Probiotic treatment with E faecalis improves symptoms of seasonal allergic rhinitis

The results are in line with similar studies showing the beneficial effects of E. faecalis. Furthermore, the data showed that allergic symptoms were alleviated during the COVID-19 pandemic situation. This is in line with previous studies and might be explained by a reduced confrontation with pollen due to masks, psychological factors, or lockdown situations.

Although allergic rhinitis treatment has been proven to be effective, it is expensive, does not completely resolve symptoms, and is related to side effects. Previous studies have indicated that probiotics may be a new promising treatment for allergic rhinitis. Michael Schaefer, Medical School Berlin, Berlin, Germany, and colleagues aimed to evaluate the effects of a single bacterial strain, Enterococcus faecalis on symptoms of allergic rhinitis. Beneficial effects of E. faecalis have been reported before but not in seasonal allergic rhinitis.

For this purpose, the researchers enrolled participants from springtime 2019 to 2021. 36 were excluded out of 125 participants. The study was stopped (2020) in the COVID-19 pandemic and continued in 2021 (25 subjects before the pandemic, 64 in 2021).

The study was designed as a randomized placebo-controlled four-arm study. E. faecalis (PROB) was compared to a double-blind placebo (DBP) and a treatment-as-usual (TAU) control condition. After the end of the trial, the probiotic was offered to all patients for a further 4 weeks.

E. faecalis (DSM 16440), a Gram-positive probiotic species, was used that is a constituent of Symbioflor1® (cells and autolysate of 1.5 × 107 to 4.5 × 107 colony-forming units [CFU]). The control arms used placebo drops including the carrier solution of the probiotic treatment.

Participants completed questionnaires and were randomized into one of the four arms. The DBP and PROB conditions were kept secluded following a randomization scheme provided by the sponsor. Participants took 30 drops three times per day (groups 1–3) and were told to continue their usual allergic pharmacological treatments. Following 4 weeks, all participants were invited for a second appointment to examine allergic symptoms.

The study led to the following findings:

• Comparison of baseline data revealed no differences (including frequency of medical treatments).

• Dropout of participants was not evenly distributed (eight in DBP, nine in PROB, and none in TAU). One patient (DBP group) reported an adverse effect (gastrointestinal complaints).

• Findings showed a greater improvement with the probiotic treatment (PROB) compared to both DBP and TAU concerning symptoms over the past 12 h (analysis of covariance [ANCOVA] for all three groups with baseline scores as covariates).

• Results for the RQLQ also demonstrated stronger improvements for the probiotic group but failed to reach the level of significance. TNSS results showed improvements for the PROB group for the last 12 hours.

• Significantly stronger effects for the time before the pandemic (for TNNS and RQLQ). Baseline data of allergic symptoms were higher before the pandemic (results are reported in a separate publication).

"Although the results indicate that probiotic treatment with E faecalis is effective in reducing the symptoms of allergic rhinitis, generalization may not yet be possible due to limitations such as spontaneous symptom improvement and a short evaluation time," the researchers wrote. "Therefore, there is a need for further studies with bigger sample sizes to replicate the results."

Reference:

Schaefer, M., Zimmermann, K., & Enck, P. (2023). Probiotic treatment (Enterococcus faecalis) improves symptoms of seasonal allergic rhinitis: A randomized controlled trial. International Forum of Allergy & Rhinology, 13(10), 1974-1977. https://doi.org/10.1002/alr.23154