医院感染患者与健康者呼吸道分离肺炎克雷伯菌携带整合子的分析比较

Klebsiella pneumoniaecarrying integrons isolated from respiratory tracts of nosocomial infection patients and healthy population

目的分析比较来源于南京地区部分社区健康成年人鼻咽部与住院患者分离的肺炎克雷伯菌(KPN)耐药性、携带整合子的特征及基因盒种类。方法于医院体检中心采集健康体检者的鼻咽拭子,按《全国临床检验操作规程》进行培养、分离及鉴定KPN;运用法国生物梅里埃公司VITEK细菌分析系统,鉴定住院患者痰标本中的KPN;应用纸片扩散法对抗菌药物进行耐药性监测和分析;应用PCR法扩增整合子;对PCR产物纯化、测序、并对结果进行分析。结果来源于临床痰标本的24株KPN,10株为Ⅰ类整合子阳性株,整合子阳性率为41.7%,明显高于24株健康者定植菌分离KPN整合子的阳性率4.2%,差异有统计学意义(P<0.01);医院感染患者检出的KPN对13种抗菌药物总的耐药率为16.7%～83.3%,明显高于健康者分离KPN的4.2%～45.8%;且携带有氨基糖苷类、磺胺类、氯霉素抗菌药物耐药基因盒。结论医院感染患者分离的KPN整合子阳性率及耐药率,显著高于健康者呼吸道分离的KPN,健康者携带菌株可分离出Ⅰ类整合子,提示应从基因水平上检测不同人群细菌耐药性。

OBJECTIVE To analyze and compare the drug resistance,the characteristics of Klebsiella pneumoniae carrying integrons and gene cassettes and the colonized bacteria isolated from the healthy population in Nanjing.METHODS The nasopharyngeal samples of healthy adults were collected at the physical examination center,the culture,isolation and the identification of K.pneumoniae isolates were performed according to National Clinical Laboratory Procedures,the identification of K.pneumoniae cultured from sputum specimens of the hospitalized patients was performed by VITEK bacteria analyzer of BioMérieux,France;the surveillance of drug resistance was performed with K-B diffusion method;the integrons were amplified by PCR,then the PCR products were purified and sequenced.RESULTS Of 24 strains of K.pneumoniae isolated from clinical sputum samples,there were 10 isolates carrying class I integrons with the positive rate of 41.7%（P=0.002）,significantly higher than 4.2% of the 24 strains of colonized K.pneumoniae from the healthy subjects,the difference was statistically significant（P=0.002）;the drug resistance rates of K.pneumoniae isolates from the patients with infections to 13 antibiotics ranged from 16.7% to 83.3%,significantly higher than from 4.2% to 45.8% of the K.pneumoniae isolates from the healthy population;the variable region of the integrons contained drug resistance gene cassettes including genes coding resistance to aminoglycosides,sulfanilamides and chloramphenicol.CONCLUSION The positive rate and drug resistance rate of K.pneumoniae isolates carrying integrons isolated from the patients with nosocomial infections are significantly higher than those of the isolates from the respiratory tracts of the healthy population;class I integron can be detected in K.pneumonia strains isolated from the healthy population,which indicates that the drug resistance of the bacteria from various populations should be detected from the gene level.