Introduction

Polyols have been used for decades as a substitute for sucrose [1-4]. The most commonly used polyols for consumption are sorbitol, mannitol, xylitol, erythritol, maltitol, lactitol and isomalt [5]. Besides having fewer calories than regular sucrose, i.e., table sugar, polyols have other reported health benefits, especially in regards to oral health [6]. Well publicized studies showing the effectiveness of xylitol at reducing dental disease have been reported for decades, all with results demonstrating safety and effectiveness [7-9]. The well-publicized “Turku” and the “Belize” studies reported on the caries reduction by xylitol, with xylitol being more effective than sorbitol [10,11]. Xylitol chewing gums, toothpastes, lollipops, candies and mouth rinses are all part of a complete dental oral hygiene program [12]. Erythritol and xylitol are polyols that repeatedly have been demonstrated to possess anti-cariogenic and anti-periodontal disease properties [13]. Polyols (particularly the non-hexitol alditols or “sugar alcohols” erythritol and xylitol) have been found effective in inhibiting the transition to and maturation of biofilms from planktonic cells [14]. Xylitol clearly inhibits the formation of mixed species biofilms, in vitro [15].

Erythritol suppresses the maturation of biofilms and contributed to a healthier oral ecosystem [16]. Polyols can suppress the growth and virulence expression of mixed bacterial biofilms. Erythritol was the most effective polyol in suppressing the growth and organization of dental pathogens. Erythritol also exerted inhibitory effects on several pathways reduced growths through DNA and RNA depletion, attenuated extracellular matrix production and alterations of dipeptide acquisition and amino acid metabolism [17].

The bacteria associated with Autism Spectrum Disorder have been reported in the literature, with similar results independent of research institution and locality [18]. Autism Spectrum Disorder (ASD) has been linked to propionic acid producing bacterial species, such as, Clostridia bolteae and Clostridia histolyticum [19-22]. Conversely the presence of Clostridia sporogenes could help protect against ASD by combining propionic acid with indole to produce 3-Indole Propionate, a neural protective metabolite, thereby neutralizing the epigenetic effect of propionic acid [23-25]. It has been theorized that the absence of C. sporogenes in the soil is related to the use of glyphosate, known by the trade name Roundup [18]. Absence of C. sporogenes in the soil and the environment could possibly shift the maternal microbiome, resulting in epigenetic changes in the fetus or infant. Bacteroides vulgatus also has been implicated in ASD as reported in the Frontiers in Microbiology by Coretti et al. [26].

Clostridia difficile (Cdif) is a gram-positive bacterium that is implicated in antibiotic-associated diarrhea. The relatively recent emergence of a newer hyper-virulent North American strain (NAP1) has been associated with the increase in incidence and severity of C. difficile infections (CDI) over the last decade [27]. Antibiotic overuse remains the leading risk factor for C. difficile infection. Several classes of antibiotics such as penicillins, cephalosporins, fluoroquinolones, and clindamycin have been implicated in causing CDI.

Besides antibiotic usage, other risk factors are reported to include advanced age, chemotherapy, use of proton pump inhibitors, chronic renal disease, chronic liver disease and malnutrition [28,29]. Treatment options include discontinuing the causative antibiotic and administering either vancomycin or fidaxomicin. Another option is fecal transplantation, the process in which feces from a healthy donor are transplanted into the intestinal tract of a person with the disrupted microbial balance. This protocol has reported an 80% to 90% success rate in reducing the recurrence of C. difficile infections [30]. There remains some opposition to Fecal Transplantation Therapy due to the basic nature of the procedure and potential complications [31]. A simpler, safer and “cleaner” technique would be more appealing to patients and clinicians.

Materials and Methods

Bacterial isolates and media: C. bolteae and C. histolytica strains were kindly provided by Dr. Emma Allen- Verco PhD. (University of Guelph/Canada). B. vulgatis (8482) and B. longum (15707) were obtained from the American Type Culture Collection (ATCCC/Manassas Va.). C. difficile strains 5555 and 5557 were provided by Dr. Larry Kociolek MD (Lurie Children’s Hospital, Chicago, IL). All studies used a basal media of Brain Heart Infusion broth supplemented with 2% sucrose (BHI/Suc). Polyols were prepared separately at high concentrations in BHI/Suc for assay plate preparations. Xylitol was added to 60% (w/v) and Erythritol was prepared at 30% (w/v) in BHI/Suc. These polyol levels were the maximum achievable based on solubility. Final media preparations were sterilized and placed in an anaerobic chamber for at least 2 hours after preparation to cool and remain in a reduced state.

Assay Procedures

Assays were prepared in the anaerobic chamber. 96 well plates were employed with each test preparation in triplicate wells by adding 100 mcL of BHI/Suc at 2x concentration to all test wells. Bacterial preparations were made in BHI/Suc adjusted to a Macfarland standard concentration of 0.5. Final assay inocula of each strain with a further 1:100 fold dilution. 100 mcL of bacterial inocula was added to each test well with or without a polyol. Plates were incubated anaerobically for 24 or 48 hours and terminated when bacterial growth reached a easily visible level in control wells. Plate were then transferred to a plate spectrophotometer and read at 620 nm wavelength. Mean OD values for each well were calculated and OD values vs. polyol concentration were plotted. 

Results

Seven strains were tested for polyol inhibitory activity C. histolyticum, B. vulgatus, C. bolteae (x2), C. difficile (x2), and Bifidobacterium longham. All strains grew to variable bacterial density levels. B. vulgatus had the poorest growth but still had measurable mean OD values to suggest polyol activity. Detailed OD values vs. polyol concentration are plotted as follows with relative inhibition inflection points (Figures 1-7).

Figure 1: Xylitol begins inhibiting C. histolyticum with only a 2% concentration. The probiotic is also inhibited and supplementation may be advised.

Figure 2: Erythritol inhibits at around a 2% concentration but inhibits the probiotic more that xylitol.

Figure 3: C. bolteae strains inhibited by a very low concentration of xylitol, but less so at a 2% level.

Figure 4: Erythritol inhibits the C. bolteae strains at a very low concentration and in a more linear path than xylitol.

Figure 5: Both erythritol and xylitol inhibits B. vulgatis at only a 0.25% concentration.

Figure 6: At 2% concentration, xylitol generally inhibit C. difficile strains, although C.diff 5557 is inhibit in a more linear manner and at a lower concentration.

Figure 7: Erythritol seems to inhibit C. diff only after reaching a higher concentration. Most dental products contain 20% xylitol for effectiveness. There are no popular dental products with a high erythritol concentration, although some commercial drinks use erythritol as a sweetener.

Discussion

Erythritol inhibits ASD bacteria at a lower concentration than xylitol. Both polyols were capable of significant inhibition of the ASD associated bacteria, in addition to the inhibition of antibiotic resistant C. diff strains. Erythritol may inhibit Bacteroides vulgatus better than xylitol but additional studies with a more optimal media for B. vulgatis need to be performed. However, Xylitol should be considered as a treatment for C. difficile infection due to its low cost and availability. In addition, xylitol and erythritol are considered safe food additives with decades of use in the prevention of oral diseases, such as periodontal disease and dental cavities.

Autism spectrum disorders are likely caused by a combination of microbiome, environment, and the epigenetic interaction [32-34]. Recent research shows that more than 50% of children with autism have GI symptoms, food allergies, and maldigestion or malabsorption issues [35]. Propionic acid is used as a food additive and is also a bacterial byproduct. Propionic acid uptake may be related to lack of the bacterial gluten metabolizers and resultant leaky gut. Elimination of calcium propionate as a bread additive/preservative may be beneficial in reducing the behaviors associated with ASD [36]. Shifting the oral and gut microbiome with polyols may also be successful in reducing behaviors associated with ASD. More research, large well-designed clinical trials are indicated for protocols illuminating therapies effective with reducing the symptoms of ASD [37].

Conclusion

Xylitol and erythritol at sufficient concentrations were able to inhibit the growth of bacterial strains that have been associated with the development of ASD. Further research into the use of polyols for the treatment and possible prevention of ASD is recommended. Large clinical trials with patients that are correctly diagnosed with ASD then treated with xylitol supplementation and the resultant effects on behavior should be carefully explored. In addition, the uses of polyols to treat C. difficile infections also require clinical trials.

References

1. Horecker BL, Lang K, Takagi Y. International symposium on metabolism, physiology and clinical uses of pentoses and pentitols (1969) Springer-Verlag, Berlin, Germany.
2. Sipple HL, McNutt KW. Sugars in Nutrition (1974) Academic Press, New York, USA.
3. Hefferen JJ, Koehler HM. Foods, Nutrition and Dental Health (1981) Pathotox Publishers, Park Forest South, IL, USA.
4. Rugg-Gunn J. Sugarless, the Way Forward: Proceedings of an International Symposium (1991) Elsevier Applied Science, London, UK.
5. Rice T, Zannini E, Arendt EK, Coffey A. A review of polyols - biotechnological production, food applications, regulation, labeling and health effects (2019) Crit Rev Food Sci Nutr Pp: 1-18. https://doi.org/10.1080/10408398.2019.1625859
6. Scheie OB, Fejerskov. Xylitol in caries prevention: what is the evidence for clinical efficacy? (1998) Oral Dis 4.
7. Edgar WM. Sugar substitutes, chewing gum and dental caries - a review (1998) British Dental Journal 184: 29-32.
8. Mandel D. Caries prevention – current strategies, new directions (1996) J American Dental Association 127: 1477-1488.
9. Trahan L. Xylitol: a review of its action on mutans streptococci and dental plaque - its clinical significance (1995) The International Dental Journal 45: 77-92.
10. Scheinin A, Mäkinen KK, Kalevi Y. Turku sugar studies. V. Final report on the effect of sucrose, fructose and xylitol diets on the caries incidence in man (1976) Acta odontologica Scandin 34: 179-216. https://doi.org/10.3109/00016357608997711
11. Mäkinen KK, Bennett CA, Hujoel PP. Xylitol chewing gums and caries rates: a 40-month cohort study (1995) J Dent Res 74: 1904-1913. https://doi.org/10.1177/00220345950740121501
12. Cannon ML and Peldyak JN. The prevention and treatment of neural arterial gingival simplex (2019) Dental Res Manag 3: 32-37. https://doi.org/10.33805/2572-6978.123
13. Sánchez MC, Romero-Lastra P, Ribeiro-Vidal H, Llama-Palacios A and Figueroa E. Comparative gene expression analysis of planktonic Porphyromonas gingivalis ATCC 33277 in the presence of a growing biofilm versus planktonic cells (2019) BMC Microbiol 19: 58. https://doi.org/10.1186/s12866-019-1423-9
14. Badet C, Furiga A and Thébaud N.Effect of xylitol on an in vitro model of oral biofilm (2008) Oral Health Prev Dent 6: 337-341.
15. Janus MM, Volgenant CMC, Brandt BW, Buijs MJ, Keijser BJF, et al. Effect of erythritol on microbial ecology of in vitro gingivitis biofilms (2017) J Oral Microbiol 9: 1. https://doi.org/10.1080/20002297.2017.1337477
16. Hashino E, Kuboniwa M, Alghamdi SA, Yamaguchi M, Yamamoto R, et al. Erythritol alters microstructure and metabolomic profiles of biofilm composed of Streptococcus gordonii and Porphyromonas gingivalis (2013) Mol Oral Microbiol 28: 435-451. https://doi.org/10.1111/omi.12037
17. Janakiram C, Deepan Kumar CV and Joseph J. Xylitol in preventing dental caries: a systematic review and meta-analyses (2017) J Nat Sci Biol Med 8: 16-21. https://doi.org/10.4103/0976-9668.198344
18. Argou-Cardozo I and Zeidán-Chuliá F. Clostridium Bacteria and Autism Spectrum Conditions: A Systematic Review and Hypothetical Contribution of Environmental Glyphosate Levels (2018) Med Sci (Basel) 6: 29. https://doi.org/10.3390/medsci6020029  
19. MacFabe DF, Cain DP, Rodriguez-Capote K, Franklin AE, Hoffman JE, et al. Neurobiological effects of intraventricular propionic acid in rats: possible role of short chain fatty acids on the pathogenesis and characteristics of autism spectrum disorders (2007) Behav Brain Res 176: 149-169. https://doi.org/10.1016/j.bbr.2006.07.025
20. Shultz SR, MacFabe DF, Ossenkopp KP, Scratch S, Whelan J, et al. Intracerebroventricular injection of propionic acid, an enteric bacterial metabolic end-product, impairs social behavior in the rat: implications for an animal model of autism (2008) Neuropharmacology 54: 901-911. https://doi.org/10.1016/j.neuropharm.2008.01.013
21. Shultz SR, Macfabe DF, Martin S, Jackson J, Taylor R, et al. Intracerebroventricular injections of the enteric bacterial metabolic product propionic acid impairs cognition and sensorimotor ability in the Long-Evans rat: further development of a rodent model of autism (2009) Behav Brain Res 200: 33-34. https://doi.org/10.1016/j.bbr.2008.12.023
22. MacFabe DF, Cain NE, Boon F, Ossenkopp KP and Cain DP. Effects of the enteric bacterial metabolic product propionic acid on object-directed behavior, social behavior, cognition, and neuroinflammation in adolescent rats: Relevance to autism spectrum disorder (2011) Behav Brain Res 217: 47-54. https://doi.org/10.1016/j.bbr.2010.10.005
23. Rose S, Bennuri SC, Davis JE, Wynne R, Slattery JC, et al. Butyrate enhances mitochondrial function during oxidative stress in cell lines from boys with autism (2018) Translational Psychiatry 8: 42. https://doi.org/10.1038/s41398-017-0089-z
24. Wikoff WR, Anfora AT, Liu J, Schultz PG, Lesley SA, et al. Metabolomics analysis reveals large effects of gut microflora on mammalian blood metabolites (2009) Proceedings of the National Academy of Sciences of the United States of America, USA 106: 3698-3703. https://doi.org/10.1073/pnas.0812874106
25. Parthasarathy A, Cross PJ, Dobson R, Adams LE, Savka MA, et al. A Three-Ring Circus: Metabolism of the three proteogenic aromatic amino acids and their role in the health of plants and animals (2018) Front Mol Biosci 5: 29. https://doi.org/10.3389/fmolb.2018.00029
26. Coretti L, Paparo L, Riccio MP, Amato F, Cuomo M, et al. Gut microbiota features in young children with autism spectrum disorders (2018) Frontiers in microbiology 9: 3146. https://doi.org/10.3389/fmicb.2018.03146
27. See I, Mu Y, Cohen J, Beldavs ZG, Winston LG, et al. NAP1 strain type predicts outcomes from Clostridium difficile infection (2014) Clin Infect Dis 58: 1394-1400.
28. Khanafer N, Vanhems P, Barbut F, Luxemburger C, CDI01 Study group, et al. Factors associated with Clostridium difficile infection: A nested case-control study in a three year prospective cohort (2017) Anaerobe 44: 117-123.
29. Arriola V, Tischendorf J, Musuuza J, Barker A, Rozelle JW, et al. Assessing the risk of hospital-acquired clostridium difficile infection with proton pump inhibitor use: a meta-analysis (2016) Infect Control Hosp Epidemiol 37: 1408-1417.
30. Kassam Z, Lee CH, Hunt RH. Review of the emerging treatment of Clostridium difficile infection with fecal microbiota transplantation and insights into future challenges (2014) Clin Lab Med 34: 787-798.
31. van Beurden YH, de Groot PF, van Nood E, Nieuwdorp M, Keller JJ, et al. Complications, effectiveness, and long term follow-up of fecal microbiota transfer by nasoduodenal tube for treatment of recurrent Clostridium difficile infection (2017) United European gastroenterology journal 5: 868-879. https://doi.org/10.1177/2050640616678099
32. Macfabe DF. The role of enteric bacterial metabolites in mitochondrial dysfunction in autism – from animal models to human population. Microb Ecol Health Dis.
33. Midtvedt T. The gut: a triggering place for autism – possibilities and challenges (2012) Microb Ecol Health Dis 23. https://doi.org/10.3402/mehd.v23i0.18982
34. Mangiola F, Ianiro G, Franceschi F, Fagiuoli S, Gasbarrini G, et al. Gut microbiota in autism and mood disorders (2016) World J Gastroenterol 361-368. https://doi.org/10.3748/wjg.v22.i1.361
35. Horvath K, Papadimitriou JC, Rabsztyn A, Drachenberg C, Tildon JT. Gastrointestinal abnormalities in children with autistic disorder (1999) J Pediatr 135: 559-563.
36. Dengate S and Ruben A. Controlled trial of cumulative behavioural effects of a common bread preservative (2002) J Paediatrics and child health 38: 373-376. https://doi.org/10.1046/j.1440-1754.2002.00009.x
37. Kang DW, Adams JB, Coleman DM, Pollard EL, Maldonado J, et al. Long-term benefit of Microbiota Transfer Therapy on autism symptoms and gut microbiota (2019) Scientific reports 9: 5821. https://doi.org/10.1038/s41598-019-42183-0

^*Corresponding author:
Cannon ML, Ann and Robert Lurie Children’s Hospital, Northwestern University,Feinberg School of Medicine, Chicago, USA, E-mail: drmarkcannon@outlook.com

Citation:
Cannon ML, Merchant M, Kabat W, Unruh B and Ramones A. Inhibition of autism spectrum disorder associated bacteria and c. difficile by polyols (2020) Edelweiss Appli Sci Tech 4: 33-36.

Keywords

Autism Spectrum Disorder, Polyol, Bacterial strains, Optical density.