Bacteria are everywhere, even in our bodies. While some might be dangerous, many have beneficial, positive roles. Researchers have now found that there are lactobacilli in the urinary tracts of human females that can outcompete and kill pathogenic bacteria that may be present there. These findings, which have been reported in Frontiers in Cellular and Infection Microbiology, could help lead to new preventions or therapeutics for urinary tract infections (UTIs).
"Our group is primarily focusing on trying to find alternatives to traditional antibiotic therapy because we know the antimicrobials are failing more and more often," said research leader Dr. Tanya Sysoeva, an assistant professor at the University of Alabama. "Pathogens are notorious about picking up resistances."
In this work, the researchers analyzed samples of bacteria collected from post-menopausal women, some healthy, some with diseases. The microbes in the urinary tract are different from those found elsewhere in the body, like the gut or mouth. In humans, the urinary tract tends to host a diverse community primarily made up of bacteria (as opposed to viruses or archaea, for example), and the levels are low. Most female urinary tract microbiomes are thought to be colonized primarily by lactobacilli, which form lactic acid, so the investigators focused on these microbes.
The researchers called this commensal urinary microbiome the urobiome. It varies a lot from one person to another and even in the same person over time, " .. but the composition seems to associate with urinary and general health," added Sysoeva.
The researchers found that lactobacilli seem to eliminate pathogens from the urinary tract, even when those pathogens carry multiple antibiotic resistance genes.
"It is very exciting to realize that the human bladder is, or can be, colonized by those lactobacilli and possibly be protected from the infection," said Sysoeva.
They determined that lactobacilli that had been isolated from women with recurrent UTIs could inhibit microbial pathogens in lab tests. In some cases, the healthy lactobacilli were able to co-exist with pathogens, Sysoeva revealed. However, more work will be needed before we know why they can occupy the same microbiome in some cases, and the pathogens are eliminated in others. This work was also performed using samples that had been stored, and not in vitro, so other factors be be having some influence.
The more we know about the various microbiomes in the human body, the more we can ensure that their composition is optimized for the best health of an individual. Microbes might also be useful in diagnostic tests, for example, where the presence of a specific type or strain of microorganism indicates some disease or health condition, Sysoeva suggested. The microbes in our body live in a complex environment that can change in a variety of ways, such as due to health or medication.
"We observe that healthy patients tend to be colonized by certain types of lactobacilli but not others, and that the mechanisms of how microbes compete or kill each other vary," added Sysoeva.
However, Sysoeva cautioned that, "We cannot just tell people to eat yogurt or a random lactobacilli-containing probiotic." The right strains have to be identified and possibly optimized for the right applications first. But, the research continues.