Vancouver-based researchers have identified four strains of bacteria that they believe babies need in their digestive tract to prevent asthma, opening up the possibility of a preventive treatment.

The work published Wednesday in Science Translational Medicine fleshes out recent studies pointing toward the importance of a wide variety of bacteria in the human gut — known collectively as microbiota — for good health. It's the first time specific bacteria have been linked to asthma.

Scientists at the University of British Columbia and BC Children's Hospital found the bacterial strains Faecalibacterium, Lachnospira, Veillonella and Rothia were lacking in fecal samples from three-month old babies who tested positive for a predisposition to asthma.

The samples came from 319 babies in the Canadian Healthy Infant Longitudinal Development (CHILD) study. Those children are now between three and five years old and some have developed asthma as predicted, said co-author Dr. Stuart Turvey, pediatric immunologist at BC Children's Hospital and director of clinical research at the Child & Family Research Institute.

"What this study helps emphasize — and there's a growing awareness of this recently — is that we need to rethink our relationship with bacteria," Turvey said.

"From a clinical perspective we often think of bacteria as harmful and they need to be killed by antibiotics or other sanitizing agents; but the reality is that we as a species have evolved with those bacteria and they're really important for our health. I think respecting bacteria is an important message."

Yet little is known about how the four types of bacteria come to be in the human body, explained UBC microbiologist Brett Finlay, co-author of the study.

Previous research has shown that babies take on bacteria via vaginal birth and breast feeding and daily living, including having a pet in the house or even living on a farm. Antibiotic use in the first months of life — something that kills both harmful and helpful bacteria in the body — has been linked to asthma in past studies, said Finlay, but the sample size in this research was too small to reach the same conclusion.

"It's a tricky line to walk," Finlay said. "I think more prudence is needed in the use of antibiotics. Treasure them and use them when they're needed, but don't use them unless absolutely necessary."

Asthma rates have been rising over the last 20 years and the condition affects an estimated 3 million Canadians.

Researchers hope isolating the types of bacteria missing in kids who go on to develop asthma could lead to a probiotic medicine to prevent it. UBC has taken out a patent on the idea and is in discussions with drug companies about how to achieve that, Finlay said.

It may also help refine tests for predicting which children will develop asthma.

The study isn't promising for anyone who already has asthma because it also found that by the age of one, all children in the study had acquired the bacteria given the shorthand name FLVR. The theory is that gut flora gained during the first 100 days of life help shape a baby's developing immune system, Finlay said, which in turn influences whether they will develop conditions like asthma.

The scientists confirmed the concept by inoculating newborn mice with the FLVR bacteria and found they developed less severe asthma.

Studies on the topic will continue with fecal samples from children in Ecuador to see if the results are similar.

More than 3,500 children from across Canada have been followed from before birth to age five in the CHILD Study as researchers seek the cause of asthma and allergies. Both the CHILD study and Wednesday's research were funded in part by the Canadian Institutes of Health Research.

See the research here.

eellis@vancouversun.com

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