data). Neu noted that the Gardnerella genus (which is in the Actinobacteria phylum), when it is associated with bacterial vaginosis, has been associated with premature delivery.

Diseases in Preterm Babies: Role of the Microbiome

About 7 percent of babies in neonatal intensive care units (ICUs) who weigh less than 1,500 grams develop necrotizing enterocolitis (NEC). About 30 percent of babies who develop NEC do not survive. Of those who do survive, about 50 percent suffer significant neurodevelopmental delays. Symptoms include abdominal distention, redness around the belly button, and specific X-ray findings (Neu and Walker, 2011). Surgical treatment for NEC often results in a shortened gut, which requires about $1.5 million in medical care during the first 5 years of life.

In an ongoing microbiota study of babies with NEC, Neu and colleagues have been collecting weekly stool samples from NEC babies and carefully matched non-NEC babies (i.e., matched with respect to gestational age, size, time in the neonatal ICU). Their first results revealed differences in demography (i.e., babies with NEC were more likely to be formula-fed than breast milk–fed), antibiotic administration (i.e., babies with NEC were administered more antibiotics than control babies were), and fetal microbiota (Mai et al., 2011). With respect to fetal microbiota, the NEC and control babies demonstrated a marked difference in Firmicutes prevalence one week before diagnosis (60.68 percent in NEC babies, compared to 31.49 percent in controls) and a marked difference in Proteobacteria composition within 72 hours of diagnosis (70.9 percent in NEC babies, compared to 31.49 percent in controls). At the species, or operational taxonomic unit (OTU), level, there appear to be significant differences in Klebsiella spp. and Cronobacter spp.

Another recent study reported similar findings with respect to the relationship between antibiotic administration and NEC, with greater antibiotic use increasing the risk of NEC (Alexander et al., 2011). According to Clark and colleagues (2006), antibiotics are among the top 10 drugs administered to babies in neonatal ICUs, with about 95 percent of all babies being administered at least 48-72 hours of either ampicillin or gentamicin. As reviewed by Preidis and Versalovic (2009), an association between antibiotic administration and lower microbial species diversity has been observed in infants.

Late-onset sepsis is another prevalent disease among premature babies, affecting about 37 percent of babies born at less than 28 weeks’ gestation, with fetal microbiota associations. According to Neu, coagulase-negative Staphylococcus spp., Escherichia coli, Klebsiella spp., Pseudomonas spp., and Enterococcus spp. are the most common microorganisms in blood



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