Evaluation of the 99mtechnetium labelling effect on Pseudomonas aeruginosa surface properties

Gamma emitter isotopes present some advantages over beta emitters as radioisotopic microbial labels. The labelling of bacteria with 99mtechnetium (99mTc) has recently been described. However, it was not ascertained whether the labelling process modifies microbial physicochemical surface properties important in the interaction between bacteria and eukaryotic cells. In the present study, we evaluated the effect of the labelling process on Pseudomonas aeruginosa surface charge, hydrophobicity, adherence to human buccal epithelial cells and phagocytosis by human leukocytes. No significant differences in electrophoretic mobility or cationized ferritin distribution was observed on the cell surface of labelled and unlabelled bacteria. 99mTc labelling did not modify the hydrophobicity adhesiveness or phagocytosis of P. aeruginosa. It is concluded that bacterial labelling with 99mTc may be a useful method for the numeration of bacteria and the analysis of their functional properties.