Adenosine Triphosphate Measurements Research Articles

Monitoring of endoscope reprocessing with an adenosine triphosphate (ATP) bioluminescence method.

Background: The arising challenges over endoscope reprocessing quality proposes to look for possibilities to measure and control the process of endoscope reprocessing.Aim: The goal of this study was to evaluate the feasibility of monitoring endoscope reprocessing with an adenosine triphosphate (ATP) based bioluminescence system.Methods: 60 samples of eight gastroscopes have been assessed from routine clinical use in a major university hospital in Germany. Endoscopes have been assessed with an ATP system and microbial cultures at different timepoints during the reprocessing. Findings: After the bedside flush the mean ATP level in relative light units (RLU) was 19,437 RLU, after the manual cleaning 667 RLU and after the automated endoscope reprocessor (AER) 227 RLU. After the manual cleaning the mean total viable count (TVC) per endoscope was 15.3 CFU/10 ml, and after the AER 5.7 CFU/10 ml. Our results show that there are reprocessing cycles which are not able to clean a patient used endoscope.Conclusion: Our data suggest that monitoring of flexible endoscope with ATP can identify a number of different influence factors, like the endoscope condition and the endoscopic procedure, or especially the quality of the bedside flush and manual cleaning before the AER. More process control is one option to identify and improve influence factors to finally increase the overall reprocessing quality, best of all by different methods. ATP measurement seems to be a valid technique that allows an immediate repeat of the manual cleaning if the ATP results after manual cleaning exceed the established cutoff of 200 RLU.

アデノシン三リン酸測定を用いた冷温水槽の循環水の腐敗評価

アデノシン三リン酸測定を用いた冷温水槽の循環水の腐敗評価

Direct measurement of ATP in seawater and application of ATP to monitor bacterial growth potential in SWRO pre-treatment systems

The use of adenosine triphosphate (ATP) to monitor bacterial growth potential of seawater is currently not possible as ATP cannot be accurately measured at low concentration in seawater using commercially available luciferase-based ATP detection. The limitation is due to interference of salt with the luciferin–luciferase reaction, which inhibits light production. This research demonstrates that new reagents developed for (i) ATP extraction from microbial cells and (ii) ATP detection in seawater are able to reliably detect Microbial ATP as low as 0.3 ng L–1 in seawater. The luminescence signal of the new detection reagent is significantly higher (>20 times) than the luminescence signal of the freshwater reagent, when applied in seawater. ATP can now be used to monitor bacterial growth potential (BGP) through pre-treatment trains of seawater reverse osmosis (SWRO) plants. The level of detection of the new BGP test is significantly lower than the estimated threshold value required to prevent biofouling in SWRO systems. The new reagents have been used to monitor Microbial ATP in coastal North Sea water. Moreover, Microbial ATP has been applied to monitor the bacterial growth potential (using indigenous bacteria) through the pre-treatment train of an SWRO desalination plant. A significant reduction (>55%) of the bacterial growth potential was found through the dual media filtration with 4.5 mg-Fe(III) L–1 coagulant. Overall, the new reagents can detect low Microbial ATP concentrations in seawater and can be used to monitor bacterial growth potential in seawater desalination plants.

Evaluation of Novel Process Indicators for Rapid Monitoring of Hydrogen Peroxide Decontamination Processes.

Geobacillus stearothermophilus spores on stainless steel discs are routinely used as biological indicators for the validation of hydrogen peroxide bio-decontamination processes. Given ongoing concerns about the reliability and response time of biological indicators, we explored the potential for an enzyme-based approach to decontamination process evaluation. Thermostable adenylate kinase enzyme was coated onto a solid support and exposed to hydrogen peroxide vapour, in parallel with standard commercial 6-log biological indicators, during a series of vapour-phase hydrogen peroxide cycles in a flexible film isolator. The exposed biological indicators were enumerated to define the degree of kill at different time intervals and the results compared to the thermostable adenylate kinase values, as determined by measuring adenosine triphosphate produced by residual active enzyme. Both biological indicators and the thermostable adenylate kinase indicators exhibited a biphasic inactivation profile during the process. There was significant variance between individual cycles, with some cycles showing complete inactivation of the biological indicators to the limit of detection of the assay, within 6 min, whereas biological indicators in some cycles were inactivated at a time greater than 12 min. The log-kill of the biological indicators at intermediate time points were plotted and compared to the fully quantifiable measurements derived from the thermostable adenylate kinase indicators at the same time points. The results demonstrated very similar inactivation profiles for the enzyme and for the biological indicators, thus it was possible to define a relationship between relative light units measurement and biological indicator kill. This indicates that it is possible to use thermostable adenylate kinase measurement as a direct measure of vapour-phase hydrogen peroxide bio-decontamination performance, expressed in terms of log reduction. Because thermostable adenylate kinase measurement can be achieved within a few minutes of vapour-phase hydrogen peroxide cycle completion, compared with a minimum of 7 days for the evaluation of biological indicator growth, this offers a potentially valuable tool for rapid vapour-phase hydrogen peroxide bio-decontamination cycle development and subsequent re-qualification.LAY ABSTRACT: Pharmaceutical product manufacture is performed in controlled cleanroom and closed chamber environments (isolators) to reduce the risk of contamination. These environments undergo regular decontamination to control microbial contamination levels, using a range of methods, one of which is to vaporize hydrogen peroxide (a chemical disinfectant) into a gas or an aerosol and disperse it throughout the environment, killing any microorganisms present. Biological indicators, which consist of a small steel coupon carrying a population of bacterial spores that are more resistant to hydrogen peroxide than are most microorganisms, are placed within the environment, and then tested for growth following treatment to ensure the process was effective. Confirmation of growth/no growth (and therefore hydrogen peroxide cycle efficacy) can take up to 7 days, which significantly increases time and cost of developing and confirming cycle efficacy. This study tests whether a new technology which uses a robust enzyme, thermostable adenylate kinase, could be used to predict biological indicator growth. The study shows this method can be used to confirm hydrogen peroxide cycle efficacy, by predicting whether the BI is killed at a specific time point or not and results are obtained in a few minutes rather than 7 days. This potentially offers significant time and cost benefits.

Ozone regeneration of granular activated carbon for trihalomethane control

Spatial and temporal variations of trihalomethanes (THMs) in distribution systems have challenged water treatment facilities to comply with disinfection byproduct rules. In this study, granular activated carbon (GAC) and modified GAC (i.e., Ag-GAC and TiO2-GAC) were used to treat chlorinated tap water containing CHCl3 (15–21μg/L), CHBrCl2 (13–16μg/L), CHBr2Cl (13–14μg/L), and CHBr3 (3μg/L). Following breakthrough of dissolved organic carbon (DOC), GAC were regenerated using conventional and novel methods. GAC regeneration efficiency was assessed by measuring adsorptive (DOC, UV absorbance at 254nm, and THMs) and physical (surface area and pore volume) properties. Thermal regeneration resulted in a brief period of additional DOC adsorption (bed volume, BV, ∼6000), while ozone regeneration was ineffective regardless of the GAC type. THM adsorption was restored by either method (e.g., BV for ≥80% breakthrough, CHBr3 ∼44,000>CHBr2Cl ∼35,000>CHBrCl2 ∼31,000>CHCl3 ∼7000). Cellular and attached adenosine triphosphate measurements illustrated the antimicrobial effects of Ag-GAC, which may have allowed for the extended THM adsorption compared to the other GAC types. The results illustrate that ozone regeneration may be a viable in-situ alternative for the adsorption of THMs during localized treatment in drinking water distribution systems.

A suggested sampling algorithm for use with ATP testing in cleanliness measurement

Abstract Introduction Rapid Adenosine Triphosphate (ATP) testing is becoming a commonly used method to measure cleanliness on reusable medical devices and healthcare environmental surfaces. Unfortunately, ATP testing devices suffer from inherent variability from a number of sources including imprecision in ATP measurement. Method This paper proposes a new sampling algorithm which reduces the impact of inherent variability and thus improves decision making when using ATP testing. Conclusion This algorithm can be applied across a variety of applications to provide more reliable data on measurable cleanliness standards for both medical devices and environmental surfaces. Formal trials using the new ATP sampling algorithm are required.

Simultaneous analysis of adenosine triphosphate and its metabolites in Saccharomyces Cerevisiae using RP-HPLC

In order to assess the contribution of adenosine triphosphate and its metabolites to the cellular metabolism process in Saccharomyces cerevisiae, it is very important to simultaneously determine the relative concentrations of ATP and its metabolites. In this study, a fast, simple reversed-phase high-performance liquid chromatography with high selectivity was developed to simultaneously measure adenosine triphosphate and its metabolites (adenosine diphosphate, adenosine monophosphate, and cyclic adenosine monophosphate) in yeast. The method was performed under the gradient grogram, and the detection was monitored at 254 nm. Analysis was achieved within 25 min. The four components can be detected with linear response over the concentration range from 1 to 100 mg L−1 with excellent correlation coefficients (r2) > 0.999. The recovery of the four analytes was 92.9%, 90.4%, 99.1%, and 105.1%, respectively. To demonstrate the good analysis of yeast samples, changes in the four adenine nucleotides levels caused by caloric restriction in yeast were determined. It is expected that the current method may contribute to further metabolomics and system biology investigations of yeast.

Immune function monitoring in lung transplantation using adenosine triphosphate production: time trends and relationship to postoperative infection.

The ImmuKnow (IK) assay is a comprehensive immune function test that involves measuring adenosine triphosphate produced by the cluster of differentiation 4+ T lymphocytes in peripheral blood. The aim of this study was to analyze the time trends of IK values and assess the relationship between IK values and infections in lung transplants. We prospectively collected 178 blood samples from 22 deceased-donor lung transplant (DDLT) recipients and 17 living-donor lobar lung transplant (LDLLT) recipients. A surveillance IK assay was performed postoperatively, then after 1week and 1, 3, 6, and 12months. Time trends of IK values in stable recipients peaked 1week after DDLT (477±247 ATP ng/ml), and 1month after LDLLT (433±134ng/ml), followed by a gradual decline over 1year. The mean IK values in infections were significantly lower than those in the stable state (119 vs 312 ATP ng/ml, p=0.0002). IK values increased sharply after lung transplantation and then decreased gradually over time in the first year, suggesting a natural history of immune function. IK values were also significantly reduced during infections. These results may provide new insights into the utility of immune monitoring after lung transplantation.

Use of ATP Readings to Predict a Successful Hygiene Intervention in the Workplace to Reduce the Spread of Viruses on Fomites.

The purpose of this study was to validate the use of adenosine triphosphate (ATP) for evaluating hygiene intervention effectiveness in reducing viral dissemination in an office environment. The bacterial virus MS-2 was used to evaluate two scenarios, one where the hand of an individual was contaminated and another where a fomite was contaminated. MS-2 was selected as a model because its shape and size are similar to many human pathogenic viruses. Two separate experiments were conducted, one in which the entrance door push plate was inoculated and the other in which the hand of one selected employee was inoculated. In both scenarios, 54 selected surfaces in the office were tested to assess the dissemination of the virus within the office. Associated surface contamination was also measured employing an ATP meter. More than half of the tested hands and surfaces in the office were contaminated with MS-2 within 4h. Next, an intervention was conducted, and each scenario was repeated. Half of the participating employees were provided hand sanitizer, facial tissues, and disinfecting wipes, and were instructed in their use. A significant (p<0.05) reduction was observed in the number of surfaces contaminated with virus. This reduction in viral spread was evident from the results of both viral culture and the surface ATP measurements, although there was no direct correlation between ATP measurements with respect to viral concentration. Although ATP does not measure viruses, these results demonstrate that ATP measurements could be useful for evaluating the effectiveness of hygiene interventions aimed at preventing viral spread in the workplace.

Non-invasive assessment of phosphate metabolism and oxidative capacity in working skeletal muscle in healthy young Chinese volunteers using (31)P Magnetic Resonance Spectroscopy.

Background. Generally, males display greater strength and muscle capacity than females while performing a task. Muscle biopsy is regarded as the reference method of evaluating muscle functions; however, it is invasive and has sampling errors, and is not practical for longitudinal studies and dynamic measurement during excise. In this study, we built an in-house force control and gauge system for quantitatively applying force to quadriceps while the subjects underwent 31P Magnetic Resonance Spectroscopy (31P-MRS); our aim was to investigate if there is a sex difference of phosphate metabolite change in working muscles in young heathy Chinese volunteers.Methods. Volunteers performed knee-extending excises using a force control and gauge system while lying prone in a Philips 3T Magnetic Resonance (MR) scanner. The 31P-MRS coil was firmly placed under the middle of the quadriceps . 31P-MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr) and adenosine triphosphate (ATP) were acquired from quadriceps while subjects were in a state of pre-, during- and post-exercise. The PCr, Pi, PCr/Pi, PCr/ATP, pH, work/energy cost ratio (WE), kPCr and oxidative capacity were compared between males and females.Results. A total of 17 volunteers underwent the study. Males: N = 10, age = 23.30 ± 1.25years; females: N = 7, age = 23.57 ± 0.79 years. In this study, males had significantly greater WE (16.33 ± 6.46 vs. 7.82 ± 2.16, p = 0.002) than females. Among PCr, Pi, PCr/Pi, PCr/ATP, pH, kPCr and oxidative capacity at different exercise status, only PCr/Pi (during-exercise, males = 5.630 ± 1.647, females = 4.014 ± 1.298, p = 0.047), PCr/ATP (during-exercise, males =1.273 ± 0.219, females = 1.523 ± 0.167, p = 0.025), and ATP (post-exercise, males = 24.469 ± 3.911 mmol/kg, females = 18.353 ± 4.818 mmol/kg, p = 0.035) had significant sex differences. Males had significantly greater PCr/Pi, but less PCr/ATP than females during exercise, suggesting males had higher energy transfer efficiency than females. At the post-exercise status, the recovery of PCr did not show sex difference.Conclusions. Our in-house force control and gauge system quantitatively applied force during the exercise for 31P-MRS experiments, and a sex difference of higher energy transfer efficiency and WE was detected in males with mild loaded exercising quadriceps. This noninvasive technology allows us to further study and understand the sex difference of high energy phosphate metabolism in the future.

Real-time monitoring of cisplatin cytotoxicity on three-dimensional spheroid tumor cells

Three-dimensional (3D) cell cultivation is a powerful technique for monitoring and understanding diverse cellular mechanisms in developmental cancer and neuronal biology, tissue engineering, and drug development. 3D systems could relate better to in vivo models than two-dimensional (2D) cultures. Several factors, such as cell type, survival rate, proliferation rate, and gene and protein expression patterns, determine whether a particular cell line can be adapted to a 3D system. The 3D system may overcome some of the limitations of 2D cultures in terms of cell–cell communication and cell networks, which are essential for understanding differentiation, structural organization, shape, and extended connections with other cells or organs. Here, the effect of the anticancer drug cisplatin, also known as cis-diamminedichloroplatinum (II) or CDDP, on adenosine triphosphate (ATP) generation was investigated using 3D spheroid-forming cells and real-time monitoring for 7 days. First, 12 cell lines were screened for their ability to form 3D spheroids: prostate (DU145), testis (F9), embryonic fibroblast (NIH-3T3), muscle (C2C12), embryonic kidney (293T), neuroblastoma (SH-SY5Y), adenocarcinomic alveolar basal epithelial cell (A549), cervical cancer (HeLa), HeLa contaminant (HEp2), pituitary epithelial-like cell (GH3), embryonic cell (PA317), and osteosarcoma (U-2OS) cells. Of these, eight cell lines were selected: NIH-3T3, C2C12, 293T, SH-SY5Y, A549, HeLa, PA317, and U-2OS; and five underwent real-time monitoring of CDDP cytotoxicity: HeLa, A549, 293T, SH-SY5Y, and U-2OS. ATP generation was blocked 1 day after addition of 50 μM CDDP, but cytotoxicity in HeLa, A549, SH-SY5Y, and U-2OS cells could be visualized only 4 days after treatment. In 293T cells, CDDP failed to kill entirely the culture and ATP generation was only partially blocked after 1 day. This suggests potential CDDP resistance of 293T cells or metabolic clearance of the drug. Real-time monitoring and ATP measurements directly confirmed the cytotoxicity of CDDP, indicating that CDDP may interfere with mitochondrial activity.

Inactivation efficiency of Escherichia coli and autochthonous bacteria during ozonation of municipal wastewater effluents quantified with flow cytometry and adenosine tri-phosphate analyses

Inactivation kinetics of autochthonous bacteria during ozonation of wastewater effluents were investigated using cultivation-independent flow cytometry (FCM) with total cell count (TCC) and intact cell count (ICC) and intracellular adenosine triphosphate (ATP) analysis. The principles of the methods including ozone inactivation kinetics were demonstrated with laboratory-cultured Escherichia coli spiked into filtered and sterilized wastewater effluent. Both intracellular ATP and ICC decreased with increasing ozone doses, with ICC being the more conservative parameter. The log-inactivation levels (−log(N/N0) of E. coli reached the method detection limits for FCM (∼3) and ATP (∼1.7) at specific ozone doses of ≥0.5 gO3/gDOC. During ozonation of four real wastewater effluents, the log-inactivation of autochthonous bacteria with FCM ICC was 0.3–1.0 for 0.25 gO3/gDOC and increased to 1.1–2.1 for 0.5 gO3/gDOC, but remained at a similar level of 1.5–2.8 for a further increase of the specific ozone doses to 1.0 and 1.5 gO3/gDOC. The FCM data also showed that autochthonous bacteria were composed of communities with high and low ozone reactivity. The inactivation levels measured with intracellular ATP were reasonably correlated to ICC (r2 = 0.8). Overall, FCM and ATP measurements were demonstrated to be useful tools to monitor the inactivation of autochthonous bacteria during ozonation of municipal wastewater effluents.

Development and application of an accelerated biofouling test in flat cell

This paper discusses the steps followed to establish an accelerated reverse osmosis membrane biofouling test protocol. Easily bioassimilable nutrients were dosed into water from the Ebro River which was fed into a membrane flat cell pilot plant. The membrane biofouling results were determined by measuring adenosine triphosphate and total organic carbon extracted from the exposed membrane and feed spacer. This strategy was chosen because the equipment does not have pressure drop measurement capability and the observed change in flux or salt rejection was not significant under the testing conditions. The duration of the experiment was set to 3 d to enable rapid screening of different membrane types, yet enable a smooth evolution of biofilm. This study determined that achieving a similar amount of biofouling in each of the three cells was very sensitive to the level of bioassimilable nutrients were dosed to the water. For the Ebro River water, 0.2 mg/L of carbon, 0.04 mg/L of nitrogen, and 0.02 mg/L of phosphorous was determined to provide the best result.

Effectiveness of hand hygiene depends on the patient's health condition and care environment.

The present authors examined how patient hand contamination was associated with underlying disease and treatment environment in order to determine effective hand hygiene methods. Samples were collected from inpatients (45 with hematological malignancies, 48 postoperative), outpatients (48 undergoing hemodialysis, 55 on chemotherapy), and 44 individuals living in nursing homes. All participants provided informed consent for study participation. All subjects performed hand hygiene. Before and after hand hygiene, samples of bacteria were collected from the palm of the hand onto agar media. Bacteria were counted and bacterial strains were identified. The authors then collected smear samples from the contralateral palm and measured adenosine triphosphate (ATP) levels. Patient hand contamination was the highest in hemodialysis patients, followed by residents of nursing homes, postoperative patients, patients with cancer receiving chemotherapy, and patients of hematological malignancies. Regardless of the underlying disease and treatment environment, patients were able to reduce the number of bacterial colonies and ATP by proper hand hygiene. Compared with wet wipes, hand washing seemed to remove bacteria more effectively. Methicillin-resistant Staphylococcus aureus (MRSA) was detected in 30 subjects, none of whom were patients of hematological malignancies. Of these, 19 tested negative for MRSA after performing proper hand hygiene. Patient hand contamination is affected by underlying disease and care environment, but can be reduced by encouraging proper hand washing. Proper patient hand hygiene can reduce MRSA on patients' hands, and thus may serve as an effective tool for prevention of healthcare-associated infections.

ATP Measurement in the Last Rinse Water of Automated Washer-Disinfectors: The Added Value of Every Load Monitoring

Objective: To assess whether monitoring every loads of automated washer-disinfectors (AWDs) by testing the last rinse water with Adenosine Triphosphate (ATP) would have an added value to document effective and reproducible AWD processes. Methods: Every load monitoring (ELM) of the last rinse water with ATP was performed on three AWDs at the sterilization department of a 329 acute-bed hospital in Italy. No change were made in the routine procedures, except the last rinse water of a process was collected with a water sampler and tested on ATP. Data from negative controls and empty cycles were also obtained for comparison. ATP values were analysed according to AWD, load, and process characteristics. Results: A total of 435 ATP tests were performed, including 74 negative, 74 empty runs and 287 regular load tests. ATP values from regular loads ranged between 2 and 452 RLUs and 1.3%, 0.7%, 0.3% out of the 287 measurements was above 200, 300, and 400 RLUs, respectively. ATP values from negative tests and empty runs differed significantly (p<0.001) from the regular loads with a median value [I quartile; III quartile] of 4[2;5], 5[3;7], and 12[7;22] RLU, respectively. Analysis of ATP values from regular loads grouped by load pre-treatment, AWD washing program, load material or load amount showed significant differences between groups. No significant differences in ATP data were found among AWDs. Conclusion: The measurement of ATP in the last rinse water of AWDs showed that characteristics and quantities of the load relate to the ATP readings. The test is advised as an informative additional test to visual inspection for monitoring every load of an AWD.

新鮮ヒト血液を用いたアデノシン三リン酸測定法の洗浄評価判定法の有用性に関する検討

新鮮ヒト血液を用いたアデノシン三リン酸測定法の洗浄評価判定法の有用性に関する検討

Copper Complex in Poly(vinyl chloride) as a Nitric Oxide-Generating Catalyst for the Control of Nitrifying Bacterial Biofilms.

In this study, catalytic generation of nitric oxide by a copper(II) complex embedded within a poly(vinyl chloride) matrix in the presence of nitrite (source of nitric oxide) and ascorbic acid (reducing agent) was shown to effectively control the formation and dispersion of nitrifying bacteria biofilms. Amperometric measurements indicated increased and prolonged generation of nitric oxide with the addition of the copper complex when compared to that with nitrite and ascorbic acid alone. The effectiveness of the copper complex-nitrite-ascorbic acid system for biofilm control was quantified using protein analysis, which showed enhanced biofilm suppression when the copper complex was used in comparison to that with nitrite and ascorbic acid treatment alone. Confocal laser scanning microscopy (CLSM) and LIVE/DEAD staining revealed a reduction in cell surface coverage without a loss of viability with the copper complex and up to 5 mM of nitrite and ascorbic acid, suggesting that the nitric oxide generated from the system inhibits proliferation of the cells on surfaces. Induction of nitric oxide production by the copper complex system also triggered the dispersal of pre-established biofilms. However, the addition of a high concentration of nitrite and ascorbic acid to a pre-established biofilm induced bacterial membrane damage and strongly decreased the metabolic activity of planktonic and biofilm cells, as revealed by CLSM with LIVE/DEAD staining and intracellular adenosine triphosphate measurements, respectively. This study highlights the utility of the catalytic generation of nitric oxide for the long-term suppression and removal of nitrifying bacterial biofilms.

Considerable discrepancies among HPC, ATP, and FCM detection methods in evaluating the disinfection efficiency of Gram-positive and -negative bacterium by ultraviolet radiation and chlorination

Up to now, the effects of ultraviolet (UV) and chlorine disinfection on microbes have been evaluated by heterotrophic plate counting (HPC). Recently, with the application of flow cytometry (FCM) in aquatic environment, it is used to analyze the membrane integrity, DNA damage and enzymatic activity of bacteria. The present work investigated the disinfection efficacy of UV-C and chlorine on E. coli (Gram negative) and Bacillus subtilis (Gram positive) and compared the detection methods for disinfection efficacy with HPC, Adenosine triphosphate (ATP), and FCM. The results show that there are considerable discrepancies among HPC, ATP, and FCM detection for E. coli and B. subtilis when disinfected by UV and chlorine. Specifically, the bacterium was sharply inactivated when evaluated by HPC, whereas the more gentle inactivation trend was observed when detected by ATP and FCM during both UV and chlorine disinfections for E. coli. In addition, for B. subtilis disinfection, the results between ATP and HPC detection were of little difference, especially with chlorine disinfection; thus, ATP measurement could be a replacement of HPC as it was much more fast and convenient. The results of FCM demonstrated that most of the bacteria undergo viable but non-culturable (VBNC) states which could not be detected by HPC but had the infection ability. Considering the risk of VBNC cells and the limitation of HPC, the following was suggested: when applied UV-C disinfection, HPC should combine ATP or FCM to evaluate the microbial viability, whereas FCM was a powerful tool to distinguish viable, but non-culturable cells (VBNC) applied for chlorine disinfection.

Time series evaluation of the 3M™ Clean-Trace™ ATP detection device to confirm swab effectiveness

As of 2012, a downward trend in infection rates for hospital onset of both Clostridium difficile infections and methicillin-resistant Staphylococcus aureus bloodstream infections (2% and 4% decrease respectively) has been noted. Despite the success with these two organisms, several infectious pathogens in the healthcare setting have not decreased. This lack of downward trend highlights the importance of continuing to find and assess rapid detection methods to help confirm that hospital cleaning efforts meet and exceed standards of cleanliness demonstrated to reduce numbers of healthcare- associated infections (HAIs) of these pathogens. This study set out to determine the effectiveness of the swab 3M™ Clean-Trace™ Adenosine Triphosphate (ATP) System over time by comparing the ATP measurements of the culturable organisms to the corresponding quantitative microbiology. The organisms evaluated included: Acinetobacter baumannii, Bacillus anthracis Sterne endospores and vegetative cells, Candida albicans, Clostridium difficile, Escherichia coli, Enterococcus faecalis, methicillin-resistant Staphylococcus aureus and Mycobacterium smegmatis. A combined organisms analysis did not demonstrate a significant reduction in measured ATP levels over the course of the organisms’ exposures in a controlled environment. The quantitative microbiology did, however, demonstrate a large initial organism die-off within the first 60 min (P < 0.001) of controlled environmental exposure, although the trend did not continue over the remaining 3 h of observation. The live versus dead experimental design yielded 100% microbial kill and a one log reduction (P < 0.019) between pre-exposure and post-exposure ATP measurements. This study did not demonstrate a significant effect of time in reducing ATP measures over the time periods evaluated. ATP measurements were approximately the same, regardless of the initial organism die-off. Additionally, the live versus dead analysis confirms that ATP bioluminescence is not sensitive enough to distinguish between viable organisms and organic debris remnants on sterilised equipment.

The effect of different aeration conditions in activated sludge – Side-stream system on sludge production, sludge degradation rates, active biomass and extracellular polymeric substances

On-site minimization of excess sludge production is a relevant strategy for the operation of small-scale and decentralized wastewater treatment plants. In the study, we evaluated the potential of activated sludge systems equipped with side-stream reactors (SSRs). This study especially focused on how the sequential exposure of sludge to different aeration conditions in the side-stream reactors influences the overall degradation of sludge and of its specific fractions (active biomass, extracellular polymeric substances (EPS), EPS proteins, EPS carbohydrates). We found that increasing the solid retention time from 25 to 40 and 80 days enhanced sludge degradation for all aeration conditions tested in the side-stream reactor. Also, the highest specific degradation rate and in turn the lowest sludge production were achieved when maintaining aerobic conditions in the side-stream reactors. The different sludge fractions in terms of active biomass (quantified based on adenosine tri-phosphate (ATP) measurements), EPS proteins and EPS carbohydrates were quantified before and after passage through the SSR. The relative amounts of active biomass and EPS to volatile suspended solids (VSS) did not changed when exposed to different aeration conditions in the SSRs, which indicates that long SRT and starvation in the SSRs did not promote the degradation of a specific sludge fraction. Overall, our study helps to better understand mechanisms of enhanced sludge degradation in systems operated at long SRTs.