While the conversation surrounding obesity often points to lifestyle changes as the hallmark for prolonged weight management, new research points towards molecular mechanisms one culprit in increased BMI. For example, giving antibiotics to children leads to long-term metabolic consequences, primarily from disruption of the child’s microbiome during development.
Microbiome is the catchall term for the set of microorganisms (bacteria, fungi, and viruses) in and on the human body. Each individual organ or body system, such as the mouth, gut, or feet, has its own microbiome. As most organisms reside in the gastrointestinal tract, most research has focused on altered states of the gut microbiome in relation to health and disease, particularly obesity.
This current study, out of NYU’s Langone Medical Center, sought to determine the effect of orally administered antibiotics (low-dose penicillin, LDP) on the gut microbiome of developing mice, with the goal of determining the long-term metabolic effects. The researchers began by dividing mice into four groups: normal diet, no LDP (negative control); high fat diet, no LDP (positive control); normal diet, LDP; and high fat diet, LDP. The LDP was given for one month, starting four weeks after birth.
The mice given no LDP and fed a normal diet did not gain weight, while the same mice fed a high fat diet did gain weight; both results were expected. The mice fed a normal diet but given LDP also did not gain weight. Mice fed a high fat diet along with LDP initially gained some weight, but after the antibiotic treatment was discontinued the animals gained a massive amount of weight, significantly more than the high fat diet mice that did not receive LDP.
To further test whether the altered gut microbiome was the culprit, the researchers transplanted the gut microbiomes of each of the treatment mice into germ-free mice. Germ-free mice have no microorganisms in or on them, so any physiological effect observed can be attributed directly to the microorganisms introduced by the researchers. All the germ-free mice reacted the same as the previous mice, in that the most weight gain was seen in the mice fed a high fat diet with gut microbiomes derived from mice given LDP early in life. This theory was also confirmed in older mice, showing that antibiotic treatment and dietary changes do not have an effect after early development.
It is known that farmers often use antibiotics early in livestock development to fatten the animals. This study though is the first to reveal that early antibiotic use, resulting in a disturbed gut microbiome, can have profound and lasting effects on an organism’s metabolic profile. Says Dr. Martin J. Blaser, corresponding author on the paper, “A lot of work on obesity has been focused on diet and calories. That has not been sufficient to explain the obesity epidemic.” Perhaps this is a crucial new avenue worth exploring to combat the epidemic. For more infectious disease news and information, visit and “like” the Infectious Disease News Facebook page