Nichols W W, Dorrington S M, Slack M P, Walmsley H L
Regional Public Health Laboratory, John Radcliffe Hospital, Oxford, United Kingdom.
Antimicrob Agents Chemother. 1988 Apr;32(4):518-23. doi: 10.1128/AAC.32.4.518.
[3H]tobramycin bound to sodium alginate and to exopolysaccharide prepared from two mucoid strains of Pseudomonas aeruginosa. Binding to sodium alginate was similar to binding to exopolysaccharide, both in the dependence on tobramycin concentration and in the maximum binding observed at saturation. Incorporation of sodium alginate into agar plates reduced the zone sizes of growth inhibition caused by tobramycin. The reductions in zone sizes were quantitatively accounted for by the binding of tobramycin to sodium alginate during diffusion of the antibiotic away from the well in which it had been placed at the start of the experiment. However, the binding of tobramycin to the exopolysaccharide of P. aeruginosa, and the resulting inhibition of diffusion of the antibiotic, did not significantly increase the penetration time of a spherical microcolony with a radius of 125 micron, such as might be found in the respiratory tract of a patient with cystic fibrosis (from a 90% penetration time of 12 s in the absence of exopolysaccharide to one of 35 s with an exopolysaccharide concentration of 1.0% [wt/vol]).
[3H]妥布霉素与海藻酸钠以及由两株黏液型铜绿假单胞菌制备的胞外多糖结合。妥布霉素与海藻酸钠的结合和与胞外多糖的结合相似，在对妥布霉素浓度的依赖性以及饱和时观察到的最大结合量方面均如此。将海藻酸钠掺入琼脂平板中会减小妥布霉素引起的生长抑制圈大小。在实验开始时将抗生素置于孔中，抗生素从孔中扩散期间，妥布霉素与海藻酸钠的结合在数量上解释了生长抑制圈大小的减小。然而，妥布霉素与铜绿假单胞菌胞外多糖的结合以及由此导致的抗生素扩散抑制，并未显著增加半径为125微米的球形微菌落的穿透时间，例如在囊性纤维化患者的呼吸道中可能发现的微菌落（在没有胞外多糖的情况下90%穿透时间为12秒，在胞外多糖浓度为1.0%[重量/体积]时为35秒）。
