Comparative Analysis of Fecal Microbiota Between Infants With Cow Milk-induced Proctocolitis and Healthy Controls

Purpose: This study aimed to analyze the gut microbiota in stool samples from exclusively breastfed infants diagnosed with cow milk-induced allergic proctocolitis (CMIAP), with a focus on controlling potential factors that could interfere with the microbiota and to compare the findings with those derived from healthy infants. Methods 16S-rRNA gene sequencing by Illumina MiSeq sequencing system was used to analyze the fecal microbiota. The β-diversity and α-diversity indices were determined to assess the species richness, evenness and group dissimilarities. The results were analyzed by QIIME 2 and R software. Linear discriminant analysis (LDA) and effect size analysis (LefSe) was performed to identify specific microbial taxa that significantly differed between the proctocolitis group and the healthy control group. Results 25 infants including 16 infants with CMIAP and 9 healthy infants recruited. Bray-Curtis dissimilarity between the two groups was statistically significant (p-value = 0.001). At the phylum level, the proctocolitis group exhibited a significantly lower abundance of Actinobacteriota (LDA score 5.80 vs. 5.58, p = 0.001) and a higher abundance of Proteobacteria (LDA score 5.53 vs. 5.22, p = 0.044). At the class level, the proctocolitis group showed a higher abundance of Gammaproteobacteria (LDA score 5.57 vs. 5.17, p = 0.027) and lower abundances of Actinobacteria (LDA score 5.37 vs. 5.75, p = 0.0003) and Coriobacteriia (LDA score 4.56 vs. 4.93, p = 0.043). At the genus level proctocolitis group showed a higher abundance of Rumnicocus (LDA score 5.063 vs. 4.64, p = 0.035) and a lower abundance of Bifidobacterium (LDA score 5.63 vs 5.63, p = 0.0002) Conclusions The findings suggest significant differences in the gut microbiota composition between infants with proctocolitis and healthy infants. This study underscores the importance of studying the gut microbiota in proctocolitis and highlights the need for continued research in this field to better understand the complex interplay between gut microbiota and health outcomes in infants with proctocolitis.