Chemotherapy treatment in pediatric patients with acute myeloid leukemia receiving antimicrobial prophylaxis leads to a relative increase of colonization with potentially pathogenic bacteria in the gut
Van Vliet MJ et al. - In a study to analyze the effect of chemotherapy treatment and antimicrobial prophylaxis on intestinal bacterial populations (microbiota) among pediatric pts with acute myeloid leukemia (AML) who are prone to intestinal mucositis and infections, it appears that these pts with AML are unable to maintain colonization resistance because of a decrease in anaerobic bacteria and an increase in potentially pathogenic aerobic enterococci. This disturbance in the balance between anaerobic and aerobic bacteria will further increase the risk of gram-positive aerobic infections among immunocompromised pts with cancer. Methods- During 36 chemotherapy cycles, fecal samples were collected from pediatric pts with AML.
- Fecal bacterial populations were analyzed by polymerase chain reaction denaturing gradient gel electrophoresis fingerprinting.
- Fluorescent in situ hybridization (FISH) analysis with specific bacterial oligonucleotide probes was used to quantify fecal bacteria.
Results- During chemotherapy treatment, the total number of bacteria in fecal samples was 10-9 per gram of dry weight feces, which was 100?fold lower than that in healthy control samples.
- FISH analysis showed that this decrease was the result of an up to 10,000-fold decrease in anaerobic bacteria, partly compensated for by a 100-fold increase in potentially pathogenic enterococci.
- Additional experiments showed that both prophylactic and therapeutic use of antibiotics could not sufficiently explain the tremendous changes in intestinal microbial composition.
- In vitro tests showed a direct bacteriostatic effect of chemotherapeutics.
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