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Nonsterile uterine environment led to pathogenic bacteria increase in preemies

WASHINGTON — Premature infants exposed to a nonsterile uterine environment — prolonged preterm premature rupture of membranes and chorioamnionitis — have an increase of pathogenic bacteria in the developing gut microbiome, according to study results presented at the 2013 Pediatric Academic Societies Annual Meeting.

“Compared to healthy full-term infants, the microbial community of preterm infants consists of dramatically fewer beneficial species, lower bacterial diversity and more pathogens,” Diana Chernikova, an MD and PhD student at the Geisel School of Medicine at Dartmouth University, said at a presentation during the meeting. “Perinatal exposures have been shown to play an essential role in complex microbial acquisition patterns of infancy.”

The study analyzed the intestinal microbiome of nine premature infants to determine whether maternal exposures were related to patterns in the neonatal microbiome. Researchers collected weekly stool samples for 5 to 11 weeks and performed bacterial DNA extraction followed by 454 massively parallel pyrosequencing.

Researchers found that participants whose mothers had prolonged rupture of membranes had significantly lower diversity (P=.058), but increased Staphylococcus and Streptococcus abundance at all time points and an increase in a number of pathogens.

Researchers also found that participants whose mothers had chorioamnionitis showed an increase of many pathogenic bacteria, including Serratia, and a decrease in protective bacteria, including Klebsiella and Veillonella.

According to researchers, participants who were delivered vaginally were found to have a less diverse microbiome compared with those delivered by cesarean section. These participants also have an increase in abundance of Stenotrophomonas, Salmonella and Lactobacillus over time.

Researchers also found that maternal antibiotic use was associated with decreased neonatal microbial diversity, which was associated with an increased risk for late-onset neonatal sepsis.

“Overall, higher-risk maternal complications appear to significantly inform the diversity and bacteriology of the premature gut microbiome, and these findings persist overtime,” Chernikova said. “This highlights potential opportunities for interventions with probiotics or altered antibiotic regimens.”

For more information:

Chernikova D. #3360.8. Presented at: Pediatric Academic Societies Annual Meeting; May 4-7, 2013; Washington.