Transanal irrigation influences gut microbiota in a way that could have a positive effect on the immune system, contributing to a reduction of urinary tract infections.
The human bowel is colonized by hundreds of trillions of bacteria that act as a barrier against pathogens, stimulate the host immune system, and produce a great variety of compounds from the metabolism of dietary intake that could affect the host. The gut microbiota consists mainly of Firmicutes and Bacteroidetes, but the composition is affected by factors such as age, diet, obesity, and intestinal motility as well as diseases and conditions like constipation.
Exploring effects of TAI on gut microbiota
The aim of the small clinical study summarized here was to investigate the changes in gut microbiota after use of transanal irrigation (TAI) in children with Spina Bifida (SB) using a technique called 16S rRNA sequencing. This technique detects microbes that have not yet been cultured but can be assigned as relatives of cultured representatives with known function.
Patients with neurogenic diseases affecting the spinal cord such as SB often present disturbance of bladder and bowel function and have an increased incidence of urinary tract infection (UTI). Immune function is therefore crucial in patients with spinal cord lesions. Those patients are commonly treated with intermittent catheterization (IC) for their neurogenic bladder and possibly treated with TAI for their neurogenic bowel.
Study parameters
Children with SB and confirmed neurogenic bowel dysfunction (NBD), with the Bristol stool scale and NBD score, and using IC were included in this study and started on TAI. Since obesity may affect the gut microbiota obese children, body mass index over 25 kg/m2, were excluded. It was also prohibited to use prebiotics, probiotics, antibiotics, or medication for the treatment of constipation, or to do any modifications to the diet during the study.
The following were collected from the included patients before start of TAI:
- Fecal samples - for analysis of the gut microbiota
- Urine cultures - for testing of bacteriuria (104 colony forming units/mL or larger was regarded as bacteriuria)
- Bristol stool scale – to see changes in bowel function
- NBD score - to see changes in bowel function
Fecal samples were also collected from 10 matched, healthy controls to see if there were differences in the microbiota between healthy individuals and the constipated SB patients before starting with TAI. This showed that following microbiotas Faecalibacterium, Blautia, Roseburia, Lachnospira, and Dialister were decreased in SB patients while Oscillospira was significantly increased in the SB patients before they started with TAI. This result supports the assertion that gut microbiota is affected by constipation.
The selected SB patients used TAI every two days for 3 months, then changes in bowel function, urine culture and microbiota were measured.
Main findings
TAI significantly improved the bowel function as showed by the increase on the Bristol scale and decrease in total NBD score. When looking into the specific questions in the NBD score it was seen that there were no significant changes in the frequency of fecal incontinence. It was also observed that 82% of the SB patients had asymptomatic UTI predominantly caused by Escherichia coli (E. coli) before TAI, which then decreased to 55% after TAI (not statistically significant). Therefore, it was assumed that TAI, by improving bowel habit and washing of the colorectal tract, can reduce the risk of bladder contamination by E. coli.
There were changes in gut microbiota after TAI in the SB patients, Bacteroides and Roseburia was significantly increased and Turicibacter was significantly decreased. Bacteroides, a Bacteroidetes, and Roseburia, a Firmicutes, ferment indigestible carbohydrates, generate short-chain fatty acids (SCFAs) and produce high levels of acetate, propionate, or butyrate. Roseburia has earlier been shown by others to be decreased in patients with functional constipation, irritable bowel syndrome (IBS) constipated patients as well as in SCI patients compared with healthy controls. A positive correlation with the Bristol stool scale and increase in Roseburia was seen, which is possibly because butyrate plays a regulatory role in the intestinal motility and host immune system.
Study limitations and conclusions
The authors point out some limitations to their study such as the small number of patients, but confounding effects of age, diet, obesity, and intestinal motility on gut microbiota were excluded by comparing gut microbial composition before and after the TAI treatment. Also, they did not investigate the gut microbiotas metabolites, such as SCFAs.
In conclusion, TAI significantly improved constipation and significantly increased the abundance in Roseburia. This may contribute to improvements in the host immune system, resulting in the tendency for UTIs to be reduced, despite persistent fecal incontinence. Therefore, the authors states that TAI combined with IC could be beneficial for improving bowel dysfunction in constipated patients with spinal cord lesions such as SB.