Modification and evaluation of Brucella broth based Campylobacter jejuni transport medium / 生物医学与环境科学（英文）

Reliable transport of Campylobacter jejuni isolates is critical to microbial epidemiology research, especially in developing countries without a good temperature control mailing system. Various factors, including oxygen, temperature, transport medium composition, could affect the survival of C. jejuni. In this study, the protective effects of different ingredients in C. jejuni transport media at 4 °C and 25 °C and under aerobic condition were quantitatively evaluated respectively. The results showed that enriched medium, supplementation with 5% blood and being kept at 4 °C could improve the viability of different C. jejuni strains during transport. In addition, supplementation with 25 mmol/L L-fucose in Wang's transport medium could significantly improve the survival of C. jejuni at both 4 °C and 25 °C. To the best of our knowledge, this is the first report to evaluate the protective effect of L-fucose in enriched C. jejuni transport medium which is feasible in developing countries without an effective cold chain mailing system. These data will be good reference for C. jejuni transport medium improvement in future.

Characterization of Staphylococcus aureus isolated from clinical specimens by matrix assisted laser desorption/ionization time-of-flight mass spectrometry / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To develop a matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) approach to identify Staphylococcus aureus (S. aureus) and differentiate methicillin-resistant S. aureus (MRSA) from methicillin-sensitive S. aureus (MSSA).</p><p><b>METHODS</b>A total of 100 S. aureus strains isolated from clinical specimens and farm workers were collected and analyzed by MALDI-TOF-MS. And data obtained were interpreted with biotyper software.</p><p><b>RESULTS</b>Ninety-two strains were identified by MALDI-TOF-MS as S. aureus at a level of secure genus and probable species, and 4 strains were identified at probable genus after their cultivation, spectral collection and data preprocessing. One strain was identified as S. aureus with lower score. It was revealed that identification of S. aureus by MALDI-TOF-MS was highly correlated with typing by biochemical and serological methods with an accuracy as high as 97%. The biotyper cluster analysis showed that 100 isolates were divided into 2 types at the distance level of 400. Higher peak intensity in the mass of both 3784 Da and 5700 Da was observed in MRSA, whereas that was absent from MSSA.</p><p><b>CONCLUSION</b>MALDI-TOF-MS is considered a simple, rapid and highly reproducible technique with high-throughput and accuracy for the identification of S. aureus and it can reliably differentiate MRSA from MSSA.</p>

Development of pulsed field gel electrophoresis and application for characterization and identification of Lactobacillus and Streptococcus thermophilus / 中华预防医学杂志

<p><b>OBJECTIVE</b>To develop a pulsed field gel electrophoresis (PFGE) method for molecular typing of Lactobacillus and Streptococcus thermophilus (S. thermophilus) and to apply it in identification and characterization of both bacteria isolated from yoghurt collected from Beijing supermarket.</p><p><b>METHODS</b>The five most useful restriction enzymes including Apa I, Not I, Sfi I, Xba I and Sma I were chosen to cut DNA of 52 strains of Lactobacillus, S. thermophilus as well as associated standard bacteria strains. The endonucleases and electrophoresis conditions for PFGE analysis were optimized and applied in molecular typing of Lactobacillus and S.thermophilus isolates. Cluster analysis based on the PFGE data was conducted. The identification results of PFGE were compared with those obtained in biochemical and 16s ribosomal RNA PCR identification tests.</p><p><b>RESULTS</b>Not I was suitable for L. bulgaricus, L. fermentum and L. delbrueckii digestion. While Apa I was an appropriate endonuclease for S. thermophilus, L. acidophilus and L. casei digestion. The results of molecular typing indicated that 24 strains of L.bulgaricus and 15 strains of S. thermophilus were grouped into 8 types by PFGE method, respectively. While 7 strains of L.acidophilus were grouped into 3 types and 2 strains of L. delbrueckii were grouped into 2 different PFGE types.</p><p><b>CONCLUSION</b>The results of PFGE analysis are in compliance with those of 16s rRNA PCR and biochemical identification. The PFGE method developed in this study is suitable for molecular characterization of both Lactobacillus and S. thermophilus.</p>

Study on integrons in Escherichia coli which producing extended-spectrum β-lactamases,isolated from stool specimen of chicken / 中华流行病学杂志

Objective To analysis the dissemination of integrons in the extended-spectrumβ-laetamases(ESBLs)producing Escherichia coli,isolated from stool specimen of chicken and to study the relations between the resistance and the integrons of these isolates.Methods The Escherichia coli isolates were collected from Gansu,Hubei,Sichuan provinces and Beijing municipal city，and were isolated from stool specimen of chickens.Using WHONET software,the Escherichia coli producing ESBLs were selected，and then detected by PCR method class 1,2,3,4 integrmse.PCR products of the variable region of the integron were sequenced.Results 54 of the 224(24.1％)isolates were ESBLs producing Escherichia coli.Class 1 integron were detected in 63.0％of the isolates,and aadAl,aadA2,aadA5,aadA22,dfrAl2,dfrA17,dfrI,aar-3 were found in the variable region and aad A gene encodes resistant to streptomycin，spectinomyein,dfr gene to trimethoprim and aar to rifampicin.We realized that aadA 22 was the first time detected in China.C1ass 2 integron were detected in 5.6％ of the isolates,Class 3 integron was detected in 3 isolates.Conclusion Class 1 integron Was the most commonly seen integron in Escherichia coli,encoding the resistance to streptomycin.spectinomycin and trimethoprim.Integrons were contributed to the horizontal transfer of resistant genes in the same or different species,suggesting that the antimicrobial resistance and the dissemination of integrons should be monitored.

Determination of the allergic impurities in the parenteral injection of Chinese traditional medicines containing Salvia miltiorrhiza / 药学学报

The residual protein mixture (the content is 4%, approximately), called Salvia miltiorrhiza antigen, was extracted from the Salvia miltiorrhiza cruel materials by mimicking the alcohol-deposit extracts process. Both rabbits and guinea pigs sensitized by Salvia miltiorrhiza could produce specified antibodies. Large molecular antigenic impurities were extracted from the Danshen injection and Xiangdan injection using the centrifugal filtering method. The test results of active systemic anaphylaxis (ASA) and passive cutaneous anaphylaxis (PCA) in guinea pigs confirmed that the extracted antigenic impurities could induce the anaphylaxis reaction in the animals which were sensitized by the Salvia miltiorrhiza antigen. Using the specified antibody produced from rabbits which were sensitiyed by Salvia miltiorrhiza, ELISA test method was developed to test the residual Salvia miltiorrhiza antigenic materials contained in the parenteral Chinese traditional medicines. Calculated as residual protein, the linear range was 0.08-5.12 microg x mL(-1) (r2 = 0.9906), the detection limit and quantization limit are 0.08 microg x mL(-1) and 0.4 microg x mL(-1), respectively. 308 batches of parenteral Chinese traditional medicines containing water-soluable components of Salvia miltiorrhiza were tested, and the Salvia miltiorrhiza antigenic impurities were spotted in 35 (11.4%) batches of samples. The test results show that the extracting process currently used can not remove the Salvia miltiorrhiza antigenic impurities completely, and this may be one of the reasons for anaphylactic reaction in clinics. The proposed ELISA method can be used for improving the manufacture process and for routine quality control of drug products.

Detection and analysis of antibiotic resistance of Salmonella from retail meats in some districts of Shaanxi province / 中华预防医学杂志

<p><b>OBJECTIVE</b>Salmonella isolates recovered from retail meats that were collected in supermarkets and free markets in Xi'an and Yangling areas of Shaanxi province were studied to determine antibiotic susceptibility.</p><p><b>METHOD</b>Antimicrobial susceptibility to 14 antibiotics of 193 salmonella isolates were determined by using agar dilution method, which was recommended by National Committee of Clinical Laboratory Standard (NCCLS), and E.coli ATCC25922 and E.faecalis ATCC29212 as standard control strains.</p><p><b>RESULTS</b>The 44.6% of the salmonella isolates were resistant to sulfamethoxazole, followed by resistance to kanamycin (40.9%), tetracycline (37.8%), amoxicillin (26.9%), ampicillin (25.4%), gentamicin (23.3%) and chloramphenicol (21.8%). Some isolates also showed resistance to fluoroquinolones, the rates for ciprofloxacin, enrofloxacin, levofloxacin and gatifloxacin were 22.3%, 21.8%, 20.8% and 21.2%, respectively. 55 isolates (28.5%) were multidrug resistant (MDR) strains, 28 of 193 isolates (14.5%) could resist at least 13 antibiotics, 24 isolates (12.4%) were resistant to from 4 to 12 antibiotics.</p><p><b>CONCLUSION</b>Salmonella isolates recovered from retail meats in Xi'an district of Shaanxi province were seriously resistant to antimicrobials commonly used as human and veterinary medicine.</p>

Comparison of multilocus sequence typing system and pulsed-field gel electrophoresis in typing of Salmonella enteritidis / 中华流行病学杂志

<p><b>OBJECTIVE</b>To compare the discriminatory ability between multilocus sequence typing system (MLST) and pulsed-field gel electrophoresis (PFGE).</p><p><b>METHODS</b>Salmonella enteritidis strains, isolated from food in China were identified by MLST, under PCR products of thrA, purE, sucA, aroC, hemD, dnaN and Sdf I. The same set of strains was typed by PFGE using Xba I, Spe I as the restriction enzyme in order to compare the discriminatory power of the methods.</p><p><b>RESULTS</b>Data from MLST revealed the lack of diversity among the strains of the same serotype and the number of variable nucleotide sites per locus ranged from 1 to 23 between Salmonella typhi LT2 and other serotypes of Salmonella. However, 50 Salmonella enteritidis strains were identified as 11 patterns and more sub-patterns by PFGE.</p><p><b>CONCLUSION</b>In strain typing, PFGE was the highly discriminatory method comparing to the MLST system.</p>