Urine Test Identifies Risk of Necrotizing Enterocolitis

In premature babies, abnormal gut bacteria can be found days before the onset of the devastating intestinal disease known as necrotizing enterocolitis (NEC).

Examination of stool samples from preterm infants by molecular techniques and urinary metabolomic analysis has revealed differences between those at risk of NEC and those who will not develop the disease.

Scientists at Cincinnati Children's Hospital (OH, USA) collaborating with other institutes, studied between October 2009 and August 2010, a total of 35 preterm infants of less than 29 weeks gestational age and whose weight was less than 1,200 grams at birth, The primary analysis included 11 infants who developed NEC and 21 control infants. The infant microbiome was analyzed by postnatal periods, 4 to 9 days and 10 to 16 days.

Bacterial DNA was extracted from infant stool samples using one of two methods: phenol-chloroform or the QiaAmp DNA stool kit (Qiagen Sciences; Germantown, MD, USA). The 16S ribosomal ribonucleic acid ( rRNA) gene was amplified and sequenced using 454 FLX Titanium sequencing (454 Life Sciences, Branford, CT, USA). Urine samples were analyzed by nuclear magnetic resonance.

Babies who later went on to develop NEC had a lower diversity of gut bacteria 4 to 9 days after birth, with increased level of Firmicutes or Enterobacteriaceae, but lacked the Propionibacterium found in healthy babies. All of the babies with NEC also had unusual levels of specific bacteria. Babies whose NEC started early, between 7 to 12 days after birth had abnormally high levels of Firmicutes, while babies whose NEC started later, 19 to 31 days, had high levels of Enterobacteriaceae. No difference was found in the relative abundance of Propionibacterium between NEC and control samples collected from days 10 to 16 of life.

No urinary metabolites differed significantly among all NEC cases and controls. However, three metabolites, alanine, pyridoxine (4-pyridoxate) and histidine, significantly distinguished NEC-I and NEC-II from each other as well as one of the NEC sub-types from controls.

Alanine was significantly higher in NEC-I versus NEC-II and NEC-I versus the control samples though the metabolite did not differ between all NEC versus control samples.

Ardythe L. Morrow, PhD, the senior author of the study said, "Our data show that onset of NEC appears to be related to having abnormally high levels of specific bacteria in the gut during the first week or two of life. Our data also indicate that a simple urine test looking at levels of alanine and histidine, which appear altered by these bacteria, can be used early in life to identify babies at risk of NEC." The study was published on April 16, 2013, in the journal Microbiome.

Related Links:
Cincinnati Children's Hospital
Qiagen Sciences
454 Life Sciences