RESUMO
@#Objective To detect the virulence gene of E. coli from calves with diarrhea in Tongliao City，Inner Mongolia Autonomous Region，China and analyze its antimicrobial resistance as well as the distribution of antimicrobial resistant genes. Methods The sensitivities of 82 E. coli isolates from the fecal samples of calves with diarrhea to thirteen kinds of antibiotics were determined by disk diffusion test. The carrying statuses of thirteen virulence genes and twelve antimicrobial resistant genes of the E. coli isolates were determined by PCR，based on which the phylogenetic background was investigated. Results Of the 82 pathogenic E. coli isolates，48. 78%（40／82）、31. 71%（26／82）、14. 63%（12／82）and 4. 88%（4／82）belonged to phylogenic groups A，B1，B2 and D respectively，indicating that the prominent one was group A. A total of 11 virulence genes were detected in 82 isolates. The detection rates of irp2，fyuA，eaeA and STb genes were 79. 27%（65／82），63. 41%（52／82），53. 66%（44／82）and 50%（41／82）respectively，while those of other virulence genes were less than 50%，and no tsh or LT1 was detected. The 82 isolates were significantly resistant to 13 kinds of antibiotics，in which the resistant rates to tetracycline，doxycycline and amoxicillin were 100%（82／82），97. 56%（80／82）and 90. 24%（74／82）respectively. All the isolates were mutidrug resistant，most of which were resistant to eight kinds of antibiotics（16／82，19. 51%）. A total of twelve antimicrobial resistant genes were detected in the 82 isolates，in which the positive rates of genes resistant to β ‑ lactams（blaTEM），sulfonamide（sul1 and sul2），tetracycline（tetB and tetD）and aminoglycosides（aadB）were more than 70%. Conclusion The 82 pathogenic E. coli isolates mainly belonged to group A，with high detection rates of virulence gene and antimicrobial resistant gene as well as high and multiple drug resistance. The study provided a reference for the prevention and treatment of and clinical medication of E. coli‑associated diseases in calves in Tongliao Region.
RESUMO
<p><b>OBJECTIVE</b>To explore the effect of changes of processing time on the surface properties of titanium coating formed by micro-arc oxidation (MAO).</p><p><b>METHODS</b>Forty-four disc-shaped pure titanium specimens with 10 mm diameter and 1 mm thickness were equally divided into 4 groups and processed by MAO technique in electrolytes containing 0.2 mol/L calcium acetate (CA) and 0.02 mol/L β-glycerol phosphate disodium salt pentahydrate (β-GP). The processing time were set at 1 min, 5 min, 10 min and 15 min respectively. The topograph of the MAO film surface and the film-substrate interface was observed by a scanning electron microscopy (SEM), and the composition was analyzed by an energy dispersive spectroscope (EDS) incorporated in the SEM. The phase and the microstructure of the film were analyzed by X-ray diffraction (XRD). The roughness of the film was measured using a roughness tester. The surface static contact angle was detected by a contact angle measurement instrument and the surface energy was calculated accordingly.</p><p><b>RESULTS</b>With the increase of processing time from 1 min to 15 min, the pore size increased from (1.30 ± 0.07) µm to (1.55 ± 0.09) µm, and film thickness increased from (10.2 ± 1.1) µm to (20.9 ± 2.9) µm. The content of the Ca in the film increased accordingly, and Ca/P increased from 1.99 to 2.45, and the surface energy increased from 24.62 mJ/m(2) to 39.49 mJ/m(2). Meanwhile, the XRD pattern indicated that rutile increased but anatase and titanium decreased gradually. At the time of 15 min, part of the MAO film peeled off.</p><p><b>CONCLUSIONS</b>Processing time has impact on the thickness, surface topography, crystal component and surface energy of titanium MAO coating. MAO film treated for 5 - 10 min demonstrated favorable surface properties.</p>