Quantification of Cross-Contamination of Campylobacter jejuni during Food Preparation in a Model Kitchen in China.

ABSTRACT: Numerous outbreak investigations and case-control studies of campylobacteriosis have provided evidence that handling Campylobacter-contaminated chicken products is a high risk factor for infection and illness. In this study, the cross-contamination and transfer rates of Campylobacter jejuni from chicken to ready-to-eat food were determined in various food handling scenarios. Skinless raw chicken breasts were artificially contaminated with C. jejuni and diced on cutting boards of three different materials. Whether cold water, cold water with detergent, or hot water was used, statistically significant differences were found between the transfer rates of C. jejuni to unwashed and washed cutting boards or hands, respectively. When both kitchen knife and cutting board were reused after dicing the artificially contaminated chicken, the transfer rates of C. jejuni to cucumber cut on bamboo, wooden, and plastic cutting boards were 16.28, 12.82, and 5.32%, respectively. The transfer rates from chicken to bread, a large lift-up water faucet handle, and a small twist faucet handle via unwashed hands were 0.49, 4.64, and 3.14%, respectively. This research provides scientific evidence that various types of contaminated kitchenware and cook's hands are vital potential vehicles for the cross-contamination of Campylobacter from raw chicken to ready-to-eat food and emphasizes the importance of timely and proper cleaning to prevent cross-contamination during food handling; therefore, high-quality consumer education to reduce the risk of foodborne infection is urgent and necessary.

[Analysis of Anthropogenic Reactive Nitrogen Emissions and Its Features on a Prefecture-level City in Fujian Province].

The impacts of reactive nitrogen (Nr) on the environment significantly increase with population and rapid urbanization. In order to study gaseous Nr and Nr loads to waterbodies at the provincial scale, we established anthropogenic emission inventories in prefecture-level cities in Fujian Province and analyzed the changes in Nr emissions for the years 2000, 2005, and 2010. The total Nr emissions were calculated as 538.4, 587.0, and 620.0 Gg in those three years, respectively. The emissions of Nr increased in nine prefecture-level cities except in Zhangzhou. Among these nine cities, Putian is the fastest growing one. The largest emitters were Zhangzhou and Quanzhou, while Ningde and Xiamen were the smallest ones. Agricultural ecosystems and livestock were the main sources of Nr emissions, both of them accounting for more than 90% of total anthropogenic Nr emissions. Despite rapid growth, energy activities had a minor contribution to total Nr emissions. The per area Nr emissions of each prefecture-level city were highest in Xiamen in the southeast coastal area and lowest in Sanming located in the northwest inland region in 2010. However, the patterns of GDP, population, and emission intensities showed the opposite trends to per area Nr emissions, lowest in Xiamen and highest in Nanping. We further discussed the significance of Nr emissions reductions in different areas based on the analysis of the characteristics of Nr emission sources in prefecture-level cities. The results provide a scientific basis for reducing Nr emissions in Fujian Province and its prefecture-level cities.

Modification and evaluation of Brucella broth based Campylobacter jejuni transport medium.

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.

OBJECTIVE: 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). METHODS: 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. RESULTS: 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. CONCLUSION: 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.

[Dynamics and environmental load of food carbon consumption during urbanization: a case study of Xiamen City, China].

With the rapid urbanization, city plays a more and more significant role in the carbon cycle of urban ecosystem. The contribution of household food carbon consumption to urban carbon cycle has become increasingly important, and has been the hot issues of the urban carbon cycle study. We analyzed the dynamics of the food carbon consumption in Xiamen City from 1988 to 2010, evaluated and forecasted the trends of food carbon consumption and its environmental load. The results showed that, from 1988 to 2010, per capita food consumption and per capita food carbon consumption declined by 6% and 25%, respectively. However, due to the rapid growth of population, the total food consumption and total food carbon consumption increased by 116% and 70%, respectively. The rising of total food carbon consumption led to the increasing environmental load of food carbon. The environmental load of food carbon increased from 98 800 t to 166 200 t, particularly there is a dramatic increase of carbon input into soil in recent years. From 2011 to 2024, total food carbon consumption and environmental load will continue to rise and then decline in 2025. Per capita food carbon consumption will decline continuously from 2011. The analysis of household food consumption showed that per household food carbon consumption was affected by household income, food cost and household persons. High food carbon consumption household usually had in average three persons eating at home, spent in average 3 125 yuan x month(-1) on food, the per household food carbon consumption was 1 134.91 kg,and the per capita food carbon consumption was 378.30 kg. Per capita food carbon consumption of high-consumption family was 4.84 times higher than that of low-consumption family.

[Study on greenhouse gas emissions from urban waste disposal system: a case study in Xiamen].

Waste disposal is one of the sources of greenhouse gas (GHG) emissions from urban human activities. According to the method recommended by IPCC Guidelines for National Greenhouse Gas Inventories 2006, a calculation model was established to assess GHG emissions of waste disposal in Xiamen. Then GHG emissions from waste disposal in Xiamen during the year of 2005-2010 were estimated, including solid waste landfill, solid waste incineration and wastewater treatment. The results showed that total GHG emissions quantified in carbon dioxide equivalents (CO2e) from waste disposal was 406.3 kt in 2005, and increased to 704.6 kt in 2010. Because of the improvement of wastewater treatment process and rapid increasing municipal solid waste (MSW), the main source of emissions was from wastewater treatment turning to solid waste landfill. GHG emissions from solid waste landfill accounted for about 90% of total emissions from solid waste disposal process in 2005, and the proportion decreased to 75% in 2010. GHG emissions (quantified in CO2e) from waste water treatment reached the highest value 325.5 kt in 2007. Chemical raw materials and chemical industry have been the highest CH4 emission industry during 2005-2010, which accounted for more than 55% of total CH4 emission from industrial wastewater treatment.

[Development of pulsed field gel electrophoresis and application for characterization and identification of Lactobacillus and Streptococcus thermophilus].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

[Impact of atmospheric total suspended particulate pollution on photosynthetic parameters of street mango trees in Xiamen City].

With the development of urbanization, total suspended particulate (TSP) pollution is getting serious, and the normal physiological processes of urban vegetation are profoundly affected while adsorbing and purifying the particulates. In this study, four areas were selected, i.e., Tingxi reservoir (clean control area), Xiamen University (cultural and educational area), Xianyue (business area), and Haicang (industrial area), with their atmospheric TSP concentrations and the photosynthetic parameters of street Mango (Mangifera indica) trees monitored in April and May, 2009. The daily average concentration of TSP in Tingxi, Xiamen University, Xianyue, and Haicang was 0.061, 0.113, 0.120 and 0.205 mg x m(-3), respectively, and the impact of TSP stress on M. indica was in the sequence of Haicang > Xianyue > Xiamen University > Tingxi. TSP pollution negatively affected the net photosynthetic rate, stomatal conductance, and transpiration rate of M. indica, and induced intercellular CO2 concentration changed significantly. High TSP concentration could cause the decline of net photosynthetic rate via stomatal limitation.

[Urban sustainability assessment based on eco-efficiency and its application].

Comprehensive assessment on urban ecological system is one of important issues for regional sustainable development research. Urban eco-efficiency is the effective tool to integrate sustainabable strategies into the development planning and management initiatives, which expresses the relationship of inputs of ecological impact and outputs of social welfare. An evaluation model of urban sustainability based on eco-efficiency was proposed by integrating Ecological Footprint model and Human Development Index. Using this model, a case study of Xiamen City was carried out using the statistical data from 2000 to 2006. There is a fluctuation of ecoefficiency which showed a steady increase first, then a sharp decline and a marginal increase towards the end. During 2000-2006, the per-capita ecological footprint increases from 4.279 hm2 to 5.462 hm2; and the Human Development Index increases from 0.831 to 0.896; thus the eco-efficiency, resource efficiency and environmental efficiency declines by 15.5%, 15.7% and 15.3% respectively. Xiamen experiences sustainability hypo-increasing phase first, sustainability increasing phase secondly, then sustainability decreasing phase, and sustainability increasing phase in the end. On the whole, the urban sustainability shows a decreasing trend.

[Theoretical thinking in sustainable city construction of China].

Based on the concept of ecosystem services and welfare, a definition of a sustainable city is proposed, and a quantitative model to describe sustainable welfare is established. With the analysis of the major issues and driving forces of sustainable city construction in China, the approaches for sustainable city construction are proposed as follows: to promote study on the theory and methodology of sustainable city construction, to set up and perfect institutional and management systems, and to establish a performance assessment system and an effective operation mechanism for sustainable city construction in China.

[Determination of the allergic impurities in the parenteral injection of Chinese traditional medicines containing Salvia miltiorrhiza].

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].

OBJECTIVE: 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. METHOD: 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. RESULTS: 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. CONCLUSION: 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.

[Study on integrons in Escherichia coli which producing extended-spectrum beta-lactamases, isolated from stool specimen of chicken].

OBJECTIVE: To analysis the dissemination of integrons in the extended-spectrum beta-lactamases (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 integrase. 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 aadA1, aadA2, aadA5, aadA22, dfrA12, dfrA17, dfrI, aar-3 were found in the variable region and aadA gene encodes resistant to streptomycin, spectinomycin, dfr gene to trimethoprim and aar to rifampicin. We realized that aadA22 was the first time detected in China. Class 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.

[Comparison of multilocus sequence typing system and pulsed-field gel electrophoresis in typing of Salmonella enteritidis].

OBJECTIVE: To compare the discriminatory ability between multilocus sequence typing system (MLST) and pulsed-field gel electrophoresis (PFGE). METHODS: 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. RESULTS: 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. CONCLUSION: In strain typing, PFGE was the highly discriminatory method comparing to the MLST system.