ABSTRACT
<p><b>OBJECTIVE</b>To study the changes in gut microbiota and serum D-lactate level and their significance in children with recurrent pneumonia.</p><p><b>METHODS</b>The stool and blood samples were collected from 30 children with recurrent pneumonia (recurrent group), 30 children with acute pneumonia (acute group), and 15 children receiving surgical operation (surgery group). The 16S rRNA fluorescent quantitative polymerase chain reaction (FQ-PCR) was applied to determine the numbers of Bifidobacterium and Escherichia coli in stool samples, and the ratio between the logarithmic values of the numbers of Bifidobacterium and Escherichia coli (B/E value) was calculated. The serum D-lactate level was measured, and correlation analysis was performed.</p><p><b>RESULTS</b>The recurrent group had a significantly lower number of Bifidobacterium and a significantly lower B/E value than the acute group and the surgery group (P<0.05), as well as a significantly higher number of Escherichia coli than the surgery group (P<0.05). There was no significant difference in the number of Escherichia coli between the recurrent group and the acute group. The recurrent group had a significantly higher serum D-lactate level than the acute group and the surgery group (P<0.05). In the recurrent group, B/E value was negatively correlated with serum D-lactate level (r=-0.539, P<0.05).</p><p><b>CONCLUSIONS</b>Children with recurrent pneumonia may have biological and mechanical barrier damage in the intestinal mucosa.</p>