Objective:To explore the effect of sub-inhibitory concentration of imipenem on the bio-activities of methicillin resistant Staphylococcus aureus(MRSA) and illuminate the inhibitory effects of carbapenem antibioty on the activity of MRSA and their mechanisms,and to provide the basis for using the carbapenem antibiotics in the treatment of MRSA infection.Methods:Five ST239 type of MRSA clinical isolates were selected and were co-cultured with 1/10 and 1/2 minimal inhibitory concentration (MIC) of imipenem for 1.5,6.0 and 12.0 h,which were divided into control group(no imipenem),1/10MIC group(1/10MIC of imipenem),and 1/2MIC group(1/2MIC of imipenem).Fluorescent quantitative real-time PCR method was used to determine the relative mRNA expression levels of virulence-related genes fibronectin A(fnbA),staphylococcal protein A(spa),α-hemolysin(Hla),leukocidin D(lek-D),leukocidin E(lek-E),and enterotoxin A in various groups;Spectrophotometry was used to detect the proliferation activity of MRSA strains in various groups in vitro.Results:After co-culture for 6.0 and 12.0 h,the proliferation activities of 5 trains of MRSA in 1/2MIC group in vitro were significantly decreased compared with control group (P<0.01).The relative mRNA expression levels of 6 virulence-related genes of 5 strains of MRSA in 1/10MIC and 1/2MIC groups were significantly decreased compared with control group(P<0.01).After co-culture for 12.0 h,the mRNA expressions of all the tested virulence-related genes were not found.Conclusion:The sub-inhibitory concentration of imipenem shows obviously inhibitory effect on the mRNA expressions of multiple virulence-related genes of ST 239 type of MRSA strains,and higher concentration of imipenem can suppress the proliferation of MRSA strains in vitro.Imipenem shows the potential value in the treatment of the severe MRSA infected patients.

Objective To study the genotypic and biological characteristics of catheter-related MRSE isolates and to further provide information for the diagnosis and prevention of catheter-related bloodstream infection. Methods Thirty strains of catheter-related MRSE isolates were collected from venosus blood and whole blood of 30 inpatients including 20 males and 10 females from Beijing Tongren Hospital, Capital Medical University from January 2006 to December 2009. The genetic features of these strains were determined by MLST. PCR was used to detect the icoA gene (encoding the polysaccharide intercellular adhesion associated with pathogenicity), and the antimicrobial susceptibility test was detected by disc diffusion test. Results A total of 15 STs were obtained from 30 strains ST259, ST20, ST2 and ST235 were common clones obtained from 17 strains. Four novel STs were found and uploaded to the MLST database (http://www. mlst. net), including ST259 (6 strains), ST260 (1 strain), ST261 (1 strain) and ST262 (1 strain). The ST259 was the dominant clone of catheter-related MRSE isolates in this hospital, and 3 strains carrying icaA gene were detected in this study. Conclusion Some ST259 isolates express high pathogenesis among the four novel STs, which may make them as the pandemic strains in nosocomial infection, and this would increase the difficulty of the prevention and control of nosocomial infection.

Objective Based on active monitoring MRSA carriage for hospitalized patients, the relationship between colonization pressure and MRSA cross transmission in wards without rigorous contactisolation measures was analyzed, and the role of colonization pressure in predicting MRSA cross transmission was further evaluated. Methods From March to December 2009, active MRSA colonization screening was performed for 240 hospitalized patients in emergency ward and 94 cases in RICU in our hospital. rep-PCR method was employed to do homology analysis on MRSA strains obtained in this study. MRSA weekly colonization pressure, threshold colonization pressure ,cross transmission rate were calculated respectively. RR of MRSA cross transmission under higher level of colonization pressure and lower level of colonization pressure was analyzed. Results MRSA carriage rates on admission for patients in emergency wards and RICU were 6. 25% (15/2A0) and 13. 83 % (13/94) ,and MRSA cross transmission occurred in 13 weeks and 14 weeks in above two units, respectively. Threshold colonization pressures for above two units were 6. 49%and 17. 66%, respectively. For emergency ward, the MRSA cross transmission rate under higher level of colonization pressure was significantly higher than that under lower level of colonization pressure (x2 = 7. 10,P＜0. 01), the RR of MRSA transmission was 9. 61 (95% CI:1. 25-74.00). For RICU, the MRSA cross transmission rate under higher level of colonization pressure was significantly higher than that under lower level of colonization pressure(x2 = 12. 60, P＜0. 01 ), the RR of MRSA transmission was 15.87 (95% CI:2. 06-122. 10). Conclusions Higher level of colonization pressure is an important risk factor for MRSA transmission, and average colonization pressure can be used as a prediction index for MRSA transmission and strengthening prevention and control measures.

Objective To elucidate the difference between methicillin-resistant Staphylococcus aureus (MRSA)and methicillin-sensitive S.aureus (MSSA)in terms of genotypes and distribution of virulence genes with the clinical strains isolated from Hohhot,and explore the relationship between the changing resistance of S.aureus and the virulence transition.Methods Pulsed field gel electrophoresis (PFGE)and multi locus sequence typing (MLST)methods were employed to do molecular typing for 30 MRSA strains and 30 MSSA strains isolated from inpatients in Hohhot,Inner Mongolia.PCR method was used to profile the distribution of virulence genes among these strains.Results PFGE typing results showed that 60 S.aureus strains were classified into 19 major types.MSSA strains belonged to 16 types,mainly types I and H.MRSA strains mainly belonged to types of K and M.Among the 20 strains with different PFGE types,MRSA strains were mainly identified as ST-239 type.but the prevalence of sec ,seg ,sei,sem,sen,seo,fnbB ,ebpS and cap 5 was higher in MSSA strains than in MRSA strains (P<0.05).Conclusions The clinical strains of S .aureus isolated from Hohhot showed diverse genotyping features.ST-239 was the major PFGE type of MRSA strains.The prevalence of virulence genes was higher in MSSA strains than in MRSA strains. Characteristic cluster is found for specific virulence genes.The results also suggest that acquisition of specific antibiotic resistance may be associated with change of specific virulence feature in S.aureus.

BACKGROUND:The hardened acrylic resin bone cement composite after implantation into human body can resist an intensity of 78-93 MPa. But a large amount of heat energy is released by bone cement during the process of solidification and it wil kil normal cel s, leading to peripheral tissue necrosis. OBJECTIVE:To investigate the characteristics of induced knee joint osteoarthritis after application of acrylic resin bone cement composite as a bone substitute for subchondral bone. METHODS:Thirty male Japanese big ear rabbits were randomly and equal y divided into four experimental groups (A, B, C, D) and a blank control group. After removal of subchondral bone on the right medial tibial plateau, polymethyl methacrylate powder/hydroxyapatite composite materials were implanted in rabbits in the experimental groups A, B, C, and D. Rabbits in the blank control group were only subjected to exposure of periosteum on the left medial tibial plateau. At 3, 6, 9 and 12 weeks after removal of subchondral bone, rabbits in the experimental groups A, B, C and D were sacrificed, and subchondral bone specimens were taken for hematoxylin-eosin staining and matrix metal oproteinase expression analysis. At the same time, interleukin-1βand tumor necrosis factor-ɑ levels in the synovial fluid were determined. RESULTS AND CONCLUSION:Mankin score in the experimental group C was significantly higher than in the blank control group and experimental group A (P<0.05). Mankin score in the experimental group D was significantly higher than in the experimental group B (P<0.05). The gray scale of matrix metal oproteinase-1 was highest in the blank control group, fol owed by experimental groups A, B, C, and the last in the experimental group D (P<0.05). Interleukin-1β and tumor necrosis factor-ɑ levels in the synovial fluid were highest in the experimental group D, fol owed by experimental groups C, B, A and the last in the blank control group (P<0.05). These findings suggest that acrylic resin bone cement composite as a bone substitute for subchondral bone induces knee joint osteoarthritis and leads to increases in matrix metal oproteinase-1 and tumor necrosis factor-ɑ levels in the synovial fluid.

Objective To investigate the implementation effects of control measures and the dynamic prevalence of drinking-water-borne endemic fluorosis,in order to provide a scientific basis for developing control measures against the disease.Methods According to the Surveillance Scheme of Drinking-Water-Borne Endemic Fluorosis,137 counties were selected as monitoring counties in national 27 provinces (autonomous regions,municipalities) and Xin Jiang Production and Construction Corps.Three epidemic villages were selected as fixed monitoring villages in each county.The operating condition and the fluoride level of water improvement projects were investigated in the villages with water improvement projects.The fluoride level of drinking water was tested in the villages without water improvement projects.The fluoride content in drinking water was detected by the Standard Test Method for Drinking Water (GB/T 5750.5-2006).The preyalence of dental fluorosis of all children aged 8-12 were surveyed,and dental fluorosis was diagnosed by Clinical Diagnostic Criteria of Dental Fluorosis (WS/T 208-2011).Results ①427 villages were surveyed in 2012,among which the villages with water improvement projects accounted for 75.88％ (324/427).② 299 water improvement projects were investigated.Normal operation rates of those were 89.30％ (267/299).The qualified rate of fluoride content was 75.78％ (219/289).Totally 103 villages without water improvement projects were monitored.Villages with fluoride level ＞ 1.2-2.0 mg/L,＞ 2.0-4.0 mg/L and ＞ 4.0 mg/L accounted for 48.54％ (50/103),29.13％ (30/103) and 9.71％ (10/103),respectively.(③The national detection rate of dental fluorosis and community fluorosis index (CFI) in children aged 8-12 were 31.24％ (8 677/27 773) and 0.66.The detection rate and CFI of the villages with normal operation projects and the qualified fluoride content were 24.04％ (3 999/16 634) and 0.51.The detection rate and CFI of the villages with water improvement projects under abnormal operation or excessive fluoride were 40.77％ (1 654/4 057) and 0.91.The rate and CFI of the villages without water improvement projects were 42.70％ (3 024/7 082) and 0.86.Conclusions The rate of water improvement projects of the whole country is lower.The national normal operation rate of water defluoridation improvement projects is below 90％,and the qualified rate of fluoride content in drinking water is below 80％.The prevalence of dental fluorosis in children aged 8-12 is very mild.

Objective To investigate the protective effects of Angelicae Sinensis Radix and Angelicae Sinensis Radix polysaccharides on immune function injury induced by X rays in SD rats. Methods Forty SD rats were randomly divided into control group, model group, Angelicae Sinensis Radix Decoction group, Angelicae Sinensis Radix polysaccharide group and positive medicine group. After routine feeding for 14 day, each administration group was given relevant medicine for gavage, while control group and model group were given the same amount of distilled water for gavage, once a day for 7 d. From the 8th day, except for the control group, the rats in the rest of groups were subjected to whole-body X ray irradiation, continuous exposure to 2 d; the total absorbed dose was 6 Gy. The rats were killed by femoral artery after irradiate 3 d. The WBC count, RBC, HGB, and PLT in peripheral blood were observed by blood routine test; the number of nucleated cells in the bone marrow was observed by nucleated cell count method; the pathological changes of spleen were observed by HE staining under microscope; the contents of IFN-γ and IL-4 in serum were detected by ELISA. Results Compared with the control group, the spleen index WBC, number of bone marrow nucleated cells and serum contents of IL-4 and IFN-γ in model group was significantly lower (P<0.05), The contents of RBC and HGB increased (P<0.05). Compared with the model group, WBC, number of bone marrow nucleated cells, and the contents of IL-4 and IFN-γ in serum of each administration group increased significantly (P<0.05); RBC and HGB decreased significantly (P<0.05). Conclusion Angelicae Sinensis Radix and Angelicae Sinensis Radix polysaccharides have protective effects on the immune function injure induced by X ray in SD rats.

Objective:To assess the efficacy of different non-drug smoking cessation interventions on smoking cessation among the high-risk populations of lung cancer screening by network meta-analysis.Methods:PubMed, MEDLINE (Ovid), PsychINFO, CNKI, WanFang and VIP databases were searched for randomized controlled clinical trials published from January 2010 to September 2020.According to the eligibility criteria, the retrieval literature was screened, the quality evaluation and data extraction were conducted, then, the statistical analysis was performed by using the Stata 14.0 software.Results:A total of 28 trials were included, including 34 640 cases of high-risk population, involving intervention measures, including 5R short quit smoking intervention, cognitive behavior therapy, award model quit smoking intervention, motivational interview, network intervention, telephone intervention, incentive mechanism plus telephone intervention, network plus telephone intervention, conventional treatment and blank group.The results of network meta-analysis showed that on the 7-day follow-up of 6 months, according to the score of SUCRA, the ranking of smoking cessation rate was 5R short smoking cessation intervention (0.88), cognitive behavior therapy (0.85), AWARD model smoking cessation intervention (0.80), incentive mechanism plus telephone intervention (0.73), motivational interview (0.53), Internet plus telephone intervention (0.40), Internet intervention (0.37), telephone intervention (0.31), conventional treatment (0.13) and blank group (0.03). However, on the 7-day smoking cessation rate of 12-month follow-up, the ranking of smoking cessation rate was 5R short smoking cessation intervention (0.94), AWARD model smoking cessation intervention (0.81), motivational interview (0.51), network intervention (0.40), telephone intervention (0.19) and conventional treatment (0.14).Conclusions:The existing evidence shows that no matter the length of follow-up, 5R short smoking cessation intervention has the best effect on smoking cessation in high-risk population of lung cancer screening.

Objective To get knowledge of the molecular epidemiological characteristics of human derived Brucella isolated in Hohhot,and to provide experimental basis in guiding prevention and treatment of Brucella infection.Methods Twenty-seven Brucella isolates derived from patients in Affiliated Hospital of Inner Mongolian Medical University from 2013 to 2015 were identified by routine bacteriological methods and molecular methods.Multiple-locus variable number tandem repeats analysis (MLVA-16) was used to detect molecular typing and do cluster analysis.Sixteen virulent genes were detected and analyzed by polymerase chain reaction (PCR).Results Twenty-seven Brucella isolates were identified as Brucella melitensis (B.melitensis) by routine bacteriological methods and PCR.Out of them,six isolates were B.melitensis biovar 1,and twenty-one isolates were B.melitensis biovar 3.MLVA-16 analysis showed that seven genotypes were obtained from nine Brucella isolates,which showed significant difference in variable number of tandem repeats,which suggested that they originated from sporadic outbreak.Moreover,two isolates were clustered into the same clade,which suggested they were epidemiologically correlated and may be derived from the same origin.Sixteen virulent genes were detected in all of the twenty-seven isolates.Conclusions Brucella isolates from patients in Hohhot are mainly B.melitensis biovar 3 and B.melitensis biovar 1,and the distribution profile of multiple virulence genes is similar.Some isolates have showed epidemic correlation,and the epidemic mechanism should be further explored.

Objective To identify Brucella species by means of bacteriological and polymerase chain reaction(PCR)methods,and to understand the drug susceptibility by in vitro susceptibility test of these strains to eight antimicrobial drugs.Methods The isolated Brucella strains were identified by standard method with conventional positive serum experiment,monophase specificity serum(A,M and R) agglutination experiment and brucella phage splitting experiment(Tb and BK2).Reference strains were set as control group.Molecular typing was performed by polymerase chain reaction(PCR)targeting Brucella surface protein 31(BCSP-31)and(abortus melitensis ovis suis,AMOS)-PCR assay which is able to distinguish among B.abortus,B.melitensis,B.ovis and B.porcine.Microdilution broth method was used to determine the minimum inhibitory concentrations(MIC)of 8 antibiotics to 27 Brucella strains isolated from blood culture,including azithromucin,ciprofloxacin,levofloxacin,doxycycline,rifampicin, gentamicin,acheomycin,and streptomycin.Results Twenty-seven strains were identified as B. melitensis,of which 21 were B.melitensis biovar 3 isolates,6 were B.melitensis biovar 1.The BCSP-31-PCR confirmed that all 27 isolates were Brucella.spp.AMOS-PCR assay confirmed that all isolates were B.melitensis.All isolates were susceptible to ciprofloxacin,levofloxacin,doxycycline,gentamicin, acheomycin,and streptomycin.Doxycycline was the most effective antibiotic(MIC900.064 mg/L),while rifampicin was moderately active to 3 isolates(MIC 2 mg/L).Conclusions Brucella isolates are susceptible in vitro to the antibiotics recommended by world health organization.Regular evaluation of antibiotic susceptibilities of Brucella strains is helpful for epidemiological investigation and antibiotic resistance monitor.