterials 284: 121470.