产AmpC酶阴沟肠杆菌耐药与ampR调节基因的研究

The resistance of AmpC-producing Enterobacter cloacae and ampR regulatory gene

目的对阴沟肠杆菌产AmpC酶菌株的检出率、耐药性及ampR调节基因序列进行分析,探讨阴沟肠杆菌产AmpC酶菌株的耐药性与ampR调节基因的关系。方法采用琼脂稀释法对阴沟肠杆菌进行药敏试验,酶粗提物头孢西丁三维试验检测AmpC酶,经表型筛选法筛选,对其中2株去阻遏高产突变株和1株高度诱导株产AmpC酶的ampR基因行PCR扩增并对产物序列进行分析。结果阴沟肠杆菌产AmpC酶株的检出率为26·1%。产AmpC酶株中检出去阻遏高产突变株9株,高度诱导株2株,阴沟肠杆菌去阻遏高产突变株ampR基因的氨基酸序列Asp-135→Asn发生突变。结论产AmpC酶细菌多呈多重耐药,亚胺培南是治疗产AmpC酶细菌感染的较可靠的药物。阴沟肠杆菌ampR基因突变可能与其去阻遏表达有关。

Objective To investigate the prevalence of AmpC-producing Enterobaeter cloacae isolates in our hospital and observe the resistance of these strains. To study the relationship between drug resistance and the mutant of ampR regulatory gene in AmpC-producing Enterobaeter cloacae. Methods The susceptibility tests were performed by the way of agar twofold dilution with the standard of NCCLS. AmpC enzyme was examined by cefoxitin three dimension test. The nucleotide sequence of ampR gene that amplified by PCR were detected by automatic sequencer. Results The incidence of AmpC-producing Enterobaeter cloacae were 26. 1% . According to the phenotype screening test, there were 9 derepressed strains and 2 hyperinducible strains producing AmpC. The ampR sequences of derepressed strains showed their amino acid sequences were Asp-135 to Asn. Conclusions Most of the AmpC-producing strains were muhidrug resistance, and imipenem is still the proper antibiotic for treatment of the infections caused by AmpC- producing bacteria. The mutant of ampR regulator gene may be associated with the derepressing of AmpC enzyme.