细菌β-内酰胺酶及外膜蛋白改变与耐药性关系的研究

RELATIONSHIP BETWEEN BACTERIAL RESISTANCE AND VARIATION OF β-LACTAMASES AND OUTER MEMBRANE PROTEINS

本文通过细菌β-内酰胺酶活性检测及外膜蛋白电泳分析,研究了它们在细菌耐药性中的作用。结果指出:4株耐Aztreonam(Az)菌株,β-内酰胺酶明显升高,活性达349～1235U,对青霉素类、头孢菌素类产生耐药(MIC≥25μg/ml),但对四环素、氯霉素、诺氟沙星、链霉素等非β-内酰胺抗生素及Imipenem仍敏感。另一株耐AZ,株,β-内酰胺酶无明显升高,但外膜蛋白变化明显,和相应敏感株比较,分子量为36 K、37K蛋白带缺失,37.5 K蛋白减少,39K蛋白增加,对头孢菌素类、四环类、氯霉素、诺氟沙星耐药,但对链霉素,Imipenem及青霉素仍敏感。

The β-lactamases and outer membrane proteins(OMP) of the E. cloacae were examined to determine their relative contributions to bacterial resistance by using ultraviolet spectrophotometry and SDS-pol-yacrylamide gel electrophoresis(PAGE).The results revealed that 4 strains of Azthreonam (AZ)-resistant E.cloacae, of which the high levels of β-lactamase were produced, and resistant to Penicillins and Cephalosporins (MIC≥25μg/ml), but still susceptible to Imipenem(IMP)and antibiotics not belonging to β-lactams such as Tetracycline(TC), Chloramphenical (CP),Norfloxacin(NFLX)and Streptomycin(SM). The other AZ resistant E.cloacae was resistant to Cephalosporins,TC,CP and NFLX,but still susceptible to SM, IMP and Penicilins. The examination of the β-lactamase and OMPs of this strain showed that the level of the β-lactamase was not high, but the OMPs varied significantly compared with the corresponding wild strain, the 36 and 37 K Dal proteins were missing, 37.5 K Dalprotein was diminished while 39K Dal protein was increased.