黏质沙雷菌中AmpC酶的检测及药敏率分析

Antimicrobial resistance of AmpC-producing serratia marcescens in Anhui

目的了解安徽省临床分离的104株黏质沙雷菌中AmpC酶的产生情况及其对常用抗菌药物的耐药特征,以指导临床合理用药。方法采用头孢西丁纸片扩散法筛选疑产AmpC酶阳性菌株,并用酶粗提物进行三维试验确证产AmpC酶菌株。药敏试验采用琼脂稀释法,依据CLSI 2010年推荐的标准进行判读结果。结果 104株黏质沙雷菌在呼吸道痰标本中检出率最高,达59.6%;主要分布于呼吸内科、重症监护病房、老年病科等;头孢西丁纸片筛选法阳性率为39.4%,经三维试验确证产AmpC酶的有8株,阳性率为7.7%。产AmpC酶菌株除对亚胺培南、美罗培南全部敏感及对头孢吡肟、左氧氟沙星和加替沙星敏感率较高外,对其他大多数抗菌药物耐药率均高于非产酶株。结论产AmpC酶黏质沙雷菌对临床常用抗菌药物的耐药率均较高,对产酶株临床经验用药可选用碳青霉烯类、氟喹喏酮类及四代头孢菌素类抗菌药物。

Objective To investigate the resistance of AmpC-producing Serratia marcescens for providing the scientific evidence in clinical diagnosis and treatment.Methods Potential AmpC-producing strains were detected by the cefoxitin disk diffusion method as described by CLSI 2010.Three-dimensional test was adopted for confirming AmpC-producing strains.The MICs of Serratia marcescens were determined by broth microdilution method.The results were judged according to the criteria recommended by CLSI 2010.Results The majority of Serratia marcescens were isolated from the specimen of sputum,accounting for 59.6%.The bacteria were mostly detected in Respiratory department,followed by Intensive Care Unit,Gerontology Department.41 of 104 isolates were identified as resistant to cefoxitin,accounting for 39.4%.8 strains（7.7%） produced AmpC β-lactamases.The antimicrobial susceptibility test showed that all strains were sensitive to imipenem and meropenem.The rates of resistance to cefepime,levofloxacin and gatifloxacin remained relatively unchanged between AmpC-producing strains and non-AmpC-producing strains.The resistant rates to other antimicrobial agents were significantly statistical difference（P0.05） between the AmpC-producers and the non-AmpC-producers.Conclusion It showed that the production of AmpC β-lactamases in Serratia marcescens confers a high level of resistance to most kinds of antimicrobial agents.Carbapenems,fluoroquinolones,and fourth generation cephalosporins should be selected in empirical therapy of serious infections caused by AmpC-producing Serratia marcescens.