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Infants who are exposed to a diverse range of bacterial species in house dust during the first year of life are less likely to develop asthma in early childhood, according to a new study. 

The research noted that children who are neither allergic nor prone to wheezing as three-year-old are the most likely to have been exposed to high levels of bacteria. 

Researchers also added that some of the protective bacteria are abundant in cockroaches in mice. 

The research also found that exposure during the first year of life to household dust containing higher levels of two specific groups of bacteria that are abundant in the human gut -- Bacteriodes and Firmicutes -- was associated with less asthma risk in the analysis of data from 104 inner-city babies in four cities, the press release added. 

Researchers said that there is no obvious mechanism that would explain this association but the findings support the previous researches that suggested the influence of microbial species in shaping immune responses. 

"Early-life allergies and wheezing illnesses are the two main risk factors for childhood asthma," said James Gern, MD, a professor of pediatrics and medicine at the University of Wisconsin School of Medicine and Public Health in Madison, in a press release. 

"Strict avoidance of allergens to lower asthma risk has been unsuccessful. Maybe permitting allergen exposures, with increased exposure to the sources of certain microbes, might be more successful in reducing asthma risk," said UCSF pulmonologist Homer Boushey, MD, in the press release. 

"If confirmed by other studies, these findings might even have us think of returning to the patterns of exposure of the 1940's, when families were larger, food was less processed and sterilized, and children spent a lot of their time outdoors," he said.

"These findings suggest that concomitant exposure to high levels of certain allergens and bacteria in early life may be beneficial," the researchers wrote in the journal paper.

The study has been published in the Journal of Allergy and Clinical Immunology.