scholarly journals Endotoxin contamination in the dental surgery

2007 ◽  
Vol 56 (9) ◽  
pp. 1230-1234 ◽  
Author(s):  
M. K. Huntington ◽  
J. F. Williams ◽  
C. D. Mackenzie
Keyword(s):  
Bacterial Load ◽  
Dental Surgery ◽  
Paired Samples ◽  
Dental Procedures ◽  
Large Numbers ◽  
Endotoxin Exposure ◽  
Endotoxin Contamination ◽  
Plate Counts ◽  
High Concentrations ◽  
Heterotrophic Plate Counts

Dental waterlines contain large numbers of Gram-negative bacteria. Endotoxin, a component of such organisms, has significant health implications. Paired samples of dental unit water and the aerosols generated during dental procedures were collected, and assayed for bacteria and endotoxin levels, using heterotrophic plate counts and the Limulus amoebocyte lysate test. Consistent with published studies, the extent of bacterial contamination in the dental waters sampled for this investigation surpassed the levels associated with potable water, with counts in excess of 2.0×106 c.f.u. ml−1 in some samples. Correspondingly high concentrations of endotoxin [up to 15 000 endotoxin units (EU) ml−1] were present in the water. A statistically significant Spearman correlation coefficient of ρ=0.94 between endotoxin (EU ml−1) and bacterial load (c.f.u. ml−1) was demonstrated. All of the aerosol samples contained detectable endotoxin. Further studies of the consequences of dental endotoxin exposure, and evaluation of means to prevent exposure, are warranted.

Microbial Spoilage of Tofu (Soybean Curd)

1993 ◽  
Vol 56 (2) ◽  
pp. 157-164 ◽  
Author(s):  
KHADIJA E. FOUAD ◽  
GEORGE D. HEGEMAN
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Bacterial Load ◽  
Enteric Bacteria ◽  
Ph Measurements ◽  
Pressure Cooking ◽  
Large Numbers ◽  
Major Species ◽  
Pseudomonas Species ◽  
Plate Counts

Plate counts and pH measurements were performed on tofu from different aged lots. The pH declined from to 5.8 to 5.2 with age. Aerobic plate counts of 1- and 30-d-old samples were approximately 106 CFU/g. Older samples had counts of about 108 CFU/g. Anaerobic counts rose from 106 CFU/g in the 1-d-old lot to a high of 109 CFU/g in the 30-d-old lot. The major species from the different age lots were lactic acid bacteria, enteric bacteria, and Pseudomonas species. Representatives from each of these groups were inoculated into autoclaved tofu and incubated at 5°C for 23 d. CFU/ml and pH of both water and cake were measured. Turbidity, mg protein per ml, and mg NH4+ per mi of the water were measured. All species tested increased in numbers in the tofu and caused changes in at least some of the characteristics measured. Samples were taken during the manufacture of tofu, and all organisms found in each sample were characterized. All organisms that were shown capable of causing spoilage in tofu were present in large numbers early in manufacture but were no longer found in samples subsequent to pressure cooking. All of the spoilage organisms reappeared later during manufacture. These data indicate that tofu is spoiled by enteric bacteria and Pseudomonas species, as well as by lactic acid bacteria. The spoilage organisms are probably introduced by equipment and personnel with which the product comes in contact after it is pressure cooked. In addition, aerobic plate counts can underestimate the bacterial load in tofu, and therefore, anaerobic plate counts should also be performed.

Parameters predictive of Legionella contamination in hot water systems: Association with trace elements and heterotrophic plate counts

2011 ◽  
Vol 45 (6) ◽  
pp. 2315-2321 ◽  
Author(s):  
Annalisa Bargellini ◽  
Isabella Marchesi ◽  
Elena Righi ◽  
Angela Ferrari ◽  
Stefano Cencetti ◽  
...  
Keyword(s):  
Trace Elements ◽  
Water Systems ◽  
Hot Water ◽  
Plate Counts ◽  
Heterotrophic Plate Counts

scholarly journals Bacteriological investigation of the washing and sterilization of food containers

1947 ◽  
Vol 45 (2) ◽  
pp. 151-158 ◽  
Author(s):  
R. Knox ◽  
Jacqueline Walker
Keyword(s):  
Great Improvement ◽  
Hot Water ◽  
Routine Method ◽  
Steam Sterilization ◽  
Education Department ◽  
Large Numbers ◽  
Before And After ◽  
Plate Counts ◽  
Bacteriological Investigation ◽  
Washing Water

1. We have investigated bacteriologically the conditions in a central meals kitchen from which about 3000 meals were issued daily to some 65 departments.2. Plate counts showed that the containers in which the meals were sent out contained large numbers of organisms, from several thousand to several hundred thousand per container.3. Counts of this order were obtained both before and after the routine method of washing.4. These counts were reduced to the order of a few hundred or less per container by steam sterilization.5. Exposure for 2–3 min. to steam from a simple jet sterilizer was effective for all except large insulated lids which required at least 5 min.6. Treatment for 5 min. in a chamber filled with steam from a boiler was effective with all types of containers and lids tested.7. If containers are to be sterilized at all they must be sterilized each time they are to be used.8. A great improvement in the bacteriological counts can be achieved by attention to the hygiene of washing, e.g. by the use of plenty of hot water with soap and soda or perhaps preferably with detergents, with a second sink of very hot water for rinsing, and by using fresh sterilized dish-cloths each time the washing water is changed.9. Counts almost as good as those given by steam sterilization were obtained by washing with soap and water at 48–50° C., wiping with a sterilized dish-cloth and then rinsing in a second sink of water at 75–80° C.10. The arguments for and against steam sterilization are discussed.This investigation was greatly helped by the co-operation of the Leicester Education Department.

The initial stages in the action of an insecticidal delta-endotoxin of Bacillus thuringiensis var. israelensis on the epithelial cells of the malpighian tubules of the insect, Rhodnius prolixus

1988 ◽  
Vol 90 (1) ◽  
pp. 131-144
Author(s):  
S.H. Maddrell ◽  
N.J. Lane ◽  
J.B. Harrison ◽  
J.A. Overton ◽  
R.B. Moreton
Keyword(s):  
Bacillus Thuringiensis ◽  
Intercellular Junctions ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Ultrastructural Changes ◽  
Cytoplasmic Vacuolization ◽  
Large Numbers ◽  
Delta Endotoxin ◽  
High Concentrations ◽  
Very High

The effects of the 27 X 10(3) Mr insecticidal delta-endotoxin from Bacillus thuringiensis var. israelensis have been studied using, as a model system, isolated insect Malpighian tubules. At all concentrations of the toxin higher than 1 microgram ml-1 (4 X 10(−8) moll-1) applied to the outer surface of the tubules, fluid secretion failed within about 30 min. Except at very high concentrations, where failure always takes at least 30 s, there was an inverse relationship between the concentration of toxin and the time of failure of toxin-treated tubules. During exposure to toxin, the tubules were initially unaffected for a relatively long period and then rapid failure occurred. If the tubules were removed into toxin-free saline just before failure would have occurred, fluid secretion remained normal for at least 2 h, but on return to the origin toxin-containing saline failure was almost immediate. The toxin was found not to bind to the basement membrane. Ultrastructural changes became evident as tubule failure occurred. These initially involved modifications to the basal side of the cells, but later also to the luminal microvilli. Intercellular junctions became disassociated and cytoplasmic vacuolization occurred. The population of intramembranous particles in the basal membranes became reduced with time. Our findings suggest the following hypothesis for the initial stages in the interaction of the toxin with the tubules. Toxin molecules attach to the accessible cell membranes progressively and irreversibly. They do not readily associate by diffusing laterally in the membrane, so that toxic effects develop only when sufficiently large numbers of them attach close together. The molecules may then associate in some way as a complex, perhaps forming a pore in the membrane. Relatively few such pores lead rapidly to cell failure and death.

scholarly journals Taking Screenshots of the Invisible: A Study on Bacterial Contamination of Mobile Phones from University Students of Healthcare Professions in Rome, Italy

2020 ◽  
Vol 8 (7) ◽  
pp. 1075 ◽  
Author(s):  
Domenico Cicciarella Modica ◽  
Massimo Maurici ◽  
Gian Loreto D’Alò ◽  
Cinzia Mozzetti ◽  
Alessandra Messina ◽  
...  
Keyword(s):  
Mobile Phones ◽  
Staphylococcus Epidermidis ◽  
Univariate Analysis ◽  
Clinical Settings ◽  
Linear Regression Models ◽  
Biochemical Tests ◽  
E Coli ◽  
Plate Counts ◽  
Healthcare Professions ◽  
Heterotrophic Plate Counts

Mobile phones (MPs) are commonly used both in the personal and professional life. We assessed microbiological contamination of MPs from 108 students in healthcare professions (HPs), in relation to their demographic characteristics and MPs handling habits, collected by means of a questionnaire. Cultural and biochemical tests were performed, and statistical analyses were carried out. Staphylococci were present in 85% of MPs, Enterococci in 37%, Coliforms in 6.5%; E. coli was never detected. Staphylococcus epidermidis was the most frequently isolated staphylococcal species (72% of MPs), followed by S. capitis (14%), S. saprophyticus, S. warneri, S. xylosus (6%), and by S. aureus (4%). Heterotrophic Plate Counts (HPC) at 37 °C, ranged from 0 to 1.2 × 104 CFU/dm2 (mean = 362 CFU/dm2). In univariate analysis, the male gender only was significantly associated with higher HPCs and enterococcal contamination. Multiple linear regression models explained only 17% and 16% of the HPC 37 °C and staphylococcal load variability, respectively. Developing specific guidelines for a hygienic use of MPs in clinical settings, for preventing cross-infection risks, is advisable, as well as introducing specific training programs to HP students. MPs decontamination procedures could also be implemented in the community.

Coliforms and other microbial indicators occurrence in water and biofilm in full-scale distribution systems

2006 ◽  
Vol 54 (3) ◽  
pp. 41-48 ◽  
Author(s):  
M. Batté ◽  
C. Féliers ◽  
P. Servais ◽  
V. Gauthier ◽  
J.-C. Joret ◽  
...  
Keyword(s):  
Water Quality ◽  
Residence Time ◽  
Distribution Systems ◽  
Full Scale ◽  
Bacterial Indicators ◽  
Total Coliforms ◽  
E Coli ◽  
Plate Counts ◽  
Microbiological Water Quality ◽  
Heterotrophic Plate Counts

Biofilm and microbial water quality were studied in four middle size full-scale distribution systems (DS) in France serving 5,000–30,000 inhabitants (maximum residence time 23–160 h) through three sampling campaigns over 1 year. Three of these DSs were chosen because of a quite high occurrence of bacterial indicators (i.e. total coliforms), the last DS was considered as a reference. Biofilm was studied on cast iron coupons incubated for more than 1 month in devices continuously fed with water from the DS in conditions imitating those met in DS. The devices were located at different points (4–6) along each DS. The abundance of bacteria in biofilm was estimated by heterotrophic plate counts (HPC) after detachment of the biofilm from the support by sonication. Microbiological water quality was estimated in parallel; analysis of total coliforms, E. coli, enterococci and anaerobic sulphide-reducing bacteria spores (ASRB spores) was carried out in biofilm and water. Over the period of the study, 171 water samples and 57 biofilm samples were collected. Over these 171 waters, 19 (11%) were positive for at least one of the measured indicators while two biofilm samples were positive (3.5%). Significant differences were observed in the levels of contamination between the DSs. High residence time in the DS, low disinfectant residual and high temperature increased the risk of indicator occurrence in the water phase. Due to the low number of biofilm samples positive for bacterial indicators, the data collected in the present study did not allow observation of a direct association between biofilm and water contaminations, even if the occurrence of indicators in water appeared on DSs with the highest density of biofilm (HPC).

scholarly journals Effects of Hydrogen Peroxide on Dental Unit Biofilms and Treatment Water Contamination

2011 ◽  
Vol 05 (01) ◽  
pp. 047-059 ◽  
Author(s):  
Shih-Ming Lin ◽  
Kathy K.H. Svoboda ◽  
Anthony Giletto ◽  
Jeff Seibert ◽  
Raghunath Puttaiah
Keyword(s):  
Hydrogen Peroxide ◽  
Water Contamination ◽  
Challenge Test ◽  
Control Unit ◽  
Effluent Water ◽  
Municipal Water ◽  
Plate Counts ◽  
Contamination Levels ◽  
Heterotrophic Plate Counts

ABSTRACTObjectives: To study effects of various concentrations of hydrogen peroxide on mature waterline biofilms and in controlling planktonic (free-floating) organisms in simulated dental treatment water systems; and to study in vitro the effects of 2%, 3%, and 7% hydrogen peroxide on the removal of mature biofilms and inorganic compounds in dental waterlines. Methods: Four units of an automated dental unit water system simulation device was used for 12 weeks. All units were initially cleaned to control biofilms and inorganic deposits. H2O2 at concentrations of 1%, 2%, 3% was used weekly for periodic cleaning in three treatment group units (units 1, 2 & 3), with 0.05%, 0.15% and 0.25% H2O2 in municipal water used as irrigant respectively. The control unit (unit 4) did not have weekly cleanings and used municipal water as irrigant. Laser Scanning Confocal Microscopy and Scanning Electron Microscopy were used to study deposits on lines, and weekly heterotrophic plate counts done to study effluent water contamination. A 24 hour in vitro challenge test with 7%, 3% and 2% H2O2 on mature biofilms was conducted using harvested waterlines to study biofilm and inorganic deposit removal. Results: Heterotrophic plate counts of effluent water showed that the control unit reached contamination levels in excess of 400,000 CFU/mL while all treatment units showed contamination levels <500 CFU/mL through most of the 12 weeks. All treatment units showed varying levels of biofilm and inorganic deposit control in this short 12 week study. The in vitro challenge test showed although there was biofilm control, there was no eradication even when 7% H2O2 was used for 24 hours. Conclusions: 2% H2O2 used as a periodic cleaner, and diluted to 0.05% in municipal water for irrigation was beneficial in controlling biofilm and planktonic contamination in dental unit water systems. However, to remove well established biofilms, it may take more than 2 months when initial and multiple periodic cleanings are performed using H2O2. (Eur J Dent 2011;5:47-59)

scholarly journals Evaluation of Microbiological and Free-Living Protozoa Contamination in Dental Unit Waterlines

2019 ◽  
Vol 16 (15) ◽  
pp. 2648 ◽  
Author(s):  
Anna Maria Spagnolo ◽  
Marina Sartini ◽  
David Di Cave ◽  
Beatrice Casini ◽  
Benedetta Tuvo ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Tap Water ◽  
Microbiological Quality ◽  
Coliform Bacteria ◽  
Dental Staff ◽  
Plate Counts ◽  
Dental Unit Waterlines ◽  
Heterotrophic Plate Counts

Studies conducted over the last 40 years have demonstrated that the water output from dental unit waterlines (DUWLs) is often contaminated with high densities of microorganisms. It has been monitored the microbiological quality of the water in 30 public dental facilities in northern Italy in order to assess the health risk for patients and dental staff. In each facility, samples of water both from taps and from DUWLs were analyzed in order to evaluate heterotrophic plate counts (HPCs) at 22 °C and 36 °C, and to detect coliform bacteria, Pseudomonas aeruginosa, Legionella pneumophila and amoebae. In 100% of the samples taken from the DUWLs, the concentration of HPCs was above the threshold as determined by the Ministère de la Santé et des Solidarités (2007). The concentration of P. aeruginosa was greater than the indicated threshold in 16.67% of the hand-pieces analyzed. A total of 78.33% of samples were contaminated by L. pneumophila, while in the samples taken from the DUWLs alone, this percentage rose to 86.67%. Amoebae were detected in 60% of the samples taken from hand-pieces; all belonging to the species V. vermiformis. This study documented the presence of various microorganisms, including Legionella spp., at considerably higher concentrations in water samples from DUWLs than in samples of tap water in the same facilities, confirming the role of the internal DUWLs in increasing microbial contamination, especially in the absence of proper management of waterborne health risks.

scholarly journals Research Frontiers in Oral Toxicities of Cancer Therapies: Osteoradionecrosis of the Jaws

2019 ◽  
Vol 2019 (53) ◽  
Author(s):  
Frederik K L Spijkervet ◽  
Michael T Brennan ◽  
Douglas E Peterson ◽  
Max J H Witjes ◽  
Arjan Vissink
Keyword(s):  
Clinical Trials ◽  
Cancer Treatment ◽  
Head And Neck ◽  
Conservative Therapy ◽  
Randomized Clinical Trials ◽  
Preventive Effect ◽  
Cure Rate ◽  
Dental Surgery ◽  
Large Numbers ◽  
Increased Risk

AbstractThe deleterious effects of head and neck radiation on bone, with osteoradionecrosis (ORN) as the major disabling side effect of head and neck cancer treatment, are difficult to prevent and hard to treat. This review focuses on the current state of the science regarding the pathobiology, clinical impact, and management of ORN. With regard to the pathobiology underlying ORN, it is not yet confirmed whether the current radiation schedules by 3-dimensional conformal radiotherapy and intensity modified radiotherapy result in an unchanged, decreased, or increased risk of developing ORN when compared with conventional radiation treatment, the main risk factor being the total radiation dose delivered on any clinically significant surface of the mandible.With regard to the prevention of ORN, a thorough, early pre-irradiation dental assessment is still considered the first step to reduce the hazard of developing ORN post-radiotherapy, and hyperbaric oxygen (HBO) treatment reduces the risk of developing ORN in case of dental surgery in an irradiated field.With regard to the treatment of ORN, the focus is bidirectional: elimination of the necrotic bone and improving the vascularity of the normal tissues that were included in the radiation portal. The cure rate of limited ORN by conservative therapy is approximately 50%, and the cure rate of surgical approaches when conservative therapy has failed is approximately 40%.Whether it is effective to support conservative or surgical treatment with HBO as an adjuvant is not set. HBO treatment is shown to increase the vascularity of hard and soft tissues and has been reported to be beneficial in selected cases. However, in randomized clinical trials comparing the preventive effect of HBO on developing ORN with, eg, antibiotic coverage in patients needing dental surgery, the preventive effect of HBO was not shown to surpass that of a more conservative approach.More recently, pharmacologic management was introduced in the treatment of ORN with success, but its efficacy has to be confirmed in randomized clinical trials. The major problem of performing well-designed randomized clinical trials in ORN is having access to large numbers of patients with well-defined, comparable cases of ORN. Because many institutions will not have large numbers of such ORN cases, national and international scientific societies must be approached to join multicenter trials. Fortunately, the interest of funding organizations and the number researchers with an interest in healthy aging is growing. Research aimed at prevention and reduction of the morbidity of cancer treatment fits well within these programs.

scholarly journals Adaptation induced by self-targeting in a type I-B CRISPR-Cas system

2020 ◽  
Vol 295 (39) ◽  
pp. 13502-13515 ◽  
Author(s):  
Aris-Edda Stachler ◽  
Julia Wörtz ◽  
Omer S. Alkhnbashi ◽  
Israela Turgeman-Grott ◽  
Rachel Smith ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Genomic Dna ◽  
Haloferax Volcanii ◽  
Type I ◽  
Dna Breaks ◽  
End Joining ◽  
Low Level ◽  
Large Numbers ◽  
High Concentrations ◽  
Cas Proteins

Haloferax volcanii is, to our knowledge, the only prokaryote known to tolerate CRISPR-Cas–mediated damage to its genome in the WT background; the resulting cleavage of the genome is repaired by homologous recombination restoring the WT version. In mutant Haloferax strains with enhanced self-targeting, cell fitness decreases and microhomology-mediated end joining becomes active, generating deletions in the targeted gene. Here we use self-targeting to investigate adaptation in H. volcanii CRISPR-Cas type I-B. We show that self-targeting and genome breakage events that are induced by self-targeting, such as those catalyzed by active transposases, can generate DNA fragments that are used by the CRISPR-Cas adaptation machinery for integration into the CRISPR loci. Low cellular concentrations of self-targeting crRNAs resulted in acquisition of large numbers of spacers originating from the entire genomic DNA. In contrast, high concentrations of self-targeting crRNAs resulted in lower acquisition that was mostly centered on the targeting site. Furthermore, we observed naïve spacer acquisition at a low level in WT Haloferax cells and with higher efficiency upon overexpression of the Cas proteins Cas1, Cas2, and Cas4. Taken together, these findings indicate that naïve adaptation is a regulated process in H. volcanii that operates at low basal levels and is induced by DNA breaks.

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