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Bifidobacteria may protect infants from antimicrobial-resistant infections
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Previous studies have demonstrated the benefits of breastfeeding on the infant gut. However, research published in mSphere suggests that infants with a high level of Bifidobacterium, a bacterium commonly seen in the breastfed infant microbiome, may also be protected from several antimicrobial-resistant infections.
“Bifidobacterium can be very dominant as long as an infant is breastfed, and then bacterial levels drop off during weaning,” Diana H. Taft, PhD, a postdoctoral researcher at the University of California, Davis’ department of food science and technology, said in a press release.
The researchers assessed the relationship between Bifidobacterium in the infant gut microbiome and the child’s ability to deter antimicrobial-resistant infections by testing stool samples from infants located in Bangladesh at ages 6, 11 and 15 weeks, as well as 2 years. Of the 291 infants included in the early-life analysis, more than half (60%) were delivered through cesarean section.
When all early-life samples were examined, Taft and colleagues observed 11 classes of antimicrobial-resistance genes (AGRs), including aminoglycoside, beta-lactam, fluoroquinolone, Fosfomycin, as well as macrolide, lincosamide and streptogramin B. Additionally, the researchers observed phenicol, sulfonamide, tetracycline, trimethoprim, glycopeptide and nitromidazole AGRs. When infants had low levels of Bifidobacterium present in their stool samples, all 11 AGRs were found. However, infants with high levels of the bacteria in their gut microbiome had only nine of the classes present.
The researchers also observed that infants with higher levels of Bifidobacterium at ages 6, 11 and 15 weeks had significantly fewer transferable ARGs when compared with infants with low levels of the bacterium. A median of 7.5 AGRs were observed in each sample provided by infants with high-Bifidobacterium samples (range, 2-19), whereas infants with low-Bifidobacterium levels had a median of 20 AGRs per sample (range, 6-37).
Taft and colleagues wrote that Enterobacteriaceae were the most commonly reported source of ARGs in all samples (49% per sample in the high cohort, 43% per sample in low cohort).
Once infants reached 2 years of age, the levels of Bifidobacterium dropped to less than 65% in all participants. The researchers suggest that this was expected because the introduction of complementary foods and weaning from breast milk reduce the levels of this bacterium in the gut. Because 80% of Bangladeshi women provided some breast milk to their 2-year-old children, some infants’ microbiomes were composed of mostly Bifidobacterium (more than 50%).
“As soon as you drop the bifidobacterial away with weaning, other bugs take up that space, but they are not necessarily the ones high in antimicrobial resistance,” David A. Mills, PhD, the Peter J. Shields Endowed Chair and Professor in the departments of food science and technology and viticulture and enology at UC Davis, said in the release.
No significant differences in antimicrobial resistance classes or ARGs between the low-Bifidobacterium and high-Bifidobacterium samples were observed by 2 years of age. According to the researchers, all 11 AGR classes that were present in low-Bifidobacterium samples were seen in high-Bifidobacterium samples once infants were 2 years of age.
“We are in this situation right now where we know [the early-life microbiome and a person’s health later in life] are linked, but we do not fully understand what a healthy adult microbiome looks like,” Mills said. – by Katherine Bortz
Disclosures: The authors report no relevant financial disclosures.
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