Table 2.

High-Throughput Sequencing Studies Characterizing the Gut Microbiota of Infants Who Develop Necrotizing Enterocolitis^a

Study (Year); Sequencing Technology	Participants With NEC (of Total), No.	Specimens, No.	Factors Associated With NEC Risk Conclusions
Morrow et al (2013) [33]; 16S rRNA	11 of 32	58	Low community diversity and abundance of Firmicutes or Proteobacteria
Torrazza et al (2013) [34]; 16S rRNA	18 of 53	119	Abundance of Proteobacteria or Actinobacteria
Brower-Sinning et al (2014) [30]; 16S rRNA	18 of 19	26	High abundance of anaerobes and low community diversity in intestinal tissues
Warner et al (2016) [31]; 16S rRNA	46 of 120	2720	Gammaproteobacteria and lack of diversity; Negativicutes associated with NEC protection
Ward et al (2016) [36]; WGS	16 of 165	262	Uropathogenic Escherichia coli strain types
Dobbler et al (2017) [32]; 16S rRNA and WGS	11 of 40	132	Enterobacteriaceae and low community diversity
Olm et al (2019) [37]; WGS	34 of 160	1163	Klebsiella abundance and genes encoding fimbriae and secondary metabolites
Gopalakrishna et al (2019) [38]; WGS	10 of 23	98	High abundance of Enterobacteriaceae (particularly IgA-unbound Enterobacteriaceae) and reduced anaerobes

Abbreviation: IgA, immunoglobulin A; NEC, necrotizing enterocolitis; rRNA, ribosomal RNA; WGS, whole-genome sequencing.

^aAdapted from Warner and Tarr [26].