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在甲氧西林耐药性金黄色葡萄球菌(MRSA)中,对头孢噻利、头孢唑林、头孢唑兰、头孢匹罗、头孢美唑、氟氧头孢、甲氧西林、亚胺培南等8种β-内酰胺类抗生素的最低抑菌浓度(MIC)与其对青霉素结合蛋白(PBP)的亲和力间的关系进行研究.金黄色葡萄球菌FP1775为低水平MRSA(L-MRSA)临床分离株,除对亚胺培南敏感外,耐受其它7种上述抗生素;金黄色葡萄球菌FP1777为高水平MRSA(H-MRSA),是菌株FP1775的突变株,对以上8种抗生素皆耐药.MIC用标准微量二倍稀释法测定.分别从菌株FP1775和FP11777中分离PBP1、PBP2、PBP2A、PBP3和PBP4,测定8种β-内酰胺类抗生素对PBP的结合亲和力(IC_(50)).结果显示,在H-MRSA中,β-内酰胺类抗生素对PBP2A的IC_(50)与MIC间存在显著的相关性;而在L-MRSA中,β-内酰胺类抗生素对任何PBP的IC_(50)与MIC间未表现出明显的关联.但在L-MRSA中,β-内酰胺类抗生素对PBP2A加PBP4的IC_(50)却与MIC显著相关.
In methicillin-resistant Staphylococcus aureus (MRSA), cefoselide, cefazolin, cefazolin, cefpirome, cefmetazole, oxyfloxacin, methicillin, imipenem, etc. The relationship between the minimum inhibitory concentration (MIC) of eight β-lactam antibiotics and their affinity for penicillin-binding protein (PBP) was studied. Staphylococcus aureus FP1775 is a clinical isolate of low-level MRSA (L-MRSA) In addition to sensitivity to imipenem, it is resistant to the other seven antibiotics mentioned above; Staphylococcus aureus FP1777 is a high-level MRSA (H-MRSA) strain that is a mutant strain of strain FP1775 that is resistant to the above eight antibiotics Standard micro-double dilution method.The PBP1, PBP2, PBP2A, PBP3 and PBP4 were isolated from the strains FP1775 and FP11777, and the binding affinity of the eight β-lactam antibiotics to PBP was determined (IC 50) In H-MRSA, there was a significant correlation between the IC 50 of PBP2A and the MIC of β-lactam antibiotics, while the IC 50 of any β-lactam antibiotics with any PBP in L-MRSA MIC did not show a clear correlation, but in L-MRSA, β_-lactam antibiotics on PBP2A plus PBP4 IC 50 but MIC Significant correlation.