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

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.