产气肠杆菌持续高产型AmpC β-内酰胺酶的产生与抗菌药物应用关系的研究

Research on the relationship between the emergence of constitutive high expression AmpC beta-lactamase and antibiotics therapy used in the infection caused by Enterobacter aerogenes

目的了解抗菌药物的应用与产气肠杆菌持续高产AmpCβ-内酰胺酶(简称AmpC酶)的关系,为临床合理用药提供试验依据。方法收集2011年9月至2012年3月分离自华东医院老年病区住院患者的产气肠杆菌临床菌株,用改良的三维试验检测产酶类型,用脉冲场凝胶电泳(PFGE)分析菌株的同源性,选择感染野生型和持续高产型AmpC酶的产气肠杆菌的临床病例为研究对象,进行前瞻性和回顾性研究。结果分离出产气肠杆菌19株,单产持续高产型AmpC酶的阳性率为31.58%(6/19),野生型AmpC酶的阳性率为26.32%(5/19)。呼吸道分离的痰标本中持续高产型AmpC酶菌株阳性率为83.33%,尿标本分离的阳性率为33.33%。治疗持续高产型组所用抗菌药物剂量和天数明显高于野生型组。使用头霉素类抗菌药物2周以上出现产酶类型由野生型转变为持续高产型。结论华东医院产气肠杆菌的持续高产型AmpC酶菌株阳性率高,尤以呼吸道来源的菌株更为严重,慎用或避免使用第3代及以下头孢菌素类和头霉素类抗菌药物,加强产酶类型检测及抗菌药物的合理使用。

Objective To investigate the relationship between antibiotics therapy and producing constitutive high expression AmpC beta-lactamase( AmpC) infected by Enterobacter aerogenes,in order to provide the reference for rational antibiotics. Methods Enterobacter aerogenes were isolated from September 2011 to March 2012 from elderly nosocomial patients in the elderly ward of Huadong Hospital. The modified three dimensional test was used to detect AmpC. The homology of Enterobacter aerogenes was detected by pulsed-field gel electrophoresis( PFGE). Prospective and retrospective investigations were performed on the clinical data of the patients with wild-type and constitutive high expession AmpC infected by Enterobacter aerogenes. Results A total of 19 isolates of Enterobacter aerogenes were isolated. The positive rates of constitutive high expression and wild-type AmpC were 31. 58%( 6 /19) and 26. 32%( 5/19). The positive rate of constitutive high expression AmpC from sputum samples was 83. 33%,and the positive rate from urine samples was 33. 33%. The total amount of antibiotics used to treat Enterobacter aerogenes infection producing constitutive high expression AmpC was higher than that of wild-type Enterobacter aerogenes. The wild-type Enterobacter aerogenes may be changed to the constitutive high expression when cephamycin was used to inhibit for more than 2 weeks. Conclusions The positive rate of producing constitutive high expression AmpC by Enterobacter aerogenes in Huadong Hospital is high, especially for isolates form respiratory tract. The 1st,2nd and 3rd generation cephalosporins and cephamycin should be used with caution or not be used in the course of anti-infection therapy. It is necessary to strengthen the surveillance of antimicrobial resistance and reasonably use antibiotics.