Objective To investigate the distribution and the antibiotic resistance genes carried by classⅠintegron and insertion sequence common region(ISCR1)among clinical isolates of Acinetobacter baumannii. Methods Fifty-one clinical isolates of multidrug-resistant Acinetobacter baumannii were collected. Polymerase chain reaction method was used to detect the classⅠintegrase gene, variable region of classⅠintegron, ISCR1 and genes related to antibiotics resistance lo-cated downstream of ISCR1 in 51 multidrug-resistant Acinetobacter baumannii. Antibiotics resistance genes carried by classⅠintegron and ISCR1 were performed by DNA sequencing. The relationship between classⅠintegron and ISCR1 was detected by PCR-mapping. Results Among 51 multidrug-resistant Acinetobacter baumannii isolates, 45 strains were found con-taining classⅠintegrase genes, 32 strains were found containing variable regions. Sequencing results showed that the gene cassette arrays were aacA4-catB8-aadA1, aacC1-orfA-orf-B-aadA1 and blaPSE-1-aadA2-cmlA1-aadA1. Twenty-two strains were found containing ISCR1 and 5 strains were found containing resistance genes located downstream of ISCR1. DNA sequencing results showed the resistant gene of qnrA1-ampR. The results of PCR-mapping showed that ISCR1 located directly downstream of 3' conserved segment of classⅠintegron in 20 Acinetobacter baumannii strains. Conclusion ClassⅠintegron and ISCR1 play an important role in mechanisms of drug resistance of Acinetobacter baumannii. ClassⅠintegron and ISCR1 could connect in series in Acinetobacter baumannii.

Objectives To evaluate plain radiographs and computed tomography (CT) scans in respect of assessment of articular fragment displacements (step and gap) in displaced acetabular fractures. Methods A retrospective evaluation was done to analyze the CT scans and plain radiographs of 64 patients who had been treated for displaced acetabular fractures in our hospital from January 1998 to May 2003. Of them, 20 met the inclusion criteria. In a blind method, 3 independent reviewers measured step and gap deformities on plain radiographs and CT scans utilizing a standardized measurement technique. The sensitivity and specificity of plain radiographs in detecting step and gap displacements (2 mm and 4 mm) in comparison of those of CT scans were determined. Moreover, intraclass correlation coefficient and intraobserver reliability were also calculated. Results Compared with CT, plain radiographs showed poor sensitivity in detecting step deformity (sensitivity = 44.3%). As far as fracture type was concerned, plain radiographs were particularly poor at detecting step deformity in fractures involving a single column of the acetabulum (sensitivity = 0%). Excellent intraobserver and intraclass reliability existed among the 3 reviewers. Conclusions Compared with CT scans, plain radiographs are poorly sensitive in detection of step and gap deformities in patients with acetabular fractures, and particularly poor at detecting step deformities. Therefore, in treatment of displaced acetabular fractures, CT scans are essential and should not only be used together with plain radiographs in the preoperative evaluation but also be considered in the postoperative assessment of fracture reduction and predicting future outcomes.