Changes in the oral streptococcal flora of children undergoing allogeneic bone marrow transplantation

The changes in the oral streptococcal flora of twenty children undergoing allogeneic bone marrow transplant are described. Saliva was collected from each child on four separate occasions: (i) before the conditioning regimen; (ii) 7 days post-transplantation; (iii) when the neutrophil count had risen above 0.5 x 10(9)/l; (iv) 119 days post-transplantation. Indices for dental caries, plaque, gingivitis, herpetic stomatitis and mucositis were also recorded. There was a significant decrease in the total aerobic (P0.001) and anaerobic counts (P0.0002) between baseline and 7 days post-transplantation. The proportion of the 'Streptococcus oralis group' (Streptococcus mitis and S. oralis) increased significantly from baseline 12.1% to 48.4% at 7 days post-transplantation (P0.003). The plaque and gingivitis indices increased significantly from baseline to 7 days post-transplantation (P0.001). Twenty percent of the children had either positive blood cultures or Hickman line cultures for the 'S. oralis group', and it is possible that the inflamed gingival tissues are a further site of entry for these streptococci. There were no differences in the total anaerobic counts or the proportion of the 'S. oralis group' between baseline and the end of the study in the transplant children, or between the transplant and control children.