Midurethral mesh tapes (MUT) were previously regarded as the gold standard for the management of stress incontinence. Heightened awareness of long-term, devastating complications- which include chronic pain, vaginal mesh exposure and lower urinary tract perforation- has led to the pause of the use of vaginally implanted mesh in many countries. It is not known why some women develop complications. Implant complications have often been related to a persistent inflammatory response, which differs from the foreign body reaction. Persistent inflammation has been found in explanted mesh from those with complications. The cause of persistent inflammation is thought to be multifactorial, and the local microbiome may play a role. The vaginal microbiome is dynamic throughout life stages. (1) Changes in the vaginal microbiome have been related to mesh complications. (2,3) There are, however, no published studies investigating the microbiome of mesh in women who have experienced complications. This study aims to develop a methodology to characterise the mesh microbiome and compare differences in the mesh microbiome in those with different complications (chronic pain, vaginal mesh exposure and lower urinary tract infection), route of MUT (retropubic and obturator), and menopausal status.

Women undergoing surgery to excise polypropylene MUT were prospectively recruited into one of three complication groups: chronic pain, vaginal exposure, and lower urinary tract perforation. In most cases, more than one piece of MUT was collected for each woman, by corresponding anatomical location.  Genomic material was extracted from explanted MUT and standardised by weight. The V4 region of the 16S rRNA gene was analysed using next-generation sequencing following PCR amplification. Amplicon data were assigned taxonomy using QIIME2 and RStudio.

Microbial genomic material was successfully isolated and interrogated from 47 samples of mesh, from 17 women. Of these women, 5 had chronic pain, 7 had vaginal exposure and 6 had a lower urinary tract perforation. Three women were of pre-menopausal status, and 14 menopausal. Mesh from pre-menopausal women showed greater alpha diversity, p = 0.019, compared to menopausal women. When comparing the complication groups, mesh from women with vaginal mesh exposure showed highest alpha diversity, and those with pain had the lowest, p = 0.001. There were no significant differences when comparing the route of the MUT. The predominant phyla in the mesh microbiome was Firmicutes in all complication groups, followed by Actinobacteria. This was followed by Bacteroidetes in those with vaginal exposure, and Proteobacteria in those with lower urinary tract perforation and chronic pain.

This study characterises the mesh microbiome and reveals significant differences in alpha diversity between complication groups. This suggests that changes in the richness of the mesh microbiome may lead to the development of different complications. The dominant phyla correlate with previous work on the vaginal microbiome, and the change of this with menopausal status. Lower alpha diversity in the mesh microbiome of women of menopausal status may support previous work on the changes of the vaginal microbiome associated with menopause. This may suggest the vaginal microbiome has a role to play in the mesh microbiome, and the development of complications; however the direction of this relationship has not be determined. To date, there are two published studies on the vaginal microbiome of those with mesh complications. These studies have found a shift away from a Lactobacillus dominant vaginal microbiome in those with complications. Lactobacillus belongs to the Firmicutes phylum which was found to be the predominant phyla in all groups. Therefore, it may be the diversity or abundances of other phyla which are associated with the development of complications.

This study characterises the mesh microbiome in those with complications. Although, the MUT implant is sterile at the time of insertion, a microbiome develops. The observed differences in this microbiome may result in the development of different complications. Future work will further distinguish the dominant species, differences between complication groups and correlate the mesh microbiome with the vaginal and urinary microbiome.

Huang B, Fettweis JM, Brooks JP, Jefferson KK, Buck GA. The Changing Landscape of the Vaginal Microbiome. Clin Lab Med. 2014;34(4):747
Veit-Rubin N, De Tayrac R, Cartwright R, Franklin-Revill L, Warembourg S, Dunyach-Remy C, et al. Abnormal vaginal microbiome associated with vaginal mesh complications. Neurourol Urodyn. 2019 Aug 11
Deveneau NE, Newton RJ, Agrawal A, Kinman CL, Wu G, Lei Z, et al. Shifts in Vaginal Bacterial Community Composition Are Associated With Vaginal Mesh Exposure. Female Pelvic Med Reconstr Surg. 2021 Nov 1;27(11):e681–6.