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At least 955 records · Page 53Linked to original sources
PubMed2005

An enzyme-detergent method for effective prion decontamination of surgical steel.

Prions, transmissible agents that cause Creutzfeldt-Jakob disease (CJD) and other prion diseases, are known to resist conventional sterilization procedures. Iatrogenic transmission of classical CJD via neurosurgical instruments is well documented and the involvement of lymphoreticular tissues in variant CJD (vCJD), together with the unknown population prevalence of asymptomatic vCJD infection, has led to concerns about transmission from a wide range of surgical procedures. To address this problem, conditions were sought that destroy PrP(Sc) from vCJD-infected human tissue and eradicate RML prion infectivity adsorbed onto surgical steel. Seven proteolytic enzymes were evaluated individually and in pairs at a range of temperatures and pH values and the additional effects of detergents, lipases and metal ions were assessed. A combination of proteinase K and Pronase, in conjunction with SDS, was shown to degrade PrP(Sc) material from highly concentrated vCJD-infected brain preparations to a level below detection. When RML prion-infected wires were exposed to the same enzymic treatment, intracerebral bioassay in highly susceptible hosts showed virtually no infectivity. The prion-degrading reagents identified in this study are readily available, inexpensive, non-corrosive to instruments, non-hazardous to staff and compatible with current equipment and procedures used in hospital sterilization units.

Creutzfeldt-Jakob Syndrome↗
PubMed1994

Reliability of PCR decontamination systems.

A major problem in the application of PCR is contamination with material amplified previously. Repeated PCRs result in the accumulation of intact and degraded amplicons and primer artifacts that can contaminate following amplification reactions. Post-PCR UV treatment and pre-PCR uracil DNA glycosylase (UDG) digestion have been recognized to efficiently inactivate or decompose intact amplification fragments. We show here that degraded amplification products and primer artifacts account for decreased sensitivity and may cause false-negative results. Our experiments indicate that partly degraded PCR products and primer artifacts containing sequences homologous to the primer oligonucleotides in the succeeding PCR reaction compete efficiently with sample DNA for the primers. The experiments done in this study may explain unexpectedly low PCR sensitivities reported in an increasing number of publications. In an attempt to solve this problem, we evaluated three post-PCR treatment methods to completely eliminate sequences competing for the amplification primers, namely, 8-methoxypsoralen (MOPS) or hydroxylamine treatment of amplified DNA and use of oligonucleotides containing 5'-ChemiClamps. However, all three methods did not sufficiently inhibit artificially produced carryover contaminations. In conclusion, false-positive results can be eliminated with UDG or UV treatment, but physical barriers are indispensable to avoid the occurrence of false-negative results.

Artifacts↗
PubMed2001

Risk perception of heavy metal soil contamination and attitudes toward decontamination strategies.

Contaminated soils are a common environmental risk all over the world. One major source of risk is heavy metal soil contamination caused by industrial emissions. This quasiexperimental study investigated the perception of these risks by exposed and nonexposed people, their attitudes toward bioremediation methods using hyperaccumulating plants, and the influence of long-term aspects of sustainability on the acceptance of bioremediation methods. Major findings were that people living in a contaminated area perceived the risk of the heavy metal soil contamination as higher than the general risk of contamination. Second, a factor analysis showed that the factors dread, control, and catastrophic potential were relevant for the perception and valuation of low-dose environmental risks such as the contamination of the investigated area. In addition, a cluster analysis showed that the risk of heavy metal soil contamination was perceived as similar to that of oil contamination, ozone layer, preservatives and genetic technology. It was perceived indifferently with regard to dread. The uncontrollability of heavy metal soil contamination was estimated as medium, and its catastrophic potential as low. Third, exposed and nonexposed participants preferred bioremediation methods to classical methods (e.g., excavation and chemical treatment of the soil), because they perceived the environmental and esthetical performance of the bioremediation as important criteria. Sustainability or precautionary issues, such as the prevention of harm for future generations, were highly correlated with the acceptance of the use of bioremediation methods in people's residential areas.

Adult↗
PubMed1984

A note on catalase enhanced recovery of acid injured cells of gram negative bacteria and its consequences for the assessment of the lethality of L-lactic acid decontamination of raw meat surfaces.

Addition of catalase (150 units/ml) to a rich infusion agar used for solid medium repair of acid injured pathogenic Enterobacteriaceae increased the recovery of such populations by 1-2 log cycles entailing an equal size reduction in the true lethality of this mode of processing for safety.

Animals↗
PubMed2005

Predictive model for reduction of Escherichia coli during acetic acid decontamination of chicken skin.

AIMS: The response surface methodology was used to evaluate the effect of operating variables (acetic acid concentration, spraying time and temperature) on the reduction of Escherichia coli populations on poultry breast skin in a laboratory showering process, as well as to identify the best conditions that are required to develop this operation. METHODS AND RESULTS: Skin samples were inoculated with a 24-h E. coli culture and afterwards treated according to experimental design under selected acetic acid concentration, spraying time, and solution temperature. The E. coli reduction model was significantly affected by the acetic acid concentration and spraying time (P < or = 0.05 and < or =0.01), while temperature did not show a significant effect (P > 0.05). CONCLUSION: The predictive model obtained was validated through additional confirmatory experiments and showed to be adequate, and it could be used as an approach to optimize the acetic acid spray washes during poultry carcasses processing. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of acetic acid washes in the processing of poultry does not have the capability of eliminating E. coli populations from carcasses. However, significant reductions in the initial load could be achieved.

Acetic Acid↗
PubMed2006

Biodegradation of ochratoxin A by Aspergillus section Nigri species isolated from French grapes: a potential means of ochratoxin A decontamination in grape juices and musts.

Ochratoxin A (OTA) is a very dangerous mycotoxin, the presence of which is often reported in different foods, as well as in beverages such as grapes, grape juices and wines. Detoxifying these products is therefore of prime importance in protecting consumer health, and biological approaches have been the most promising methods. In this report, 40 isolates representing the black apergilli species Aspergillus carbonarius, A. niger aggregate and A. japonicus, isolated on French grapes, were assessed for OTA degradation capacities in CZAPEK yeast extract broth (CYB) and in a synthetic grape juice medium (SGM) contaminated with OTA at 2 mg L(-1) (5 microM). It was clearly observed that in both media these fungi had the ability to degrade OTA to OTalpha (ochratoxinalpha). However, there were differences between the media used and species tested during OTA degradation. In SGM and CYB, 77% and 45% of the isolates, respectively were able to degrade more than 80% of the OTA. Despite a better growth on SGM, specific OTA degradation was higher on CYB for most of the isolates. Kinetic studies carried out on SGM with three black Aspergillus isolates all showed different OTA degradation rates. After 9 days of incubation, OTalpha had decreased, whereas an unknown compound appeared. A. niger could be the first interesting species for OTA detoxification processes, followed by A. japonicus.

Aspergillus↗
PubMed2007

Decontamination of rough titanium surfaces with diode lasers: microbiological findings on in vivo grown biofilms.

OBJECTIVES: The bactericidal efficacy of diode lasers has already been demonstrated in vitro. We investigated the reduction of aerobe bacteria - colonizing rough titanium samples in biofilms intraorally grown - by diode lasers of different wave lengths. MATERIAL AND METHODS: Twenty-two volunteers participated in the trial. They were fitted for 10 days with custom-made intraoral plastic splints carrying titanium sleeves. A part of the sleeves was then irradiated with diode lasers in different modes. The other part remained non-irradiated and served as control. Directly after irradiation, the sleeves were swabbed and the gained bacteria were first examined microscopically and then were cultured under aerobic conditions. RESULTS: The bacteria in the controls and in the treated samples were quantified. A comparison with the controls revealed a marked overall reduction of bacterial colonization in all irradiated sleeves. Continuous irradiation for 20 s reduced bacteria counts by 99.67% at 810 nm and 99.58% at 980 nm. Repeating the 20 s exposure five times reduced counts by 99.98% at 810 nm and by 99.39% at 980 nm. A 98.86% reduction was seen after irradiation in pulsed mode. A further analysis in respect of different isolated bacteria revealed that the streptococci group was reduced by 99.29-99.99%, while the staphylococci group was reduced to a lesser extent in the range 94.67-99.99%. CONCLUSION: The results are of clinical relevance. In comparison with the mean bacterial counts of the untreated samples, all irradiation programs studied in this investigation reduced mean bacterial colonization in a biofilm on intraoral rough titanium surfaces by more than 98%. The actual extent of reduction was dependent on the bacteria species as well as on the irradiation mode.

Bacteria, Aerobic↗
PubMed1981

Decontamination of cadaver corneas.

Bacterial contamination of human corneas, in vivo and post mortem, was investigated. Bacterial samples were obtained by pressing small concave agar plates directly against the corneas. More colony forming units (C.F.U.) occurred in samples obtained from patients in general anesthesia than in samples obtained from healthy persons in local anaesthesia. The largest number of C.F.U. occurred post mortem. The number of C.F.U. obtained from cadaver corneas was not correlated to post mortem time. Rinsing with water removed 86% of the C.F.U. on cadaver corneas. Rinsing with water for 30 sec followed by 2 min treatment with 0.5% polyvinylpyrrolidone-iodine (PVP-I) and repeated rinsing removed 98% of the C.F.U. Epithelial or stromal lesions were not found after 2 min of exposure to 0.5% PVP-I.

Bacteria↗
PubMed1982

Decontaminating infectious laboratory waste by autoclaving.

The temperature profile of infectious laboratory waste being autoclaved was examined relative to the type of containers used in the process. A standardized waste load (1,750 +/- 4 g) placed in the container was evaluated by using a direct readout thermocouple. The sensor of the thermocouple was placed within an unused and outdated agar plate, centrally located about 5 cm from the bottom of the container. The gravity displacement autoclave tested reached 121 degrees C within 3 min. Waste within a steel container (plus 1 liter of water) reached 108, 120, and 122 degrees C at 12, 30, and 50 min, respectively. Without the addition of water, the corresponding temperatures were 60, 110, and 120 degrees C, respectively. With a steel container, "autoclavable" plastic bags, and no additional water, the temperatures were 36, 71, and 105 degrees C, respectively. When 1 liter of water was placed in the autoclavable bag, the temperatures were 98, 115, and 121 degrees C, respectively. Waste within a polypropylene container (dimensions similar to those of the steel container) with and without the addition of 1 liter of water, reached a maximum temperature of 108 degrees C at 50 min. With a polypropylene container, autoclavable plastic bag, and 1 liter of water, the corresponding temperature was 99 degrees C. Without the addition of water, the temperature was 92 degrees C. The importance of container, moisture, and material in autoclaving was demonstrated.

Decontamination↗
PubMed2001

Influence of the natural microbial flora on the acid tolerance response of Listeria monocytogenes in a model system of fresh meat decontamination fluids.

Depending on its composition and metabolic activity, the natural flora that may be established in a meat plant environment can affect the survival, growth, and acid tolerance response (ATR) of bacterial pathogens present in the same niche. To investigate this hypothesis, changes in populations and ATR of inoculated (10(5) CFU/ml) Listeria monocytogenes were evaluated at 35 degrees C in water (10 or 85 degrees C) or acidic (2% lactic or acetic acid) washings of beef with or without prior filter sterilization. The model experiments were performed at 35 degrees C rather than lower (</=15 degrees C) temperatures to maximize the response of inoculated L. monocytogenes in the washings with or without competitive flora. Acid solution washings were free (<1.0 log CFU/ml) of natural flora before inoculation (day 0), and no microbial growth occurred during storage (35 degrees C, 8 days). Inoculated L. monocytogenes died off (negative enrichment) in acid washings within 24 h. In nonacid (water) washings, the pathogen increased (approximately 1.0 to 2.0 log CFU/ml), irrespective of natural flora, which, when present, predominated (>8.0 log CFU/ml) by day 1. The pH of inoculated water washings decreased or increased depending on absence or presence of natural flora, respectively. These microbial and pH changes modulated the ATR of L. monocytogenes at 35 degrees C. In filter-sterilized water washings, inoculated L. monocytogenes increased its ATR by at least 1.0 log CFU/ml from days 1 to 8, while in unfiltered water washings the pathogen was acid tolerant at day 1 (0.3 to 1.4 log CFU/ml reduction) and became acid sensitive (3.0 to >5.0 log CFU/ml reduction) at day 8. These results suggest that the predominant gram-negative flora of an aerobic fresh meat plant environment may sensitize bacterial pathogens to acid.

Acetic Acid↗