Gut microbiota in preterm infants receiving breast milk or mixed feeding

Table 1 Perinatal and clinical characteristics and outcomes of 40 preterm infants, n (%)

Characteristics	Type of feeding		P value
	Breast milk, n = 21	Mixed, n = 19
Gender
Female	5 (24)	9 (47)	0.113
Male	16 (76)	10 (53)
Type of delivery
Vaginal	6 (28)	4 (21)	0.582
Cesarean section	15 (71)	15 (78)
Prematurity category
Late preterm (34-36.6 gestational weeks)	0 (0)	2 (10)	0.225
Preterm (28-33.6 gestational weeks)	20 (95)	15 (79)
Extreme preterm (< 27.6 gestational weeks)	1 (5)	2 (10)
Apgar score at 5 min
0–3	0 (0)	0 (0)	0.087
4–6	2 (9)	2 (10)
7–10	19 (90)	17 (89)
Gestational weeks, mean ± SD	29 ± 2	30 ± 2	0.103
Birth weight (g), mean ± SD	1,180 ± 217	1276 ± 169	0.132
Birth height (cm), mean ± SD	37 ± 3	38 ± 2	0.338
Intubated at birth	4 (19)	5 (26)	0.581
Days to achieve full enteral feeding, mean ± SD	18 ± 10	15 ± 8	0.346
NICU stay (days), mean ± SD	28 ±19	26 ±17	0.668
Late-onset sepsis	5 (24)	2 (10)	0.413
Retinopathy	1 (5)	0 (0)	0.997
Necrotizing enterocolitis	3 (14)	4 (21)	0.685
Patent ductus arteriosus	6 (29)	5 (26)	0.994
Respiratory distress syndrome	18 (86)	19 (100)	0.239
Bronchopulmonary displasia	4 (19)	3 (16)	0.991
Intraventricular hemorrhage	10 (48)	5 (26)	0.202
Mortality	0 (0)	2 (10)	0.218

NICU: Neonatal intensive care unit.

Table 2 Comparison of relative abundances of classes and phyla between the initial and final samples

	Type of feeding
	Breast milk, n = 21			Mixed, n = 19
	Initial, mean ± SD	Final, mean ± SD	P value	Initial, mean ± SD	Final, mean ± SD	P value
Class
Bacteroidia	7.468 ± 15	6.835 ± 14	0.782	1.890 ± 3	2.872 ± 11	0.612
Flavobacteria	0.245 ± 10	0.008 ± 0.004	0.106	0.404 ± 1	0.005 ± 0.005	0.041
Sphingobacteria	0.030 ± 0.09	0.001 ± 0.001	0.155	0.055 ± 0.1	0.002 ± 0.006	0.100
Cytophagia	0.030 ± 0.10	0.001 ± 0.002	0.208	0.0004 ± 0.001	0.063 ± 0.268	0.320
Actinobacteria	2.270 ± 2.0	4.519 ± 9	0.261	1.396 ± 2	3.520 ± 10	0.398
Bacilli	14.975 ± 17	17.794 ± 17	0.539	19.112 ± 29	20.131 ± 26	0.875
Clostridia	1.664 ± 30	3.525 ± 6	0.177	1.517 ± 2	5.084 ± 15	0.326
Mollicutes	4.334 ± 17	0.054 ± 0.076	0.274	4.424 ± 19	4.607 ± 20	0.324
Erysipelotrichia	0.0001 ± 0.0005	0.0006 ± 0.001	0.253	0.028 ± 0.06	0.0002 ± 0.0008	0.063
Negativicutes	1.038 ± 3.0	2.440 ± 5	0.138	0.387 ± 1	0.337 ± 0.813	0.857
Alphaproteobacteria	0.989 ± 1.0	0.017 ± 0.011	0.005	0.570 ± 1	0.237 ± 0.623	0.103
Betaproteobacteria	23.550 ± 27.0	0.643 ± 0.290	0.001	18.517 ± 28	12.789 ± 28	0.509
Deltaproteobacteria	1.585 ± 4.0	0.200 ± 0.593	0.081	0.163 ± 0.4	0.103 ± 0.168	0.582
Epsilonproteobacteria	0.130 ± 0.4	0.001 ± 0.002	0.179	0.009 ± 0.02	0.0009 ± 0.002	0.218
Gammaproteobacteria	40.831 ± 30.0	64.381 ± 24	0.004	51.063 ± 36	50.182 ± 34	0.921
Phylum
Bacteroidetes	7.775 ± 15	6.786 ± 14	0.667	2.350 ± 3	2.943 ± 11	0.762
Actinobacteria	2.282 ± 2	4.131 ± 9	0.373	1.396 ± 2	3.520 ± 10	0.391
Firmicutes	17.678 ± 19	23.761 ± 17	0.219	21.046 ± 29	25.553 ± 28	0.558
Proteobacteria	67.087 ± 24	65.243 ± 24	0.772	70.324 ± 31	63.314 ± 31	0.403

Table 3 Statistics of alpha diversity analyzing phylum

Index	Type of feeding
	Breast milk (n = 21)			Mixed (n = 19)
	Initial, mean ± SD or median (range)	Final, mean ± SD or median (range)	P value	Initial, mean ± SD or median (range)	Final, mean ± SD or median (range)	P value
Species richness
Margalef’s index	1.60 ± 0.43	1.37 ± 0.27	0.042	1.53	1.31	0.0061
Fisher’s alpha	2.20 ± 0.68	1.82 ± 0.41	0.037	2.05	1.71	0.0071
Chao-1 index	8.33 ± 1.96	7.29 ± 1.23	0.044	8	7	0.0071
Menhinick’s index	0.9	0.7	0.079	0.8	0.7	0.0071
Species evenness or dominance
Dominance	0.63 ± 0.18	0.60 ± 0.22	0.617	0.747 ± 0.153	0.699 ± 0.189	0.396
Evenness	0.26 ± 0.09	0.29 ± 0.13	0.363	0.194 ± 0.046	0.246 ± 0.080	0.020
Brillouin’s index	0.51 ± 0.26	0.53 ± 0.33	0.807	0.344 ± 0.226	0.392 ± 0.265	0.551
Simpson’s index	98.00	0.4600	0.5891	0.253 ± 0.153	0.301 ± 0.189	0.396
Shannon’s diversity index	0.68 ± 0.29	0.65 ± 0.34	0.755	0.49 ± 0.250	0.51 ± 0.26	0.819
Equitability	0.33 ± 0.15	0.34 ± 0.19	0.873	0.226 ± 0.109	0.264 ± 0.141	0.355
Berger–Parker index	0.73 ± 0.16	0.67 ± 0.20	0.284	0.85	0.81	0.4181

¹Mann–Whitney U test for different medians.