耐亚胺培南革兰阴性杆菌产碳青霉烯酶研究

Production of carbapenemases in imipenem-resistant gram-negative rods

目的了解细菌产碳青霉烯酶及其对亚胺培南、美罗培南等碳青霉烯类抗生素耐药性之间的关系。方法应用改良 Hodge Test 和乙二胺四乙酸(EDTA)协同试验法对2003.6～2004.5收集自复旦大学华山医院的耐亚胺培南革兰阴性杆菌进行碳青霉烯酶筛选。bla_(VIM-1)、bla_(VIM-2)、bla_(IMP-1)、bla_(IMP-2)、bla_(SPM)、bla_(OXA-23)为引物进行 PCR 扩增,并对 PCR 扩增阳性产物进行 DNA 测序分析。结果在75株耐亚胺培南的铜绿假单胞菌中,共检出产 VIM-2型金属β内酰胺酶菌株2株(2/75),在10株耐亚胺培南的假单胞菌属细菌中检出2株产 VIM-2型金属B内酰胺酶(2/10),均为恶臭假单胞菌;耐亚胺培南的8株弗劳地柠檬酸杆菌和6株不动杆菌中全部分别检出 IMP 金属酶新亚型和 OXA-23型碳青霉烯酶。结论细菌产碳青霉烯酶是不动杆菌和弗劳地柠檬酸杆菌对亚胺培南和美罗培南等碳青霉烯类抗生素耐药的主要原因之一,但对铜绿假单胞菌而言,产碳青霉烯酶不是导致其对亚胺培南耐药的主要原因。

Objective To study the production of carbapenemases in carbapenem-resistant gramnegative rods. Methods Antimicrobial susceptibility testing was performed by agar dilution method. Carbapenemases were screened by Modified Hodge Test and EDTA-disk synergy test. The encoding genes of MBLs and oxacillinase were amplified and analyzed by PCR and DNA sequencing. Results Two of the 75 Pseudomonas aeruginosa isolates and 10 Pseudomonas spp. strains were found to produce VIM-2. All the 6 isolates of carbapenem-resistant Acinetobacter spp. were positive for OXA-23. All the 8 strains of Citrobacter freundii produced a new subtype of IMP. Conclusion The production of carbapenemases is among the main mechanisms of imipenem resistance in Citrobacter freundii and Acinetobacter spp. ,while in Pseudomonas aeruginosa it is not the main mechanism.