多剂量协同法检测AmpCβ-内酰胺酶

Detection of AmpC-type-β-lactamases by synergic test with multiple-dosage procedures

目的 建立一种简便有效的检测AmpCβ 内酰胺酶的方法。 方法 以邻氯西林作为AmpCβ 内酰胺酶的抑制剂 ,采用多剂量协同法检测 14株肠杆菌科细菌中的AmpC并作分型 ,用双纸片确证法和纸片协同法检测超广谱 β 内酰胺酶 (ESBL)。同时用亚胺培南作诱导试验 ,用琼脂稀释法测定诱导前后细菌对 4种抗生素的MIC。结果 14株菌中有 3株产持续高产型AmpCβ 内酰胺酶 ,7株产诱导高产型AmpCβ 内酰胺酶 ;6株产ESBL。产诱导高产型AmpCβ 内酰胺酶细菌诱导前后MIC变化较大 ,而产持续高产型AmpCβ 内酰胺酶细菌诱导前后MIC变化不大。结论 多剂量协同法方法简便 ,成本低廉 ,可作为临床微生物实验室对产AmpCβ

Objective To develop a simple,effective method to detect AmpC-type-β-lactamases.Methods Cloxacillin was used as the enzyme inhibitor.AmpC-type-β-lactamases in 14 bacteriaceae strains was detected and typed by synergic test with multiple-dosage procedure.Extended-spectrum beta-lactamases (ESBLs) were detected by the double-disc synergic test.Meanwhile,AmpC-type-β-Lactamases was induced by Imipenem and MIC results to 4 antibiotics were assayed by agar dilution before and after induction.Results Of 14 strains,three were derepressed expression AmpC-type-β-Lactamases and seven strains were highly expressed inducible AmpC-type-β-Lactamase-producing bacteria.It was showed that after induction the change of MIC results in highly expressed inducible AmpC-type-β-Lactamase-producing bacteria was greater than that in derepressed expression AmpC-type-β-Lactamase-producing bacteria.Conclusion The synergic test with multiple-dosage procedures is simple and practical method suitable for routine screening of the AmpC-type-β-lactamases in the clinical microbiology laboratory.