Medical: C-section may affect type of bacteria baby has

Microbes are with us all our lives, from before the cradle to the grave. And while some are capable of killing us, most of the microbes we carry around — inside and on our skin — are part of a microbial bouquet that makes each of us who we are.

Researchers have been studying the trillions of microbial hitchhikers accommodated by each and every person for decades, but they're still gaining new insight into how they make us tick, or sick.

One study found that there are significant differences in the bacterial colonies of newborns delivered vaginally compared to babies delivered by cesarean section.

Babies delivered through the birth canal had bacterial communities that resembled their mothers' vaginal bacteria; the C-section babies had common human skin bacterial colonies, dominated by those from the Staphylococcus genus, most of them harmless, but some that can cause severe infections.

"These differences we are seeing in this study might be related with increased health risks in C-section babies, although more research is needed," said Maria Dominguez-Bello, a researcher at the University of Puerto Rico and a lead author of the new study, published June 21 in the Proceedings of the National Academy of Sciences.

Earlier studies showed that babies born by C-section tend to be more susceptible to certain infections, allergies and asthma than babies born vaginally.

Dominguez-Bello said the study might help explain a higher infection rate among C-section babies with strains of highly drug resistant staph infections, or MRSA, infections that have been increasing in hospitals and clinics in recent years.

A 2004 study of newborn infections at hospitals in Chicago and Los Angeles found that between 64 percent and 82 percent of MRSA skin infections occurred among infants born by C-section.

The new study involved nine mothers and 10 newborns at a Venezuelan hospital, with the babies' bacteria sampled within 24 hours of birth from their skin, mouths and digestive tracts. The researchers used gene-sequencing techniques to analyze all the bacteria.

"In a sense, the skin of newborn infants is like freshly tilled soil that is awaiting seeds for planting — in this case, bacterial communities," said Noah Fier, an assistant professor of ecology and evolutionary biology at the University of Colorado, Boulder, and a co-author of the report. "The microbial communities that cluster on newborns essentially act as their first inoculation."

Babies born by C-section are microbial blank slates, apt to pick up whatever they're exposed to in a hospital delivery room or from the first people who touch them after they are born, including, in many instances, their fathers.

Internally, researchers are also finding that our gut bacteria — the several hundred or so species, 10 trillion to 100 trillion strong — that inhabit our colon and small intestine are more influential than once thought in affecting our metabolism and weight, and perhaps our immune and hormone system functions.

It appears that infants also get most of their gut bacteria from their moms, no matter how they're born, but also pick up bacterial colonies from other family members in their first weeks.

Intestinal bacteria are vital to us because we can't digest some foods, such as certain starches, without them, nor extract certain essential vitamins. But bacteria also interact with various hunger hormones that control metabolism, production of fat and even how fast food moves through the intestine.

As anyone who has taken a powerful antibiotic can attest, it's easy to disrupt our bacterial balance. Other research, in mice and humans, has shown that dieting can change the relative types of gut bacteria in obese individuals.

On the other hand, there's considerable evidence that having too many of certain kinds of intestinal bacteria can ramp up appetites and contribute to obesity, perhaps even throwing off regulation of blood sugar and fat storage.

Not surprisingly, several groups of researchers are plotting whether it might be possible to identify which of our gut microbes may encourage us to eat less, and then find some way to cull out the bugs that make us fat in favor of those that make us lean.

A number of digestive aids that claim to do this can already be found on the market, but scientists say we're likely some years away from really being able to design an ideal gut bouquet for any particular individual.

Contact Lee Bowman at BowmanL@shns.com