Description

Our Mission

Our project addresses Toxic Shock Syndrome (TSS), a severe condition linked to tampon use, caused by toxins from bacteria like Staphylococcus aureus. Current treatments, such as antibiotics, face challenges like high mortality rates and the need for frequent tampon changes, leading to significant environmental and financial costs. To solve this, we propose two innovative solutions: first, using nisin, a bacteriocin produced by Lactococcus lactis that can inhibit S. aureus by forming pores in bacterial cell membranes, and we plan to enhance its production to strengthen its antibacterial effect. Second, we will leverage Lactobacillus johnsonii, a bacterium that naturally produces hydrogen peroxide (H2O2), to inhibit S. aureus growth; by enhancing its H2O2 production, we can use this engineered bacterium in tampons to reduce TSS risk. Through these approaches, we aim to create safer tampon solutions that effectively prevent the overgrowth of harmful bacteria, ultimately promoting better menstrual health.

Image placeholder
Description

Problem Description

Our project focuses on addressing Toxic Shock Syndrome (TSS), a severe and potentially fatal condition closely associated with the use of high-absorbency tampons (Vostral, 2017). TSS is primarily caused by the bacteria Staphylococcus aureus and Streptococcus pyogenes, both naturally present in the vaginal flora. The pathogenesis of TSS involves a complex interplay of factors, primarily associated with the presence and activity of certain strains of Staphylococcus aureus that produce potent toxins, such as Toxic Shock Syndrome Toxin-1 (TSST-1). The production of these toxins can be influenced by environmental factors, such as magnesium concentration, which can be altered by highly absorbent tampons. For instance, tampons made from materials like polyester foam with carboxymethylcellulose (PEF/CMC) can act as ion exchangers, binding magnesium ions and potentially increasing the risk of TSS. The toxins trigger a systemic inflammatory response in the host, leading to clinical symptoms such as high fever, low blood pressure, and multi-organ involvement. The historical data underscores the gravity of this issue: between 1970 and 1980, 941 confirmed cases of TSS were linked to tampon use, predominantly among menstruating women, with 73 fatalities reported (Vostral, 2017) . These figures highlight the significant health risks and severe consequences associated with TSS, particularly for those using tampons. 

Recognizing the serious nature of TSS and its impact on women’s health, our project is dedicated to developing safer, more innovative tampon solutions. We aim to design tampons that introduce H2O2, stabilize the vaginal environment, and inhibit the growth of harmful bacteria. Our commitment to this research stems from the urgent need to mitigate the risks associated with tampon use, ultimately striving to enhance menstrual health and safety for women globally.

Current solutions

Currently, the cornerstone of TSS theraputics is early diagnosis and prompt treatment involving the use of broad-spectrum antibiotics. Treatment typically involves hospitalization, where patients receive antibiotics to target the underlying bacterial infection; and supportive care, such as intravenous fluids and medications to stabilize blood pressure. However, these treatments are limited by the difficult diagnosis of TSS due to its nonspecific symptoms, and the lack of solutions to toxins released. Even with modern treatment, TSS remained a disease with mortality rate of 30–70%, which posts a great challenge to women’s wellbeing and public health. 

Menstruation-related TSS is proposed to be primarily caused when women leave in a tampon for longer than the recommended amount of time while on their period, leading to overgrowth of bacteria and sometimes even sepsis. It's suggested that using the lowest absorbency necessary and change tampons frequently or completely switch to other menstruation products such as pads is currently the only ways to reduce this risk. Therefore, high absorbency tampons have largely been taken off the market, forcing women who want to precaution against these bacteria to swap tampons several times a day, leading to more material waste and money spent. Still, over the years, tampon design has seen limited innovation specifically aimed at reducing the risk of TSS. Most changes have focused on comfort, absorbency, and environmental impact, rather than significantly addressing the risk of bacterial growth and toxin production. Therefore, we propose an innovative bioengineering solution to lower the risk of TSS in menstruating women by inhibiting growth of common pathogens.

  

Our Solutions: Nisin

Nisin, which is secreted by certain lactic streptococci and also known as 'group N Streptococcus Inhibitory Substance,' has a strong inhibitory effect on many Gram-positive bacteria, including Staphylococcus aureus [1]. Nisin inhibits bacterial growth by forming pores in the cell membrane and disrupting cell wall biosynthesis through specific interactions with lipid II [2]. Nisin is characterized by its acid resistance, heat stability, and high safety profile, making it particularly well-suited to the vaginal environment, where it is less likely to have adverse effects. Therefore, we have selected nisin as a means to inhibit the growth of Staphylococcus aureus in the vagina, which can lead to Toxic Shock Syndrome (TSS). The synthesis of nisin requires the concerted action of multiple gene clusters. Nisin is produced in L. lactis starting as an unmodified precursor involving a leader and core peptide (NisA). It is then matured through dehydration by NisB and cyclization by NisC, and NisT transports it (forming the NisABCT complex) at the bacterium's old pole. Mature nisin results from the removal of the leader segment by NisP. Immunity to nisin in the producing bacteria is conferred by NisI and the NisFEG transporter system. The entire nisin production and immunity process is regulated by a two-component system (TCS) with sensor kinase NisK and response regulator NisR, which together activate nisin's promoter (P*) [1].

 

 

Fig. 1 Nisin biosynthesis, regulation, and immunity.

As important activators in the nisin synthesis process, increasing the production of NisR & K can significantly enhance the yield of nisin [3][4]. Therefore, we plan to achieve overexpression by replacing the promoters of nisR & K in the genome to boost the nisin production in our engineered strains for a stronger antibacterial effect.

 

Our solutions: H2O2

L. johnsonii is a lactic acid bacterium that naturally exists in the human digestive system. (Mattila-Sandholm, Mättö, & Saarela, 1999) There have been studies talking about its inhibitory capability on S. aureus, which is considered one of the causes of TSS. Hypotheses of the inhibitory capabilities that L. johnsonii have on S. aureus include organic acid production, bacteriocin production, and H2O2 production. (Charlier et al., 2009) H2O2 production ability of L. johnsonii arises our attention. This probiotic lactic acid bacterium (LAB) can excrete high levels of hydrogen peroxide (Pridmore et al., 2008). The production of H2O2 has been widely accepted as hypothesis to explain the inhibitory activity of vaginal LAB. A study by Klebanoff found that inhibitory effect of H2O2 produced by lactobacilli has been demonstrated in vaginal ecosystem on S. aureus. (Klebanoff et al., 1991) Therefore, improving the H2O2 production ability of L. johnsonii and introducing our engineered LAB into a tampon product which can reduce the risk of TSS becomes one goal of our team.

 

References

  1. Charlier, C., Cretenet, M., Even, S., & Le Loir, Y. (2009). Interactions between Staphylococcus aureus and lactic acid bacteria: an old story with new perspectives. International journal of food microbiology, 131(1), 30-39.
  2. Eichenbaum Z, Federle MJ, Marra D, de Vos WM, Kuipers OP, Kleerebezem M, Scott JR. Use of the lactococcal nisA promoter to regulate gene expression in gram-positive bacteria: comparison of induction level and promoter strength. Appl Environ Microbiol. 1998 Aug;64(8):2763-9. doi: 10.1128/AEM.64.8.2763-2769.1998. PMID: 9687428; PMCID: PMC106770.
  3. Field D, Fernandez de Ullivarri M, Ross RP, Hill C. After a century of nisin research - where are we now? FEMS Microbiol Rev. 2023 May 19;47(3):fuad023. doi: 10.1093/femsre/fuad023. PMID: 37300874; PMCID: PMC10257480.
  4. Hertzberger, R., Arents, J., Dekker, H. L., Pridmore, R. D., Gysler, C., Kleerebezem, M., & de Mattos, M. J. T. (2014). H2O2 production in species of the Lactobacillus acidophilus group: a central role for a novel NADH-dependent flavin reductase. Applied and environmental microbiology, 80(7), 2229-2239.
  5. Klebanoff, S. J., Hillier, S. L., Eschenbach, D. A., & Waltersdorph, A. M. (1991). Control of the microbial flora of the vagina by H202-generating lactobacilli. Journal of Infectious Diseases, 164(1), 94-100.
  6. Kuipers O, Beerthuyzen M, Ruyter P, Luesink E, Vos M. Autoregulation of Nisin Biosynthesis in Lactococcus lactis by Signal Transduction. Journal of Biological Chemistry, Volume 270, 1995, Issue 45, Pages 27299-27304, ISSN 0021-9258, doi: 10.1074/jbc.270.45.27299.
  7. Mattila-Sandholm, T., Mättö, J., & Saarela, M. (1999). Lactic acid bacteria with health claims—interactions and interference with gastrointestinal flora. International Dairy Journal, 9(1), 25-35.
  8. Pridmore, R. D., Pittet, A.-C., Praplan, F., & Cavadini, C. (2008). Hydrogen peroxide production by Lactobacillus johnsonii NCC 533 and its role in anti-Salmonella activity. FEMS microbiology letters, 283(2), 210-215.
  9. Prince A, Sandhu P, Ror P, Dash E, Sharma S, Arakha M, Jha S, Akhter Y, Saleem M. Lipid-II Independent Antimicrobial Mechanism of Nisin Depends On Its Crowding And Degree Of Oligomerization. Sci Rep 6, 37908 (2016). doi: 10.1038/srep37908.
  10. Shoff., A. R. H. W. (2023). Toxic Shock Syndrome. https://www.ncbi.nlm.nih.gov/books/NBK459345/
  11. Valladares, R. B., Graves, C., Wright, K., Gardner, C. L., Lorca, G. L., & Gonzalez, C. F. (2015). H2O2 production rate in Lactobacillus johnsonii is modulated via the interplay of a heterodimeric flavin oxidoreductase with a soluble 28 Kd PAS domain containing protein. Frontiers in Microbiology, 6, 716.
  12. Vostral, S. (2017). Toxic shock syndrome, tampons and laboratory standard-setting. CMAJ, 189(20), E726–E728. https://doi.org/10.1503/cmaj.161479