To long-time sufferers of psoriasis, it often comes as no surprise that there is a clear link between psoriasis and strep throat infections. Psoriasis often worsens significantly following an active strep throat infection (typically about two weeks later).[2] Backing up this observation, researchers have noted that individuals with chronic psoriasis and psoriatic arthritis often have higher levels of antibodies to Streptococcus pyogenes, the species that causes strep throat.[1]

The prevailing theory is that a low-level, chronic infection with streptococcal bacteria in the tonsils can drive the autoimmune reaction, with exacerbations in psoriasis following exacerbations in the throat infection.

This theory is supported by a 2012 randomized study that found a major reduction in psoriasis after patients had their tonsils removed.[3] (Ranging from a 30 percent to 90 percent reduction in disease severity). As of 2018, the consensus appears to be that tonsillectomy significantly improves psoriasis in about 75 percent of cases associated with strep throat.[4] Less drastic measures include frequent gargling with warm salt water or peroxide-based mouthwash, and using S. salivarius K12 oral probiotic lozenges.[5]

Streptococcus salivarius K12

Streptococcus salivarius is typically a predominant member of the oral microbiome in healthy humans, colonizing the mouth and upper respiratory tract early in life. We all carry different strains, with different biological effects.  Some strains may inhibit other bacteria from infecting the mouth and upper respiratory tract.  (Including Streptococcus pyogenes, the species responsible for most strep throat infections).

One particular strain of S. Salivarius, called K12 (or BLIS K12), originally isolated from a child in New Zealand, has shown a remarkable ability to prevent S. pyogenes throat infections throat in those with history of recurrent strep infections.  In one study, after 3 months of use, the children taking S. Salivarius K12 showed a 90% reduction in episodes of strep throat compared to the previous year (whereas there was no difference in the placebo group).[6]

Therefore, if you have psoriasis or psoriatic arthritis and a history of throat infections (and particularly if you developed psoriasis while younger), it might be worth experimenting with S. Salivarius K12 lozenges.  The rationale is that this probiotic can colonize the oral microbiome and displace Streptococcus pyogenes. This will prevent future active throat infections and in the process may just help prevent autoimmune flares too (although this is far from proven).

Note that other strains of S. Salivarius have other beneficial effects, but are not as effective in combatting pathogenic strep.  (S. Salivarius M18, for example, is more known for its ability to combat cavities and is often included alongside the K12 strain.)

Products containing S. Salivarius K12 include:

• BLIS Throat Health Oral Probiotic (US)
• Hyperbiotics Pro-Kids ENT (US)
• Hyperbiotics Pro-Dental (US) (UK) (CA)
• Life Extension Florassist Throat Health (US) (UK) (CA)
• Designs for Health Probiomune Lozenges (US)
• BLIS Throat Guard Daily (AU)

For probiotics to restore gut health see the full guide to the best probiotics for autoimmune disease

References

[1] El-Rachkidy, R. G., Hales, J. M., Freestone, P. P., Young, H. S., Griffiths, C. E., & Camp, R. D. (2007). Increased blood levels of IgG reactive with secreted Streptococcus pyogenes proteins in chronic plaque psoriasis. Journal of Investigative Dermatology, 127(6), 1337-1342.

Rantakokko, K., Rimpiläinen, M., Uksila, J., Jansen, C., Luukkainen, R., & Toivanen, P. (1997). Antibodies to streptococcal cell wall in psoriatic arthritis and cutaneous psoriasis. Clinical and experimental rheumatology, 15(4), 399-404.

[2] Gudjonsson, J. E., Thorarinsson, A. M., Sigurgeirsson, B., Kristinsson, K. G., & Valdimarsson, H. (2003). Streptococcal throat infections and exacerbation of chronic plaque psoriasis: a prospective study. British journal of dermatology, 149(3), 530-534.

Thorleifsdottir, R. H., Sigurdardottir, S. L., Sigurgeirsson, B., Olafsson, J. H., Sigurdsson, M. I., Petersen, H., … & Valdimarsson, H. (2012). Improvement of psoriasis after tonsillectomy is associated with a decrease in the frequency of circulating T cells that recognize streptococcal determinants and homologous skin determinants. The Journal of Immunology, 188(10), 5160-5165.

Johnston, A., Gudjonsson, J. E., Sigmundsdottir, H., Love, T. J., & Valdimarsson, H. (2004). Peripheral blood T cell responses to keratin peptides that share sequences with streptococcal M proteins are largely restricted to skin‐homing CD8+ T cells. Clinical & Experimental Immunology, 138(1), 83-93.

[3] Thorleifsdottir, R. H., Sigurdardottir, S. L., Sigurgeirsson, B., Olafsson, J. H., Sigurdsson, M. I., Petersen, H., … & Valdimarsson, H. (2012). Improvement of psoriasis after tonsillectomy is associated with a decrease in the frequency of circulating T cells that recognize streptococcal determinants and homologous skin determinants. The Journal of Immunology, 188(10), 5160-5165.

[4] Allen, H. B., Jadeja, S., Allawh, R. M., & Goyal, K. (2018). Psoriasis, chronic tonsillitis, and biofilms: Tonsillar pathologic findings supporting a microbial hypothesis. ENT: Ear, Nose & Throat Journal, 97(3).

[5] Di Pierro, F., Colombo, M., Zanvit, A., Risso, P., & Rottoli, A. S. (2014). Use of Streptococcus salivarius K12 in the prevention of streptococcal and viral pharyngotonsillitis in children. Drug, healthcare and patient safety, 6, 15.

[6] Di Pierro, F., Colombo, M., Zanvit, A., Risso, P., & Rottoli, A. S. (2014). Use of Streptococcus salivarius K12 in the prevention of streptococcal and viral pharyngotonsillitis in children. Drug, healthcare and patient safety, 6, 15.