老年人下呼吸道革兰阴性杆菌感染耐药机制研究

Study on antimicrobial resistance mechanism of gram-negative bacillus infections of respirarory tract in senile paiens

目的研究本院老年人下呼吸道感染革兰阴性杆菌产灭活酶耐药机制。包括超广谱β内酰胺酶(ESBLs)、高产头孢菌素酶(AmpC)和金属酶。通过对临床常见致病菌大肠埃希菌、肺炎克雷伯菌、阴沟肠杆菌、铜绿假单孢菌、不动杆菌和嗜麦芽窄食单胞菌等的检测结果分析,掌握本院老年患者下呼吸道感染主要病原菌的耐药规律及主要基因型,为临床经验治疗提供参考依据。方法单纸片扩散初试产ESBL菌株,用双纸片增效确认试验或自动细菌鉴定和药敏系统(VITEK)确定ESBL 菌株;用改良三维法检测去阻遏头孢菌素酶;Etest金属酶试条测定铜绿假单孢菌产金属酶的情况。用等电聚胶和测序方法对ESBL阳性株作分子基因分型。结果 80株肺炎克雷伯菌及143株大肠埃希菌产ESBL(超广谱β内酰胺酶)频率分别为27.5％和28.7％,CTX-M基因型分别占48％和56％。124株阴沟肠杆菌中有21.8％单独高产AmpC酶,8.1％单独产ESBL,3.2％即产ESBL又高产AmpC酶。71株耐亚胺培南的绿脓假单胞菌中有18.3％产金属β内酰胺酶。结论产ESBL、高产AmpC酶和金属β内酰胺酶是住院老年患者下呼吸道感染难以治愈的重要因素。CTX-M基因型是我院ESBLs流行的主要基因型。

OBJECTIVE To investigate the resistance mechanism of no molecule on the elderly lowe respiratory infection. METHODS β-lactamases of the isolates by double-disk increase. three-dimensional extract test. VITEK and Etest. RESULTS Among 80 k. Pneumonia and 143 E.coli 27.5% and 28.7% produced ESBL respectively by three-dimensioal extract testand 48% and 56% are CTX-Mgenetyperespectively. Among 124 E.cloacae isolates, 21.8% produced olny high--level AmpCβ-lactamases, 8.1% produced only ESBL, 3.2% produced both high-leve AmpCβ-lactamases and ESBL. Among 71 strains wieh resistent Impenem of pseudomonas aeruginosa 18.3% produced metallo β-lactamases. CONCLUSIONS The result showed that the strains produced expamded spectrum β-lactamases (ESBL), high-level AmpCβ-lactamases and metallo-β-lactamases are Important cause for lower respira tory infection on the elderly in-patient.