RESUMO
Objective To investigate the prevalence of integrons in A.baumannii isolates,analyze the correlation between inte- grons and resistance of A.baumannii,and study the resistance genes in integrons.Methods A total of 106 strains of A.bau- mannii were collected to test the antibiotic susceptibility by disk diffusion method.The classification of integrons was per- formed by analyzing the positive PCR products using restriction fragment length polymorphism (RFLP).The variable region of integrons was amplified by integron PCR.RFLP and DNA sequencing were used to analyze the resistance genes in integrons. Results About 52.8% (56/106) of the isolates showed integron positive.PCR-RFLP analysis revealed that they were all class I integrons.About 94.6%(53/56) of the positive strains with integrons owned the variable region,which was confirmed by integron PCR.The sizes of the amplicons ranged from 0.15 kb to 2.8 kb.All together 7 different cassette arrays were detec- ted,including genes coding resistance to aminoglycosides (aadA1,aadA2,aadA5,aadB,aacA4),sulphonamides (dfrⅫ, dfr17),?-lactam compounds (bla_(ara-10)),chloramphenicol (catB-like,catB8),and two open reading frames (orfF,orfI) with unknown function.A novel cassette array orfI-aadA1 was reported,and its GenBank accession number was DQ092497.Conclu- sions Class I integrons are widespread in A.baumannii isolates in Nanjing.The integrons are closely associated with the resist- ance and multidrug resistance in A.baumannii isolates.
RESUMO
Objective Clinical significance of using ELISA to determine ?-amyloid(A?)_(1-42) antibody levels in the sera of patients with Alzheimer's disease(AD).Methods 96 wells PVC plate was coated with A?_(1-42)peptide.Serum of AD patient was competing with mouse A?_(1-42)monoclonal antibody in this assay.The second antibody was horseradish peroxidase(HRP)conjugated goat anti-mouse IgG.Serum A?_(1-42)antibody levels were determined by ELISA.Results The sensitivity of this assay was about 1 ng/ml.The recovery rate of this test was between 96.5% and 104.7%.The residual A?_(1-42)antibody levels in human serum or horse serum after A?_(1-42)antibody was removed by absorption were less than 1 ng/ml. Serum A?_(1-42)antibody levels in 37 AD patients[(5.1?1.9)ng/ml]were remarkably lower than those in normal people[(12.6?3.3)ng/ml,P