Recurrent cystitis (RC) is a frequent infection of the urinary tract and bladder, which is extremely prevalent amongst postmenopausal women. Under healthy circumstances, the human vagina is home to a number of useful intestinal bacteria, comparable to Lactobacilli. Nevertheless, within the case of urinary tract infections (UTIs), there’s a decrease within the abundance of Lactobacilli and a rise in pathogenic bacteria, comparable to Escherichia coli (E. coli).

Previous studies have shown that changes in vaginal microbiota are a key underlying reason for the event of UTIs. Further, a couple of clinical trials have demonstrated the utility of Lactobacillus-containing vaginal suppositories within the prevention of RC. It’s unknown whether women who’ve undergone menopause (which is thought to be accompanied by a change within the vaginal microbiota) derive advantages from these suppositories. Nevertheless, there’s a scarcity of studies comparing the vaginal microbiota in postmenopausal women with RC and uncomplicated cystitis to that of healthy postmenopausal women, in addition to changes within the vaginal microbiota prior to and through intervention with Lactobacillus-containing vaginal suppositories with RC.

To bridge this gap, a team of scientists from Okayama University, Japan, demonstrated the connection between vaginal microbiota and RC by comparing the vaginal microbiota of postmenopausal women with and without cystitis. The team also investigated the relative abundance of various bacterial species within the vagina, before and after the administration of vaginal suppositories containing Lactobacillus crispatus, which was previously developed by the team, to review the therapeutic effect of Lactobacillus on this goal demographic.

The research was spearheaded by Mr. Takanori Sekito together with Dr. Takuya Sadahira and Dr. Motoo Araki from the Department of Urology at Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Science. The team also included Dr. Shuta Tomida from the Center for Comprehensive Genomic Medicine, Okayama University Hospital. The study was published in Volume 14 of the journal Frontiers in Microbiology on 18 May 2023.

The team used 16S ribosomal ribonucleic acid (rRNA)-based gene sequencing to investigate the bacterial community present within the vaginal samples from healthy postmenopausal women, those with RC, those with uncomplicated cystitis, and people who received Lactobacillus crispatus-containing vaginal suppositories for RC prevention. They found that the bacterial species present within the healthy and uncomplicated cystitis groups were significantly different, regardless that the uncomplicated cystitis group and the healthy group showed apparent similarities of their respective bacterial communities . Further, the microbiomes of the uncomplicated cystitis and healthy groups were also vastly different from those of the RC group.

When comparing the vaginal microbiome within the RC and the prevention group, while a couple of similarities in the variety of bacterial species, their relative abundance differed between the 2 groups. The team didn’t find any Lactobacilli within the vaginal samples of postmenopausal patients with RC. As an alternative, the dominant species were various members of the Enterobacteriaceae family, which incorporates many uropathogenic bacteria. That is in stark contrast to healthy vaginal microbiota, which is wealthy in healthy intestinal bacteria like Lactobacilli. Notably, the relative abundance of Lactobacilli within the RC-prevention group was much higher (19%) than within the RC group, as a consequence of the suppository.

We found that the vaginal microbiota in postmenopausal women with recurrent cystitis is actually different from that in postmenopausal women with uncomplicated cystitis or healthy women. “

Mr. Takanori Sekito

The study shows that RC occurs when Lactobacilli, a critical member of the healthy vaginal microbiota, are depleted and replaced by pathogenic bacteria, like E. coli. Current treatment for RC involves anti-microbial agents, that are liable to antibiotic resistance. This research suggests an alternate therapeutic avenue in the shape of vaginal suppositories containing Lactobacilli that can assist reduce the imbalance in vaginal microbiota, and in turn reduce RC occurrence.

Further, the frequent use of antimicrobials in cases of recurring infections may even result in severe forms cystitis, that are even harder to treat. “The Lactobacillus vaginal suppositories have the potential to be a latest preventive method to assist the various people affected by recurrent cystitis, which can’t be adequately cured by taking antimicrobials ,” Mr. Sekito concludes.

Source:

Journal reference:

Sekito, T., et al. (2023) Etiology of recurrent cystitis in postmenopausal women based on vaginal microbiota and the role of Lactobacillus vaginal suppository. Frontiers in Microbiology. doi.org/10.3389/fmicb.2023.1187479.