title: Bacterial diversity and Clostridia abundance decrease with increasing severity of necrotizing enterocolitis.
abstract: BACKGROUND
  Necrotizing enterocolitis (NEC) is a devastating neonatal gastrointestinal disease that primarily affects premature infants. It is characterized by bowel inflammation and necrosis. In spite of extensive research, there has been little progress in decreasing the incidence or mortality of NEC over the past three decades. The exact etiology of NEC has not been identified. However, it is believed to result from an inappropriate immune response to gut microbiota. Using 454-pyrosequencing analyses of 16S rRNA genes that were PCR-amplified from stool DNA specimens, we compared the gut microbiota of infants with NEC to matched controls without NEC. The infants with NEC were then categorized into three subgroups based on severity: mild, severe, and lethal. We compared the microbiota among these subgroups and between each severity group and appropriate controls.
  
  
  RESULTS
  Bacterial diversity and the relative abundance of Actinobacteria and Clostridia were significantly lower in NEC specimens compared to controls. The absence of Clostridia was significantly associated with NEC. Microbial diversity and Clostridia abundance and prevalence decreased with increasing severity of NEC.
  
  
  CONCLUSIONS
  Low bacterial diversity in stool specimens may be indicative of NEC and the severity of NEC. The low bacterial diversity, and the lack of Clostridia in lethal specimens, could indicate that the presence of a diverse bacterial population in the gut as well as the presence of taxa such as Clostridia may play a role in attenuating inflammation leading to NEC.
authors: Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Science Center, 1901 Perdido St., New Orleans, Louisiana USA.
authors: Valarie E
authors: VE
authors: McMurtry
authors: Department of Pediatrics, Children's Hospital, 200 Henry Clay Ave., New Orleans, Louisiana USA.
authors: Raegan W
authors: RW
authors: Gupta
authors: Pediatrix Medical Group of Louisiana, Baton Rouge General Medical Center, Baton Rouge, LA USA.
authors: Lynn
authors: L
authors: Tran
authors: Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Science Center, 1901 Perdido St., New Orleans, Louisiana USA.
authors: Eugene E
authors: EE
authors: Blanchard
authors: Department of Pediatrics, Children's Hospital, 200 Henry Clay Ave., New Orleans, Louisiana USA.
authors: Duna
authors: D
authors: Penn
authors: Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Science Center, 1901 Perdido St., New Orleans, Louisiana USA.
authors: Christopher M
authors: CM
authors: Taylor
authors: Department of Pediatrics, Children's Hospital, 200 Henry Clay Ave., New Orleans, Louisiana USA ; The Research Institute for Children, 200 Henry Clay Ave., New Orleans, Louisiana USA.
authors: Michael J
authors: MJ
authors: Ferris
keywords: Clostridia; Microbial diversity; Microbiota; Necrotizing enterocolitis