NMDS ordination of microbial communities for days 10 to 16 of life. (A) This ordination was based on weighted UniFrac beta diversity and run with three dimensions in the vegan package of R, resulting in a stress of 2.43. Controls are shown in black and NEC and non-NEC deaths in either red (cases identified as NEC-I in the ordination for days 4 to 9) or green (cases identified as NEC-II in the ordination for days 4 to 9). Clusters identified using the Ward minimum variance method are indicated in this ordination as A, B and D; C is identified as an outlier value. (B) Bars indicate the relative abundance of the ten most common genera in samples from individual infants, whose study numbers are noted on the horizontal axis. NEC sub-types (NEC-I and NEC-II) correspond to the NEC cases included in Cluster I and Cluster II, respectively, in the ordination of samples for days 4 to 9 (Figure 3). The clusters identified in this ordination are indicated by column headers. Clusters indicate microbial community similarity. NEC: necrotizing enterocolitis; NMDS: non-metric dimensional scaling.