Effects of high-dose methotrexate therapy on intestinal bacterial flora in children with acute lymphoblastic leukemia

Abstract

To investigate the effects of high-dose methotrexate (HDMTX) therapy on intestinal bacterial flora in children with acute lymphoblastic leukemia (ALL). Thirty-six children with ALL of pre-and post-HDMTX therapy and 36 control children were enrolled. The bacterial DNA in stool was extracted. The primers for Bacillus bifidus and Escherichia coli with the 16SrRNA/DNA sequence of bacteria were designed. The bacteria were identified through general PCR. The standard curve of both bacterial DNA was produced using a series of dilution of accurately quantified bacterial DNA. The unknown samples were measured by 16SrRNA/DNA-targeted PCR. The amount of stool Bacillus bifidus and Escherichia coli among 36 control children and 36 children with ALL of pre- and post-HDMTX therapy were obtained by using the standard curves. Bacillus bifidus logarithmic absolute value of the first day before treatment, of third day after treatment, of seventh day after treatment in patients with ALL and the control was 7.24 +/- 0.33, 6.00 +/- 0.27, 6.59 +/- 0.33, and 9.49 +/- 0.41, respectively (P < 0.01). Escherichia coli logarithmic absolute value of the first day before treatment, of third day after treatment, of seventh day after treatment in patients with ALL and the control was 6.62 +/- 0.42, 5.96 +/- 0.42, 7.02 +/- 0.41, and 7.52 +/- 0.43, respectively (P < 0.01). The logarithm of the amount of stool Bacillus bifidus and Escherichia coli in control group was higher in ALL group (F = 739.61, 88.67, P < 0.01). There were significant difference (P < 0.01) in the logarithm of the amount of stool Bacillus bifidus and Escherichia coli between pre-therapy and post-therapy group. The logarithm of the bacterium was very low on third day after treatment, but gradually increased on the seventh day after treatment. (1) HDMTX therapy has great effects on intestinal flora of Bacillus bifidus and Escherichia coli and significantly reduced the bacteria in children with ALL. (2) Probiotics had significantly decreased in ALL group than in control group.