临床分离多重耐药假单胞菌耐药机制的研究

Study on the mechanism resistance of clinically isolated multi-resistant pseudomonas strains

为了解假单胞菌对亚胺培能（ＩＭＰ）、头孢他啶（ＣＴＺ）、头孢哌酮（ＣＰＺ）和氨曲南（ＡＺ）的耐药机制。以绿脓杆菌标准株ＰＡＯ１和对照株ＴＮＰＯＯ４为对照，应用ＳＤＳ－ＰＡＧＥ外膜蛋白图谱和β－内酰胺酶测定方法，研究了临床分离的两株多重耐药绿脓杆菌和一株ＩＭＰ耐药荧光假单胞菌。结果表明：两株绿脓杆菌分离株均缺失了外膜蛋白ＯｐｒＤ＿２和外膜蛋白Ｅ（ＯｐｒＥ），并出现了４４．７ＫＤ的未知蛋白带；两株菌均产生了较高水平的β－内酰胺酶，其酶活性分别为０．６８１Ｕ／ｍｇ和０．６ｌ０Ｕ／ｍｇ，经ＩＭＰ诱导，两株菌产酶量未见显著增加；其β－内酰胺酶对上述药物的相对水解率均小于１０％。提示该两株绿脓杆菌对上述药物的多重耐药机制可能是ＯｐｒＤ＿２、ＯｐｒＥ的缺失和大量β－内酰胺酶的共同作用结果；其中对ＩＭＰ耐药的主要原因可能是ＯｐｒＤ＿２丢失。另一株ＩＭＰ耐药荧光假单胞菌出现了ＯｐｒＤ＿２含量的减少。

To understand the mechanism of multi-resistance to imipenem,cefoperazone,cef-tazidim and aztrenam of clinically isolated Pseudomonas spp,two isolates of Ps,aeruginosa with multi-resistance to the above agents and one isolate of imipenem-resistant Ps.fluorescens were ana-lyzed by SDS-PAGE outer membrane protein profile and assay of β-lactamase with reference strain PAOI and TNP004.It was found that OprD2/OprE was absent and an undnown protein(Mr,47.7KD)appeared in SDS-PAGE profile for the two clinical isolates of Ps.aeruginosa. The level ofβ-lactamase was high,0.681U/mg and 0.6l0U/mg,respectvely,The β-lactamase havc not dramati-cally incrcased after being induced by imipenem.All relative rates of hydrolysis to the above anti-Ps.aeruginosa β-lactamases were Iow(<l0%).These data favors the conclusion that the mecha-nism of multi-resistance to the above anti-Ps.aeruginosa β-lactamases might involve both the loss of OprD2/OprE and a lot of β-lactamase in the two isolates of Ps.aeruginosa. The main cause of imipenem resistance might be due to the loss of OprD2.Decrease in OprD2 was found in the imipen-em-resistant Ps.flurescens strain.