摘要目的 探讨抗碳青霉烯类抗生素肺炎克雷伯菌(CRKP)的耐药机制和毒力特点,为烧伤感染的防控及CRKP的临床治疗提供理论依据. 方法 收集从2016年2-12月笔者单位收治烧伤患者临床标本中分离的亚胺培南或美罗培南药敏纸片抑菌圈直径≤22 mm的肺炎克雷伯菌,采用K-B纸片扩散法或自动化仪器法检测菌株对头孢类、氨基糖苷类、磺胺类、喹诺酮类、碳青霉烯类等17种抗菌药物的耐药情况.采用脉冲场凝胶电泳(PFGE)进行同源性分析,采用结晶紫染色法检测生物膜形成能力,采用黏液丝试验检测高黏液表型,采用PCR法检测常见的碳青霉烯酶基因bla KPC、bla IMP、bla OXA-48、bla NDM与荚膜血清型基因K1、K2、K57和毒力相关基因rmpA. 结果 (1)共分离CRKP菌株29株.29株CRKP对亚胺培南、美罗培南、厄他培南等碳青霉烯类,头孢类,氨基糖苷类,喹诺酮类抗菌药物的耐药率均较高,对磺胺类抗菌药物和替加环素的耐药率较低.(2)29株CRKP的PFGE分型为A、B、C、D型,其中A型11株、B型10株、C型6株、D型2株.(3)29株CRKP中25株生物膜形成阳性,阳性率为86.2％.(4)29株CRKP中无黏液丝试验阳性的高黏液表型菌株.(5)29株CRKP全部携带碳青霉烯酶基因,其中11株同时携带bla NDM-I和bla OXA.48基因,1株同时携带bla NDM-1和bla KPC-2基因,12株仅携带bla KPC-2基因,5株仅携带blaNDM-1基因.79.3％ (23/29)的菌株对3种碳青霉烯类抗菌药物完全耐药.(6)29株CRKP中3株携带K2基因,其中2株对3种碳青霉烯类抗菌药物完全耐药;1株携带rmpA基因;无携带K1和K57基因的菌株. 结论 笔者单位收治烧伤患者CRKP检出率高,且大多为广泛耐药菌,其耐药机制复杂,可能存在克隆株的流行传播,需采取及时有效的医院内感染防控措施.

abstractsObjective To investigate resistance mechanism and virulence features of carbapenemsresistant Klebsiella pneumoniae (CRKP) and to provide theoretical foundation for the prevention and control of nosocomial infections in burn wards as well as clinical therapy of CRKP.Methods Strains of Klebsiella pneumoniae isolated from clinical samples of burn patients hospitalized in our unit from February to December 2016 were collected.The diameters of inhibition zone of imipemen or meropenem susceptibility disk of the above strains were≤22 mm.Kirby-Bauer disk diffusion method and automated instrument were applied to test drug resistance of the strains to 17 antibiotics of cephalosporins,aminoglycosides,sulfonamides,quinolones,and carbapenems.Pulsed-field gel electrophoresis (PFGE) was used to analyze homology of the strains.Crystal violet staining was applied to assess ability of biofilm formation of the strains.The hypermucoviscosity (HM) phenotype of the strains was determined by string test.Polymerase chain reaction was used to detect common carbapenemase genes ofbla KPC,bla IMP,bla OXA-48,and bla NDM'capsular serotype genes of K1,K2,and K57,and virulence-associated gene of rmpA.Results (1) A total of 29 CRKP strains were isolated.The 29 CRKP strains were with high drug resistance rate to carbapenems antibiotics of imipenen,meropenem,and ertapenem,and cephalosporins,aminoglycosides,and quinolones antibiotics,while the strains were with low drug resistance rate to sulfonamides antibiotics and tegafycline.(2) The 29 CRKP strains had 4 types of A,B,C,and D according to PFGE,with 11 strains of type A,10 strains of type B,6 strains of type C,and 2 strains of type D.(3) Among the 29 CRKP strains,25 strains were positive in biofilm formation,with positive rate of 86.2％.(4) None of the 29 CRKP strains was positive in the string test with HM phenotype.(5) All the 29 CRKP strains carried carbapenemase genes.Among the 29 CRKP strains,11 strains carried both bla NDM-1 and bla OXA-48 genes,1 strain carried both bla NDM-1 and bla KPC-2 genes,12 strains only carried bla KPC-2 gene,and 5 strains only carried bla NDM-1 gene.The 79.3％ (23/29)strains were completely resistant to 3 kinds of carbapenems antibiotics.(6) Among the 29 CRKP strains,3 strains carried K2 gene,2 of which were completely resistant to 3 kinds of carbapenems antibiotics,1 strain carried rmpA gene,and no strain carried K1 or K57 gene.Conclusions The detection rate of CRKP isolated from burn patients hospitalized in our unit is high.The strains are mostly extensively drug-resistant bacteria,and the mechanism of drug resistance of which is complicated.There may have clonal spread of CRKP.And appropriate measures should be taken timely and effectively to prevent nosocomial spread of CRKP.