Objective To reduce experimental costs and improve the utilization of S9, we use spiral coating technique to evaluate the activity of rat liver S9 prepared by combination inducing method as well as to establish cryopreservation method.Methods Using spiral coating technique and Ames test to evaluate the activity of self-made rat liver S9 and commercially available S9 separately.We use glycerinum as protective agent to establish cryogenic storage method, so that S9 can be in liquid form stored at -20 °C in the refrigerator.Results In the Ames assay as well as using spiral coating technique, the number of revertant colonies had dose-response relationship among the dose of S9.When conditions were the same, the number of revertant colonies in positive control was at the approximate level in presense of self-made rat liver S9 and commercially available S9 respectively.When S9 ( concentration of 38%) was added to the amount at 1.48 ~6.62 μL /μL broth dose of bacteria, it can significantly induced Salmonella typhimurium histidine strains TA100, reverse mutation rates were three times more than the control group.Conclusions Spiral coating technique can successfully evaluate the activity of rat liver S9.The inducing method of combination of PB and BF can take the place of the unducing method of PCBs in the preparation of Liver homogenate S9.

Objective To establish the chromatographic fingerprint of Curcuma wenyujin by HPLC.Methods The chromatographic fingerprint of C.wenyujin was established by HPLC with Shimadzu VP-ODS C18 column(250 mm?4.6 mm,5 ?m),acetonitrile-water(0.1 phosphoric acid) gradient elution,the flow rate of 1.0 mL/min,column temperatures of 30 ℃,and detective wavelength at 210 nm.ResultsTaking germacrone as the reference peak,14 common-peaks were selected as the fingerprint peaks.The similarities among samples of C.wenyujin among 19 approved samples and their standard chromatographic fingerprints were calculated with a software "Similarity Evaluation System for Chromatographic Fingerprint of Chinese Materia Medica" published by GPC(Version 2004A) and cluster analysis.ConclusionThis method with better accuracy and reproducibility could be used in the quality control of C.wenyujin.

BACKGROUND: The complicated localization of intramedullary nails and osteotomy more dependent on surgeons' experience limit the application of conventional total knee arthroplasty (TKA). The occurrence of three-dimensional (3D) printing technology can achieve precise localization and osteotomy in TKA.OBJECTIVE: To explore the effectiveness of 3D printing technology-aided TKA versus conventional TKA for genu varum.METHODS: Thirty-four patients with genu varum undergoing primary unilateral TKA were recruited and were then divided into two groups (n=17 per group) in accordance with the random number table. One group was treated with TKA with 3D printing guild plate (3D printing group), while the other group received the conventional TKA (conventional group).The intraoperative and postoperative blood loss, operation time, as well as the Hospital for Special Surgery score, range of motion, and lower limb mechanical alignment at 2 weeks postoperatively were compared between two groups.RESULTS AND CONCLUSION: (1) The range of motion of knee in the 3D printing group was larger than that in the conventional group, but had no significant difference at 2 weeks postoperatively (P=0.744). (2) There was no significant difference in the Hospital for Special Surgery scores between two groups at 2 weeks postoperatively (P= 0.532). (3) The postoperative lower limb mechanical alignment showed no significant difference between two groups (t=0.218, P=0.632).(4) The operation time in the 3D printing group was significantly shorter than that in the conventional group (P=0.000). (5) The blood loss in the 3D printing group was significantly less than that in the conventional group (P=0.000). (6) Our findings indicate that 3D printing technology-aided TKA exhibits similar results to the conventional TKA in the Hospital for Special Surgery scores, range of motion, and lower limb mechanical alignment, but it shortens the operation time,reduces the blood loss, and achieves precise osteotomy, which is available for the elderly with poor basic condition, and weak tolerance of surgery.

Objective To study on chromosome-and plasmid-mediated fluoroquinolones-resistant in Escherichia coli isolated from fecal samples of chicken,swine and people around the farm.Methods Anti-microbial susceptibility testing was carried out by disk diffusion testing and bmth microdilution testing.gyrA,gyrB,parC,pareE,qnr and aac(6')-I b-cr were examined by PCR,and the products were sequenced.Ex-presion of aac(6')-I b-cr by conjunction was tested too.Results The resistance to antimicmbial agents was much higher in strains isolated from chicken than that from swine and human.Among the E coli strains examined by PCR,most resistant strains carried two mutations in gyrA and/or two mutations in parC.In ad-dition,some resistant strains had mutations in parE with MIC of ciprofloxacin>16μg/ml.No(resistance) mutation was found in gyrB.Seven strains(25.O%)and one strain(11.1%)had aac(6)-I b-cr,variant isolated from chicken and swine,respectively.The strains harboring cr variant enzyme reduced the suscepti-bility to ciprofloxacin and norfloxacin by N-acetylation of the drugs. Conclusion There is a close relation-ship between high level quinolone resistance and the numbers of amino acid exchange in DNA gyrase and to-poisomeraae IV,and aac(6)-I b-cr may play some role for fluoroquinolone resistance.

Objectives To investigate characterization of imipenem resistance among imipenem non susceptible Pseudomonas aeruginosa isolated from patients who treated without imipenem and explore risk factors of imipenem resistance.Methods From April,2006 to March,2008,a total of 37 non-susceptible to imipenem without imipenem therapy isolates were collected from affiliated 3201st Hospital of Medical College of Xi'an Jiaotong University.The minimum inhibition concentration (MIC) to 11 antimicrobial agents were determined by the broth dilution method.We also tested imipenem MIC combined with efflux pump inhibitor PAβN.PCR was performed to check for the presence of carbapenem-hydrolylzing MBL genes and oprD gene.The expression level of oprD2 and ampC were evaluated by qRT-PCR.Molecular typing was performed using PFGE.Results There is significant difference ( t =- 2.9004,P ＜ 0.01 ) of the average number days of therapy between with two or more antibiotics in the 16 patients (20.0 ± 9.5 ) d and that with only one antibiotic in the other 21 patients ( 12.6 ± 4.4 ) d before imipenem-non-susceptible strains were isolated.In all 37 strains,32 strains showed resistance to more than three antibiotics.The MBL gene ( IMP-9 ) was only found in one strain,but its phenotype is negative,oprD2 gene from the 29 strains were found forward inserted by ISpa1328.Thirty-five isolated were considered to have no oprD expression.The patterns of the total DNA of 37 strains appeared six PFGE types.The 26 strains belonged to C2 PFGE type.In the presence of PAβN,all 37 strains increased sensitivity to meropenem.Conclusion Fluoroquinolones and cephalosporins treatment could play an important role in imipenem non-susceptible production in the research isolates.

Objective To characterized the Salmonella enterica serotype typhimurium isolates recovered during 2002 to 2005 from outpatients in Tongji Hospital, Wuhan China. Methods The 36 isolates from Tongji Hospital were characterized by antimicrobial-susceptibility testing and screened for class Ⅰ integrons, beta-lactamase genes, qnr, aac(6')-Ib-cr and mutations in the quinolone resistance determining regions (QRDRs) by PCR and DNA sequence analysis. All isolates were also characterized by pulsed-fieldgel electrophoresis (PFGE) to determine the genetic relateness among these isolates. Results All isolates displayed multidrug resistance and most of them harbored class Ⅰ integrons. Ciprofloxacin-resistant isolates showed significant difference compared with ciprofloxacin-susceptible isolates after PFGE analysis. All 31 ciprofloxacin resistant isolates carried at least three mutations in the QRDR of GyrA and ParC. Three ciprofloxacin resistant isolates had accumulated additional mutation in ParE. Five isolates harboring the OXA-30. Enzyme showed intermediate resistant to eefepime. Conclusions Fluoroquinolone-resistant Salmonella typhimurium isolates were widely distributed among the outpatients in Wuhan and the resistant isolates accumulated multiple antimicrobial resistant mechanisms and showed unique genetic profiles. The state and local health authority must remain vigilant for the emergence of Salmonella typhimurium resistant to both third generation cephalosporins and fluoroquinolonos.

Objective To study on plasmid-mediated quinolone-resistant in Escherichia coli strains isolated from fecal samples of chicken and swine from the nine farms around our country.Methods Antimi-crobial susceptibility testing was carried out by broth microdilution testing,gyrA,gyrB,parC,qnr and aac (6')- Ⅰ b-cr were examined by PCR,and the products were sequenced.Conjugation experiment was carried out to proved that the plasmid-mediated quinolone resistance was transferable.Results In the total 818 animal isolates,qnr and aac genes were detected in 38 (4.6%) and 75 (9.2%) strains.The qnrA,qnrB,and qnrS genes were detected in 1 (0.1%),9 (1.1%) and 28 (3.4%) of the isolates.All isolates were negative for qnrC,qnrD genes.Conclusion There is a close relationship between high level quinolone resistance and plasmid-mediated quinolone resistance.The results of the current study highlight food-producing animals as a potential reservoir of antimicrobial-resistant bacteria and clinically important resistance genes.More attention should be paid to the surveillance of such strains.

Objective To characterize the roles of different quinolone resistance mechanisms in quinolone-resistant Escherichia coli isolates,including different topoisomerase point mutations,efflux pumps and outer membrane proteins.Methotis Through homologous gene recombination methods,different quinolone-resistant mechanisms of E. coli mutants were constructed and the susceptibility changes of these mutants to different antimicrobials were measured.Resuits Efflux pumps AcrAB and outer membrane protein TolC played different roles in different E. coli isolates.Compared with other mechanisms,the mutations in topoisomerases played a dominant role in quinolone resistance.Only the mutations jn parC had no effect on quinolone resistance,which further confirmed parC was the secondary target of quinolones in E.coli.Fluoroquinolone susceptible E.coli would automatically become highly resistant to quinolones after acquiring the point mutations in both gyrA(S83L,D87N)and parC(S80I,A108V),but not requiring the over-expres-sion of efflux.Conclusion The mutations in topoisomerases play a dominant role in E.coli quinolone resistance,and the mutations in both gyrA and parC are required.

Objective To compare the efficiency of domestic MALDI-TOF MS systems Autof MS, Korea Asta MicroIDsys and Bruker Biotyper for common microorganisms identification. Methods This is a methodological comparison study. A total of 169 strains were isolated either from food in our laboratory since 2011 to 2018 or clinical samples in Chinese PLA General Hospital since 2016 to 2018. A total of 39 genus, 95 species were identified through Vitek2 Compact combined with 16S rDNA or ITS sequencing. Among them, a total of 93 Gram-negative bacteria strains, 65 Gram-positive bacteria strains, and 11 yeast strains were identified by three MALDI-TOF MS systems parallelly, while using extended direct smear method for sample preparation. The SPSS 18.0 software was used for data Statistical analysis. Results By Mass spectrometry identification, when 169 strains were at the species level confidence score and acceptable score level, 91.12％ (154/169) was correctly identified to species level by Autof MS system, 86.39％ (146/169) by ASTA MS system, and 81.66％ (138 / 169) by Bruker Biotyper MS system. The difference of identification accuracy to species level between Autof MS and Bruker Biotyper MS was statistically significant. Besides, the accuracy of genus identi fi cation was 98.82％ (167 / 169) by Autof MS mass spectrometry system and 97.04％ (164 / 169) by both ASTA MicroIDsys and Bruker Biotyper mass spectrometry system. The differences of identification accuracy to genus level among the three MS systems were not significant. Conclusions All of the three MS systems have good identification capability for common microorganisms. Autof MS systems performed slightly better than Bruker Biotyper MS systems in species level identification.

OBJECTIVETo determine Campylobacter contamination level and antimicrobial resistance patterns from chicken carcasses in supermarkets and farmer's markets of 9 districts in Beijing.

METHODSFrom August 2012 to July 2013, whole chicken carcasses (n = 240) were collected from 27 supermarkets and 18 farmer's markets of nine districts in Beijing. The level of Campylobacter contamination was enumerated by plate counting method using the modified Karmali and modified Preston agar. Presumptive Campylobacter isolates were identified and characterized by gram stain, agglumination test and a multiplex PCR method. The level of Campylobacter contamination was calculated following the USDA/FSIS Campylobacter enumeration method. Selected 151 Campylobacter isolates were further characterized by minimal inhibitory concentrations(MICs) of eight antimicrobials.

RESULTSA total of 26.3% (63/240) of the retail whole chicken carcasses were contaminated by Campylobacter and 151 Campylobacter isolates were recovered, including 85 Campylobacter jejuni isolates and 66 Campylobacter coli isolates. The P25, P50, P75 of Campylobacter contamination concentration were 7.5, 45.0 and 350.0 CFU/g, respectively. The antimicrobial resistance rate of C. jejuni and C. coli were as the following: azithromycin(AZI, 13% (11/85), 82% (54/85)), chloramphenicol (CHL, 33% (28/85), 42% (28/85)), ciprofloxacin (CIP, 95% (81/85), 100% (85/85)), doxycycline (DOX, 38% (32/85), 80% (53/85)), erythromycin (ERY, 12% (10/85), 82% (54/85)), gentamicin (GEN, 25% (21/85), 68% (45/85)), tetracycline (TET, 67% (57/85), 73% (62/85)), all isolates were susceptible to meropenem (MEP). The multi-drug resistance ratio of C. jejuni (55% (47/85) )was significantly lower than that (86% (57/66) )of C. coli (χ(2) = 16.70, P < 0.01). Among 151 Campylobacter isolates, 21 antimicrobial resistance patterns were identified, including 20 patterns among C. jejuni isolates and 10 patterns among C.coli isolates. Among C.jejuni isolates, CIP-DOX-TET was dominant (22% (19/85)), followed by CIP-TET (14% (12/85)), CHL-CIP-TET(9% (8/85)) and CHL-CIP-GEN (7% (6/85)). Among C.coli isolates,AZI-CHL-CIP-DOX-ERY-GEN-TET (35% (23/66)) was the dominant, followed by AZI-CIP-DOX-ERY-GEN-TET (21% (14/66) )and AZI-CIP-DOX-ERY-TET(15% (10/66)).

CONCLUSIONOur findings showed a high prevalence and concentration of Campylobacter contamination in retail chicken carcasses of nine districts in Beijing, especially the on-site slaughtered chicken from the farmer's markets. The resistance levels of these recovered Campylobacter isolates were serious.

Animals ; Anti-Bacterial Agents ; Campylobacter coli ; classification ; drug effects ; Campylobacter jejuni ; classification ; drug effects ; Chickens ; Drug Resistance, Multiple, Bacterial ; Food Microbiology ; Meat ; Microbial Sensitivity Tests