华西医科大学学报
華西醫科大學學報
화서의과대학학보
JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES
2001年
1期
24-26,35
,共4页
梁润琴%范昕建%冯萍%雷秉均%舒煦
樑潤琴%範昕建%馮萍%雷秉均%舒煦
량윤금%범흔건%풍평%뢰병균%서후
大肠杆菌%头孢哌酮抗性基因%β-内酰胺酶%抗性基%因
大腸桿菌%頭孢哌酮抗性基因%β-內酰胺酶%抗性基%因
대장간균%두포고동항성기인%β-내선알매%항성기%인
目的 通过对头孢哌酮抗性基因（CPZΓ）的性质研究，进一步探讨E.coliHX88108多质粒共存并介导第三代头孢菌素耐药的分子机理。方法 采用Nitrocefin法检测CPZΓ表达产物，用紫外线分光光度计测定β-内酰胺酶活性，采用试管二倍液体稀释法进行CPZΓ克隆菌株对18种抗生素的敏感性测定，同时还进行头孢哌酮(CPZ)对CPZΓ克隆菌株耐药性诱导试验和温度敏感突变试验。结果 CPZΓ表达产物为β-内酰胺酶，其酶活性强且与耐药质粒pFC表达产物的活性基本一致。CPZΓ只编码对氨苄青霉素、第一、第二代头孢菌素和第三代头孢菌素中CPZ的耐药性，而对其他抗生素敏感。实验结果还显示了质粒pFC经多次传代后介导CPZ的耐药性显著下降，诺氟沙星、氨基糖甙类耐药性消失。CPZΓ克隆菌株CPZ耐药性增加为药物诱导所致，而非温度敏感突变。结论 耐药基因CPZΓ是通过编码β-内酰胺酶介导产生CPZ耐药性的，在抗生素压力下，CPZΓ克隆菌株对CPZ的耐药可以显著增加。
目的 通過對頭孢哌酮抗性基因（CPZΓ）的性質研究，進一步探討E.coliHX88108多質粒共存併介導第三代頭孢菌素耐藥的分子機理。方法 採用Nitrocefin法檢測CPZΓ錶達產物，用紫外線分光光度計測定β-內酰胺酶活性，採用試管二倍液體稀釋法進行CPZΓ剋隆菌株對18種抗生素的敏感性測定，同時還進行頭孢哌酮(CPZ)對CPZΓ剋隆菌株耐藥性誘導試驗和溫度敏感突變試驗。結果 CPZΓ錶達產物為β-內酰胺酶，其酶活性彊且與耐藥質粒pFC錶達產物的活性基本一緻。CPZΓ隻編碼對氨芐青黴素、第一、第二代頭孢菌素和第三代頭孢菌素中CPZ的耐藥性，而對其他抗生素敏感。實驗結果還顯示瞭質粒pFC經多次傳代後介導CPZ的耐藥性顯著下降，諾氟沙星、氨基糖甙類耐藥性消失。CPZΓ剋隆菌株CPZ耐藥性增加為藥物誘導所緻，而非溫度敏感突變。結論 耐藥基因CPZΓ是通過編碼β-內酰胺酶介導產生CPZ耐藥性的，在抗生素壓力下，CPZΓ剋隆菌株對CPZ的耐藥可以顯著增加。
목적 통과대두포고동항성기인（CPZΓ）적성질연구，진일보탐토E.coliHX88108다질립공존병개도제삼대두포균소내약적분자궤리。방법 채용Nitrocefin법검측CPZΓ표체산물，용자외선분광광도계측정β-내선알매활성，채용시관이배액체희석법진행CPZΓ극륭균주대18충항생소적민감성측정，동시환진행두포고동(CPZ)대CPZΓ극륭균주내약성유도시험화온도민감돌변시험。결과 CPZΓ표체산물위β-내선알매，기매활성강차여내약질립pFC표체산물적활성기본일치。CPZΓ지편마대안변청매소、제일、제이대두포균소화제삼대두포균소중CPZ적내약성，이대기타항생소민감。실험결과환현시료질립pFC경다차전대후개도CPZ적내약성현저하강，낙불사성、안기당대류내약성소실。CPZΓ극륭균주CPZ내약성증가위약물유도소치，이비온도민감돌변。결론 내약기인CPZΓ시통과편마β-내선알매개도산생CPZ내약성적，재항생소압력하，CPZΓ극륭균주대CPZ적내약가이현저증가。
Objective To investigate the characterization of cefoperazoneresistance gene (CPZΓ) on plasmid pFC in E.coli HX88108 and inq uire into the mechanism of resistance to CPZ at the molecular level. Me thods E. coli HX88108 strain which demonstrated high-level resista nce to cefoperazone (MIC,>512μg/ml)was isolated from a severely infected patient in 1988.Five plasmids coexisting in the strain were designated pFC,pFT1,pFT2,pFT3 a nd pFX,respectively. Four plasmids except pFX conferred CPZ resistance.Cefoperaz one resistance gene(CPZΓ) has been cloned from plasmid pFC.β-lactamase as says with Nitrocefin were performed.Results The expression prod uct of CPZr was β-lactamase .The high level β-lactamase enzymatic activities against cephaloridine of CPZΓ transformants which were detected spectrophot ometrically at 260nm wave length demonstrated high level similarities to that of pFC. MICs of 18 antibiotics were determined according to a guideline of NCCLS by broth dilution method.CPZΓ transformants showed moderate level resistance to ampicillin,cefazolin,cefamandole and CPZ(MIC,64μg/ml).Meanwhile,susceptibili ty testing results demonstrated that the level of resistance to CPZ of pFC trans formant in this study (MIC,64μg/ml) was much lower than that in 1988 (MIC,>512 μg/ml) and resistance to nofloxacin and aminoglycosides was not observed. Induc tion experiment and temperature-sensitive mutation of CPZ resistance were perfo rmed.CPZΓ colonal strains revealed the higher-level of resistance to CPZ (M IC ,512μg/ml) due to antibiotic CPZ induction rather than temperature sensitive mu t ation. Clonclusion This observation suggests that resistance to antibiotics enco ded by plasmid might have been lower or lost under no antibiotic stress in a cer tain period,but higher under heavy stress.
