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Objective To study genotypes,antibiotic resistance and epidemiology of extendedspectrum β-lactamases (ESBL)-producing Shigella isolated in Tianjin,and to discuss the relationship between ESBL-producing Shigella and drug-resistance plasmid.Methods A total of 136 Shigella spp.were isolated from stool specimens of patients with diarrhea who presented mainly with bloody purulent stool from Tianjin Children's Hospital,Tianjin Medical University No.2 Hospital and Tianjin No.1 Central Hospital between May 2009 and September 2010.Suspicious ESBL-producing isolates were screened by K-B disc diffusion method. The conjugation experiment was performed in the confirmed ESBL-producing strains and antibiotic resistance was compared between clinical strains and transconjugants to confirm the plasmid-mediated resistance. The genotypes of these isolates were detected by polymerase chain reaction (PCR) using universal primers for TEM,SHV,CTX-M-1 group,CTX-M-2 group,CTX-M-9 group,respectively.Intergenic consensus PCR (ERIC-PCR) was employed to understand the molecular homology of the ESBL-producing isolates. The data were analyzed by x2 test.ResultsESBL were identified in 14.7％ (20/136) of Shigella isolates,but no AmpC enzyme were detected.Among all the Shigella isolates,16 strains were genotype CTX-M-14,4 were genotype CTX-M-15.The strains with CTX-M ESBL were resistant to multiple antibiotics,while 100％ sensitive to imipenem.The transconjugant test of 18 ESBL-producing isolates were positive,and these conjugations were only resistant to β-lactamases. Conclusions CTX-M type is the common genotype of ESBL-producing Shigella isolates in Tianjin. ESBL-producing is the main cause of multiple resistance to β-lactams.The transmission of CTX-M producing strains is mainly mediated by plasmids.
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Objective To evaluate the usefulness of DiversiLab system for genotyping of Acinetobacter baumannii.Methods Fifty-eight non-duplicated clinical Acinetobacter baumannii isolated from 15 cities in China in 2005 were typed by rep-PCR-based DiversiLab system.The results were compared with those of PFGE and multilocus sequence typing. Simpson's index of diversity was used to compare the discriminatory power among DiversiLab system, PFGE and MLST.Results Fifty-eight Acinetobacter baumannii isolates were differentiated into 5 clusters and 25 unique types by DiversiLab system. MLST identified 35 distinct sequence types, which fell into one clone complex of CC22 and 35 singletons, while PFGE resolved 5 pulsotypes and 34 unique types.Simpson's diversity indices for DiversiLab system, MLST and PFGE were O.876, O.944 and 0.961, respectively.Conclusions The discriminatory power of DiversiLab system is lower than that of PFGE and MLST.But as a simple, fast and reproducible typing method, it could be used as a first-line typing tool for the analysis of a large number of isolates.
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Objective To investigate the relationship of CAG repeat length polymorphism in the androgen receptor(AR)gene to the development of acne.Methods A total of 238 patients with ache vulgaris and 207 healthy human controls in Northeast China were included in this study.Genomic DNA was isolated and purified from the blood of these subjects.The CAG repeat lengths in the AR gene were analyzed by somatic microsatellites (STRs).Results A significant difference was found in the CAG repeat number between the male acne Patients(22.70±3.09)and male controls(23.48±2.83,P=0.046),but not between the female cases and controls(23.41±2.87 versus 23.85±0.21.P=0.12).In order to assess the risk associated with CAG repeats,the male and female subjects were dichotomized based on the median repeat length in the corresponding control group as the arbitrary cut-off point.Those men and women with a short CAG repeat length(＜23 in men,and＜24 in women)had a significantly increased risk for agne than those with a long CAG repeat length(men:95%confidence interval,1.21-3.54,OR=2.07,P=0.008;women:95%confidence interval.1.18-3.56,OR=2.05,P=0.01).Conclusions This study strongly indicates that the CAG repeat length in AR gene is associated with the development of acne in Northeast China,and those men with a short CAG repeat length seem to have a high risk for ague.Consequently,CAG repeat length may serve as a genetic susceptibility marker.
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Objective To detect the relationship between CAG repeat in IT15 gene and clinical manifestations of Huntington's disease (HD).Methods Non-denaturing polyacrylamide gel electro- phoresis method was used to detect CAG repeat.Clinical manifestations were scored by UHDRS and MMSE. Results Genotypes of IT15 were heterozygous in all 29 HD patients.CAG repeat in the HD chromosome, being 42—62,13—28 in normal chromosome,was inversely correlated with age of onset (r=-0.539,P
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Objective To study the relationship between the mutation of the inverted repeat (IR) gene in the multiple transferable resistant (mtr) system and multiple antibiotic resistance of Neisseria gonorrhoeae. Methods The antimicrobial susceptibilities of isolated strains were tested. An agar plate dilution method was used to determine the minimum inhibitory concentrations. The target genes were amplified by PCR and subjected to sequencing. Results No mutation was found in the IR gene of either of 2 sensitive or 5 penicillin-resistant Neisseria gonorrhoeas strains. Among the 17 multiple-antibiotic-resistant strains, a strain with both azithromycin- and penicillin-resistance had T/A and T/A insertions, and another had A/T deletion. Conclusion Mutations in the IR gene of the mtr system of Neisseria gonorrhoeae might result in multiple antibiotic resistance.
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Objective To analyze the epidemiological characteristics of Mycobacterium tuberculosis by enterbaeterial repetitive intergenic consensus-polymerase chain reaction(ERIC-PCR)DNA fingerprint. Methods Mycobacterium tuberculosis positive sputum samples between September 2003 to May 2006 were collected and cultured.Chromosomal DNA were extracted and ERIC-PCR DNA fingerprinting was analyzed by software,such as RAPD PHYLIP and Treeview.Results A total of 42 different fingerprints were detected.Phylogenetic analysis showed that they could be classified into three clusters,the clustering rate was 72.6%.The characteristics of ERIC-PCR fingerprint patterns were related to age,drug resistance,and type of resistance.Conclusions ERIC-PCR DNA fingerprinting technique used in this study is good for epidemiological studies with its strong discrimination,simplicity and rapidness.A high level of recent transmission is found in our city.
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ObjectiveTo detect the instabilities of DNA and chromosome in gastric carcinoma. Methods A total of 33 gastric cancer specimens were analyzed by RAPD(random amplified polymorphic DNA) PCR with nine 10-base arbitrary primers for detecting instabilities of DNA and chromosome. ResultsSample 5 and 3 showed the highest genomic changes and that there were significant differences in the ability of each primer to detect genomic instability ranging from 21% to 85%.ConclusionsThe genetic instabilities often concentrated on some special loci of chromosome e.g. repetitive sequences. It is difficult to influence the result of cancer treatment in gene therapy targeting at only one oncogene or tumor suppressor gene because of the extensive DNA variations occurred during the progression of tumor.