Home About us Contact
|
Home About us Contact | ||
|
|
||
Cross Contamination (cross + contamination)
Selected AbstractsConsumers' attitudes, knowledge, self-reported and actual hand washing behaviour: a challenge for designers of intervention materialsINTERNATIONAL JOURNAL OF CONSUMER STUDIES, Issue 3 2003D.A. Clayton Cross contamination by microbial pathogens in the kitchen environment may play an important role in many cases of food borne illnesses. Hand washing has been shown to be one of the most important factors in controlling the spread of microorganisms and in preventing the spread of disease. However, educational campaigns such as distribution of information leaflets, workshops, performance feedback and lectures have been, at best, associated with a transient improvement in compliance rates. In addition, the majority of research investigating UK consumers' food safety behaviour has examined self-reported as opposed to actual hand washing behaviour. This research utilises psychological theory in an attempt to understand how one might design a more effective hand washing campaign. Social cognition models were utilised to explore the relationship between consumers' knowledge, attitudes, self-reported and actual hand washing behaviour. The research was conducted in two stages. Firstly, salient beliefs of 100 consumers towards food safety were obtained using open-ended questions. Secondly, the food handling practices of 40 consumers were observed and their food safety attitudes and knowledge determined using structured questionnaires. All the participants were knowledgeable about hand washing techniques, intended to wash their hands and generally had positive attitudes towards the importance of washing their hands. However, none of the participants adequately washed their hands on all appropriate occasions. The attitude statement results suggest measures of perceived behavioural control, perceived barriers and perceived risk may provide developers of food safety intervention materials with more useful information compared with measures of consumers' knowledge or intention. Issues of habit and optimistic bias also need to be given consideration when designing intervention materials to change hand washing behaviour of consumers. [source] Salmonella on pig carcasses: positive pigs and cross contamination in the slaughterhouseJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2003N. Botteldoorn Abstract Aims: The purpose of this study was to investigate the prevalence of Salmonella in pigs at the moment of slaughter and in the slaughterhouse environment. Methods and Results: In total, five different commercial slaughterhouses were sampled during eight slaughterhouse visits. Carcass swabs, colon content and mesenteric lymph nodes were taken to reflect the animal status and from the slaughterhouse environmental samples were taken. Salmonella was isolated from 37% of the carcass samples as a mean value. High variations were noticed between different slaughterhouses (between 0 and 70%) and sampling days in the same abattoir (between 3 and 52%). A correlation was found between the carcass contamination and the status of the delivered animals (P = 0·01675). Cross contamination was estimated to account for 29% of the positive carcasses. The slaughterhouse environment was highly contaminated; before starting the slaughtering activities 25% of the samples were positive on average. The most prevalent serotypes isolated at the slaughterhouse environment and from the colon content were S. Typhimurium, S. Livingstone and S. Derby. On carcasses S. Typhimurium was predominately isolated (71%). The biggest variability of serotypes was found in the mesenteric lymph nodes. Serologically 56·3% of the pigs were found positive for Salmonella using a cut-off level of the optical density percentage higher than 10 (O.D.% , 10). While on individual pig level the correlation between the bacteriological and serological data was poor, because of recent Salmonella infections, a better correlation was found at the herd level on the moment of slaughtering. Conclusion: A high degree of carcass contamination is noticed after slaughtering. This contamination resulted from the delivery of Salmonella -positive pigs and cross-contamination from the slaughterhouse environment. Significance and Impact of the Study: In pigs, Salmonella carriage is high, but it is obvious that slaughterhouse hygiene is a determinative factor for managing carcass contamination. [source] Mass-directed fractionation and isolation of pharmaceutical compounds by packed-column supercritical fluid chromatography/mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2001Tao Wang An automated packed-column semi-preparative supercritical fluid chromatography/mass spectrometry (SFC/MS) system incorporating mass-directed fraction collection has been designed and implemented as an alternative to preparative HPLC and preparative HPLC/MS (PrepLC/MS) for the purification of pharmaceutical compounds. The system incorporates a single quadrupole mass spectrometer and a supercritical fluid chromatograph. Separations were achieved using a binary solvent system consisting of carbon dioxide and methanol. Purification of SFC-separated compounds was achieved incorporating mass-directed fraction collection, enabling selective isolation of the target molecular weight compound and eliminating the collection of undesired compounds (e.g., by-products, excess starting materials, etc.). Cross contamination between fractions and recoveries of the system were investigated. Mass spectrometer ionization with basic mobile additives is discussed, and examples of preparative SFC/MS chiral separations are presented. Early experiences suggest SFC will be a powerful and complementary technique to HPLC for the purification of pharmaceutical compounds. Copyright © 2001 John Wiley & Sons, Ltd. [source] Addressable Protein Patterning via Switchable Superhydrophobic Microarrays,ADVANCED FUNCTIONAL MATERIALS, Issue 15 2007J.-Y. Shiu Abstract We report on a simple process to create a switchable superhydrophobic surface where the water contact angle can be switched from a superhydrophobic state (ca.,167°) to a completely wetted state (<,10°). In the superhydrophobic state, the switchable superhydrophobic surface was resistant to the adsorption of proteins. However, once converted to a wetted state, the same surface promoted protein adsorption. We have developed a novel multicomponent protein-patterning technique based on this unique property of the switchable superhydrophobic surface. It is demonstrated that up to 100,×,100 protein spots can be created within one second. Each element on the switchable superhydrophobic microarray can be addressed individually and different types of biomolecules can be selectively deposited on the microarray without losing their activity. When integrated with microfluidic channels, the switchable superhydrophobic surface allows the parallel patterning of protein molecules to be carried out without cross contamination. [source] Silver dressings: their role in wound managementINTERNATIONAL WOUND JOURNAL, Issue 4 2006David J Leaper Abstract Dressings have a part to play in the management of wounds; whether they are sutured or open, usually chronic wounds of many aetiologies which are healing by secondary intention. They traditionally provide a moist wound environment, but this property has been extended through simple to complex, active dressings which can handle excessive exudate, aid in debridement, and promote disorganised, stalled healing. The control of infection remains a major challenge. Inappropriate antibiotic use risks allergy, toxicity and most importantly resistance, which is much reduced by the use of topical antiseptics (such as povidone iodine and chlorhexidine). The definition of what is an antimicrobial and the recognition of infection has proven difficult. Although silver has been recognised for centuries to inhibit infection its use in wound care is relatively recent. Evidence of the efficacy of the growing number of silver dressings in clinical trials, judged by the criteria of the Cochrane Collaboration, is lacking, but there are good indications for the use of silver dressings, to remove or reduce an increasing bioburden in burns and open wounds healing by secondary intention, or to act as a barrier against cross contamination of resistant organisms such as MRSA. More laboratory, and clinical data in particular, are needed to prove the value of the many silver dressings which are now available. Some confusion persists over the measurement of toxicity and antibacterial activity but all dressings provide an antibacterial action, involving several methods of delivery. Nanocrystalline technology appears to give the highest, sustained release of silver to a wound without clear risk of toxicity. [source] Salmonella on pig carcasses: positive pigs and cross contamination in the slaughterhouseJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2003N. Botteldoorn Abstract Aims: The purpose of this study was to investigate the prevalence of Salmonella in pigs at the moment of slaughter and in the slaughterhouse environment. Methods and Results: In total, five different commercial slaughterhouses were sampled during eight slaughterhouse visits. Carcass swabs, colon content and mesenteric lymph nodes were taken to reflect the animal status and from the slaughterhouse environmental samples were taken. Salmonella was isolated from 37% of the carcass samples as a mean value. High variations were noticed between different slaughterhouses (between 0 and 70%) and sampling days in the same abattoir (between 3 and 52%). A correlation was found between the carcass contamination and the status of the delivered animals (P = 0·01675). Cross contamination was estimated to account for 29% of the positive carcasses. The slaughterhouse environment was highly contaminated; before starting the slaughtering activities 25% of the samples were positive on average. The most prevalent serotypes isolated at the slaughterhouse environment and from the colon content were S. Typhimurium, S. Livingstone and S. Derby. On carcasses S. Typhimurium was predominately isolated (71%). The biggest variability of serotypes was found in the mesenteric lymph nodes. Serologically 56·3% of the pigs were found positive for Salmonella using a cut-off level of the optical density percentage higher than 10 (O.D.% , 10). While on individual pig level the correlation between the bacteriological and serological data was poor, because of recent Salmonella infections, a better correlation was found at the herd level on the moment of slaughtering. Conclusion: A high degree of carcass contamination is noticed after slaughtering. This contamination resulted from the delivery of Salmonella -positive pigs and cross-contamination from the slaughterhouse environment. Significance and Impact of the Study: In pigs, Salmonella carriage is high, but it is obvious that slaughterhouse hygiene is a determinative factor for managing carcass contamination. [source] Efficacy of Listerine® Antiseptic in reducing viral contamination of salivaJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 4 2005Timothy F. Meiller Abstract Aim: The anti-viral efficacy of oral antimicrobial rinses has not been adequately studied in terms of potential clinical significance. As a follow-up to an in vitro study on the effect of oral antiseptics on Herpes simplex virus, Type 1, this study was undertaken to evaluate the in vivo effect of an essential oil containing oral antiseptic on the reduction of viral titer in saliva during active viral infection. Method: Patients were recruited and evaluated in a single visit protocol at the onset of a perioral outbreak, consistent historically and clinically with recurrent Herpes labialis. Direct immunofluorescence of cytological smears of the lesions/oral fluids was used to confirm Herpes simplex virus types I or II. Patients were randomly assigned to one of two treatment groups: (1) active ingredient and (2) sterile water control. The viral lesion was evaluated as to clinical stage according to standard protocol. Salivary fluid samples were taken: (1) at baseline; (2) immediately following a 30 s rinse; (3) 30 min. after the 30 s rinse; and (4) on the repeat trial, also at 60 min. after the 30 s rinse. All samples were evaluated for viral titer and results compared. Results: In Trial 1, the sample population consisted of 19 males and 21 females with an average age of 29.2 and in Trial 2, 21 males, 19 females with an average age of 28. In both Trials 1 and 2, recoverable infectious virions were reduced to zero after a 30 s experimental rinse; whereas, the control rinse resulted in a non-significant (p>0.05) reduction. The experimental group also demonstrated a continued significant (p<0.05) reduction 30 min. post rinse when compared with baseline while the control group returned to baseline levels. In Trial 2, the 60 min. post rinse follow-up demonstrated a 1,2 log residual reduction from baseline in the experimental group; however, this was not significant. Conclusions: There is clinical efficacy in utilizing an oral rinse with the antimicrobial agent Listerine® Antiseptic in reducing the presence of viral contamination in oral fluids for at least 30 min. after oral rinse. The risk of viral cross contamination generated from these oral fluids in person to person contact or during dental treatment may be reduced. [source] INVITED REVIEW: Molecular analysis of predation: a review of best practice for DNA-based approachesMOLECULAR ECOLOGY, Issue 4 2008R. A. KING Abstract Molecular analysis of predation, through polymerase chain reaction amplification of prey remains within the faeces or digestive systems of predators, is a rapidly growing field, impeded by a lack of readily accessible advice on best practice. Here, we review the techniques used to date and provide guidelines accessible to those new to this field or from a different molecular biology background. Optimization begins with field collection, sample preservation, predator dissection and DNA extraction techniques, all designed to ensure good quality, uncontaminated DNA from semidigested samples. The advantages of nuclear vs. mitochondrial DNA as primer targets are reviewed, along with choice of genes and advice on primer design to maximize specificity and detection periods following ingestion of the prey by the predators. Primer and assay optimization are discussed, including cross-amplification tests and calibratory feeding experiments. Once primers have been made, the screening of field samples must guard against (through appropriate controls) cross contamination. Multiplex polymerase chain reactions provide a means of screening for many different species simultaneously. We discuss visualization of amplicons on gels, with and without incorporation of fluorescent primers. In more specialized areas, we examine the utility of temperature and denaturing gradient gel electrophoresis to examine responses of predators to prey diversity, and review the potential of quantitative polymerase chain reaction systems to quantify predation. Alternative routes by which prey DNA might get into the guts of a predator (scavenging, secondary predation) are highlighted. We look ahead to new technologies, including microarrays and pyrosequencing, which might one day be applied to this field. [source] Optimization of DNA Extraction from a Scleractinian Coral for the Detection of Thymine Dimers by Immunoassay,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Anastazia T. Banaszak ABSTRACT Ultraviolet (UV)-B is known to cause DNA damage, principally by the formation of thymine dimers, but little research has been conducted in coral reef environments where UV doses are high. The majority of tropical reef-dwelling corals form a mutualistic symbiosis with the dinoflagellate Symbiodinium but few studies have been conducted on in situ DNA damage in corals and none have investigated the symbiotic components separately. The aim of this research was to quantify DNA damage in both the coral host and the dinoflagellate symbiont. The first step in this investigation was to optimize the extraction of DNA from the host, Porites astreoides, as well as the symbiont. The optimization was divided into a series of steps: the preservation of the samples, separation of the coral tissue from the skeleton, separation of the host tissue from the algal cells to prevent cross contamination as well as the extraction and purification of genomic DNA from the algae that are located intracellularly within the invertebrate animal tissue. The best preservation method was freezing at low temperatures without ethanol. After scraping with a razor blade, the coral tissue can be divided into host and algal components and the DNA extracted using modifications of published techniques yielding DNA suitable for the quantification of thymine dimer formation using antibodies. Preliminary data suggest that in P. astreoides collected from 1 m depth, thymine dimers form approximately 2.8 times more frequently in the host DNA than in the DNA of its symbionts. [source] A method to prevent cross contamination during 2-DE by ,-amyloid peptidesPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 19 2010Heinke Schieb Abstract A method for the efficient decontamination of aluminium oxide ceramic 2-DE focusing trays from ,-amyloid peptides (A,) is reported. As these contaminations were resistant to the standard cleaning procedures, additional harsh cleaning steps were necessary for their efficient removal. Our observations suggest that specific surface properties affect the degree of adsorption of the A,-peptides. "Surface catalysed amyloid aggregation" in the aluminium oxide ceramic trays is proposed as a possible underlying mechanism for the occurrence of proteinase K-resistant forms of A,. [source] Isotopic metrology of carbon dioxide.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2003We report high-precision isotopic carbon dioxide measurements, made before and after ion source modification to gas isotope ratio mass spectrometry (IRMS) instruments. Measurement protocols were designed to explore the effects of ion source material substitution, source conductance, inlet pressure, electron emission, acceleration potential, and inlet changeover equilibration time. After modification of the IRMS instruments at the National Institute of Standards and Technology (NIST) and the Max-Planck-Institute for Chemistry (MPI-Mainz), immediate changes were observed. At NIST, measurements were no longer sensitive to inlet equilibration times greater than 15,s, and different settings of ion source conductance resulted in ,13C shifts of about 0.04, per 10, measurement difference between sample and reference, a five-fold improvement. No significant changes in machine performance were observed after a month of use. After a year, performance had degraded slightly, but was controlled by ion source cleaning and the use of low-energy ion acceleration to minimize sputtering. At MPI-Mainz, results were very similar. We report cross-contamination coefficients measured since 1996, and discuss the role of adsorption, ion implantation, and sputtering on cross contamination in mass spectrometry systems. We recommend that users of high-precision IRMS instruments test for and minimize the effects described. Published in 2003 by John Wiley & Sons, Ltd. [source] Molecular diagnosis of lyssaviruses and sequence comparison of Australian bat lyssavirus samplesAUSTRALIAN VETERINARY JOURNAL, Issue 7 2006AJ FOORD Objective To evaluate and implement molecular diagnostic tests for the detection of lyssaviruses in Australia. Design A published hemi-nested reverse transcriptase polymerase chain reaction (RT-PCR) for the detection of all lyssavirus genotypes was modified to a fully nested RT-PCR format and compared with the original assay. TaqMan assays for the detection of Australian bat lyssavirus (ABLV) were compared with both the nested and hemi-nested RT-PCR assays. The sequences of RT-PCR products were determined to assess sequence variations of the target region (nucleocapsid gene) in samples of ABLV originating from different regions. Results The nested RT-PCR assay was highly analytically specific, and at least as analytically sensitive as the hemi-nested assay. The TaqMan assays were highly analytically specific and more analytically sensitive than either RT-PCR assay, with a detection level of approximately 10 genome equivalents per µl. Sequence of the first 544 nucleotides of the nucleocapsid protein coding sequence was obtained from all samples of ABLV received at Australian Animal Health Laboratory during the study period. Conclusion The nested RT-PCR provided a means for molecular diagnosis of all tested genotypes of lyssavirus including classical rabies virus and Australian bat lyssavirus. The published TaqMan assay proved to be superior to the RT-PCR assays for the detection of ABLV in terms of analytical sensitivity. The TaqMan assay would also be faster and cross contamination is less likely. Nucleotide sequence analyses of samples of ABLV from a wide geographical range in Australia demonstrated the conserved nature of this region of the genome and therefore the suitability of this region for molecular diagnosis. [source] | ||||||||||||||||