Oral Bacterial Microflora Changes in Patients Receiving Bone Marrow Transplantation

Objectives: Bone marrow transplantation (BMT) is an established treatment for patients suffering from hematological diseases, such as leukemia. During treatment, patients undergo dramatic alteration in their immune system, followed by prolonged period of immunodeficiency. This may be accompanied by changes in nature and magnitude of oral bacterial microflora (OBM). In this study, we aimed to unveil changes in OBM of patients receiving BMT using terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis (CLA). Methods: Seven patients receiving BMT in Okayama University Medical and Dental Hospital participated. Buccal mucosal swab samples were collected at different times before and after BMT as routine treatment, with a week interval. Swab samples were subjected to conventional culture method. Simultaneously, bacterial 16S rDNA was isolated, amplified with polymerase chain reaction (PCR) using primer labeled with florescent molecule (6-FAM). Labeled PCR products were digested by endonucleases MspI or HhaI. Lengths and sizes of terminal restriction fragments (TRFs) were determined on ABI PRISM 310 Genetic Analyzer and ABI Peak Scanner software respectively. CLA was performed for detailed analysis of each TRF on 3 samples from one patient (90clones/sample). Dendograms were generated for cluster analysis of TRFs. Results: TRFs number decreased in samples collected within 2 weeks after BMT, indicating simple OBM. This result was consistent with that of CLA, where less number of species was detected. It may be due to altered immune response and/or effects of antibiotics and oral care. Species detected by culture method were not always represented by major TRF peaks, and were represented by less number of clones in CLA. Conclusions: T-RFLP analysis revealed dynamic changes of OBM during BMT. Pathogenic and opportunistic species were frequently detected by CLA before BMT, thus pointing out the importance of oral care provided for these patients.