鲍曼不动杆菌OXA-51样碳青霉烯酶基因分型与耐药性研究

目的 研究鲍曼不动杆菌中OXA-51样碳青霉烯酶基因分型及与抗菌药物耐药的相关性.方法 纸片扩散法检测174株鲍曼不动杆菌对头孢他啶、头孢曲松、阿米卡星、环丙沙星的耐药性,琼脂稀释法检测亚胺培南和美罗培南的最低抑菌浓度(MIC值);PCR扩增碳青霉烯酶VIM、IMP、OXA-23、OXA-24、OXA-51和OXA-58相关基因;对ONA-51阳性菌株进行测序和基因分型.结果 所有菌株均未检出OXA-24、OXA-58、IMP及VIM基因;15.5%(27/174)的菌株OXA-23阳性,72.4%(126/174)的菌株OXA-51阳性,其中15.5%(27/174)菌株同时产OXA-51样酶和OXA-23酶,126株OXA-51样酶阳性菌株中,82.5%(104/126)为OXA-66型,非OXA-66基因型占17.5%(22/126),本次研究发现的8个新基因型;OXA-66型的耐药性明显高于其他基因型.结论 OXA-66为本地区分离鲍曼不动杆菌产生的OXA-51样碳青霉烯酶的主要基因型;OXA-66与碳青霉烯抗生素的低水平耐药有关,且可能与其他抗菌药物的耐药性相关,临床分离鲍曼不动杆菌中发现新的OXA-51样碳青霉烯酶基因.

Genotype and drug resistance of OXA-51-like carbapenemases in Acinetobaeter baumannii

Objective To study the genotypes of OXA-51-like carbepenemases in Aeinetobacter beumannii and its association with drug resistance. Methods The susceptibility of 174 Acinetobacter baumannii against ceftazidime, cefotriaxon, amikacin and ciprofloxacin were detected with disc diffusion method. The minimum inhibitory concentration (MIC) values for meropenem and imipenem were determined with an agar dilution method. VIM, IMP, OXA-23, OXA-24, OXA-51 and OXA-58 β-lactamase genes were determined by PCR. DNA sequencing and genotyping were performed against OXA-51 positivestrains. Results All 174 isolates were negative by PCR for genes OXA-24, OXA-58, IMP and VIM. OXA-23 and OXA-51were amplified in 15.5% (27/174) and 72.4% (126/174) isolates, respectively. Therewere 15.5% (27/174) isolates producing OXA-51-like and OXA-23 carbapenemase simultaneously. Among126 OXA-51-like carbapenemase producing strains, 82.5% (104/126)were OXA-66 genotype, whereas theremaining 17.5% (22/126) strains belong to other genotype. Eight novel OXA-51-like Genotype were foundin this study. Conclusions OXA-66 were the primary genotype of OXA-51-like carbapenemases in A.baumannii. OXA-66 were related to low-level carbapenems resistance and may be associated with resistanceof other drugs. We found new OXA-51-like genotype in clinic isolates of A. baumannii in this study.