ICU患者血流感染耐碳青霉烯类鲍曼不动杆菌同源性分析

Homology analysis on carbapenemresistant Acinetobacter baumannii isolated from patients with bloodstream infection in intensive care unit

摘要:

目的了解某院重症监护病房(ICU)血流感染患者分离的耐碳青霉烯类鲍曼不动杆菌(CRAB)同源性。方法收集该院ICU 2012年1—12月血流感染患者血液、下呼吸道和静脉导管尖端分离的CRAB，进行药物敏感试验，以及运用脉冲场凝胶电泳（PFGE）分析菌株同源性。结果50株CRAB分离自患者血液26株、下呼吸道20株、静脉导管4株；对哌拉西林、哌拉西林/他唑巴坦、氨苄西林/舒巴坦、头孢曲松、头孢噻肟、头孢吡肟、亚胺培南、美罗培南、环丙沙星的耐药率均为100％。对分离自患者血液（26株）、呼吸道（6株）和静脉导管尖端（4株）的36株CRAB 进行PFGE，结果表明主要为7个PFGE型(A～G)，其中A克隆5株，B克隆2株，C克隆3株，D克隆4株，E克隆3株，F克隆8株，G克隆3株；其余8株菌为散发。该ICU分为Ⅰ、Ⅱ区，其中A、B、F克隆在两个病区间均存在。3例患者不同部位分离的CRAB为同一克隆，其中2例血液、下呼吸道、静脉导管尖端为同一克隆，另1例血液和下呼吸道为同一克隆。对其中6例患者下呼吸道分离的CRAB进行PFGE分型，3例同属D克隆。对12例血流感染患者静脉导管尖端进行培养，4例患者培养阳性，且为CRAB，分别与各自血液分离株为同一克隆。结论ICU存在CRAB血流感染流行，患者间交叉传播是医院流行的主要方式。

Abstract:

ObjectiveTo study the homology of carbapenemresistant Acinetobacter baumannii (CRAB) isolated from patients with bloodstream infection in an intensive care unit(ICU).MethodsCRAB isolated from bloodstream， lower respiratory tract， and venous catheter tips of patients with bloodstream infection in JanuaryDecember 2012 were collected and performed antimicrobial susceptibility testing, homology of isolates were identified by pulsedfield gel electrophoresis (PFGE).Results50 CRAB strains were isolated from patients’ bloodstream(n=26), lower respiratory tract (n=20), and venous catheters  (n=4); the resistant rates of CRAB to piperacillin, piperacillin / tazobactam, ampicillin / sulbactam, ceftriaxone, cefotaxime, cefepime, imipenem, meropenem, and ciprofloxacin were all 100%. 36 CRAB isolates from patients’ bloodstream (n=26),  respiratory tract (n=6), and venous catheter tips(n=4) were performed PFGE, 7 major PFGE genotypes(AG) were identified,  including clone A (n=5 )，B(n=2)，C(n=3)，D(n=4)，E(n=3)，F(n=8)，and G(n=3); the other 8 isolates were sporadic strains. This ICU was divided into section Ⅰand Ⅱ,  clone A, B, and F all  existed in both sections. CRAB isolated from different sites of 3 patients were of the same clone,  2 of these patients isolated the same clone of CRAB from bloodstream, lower respiratory tract, and venous catheter tips, 1 isolated the same clone of CRAB from bloodstream and lower respiratory tract. PFGE genotyping of CRAB from 6 patients’ lower respiratory tract revealed that 3 strains were clone D.Venous catheter tips of 12 patients were performed culture， 4 were positive for CRAB, and CRAB was of the same clone as that from patient’s respective bloodstream.ConclusionCRAB bloodstream infection prevail in ICU, cross transmission among patients is the main mode of hospital epidemic.