鲍氏不动杆菌的耐药性及同源性研究

Antibiotics Resistance and Genetic Homology of Acinetobacter baumannii

目的调查当地省级医院临床分离的鲍氏不动杆菌耐药性及产AmpC酶情况,并对AmpC酶阳性的多重耐药菌株进行同源性研究。方法药敏试验采用纸片琼脂扩散法,采用AmpC酶表型筛选法结合PCR法检测AmpC酶,利用RAPD分型技术对AmpC阳性的多重耐药鲍氏不动杆菌进行基因分型。结果106株鲍氏不动杆菌对亚胺培南耐药率最低11.1%,对青霉素类、头孢菌素类和单环β-内酰胺类抗生素耐药率均较高,特别是氨曲南和哌拉西林;对氨基糖苷类和氟喹诺酮类抗生素也有一定的耐药性;共检测出25株AmpC酶阳性菌株,产AmpC酶阳性率占总菌株数的23.58%;通过聚类分析发现5、6、10、12、13、14、20、23号菌株分为同一聚类群;8、17、18号菌株分为同一聚类群。结论鲍氏不动杆菌对各类抗生素均有不同程度的耐药性;AmpC酶表型筛选试验检测AmpC酶结果可靠,操作简便、快速,易于在临床实验室中推广使用;RAPD分型技术对鲍氏不动杆菌进行基因分型对于确定鲍氏不动杆菌菌株间的同源性,监控感染的传播有重要意义。

OBJECTIVE To investigate the status of antibiotics resistance and AmpC enzyme expression for Acinetobacter baumannii strains isolated from three Nanchang hospitals and to study the genetic homology of AmpC- positive A. baumannii strains using RAPD. METHODS The resistance tests were performed using K-B method. AmpC enzyme was determined by AmpC enzyme phenotype screening method coupled with polymerase chain reaction technique. The RAPD technique was then used＇to identify the genotypes of the AmpC-positive A. baumannii strains. RESULTS The antibiotic resistance test indicated that A. baumannii was most sensitive to imipenem, with 11.1 % of resistance rate, but highly resistant to penicillins, cephalosporins and helices β-lactam antibiotics, especially piperacillin and aztreonam. A. baumannii was resistant to aminoglycosides and quinolones antibiotics. Twenty-five out of 106 strains were identified as AmpC-positive strains,accounting for 23.58% of the whole strains. It was found that No. 5,6,10,12,13,14,20, and 23 strains belonged to the same type. No. 8,17, and 18 strains belonged to the same type. CONCLUSIONS Our results indicated that A. baumannii is resistant to all kinds of antibiotics with different extent. AmpC enzyme phenotype screening method is an easy and quick method and is promising to be popularized in clinical laboratory. Genotype identification for A. baumannii strains using RAPD method is significant for determining the genetic homology or monitoring and controlling nosocomial infections.