Transient Contamination Research Articles

(113) Hydrophilic Inflatable Penile Prothesis (HC-IPP) Discs Inoculated With Aerobic and Anaerobic Bacteria and Fungal Species Dipped in 0.05% Chlorhexidine Gluconate (CHG) Irrigation Solution and Irrigated With the Device to Evaluate Real World Situations

Abstract Introduction Hydrophilic-coated implants have significantly decreased penile prosthesis infection (PPI) since their release in 2001. However, the microbial spectrum of PPI has significantly changed. Based on recent Next Generation Sequencing literature, gram negative and fungal species are now included in the three most common organisms isolated. The Titan (Coloplast, Minneapolis, MN, USA) implant enables surgeons to choose a dipping solution according to their local biogram and preference. Irrisept (Irrimax, Lawrenceville, GA, USA) is 0.05% chlorhexidine gluconate (CHG) solution and has an extensive profile for microbial kill, including many aerobic, anaerobic, and fungal species known to cause PPI. Objective Evaluate microbial reduction on HC-IPP material dipped and irrigated with 0.05% CHG irrigation device using a validated microbiological study design: microbial contamination with microbial reduction counts following treatment. Methods An In-Vitro evaluation of the ability of an irrigation device to reduce transient bacterial contamination from a Test Substrate - pre-cut discs prepared from a HC-IPP material. Seven common PPI microorganisms - Bacteroides fragilis (A TCC #25285), Candida albicans (A TCC #10231), Enterococcus faeca/is (A TCC #29212), Escherichia coli (A TCC #25922), Pseudomonas aeruginosa (ATCC #27853), Staphylococcus aureus (ATCC #29213) and Staphylococcus epidermidis (ATCC #12228) were used for this evaluation. For each challenge species, three discs of the implant material (i.e., carriers) were pre-conditioned by immersion in 0.9% Sodium Chloride Irrigation, USP (Baseline Controls), and six discs were pre-conditioned by immersion in the test irrigation solution, (Irrisept®; Test Carriers). The pre-conditioned carriers were allowed to dry for approximately 10 minutes prior to contamination with a suspension of each test strain. Following a 2-to-3-minute drying period at room temperature, the three contaminated Baseline Carriers were evaluated for viable microbial recoveries. Three of the contaminated and dried Test Carriers were evaluated for viable microbial recoveries with no additional treatment (Pre- Rinse Test Carriers). The three remaining Test Carriers were evaluated following a rinsing procedure using 200cc of Wound Irrigation Device/Solution (Post-Rinse Test Carriers) at three time points, mimicking an in-vivo practice. Results Table 1 presents the Initial population (CFU/mL), Mean Baseline Control Recovery (normal saline log10) and the mean Post-Exposure Recovery (0.05% CHG log10), and Mean Post-Exposure Reduction (0.05% CHG log10) following three separate 150cc irrigations (one full bottle/disk with 0.05% CHG irrigation device. (lrrisept 450mL [Lot #21HDB982]). Conclusions Dipped and irrigated HC-IPP material discs with the irrigation device containing 0.05% CHG results in clinically significant log10 reductions in tested microbial strains. All previous studies on this subject matter have used zone of inhibition (ZOI) testing only. This microbiological methodology is superior as it is quantitative not qualitative, and can evaluate bactericidal, viricidal and fungicidal activity. Disclosure Yes, this is sponsored by industry/sponsor: Irrimax Corporation, Coloplast Corporation Clarification Industry funding only - investigator initiated and executed study Any of the authors act as a consultant, employee or shareholder of an industry for: Coloplast, Irrimax.

Reaction time measures of non-chromatic contamination in opponent stimuli.

Simple visual reaction times (RTs) are highly sensitive to the presence of transient activity. Transient and sustained visual mechanisms generate different RT versus contrast functions because they have different gains. To identify non-chromatic (transient) activity, we can compare RT versus contrast functions obtained with either fast or slow onset stimuli. To test this, the stimulus adopted was a temporal modulation along the red-green axis, introducing non-chromatic components by varying the red-green ratio. The technique was sensitive to departures from isoluminance for all observers; therefore, we present this method as a way to detect transient contamination in a chromatic stimulus.

White coat - is it safe?

Background: The transient contamination of medical professional’s attires including white coats is one of the major vehicles for the horizontal transmission of microorganisms in the hospital. In particular, white-coat cuffs had a higher bacterial load than the mouths of the pockets. The bacterial isolates were resistant to nearly all of the antibiotics tested. This study was conducted to determine the level and type of microbial contamination present on the white coats of medical students in order to assess the risk of transmission of pathogenic micro-organisms by this route in a hospital setting. This study was performed in tertiary care hospital to study the white coat as vehicle for bacterial dissemination and to know the way of handling, cleaning of white coat.Methods: It is observational prospective cross-sectional study conducted at tertiary care hospital. Nurses, interns, residents, technicians are included. Samples are taken from 3 sites of white coat pocket, lapel and collar.Results: We found that reason to wear white coat is dress code of the hospital. Most of the white coats were washed less than 3 days or less. Pocket was the most common site with MRCONS. Pocket (14%) is the most common contaminated site. Antibiotic sensitivity of organisms is mainly sensitive for ciprofloxacin and vancomycin.Conclusions: From the above study we confirm white coat carries microorganism hence it spreads nosocomial infection. Hand washing and multiple number white coat use should be encouraged.

Examining Patterns of Persistent Listeria Contamination in Packinghouses Using Agent-Based Models

Persistent Listeria monocytogenes contamination may occur in a packinghouse if the pathogen successfully infiltrates the facility and reaches a harborage site, where it may be difficult to remove and may contaminate produce within the facility. There is a need for simulation-based decision support tools that can predict which equipment sites are more likely to undergo persistent contamination and simulate potential corrective actions to prevent this contamination. Thus, we adapted for longer term simulation two existing applications of an agent-based model of Listeria spp. hourly contamination dynamics in produce packinghouses. Next, we developed a novel approach to identify and analyze persistent and transient Listeria contamination patterns on simulated agents representing equipment sites and employees. Testing of corrective actions showed that methods that involved targeted, facility-specific, risk-based sanitation were the most effective in reducing both the likelihood and duration of persistent contamination. Generic approaches to controlling Listeria (e.g., more concentrated sanitizers) are unlikely to be successful and suggest that use of sanitation schedules produced through facility-specific root cause analysis and hygienic design are key in reducing persistence. Hourly Listeria contamination patterns also suggest that transient contamination may be mistaken for persistent contamination, depending on the frequency of environmental sampling. Likewise, as concentrations of Listeria on most contaminated agents were predicted to be very low, there is also a possibility to mistake persistence for transient contamination of sites, or even miss it outright, due to false-negative environmental Listeria monitoring results. These findings support that agent-based models may be valuable decision support tools, aiding in the identification of contamination patterns within packinghouses and assessing the viability of specific corrective actions.

Characterizing the bioburden of ESBL-producing organisms in a neonatal unit using chromogenic culture media: a feasible and efficient environmental sampling method

IntroductionInfections due to extended spectrum beta-lactamase producing organisms (ESBL) have emerged as the leading cause of sepsis among hospitalized neonates in Botswana and much of sub-Saharan Africa and south Asia. Yet, ESBL reservoirs and transmission dynamics within the neonatal intensive care unit (NICU) environment are not well-understood. This study aimed to assess the efficiency and feasibility of a chromogenic-culture-media-based environmental sampling approach to characterize the ESBL bioburden within a NICU.MethodsA series of four point-prevalence surveys were conducted at a 36-bed NICU at a public tertiary referral hospital in Botswana from January-June 2021. Samples were collected on 4 occasions under semi-sterile technique using 1) flocked swabs & templates (flat surfaces); 2) sterile syringe & tubing (water aspiration); and 3) structured swabbing techniques (hands & equipment). Swabs were transported in physiological saline-containing tubes, vortexed, and 10 µL was inoculated onto chromogenic-agar that was selective and differential for ESBL (CHROMagar™ ESBL, Paris, France), and streaking plates to isolate individual colonies. Bacterial colonies were quantified and phenotypically characterized using biochemical identification tests.ResultsIn total, 567 samples were collected, 248 (44%) of which grew ESBL. Dense and consistent ESBL contamination was detected in and around sinks and certain high-touch surfaces, while transient contamination was demonstrated on medical equipment, caregivers/healthcare worker hands, insects, and feeding stations (including formula powder). Results were available within 24–72 h of collection. To collect, plate, and analyse 50 samples, we estimated a total expenditure of $269.40 USD for materials and 13.5 cumulative work hours among all personnel.ConclusionsUsing basic environmental sampling and laboratory techniques aided by chromogenic culture media, we identified ESBL reservoirs (sinks) and plausible transmission vehicles (medical equipment, infant formula, hands of caregivers/healthcare workers, & insects) in this NICU environment. This strategy was a simple and cost-efficient method to assess ESBL bioburden and may be feasible for use in other settings to support ongoing infection control assessments and outbreak investigations.

Genetic Diversity of Listeria monocytogenes Isolated From Three Commercial Tree Fruit Packinghouses and Evidence of Persistent and Transient Contamination.

Whole genome analysis was performed on 501 isolates obtained from a previous survey which recovered 139 positive environmental sponge samples (i.e., up to 4 isolates per sample) from a total of 719 samples collected at 40 standardized sites in 3 commercial apple packinghouse facilities (i.e., P1, P2, and P3) over 3 successive seasons in a single production year. After excluding duplicated isolates, the data from 156 isolates revealed the clonal diversity of L. monocytogenes and allowed the detection of transient contamination, persistent contamination, and cross-area transmission events. Facility P2 with the poorest sanitary conditions had the least diversity (Shannon’s index of 0.38). P2 contained a Clonal Complex (CC) 554, serogroup IVb-v1 strain that persisted throughout the year and spread across the entire facility, a singleton Sequence Type (ST) 1003, lineage III strain that persisted through two seasons and spread across two areas of the facility, and 3 other clones from transient contaminations. P1 and P3, facilities with better sanitary conditions, had much higher diversity (i.e., 15 clones with a Shannon’s index of 2.49 and 10 clones with a Shannon’s index of 2.10, respectively) that were the result of transient contamination. Facilities P1 and P3 had the highest incidence (43.1%) of lineage III isolates, followed by lineage I (31.3%) and lineage II (25.5%) isolates. Only 1 isolate in the three facilities contained a premature stop codon in virulence gene inlA. Fourteen samples yielded 2–3 clones per sample, demonstrating the importance of choosing appropriate methodologies and selecting a sufficient number of isolates per sample for studying L. monocytogenes diversity. Only 1 isolate, belonging to CC5 and from facility P3, contained a known plasmid, and this was also the only isolate containing benzalkonium chloride tolerance genes. The persistent CC554 strain did not exhibit stronger sanitizer resistance than other isolates and did not contain any confirmed molecular determinants of L. monocytogenes stress resistance that were differentially present in other isolates, such as genes involved in sanitizer tolerance, heavy metal resistance, biofilm-forming, stress survival islet 1 (SSI-1), stress survival islet 2 (SSI-2) or Listeria genomic island (LGI2).

Bacteria on Medical Professionals' White Coats in a University Hospital.

The transient contamination of medical professional's attires including white coats is one of the major vehicles for the horizontal transmission of microorganisms in the hospital environment. This study was carried out to determine the degree of contamination by bacterial agents on the white coats in a tertiary care hospital in Nepal. Sterilized uniforms with fabric patches of 10 cm × 15 cm size attached to the right and left pockets were distributed to 12 nurses of six different wards of a teaching hospital at the beginning of their work shift. Worn coats were collected at the end of the shifts and the patches were subjected for total bacterial count and identification of selected bacterial pathogens, as prioritized by the World Health Organization (WHO). Fifty percent of the sampled swatches were found to be contaminated by pathogenic bacteria. The average colony growth per square inch of the patch was 524 and 857 during first and second workdays, respectively, indicating an increase of 63.6% in colony counts. The pathogens detected on patches were Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter sp. Additional bacteria identified included Bacillus sp., Micrococcus sp., and coagulase-negative staphylococci (CoNS). The nurses working in the maternity department had their white coats highly contaminated with bacteria. On the other hand, the least bacterial contamination was recorded from the nurses of the surgery ward. One S. aureus isolate from the maternity ward was resistant to methicillin. This study showed that pathogens belonging to the WHO list of critical priority and high priority have been isolated from white coats of nurses, thus posing the risk of transmission to patients. White coats must be worn, maintained, and washed properly to reduce bacterial contamination load and to prevent cross-contamination of potential superbugs. The practice of wearing white coats outside the healthcare zone should be strictly discouraged.

Transient and Persistent Gastric Microbiome: Adherence of Bacteria in Gastric Cancer and Dyspeptic Patient Biopsies after Washing.

Helicobacter pylori is a common colonizer of the human stomach, and long-term colonization has been related to development of atrophic gastritis, peptic ulcers and gastric cancer. The increased gastric pH caused by H. pylori colonization, treatment with antibiotics or proton pump inhibitors (PPI) may allow growth of other bacteria. Previous studies have detected non-Helicobacter bacteria in stomach biopsies, but no conclusion has been made of whether these represent a transient contamination or a persistent microbiota. The aim of this study was to evaluate the transient and persistent bacterial communities of gastric biopsies. The washed or unwashed gastric biopsies were investigated by cultivation and microbiota analysis (16S rRNA gene-targeted amplicon sequencing) for the distribution of H. pylori and other non-Helicobacter bacteria. The number of cultured non-Helicobacter bacteria decreased in the washed biopsies, suggesting that they might be a transient contamination. No significant differences in the bacterial diversity were observed in the microbiome analysis between unwashed and washed biopsies. However, the bacterial diversity in biopsies shown H. pylori-positive and H. pylori-negative were significantly different, implying that H. pylori is the major modulator of the gastric microbiome. Further large-scale studies are required to investigate the transient and persistent gastric microbiota.

Listeria monocytogenes is prevalent in retail produce environments but Salmonella enterica is rare

The purpose of this study was to determine the prevalence of Listeria monocytogenes and Salmonella enterica in retail produce environments and to elucidate possible ecological niches. Thirty environmental samples per store were collected during daily operations monthly for six months in 30 retail produce departments across seven states. Selected samples were serially diluted and plated to determine aerobic plate count. Each sample was tested for L. monocytogenes and S. enterica using ROKA Atlas LmG2 and SEN assays, respectively. A total of 5,112 samples were tested for each pathogen. S. enterica was found during one sampling event in a single store; less than 0.1% of samples were positive overall. A total of 4.4% environmental samples tested positive for L. monocytogenes. L. monocytogenes was present on 8.1% of non-food contact surfaces and 1.6% of food contact surfaces tested; L. monocytogenes prevalence was highly variable among stores. Most of the positive L. monocytogenes samples were found in drains, floors, squeegees, or standing water. Genetically similar L. monocytogenes clones were found in multiple stores across multiple states. The odds of detecting L. monocytogenes increased 1.8-fold for every 1-log increase in APC (p < 0.0001). This is the first study to investigate prevalence and persistence of L. monocytogenes and S. enterica in retail produce environments. Our data suggest that some, but not all retail produce environments have high L. monocytogenes prevalence, which may cross-contaminate produce. Sites heavily contaminated with L. monocytogenes indicate potential targets for sanitation operating procedures and food safety management strategies. However, S. enterica prevalence is very low and likely due to transient contamination. Further, APC may be a cost-effective environmental monitoring tool that could indicate an environment capable of harboring L. monocytogenes.

Intermittent Clutter Suppression Method Based on Adaptive Harmonic Wavelet Transform for L-Band Radar Wind Profiler

Boundary layer radar (L-band) wind profilers frequently encounter a significant problem arising from the contamination of intermittent clutter, produced by seasonal and nocturnal migrating birds, which often yields erroneous wind velocity and boundary layer information. Classical harmonic wavelet transforms (HWTs) are inadequate in removing the transient clutter contamination under certain conditions, particularly when the clutter is significant. We implemented an adaptive complex harmonic discrete wavelet transform with an advanced statistical method to overcome the shortcomings of the classical wavelet method. This algorithm effectively eliminates the bird contamination even where the classical method fails. Finally, a multiple peak-picking (MPP) algorithm was added to select true atmospheric signals and estimate accurate moments. The obtained wind velocity measurements were compared with those derived using the conventional method and validated with global positioning system radiosonde winds. The comparison shows that the proposed method is more effective than the conventional one.

Evaluation of a benzalkonium chloride hand sanitizer in reducing transient Staphylococcus aureus bacterial skin contamination in health care workers

This study was performed to evaluate the effectiveness of a new commercially available hand sanitizer using 0.12% benzalkonium chloride (BZK) as the active ingredient in reducing transient skin contamination with Staphylococcus aureus in health care workers (HCWs), as compared with the effectiveness of a 70% ethanol-based hand sanitizer. Fingertip touch culture plates were obtained from 40 HCWs in which all HCWs used antimicrobial soap containing 0.6% chloroxylenol for handwashing according to the Centers for Disease Control and Prevention guidelines for the entire study, while continuing to use the 70% ethanol-based hand sanitizer according to the Centers for Disease Control and Prevention guidelines for the first week. After the first week, the test subjects used the BZK hand sanitizer in place of the ethanol sanitizer. A paired sample t test was conducted to compare the mean bacterial colonies grown from HCWs fingertips during the use of the BZK and ethanol hand sanitizer. The results showed a significant reduction in total bacterial colony counts of S aureus during the week of BZK use as compared with the week of 70% ethanol sanitizer use. There was a significant decrease in transient S aureus on the fingertips of HCWs in the BZK hand sanitizer use week as compared with the 70% ethanol hand sanitizer use week.

Quantitative Modelling of Deposition of Airborne Molecular Contamination

During the fabrication, micro-chips circuits are very sensitive to all kinds of contamination present in the environments fluid in contact with the wafers [1]. Therefore the fabrication is done in clean rooms and makes use of clean mini-environments (e.g. FOUPs). Historically such clean environments contain an extremely low concentration of particulate contamination, obtained by intensive filtering through different types of particle filters including HEPA filters. In contrast, the air is not purified in terms of molecular, volatile contaminants, except locally inside some specific process equipment. Measurement in state-of-art clean rooms reveal the presence of many molecular contaminants coming from different sources (environmental pollution in the intake air, but also from components and materials in the clean room construction or equipment and from process steps that make use of volatile chemicals). The dominant species are organic compounds comprising a benzene ring with various ligands. The relative molecular concentration is on the order of 1 ppb, corresponding to a molecule volume concentration, C, = 1x1010 molec./cm3. A question that typically arises in this context is that of how clean the air or gas ambient needs to be. This study addresses this issue by presenting a simple but quantitative model, built from first principles, to establish the relation between the amount of contamination in the air and the surface concentration of the contaminants that deposits on the wafer as a function of the exposure time and other relevant parameters. The transfer of contaminants from the air ambient to the surface occurs in 2 steps. Surface reaction: at the surface adhesion of molecules takes placeBulk transport in the air: the contaminants that have deposited are replenished from the volume of the air towards the surface At the surface, the initial adsorption flux, ja, is given by the the thermal bombardment flux (= arrival flux) multiplied with the sticking probability (hi) of species, I, as shown in equation (1) (blue dash-dot line). Where: v th= average thermal velocity (air: 470 m/s) Ci = volumetric density of species i in air ambient adjacent to the surface. The hi = sticking coefficient of species i on the surface, ranges typically from 10-6 to 1 [2,3]. When the resulting surface concentration of species i, si , increases, the reverse process, desorption, will occur simultaneously. A simple mass balance shows that for a case with a sticking coefficient approaching 1 and with a molecule volume concentration of 1x1010 molec./cm3 , (i.e. 1 ppb) a surface concentration of 1x1012 molec./cm2 on an infinitely large flat surface, would require all the contaminants from a volume contained in a layer with a thickness of 1 m adjacent to the surface. This simple assessment illustrates that the supply and transport from the ambient is an important limiting phenomenon. Below the focus is on estimating the potential maximum contamination achieved, assuming a sticking probability = 1. This provides an estimation for the upperlimit for the case with a lower sticking probability. The transport of contaminants in the air occurs by convection and by diffusion. In clean room ambient, laminar flow patterns are quite typical. One can approximate the transport by defining a static boundary layer adjacent to the wafer surface (with a thickness L BL) in which the (lateral) velocity is approximated as 0. Outside the boundary layer the flow is assumed to be intense enough to maintain a constant contamination concentration C i, ∞. During an initial transient phase contaminants diffuse from within the static boundary layer to the surface from a layer proportional to the diffusion length SQRT(Dt) (black dashed line). As soon as the diffusion length reaches the edge of the static boundary layer the supply flux of contaminants reaches a constant value and is determined by diffusion over the static boundary layer thickness (red solid lines). Combining the initial transient and the steady state supply yields equation (2). The values thus obtained for C = 1x1010 molec/cm3 are shown in figure 1 for 3 different values of the boundary layer thickness (LBL). Fig 1 Black and red lines represent the surface contamination as a function of time for a sticking coefficient of 1, C= 1x1010 mol/cm3 and for a static boundary layer thickness of 0.1, 1 or 10 cm. References Saga and T. Hattori, J. Electrochem. Soc 144, p. L253 (1997).Hendriks, Microelectronic Engineering, 25, p. 185 (1994).Den et al., J. Electrochem. Soc 153, G149 (2006). Figure 1

The population structure of Ochrobactrum isolated from entomopathogenic nematodes indicates interactions with the symbiotic system

Entomopathogenic nematodes (EPNs) form specific mutualistic associations with bioluminescent enterobacteria. In Heterorhabditidis indica, Ochrobactrum spp. was identified beside the symbiont Photorhabdus luminescens but its involvement in the symbiotic association in the EPNs remains unclear. This study describe the population structure and the diversity in Ochrobactrum natural populations isolated from EPNs in the Caribbean basin in order to question the existence of EPN-specialized clones and to gain a better insight into Ochrobactrum-EPNs relationships. EPN-associated Ochrobactrum and Photorhabdus strains were characterized by multi-locus sequence typing, Pulsed-Field Gel Electrophoresis fingerprinting and phenotypic traits.Population study showed the absence of EPN-specialized clones in O. intermedium and O. anthropi but suggested the success of some particular lineages. A low level of genetic and genomic diversification of Ochrobactrum isolated from the natural population of Caribbean nematodes was observed comparatively to the diversity of human-associated Ochrobactrum strains. Correspondences between Ochrobactrum and P. luminescens PFGE clusters have been observed, particularly in the case of nematodes from Dominican Republic and Puerto Rico. O. intermedium and O. anthropi associated to EPNs formed less biofilm than human-associated strains.These results evoke interactions between Ochrobactrum and the EPN symbiotic system rather than transient contamination. The main hypothesis to investigate is a toxic/antitoxic relationship because of the ability of Ochrobactrum to resist to antimicrobial and toxic compounds produced by Photorhabdus.

The potency of commonly used disinfectants on bacteria isolated from in-animate surfaces in the microbiology laboratory, Umaru Musa Yardua university Katsina

Disinfection is the process of removing microorganisms including potentially pathogenic ones from the surface of in-animate objects. The ubiquity of microorganisms has implicated door knobs, human hands, desks surfaces etc. to be reservoirs of microorganisms. This study analyses three (3) samples from five (5) inanimate surfaces of the Microbiology laboratory, three different organisms were isolated and identified using series of biochemical tests, phenol coefficient and surface disinfection test were also carried out. The phenol coefficient test involve exposure of the isolates to different dilution of test disinfectants to determine the highest dilution factor that inhibit microbial growth while surface disinfection test involved the use of soiled slides to test the potency of the test disinfectants on the isolates. The organisms isolated were Staphylococcus aureus, Klebsiella sp. and E. coli. Klebsiella sp. showed the highest resistance to the test disinfectants than E. coli and S. aureus. The result of this study confirms the contamination of inanimate surfaces with variety of pathogenic bacteria (S. aureus 25%, E. coli 23% and Klebsiella sp. 52%). Disinfectant A had the highest phenol coefficient of 6.0, C had 4.0 and disinfectant B had the lowest phenol coefficient of 3.0. Microorganisms live as transient contaminants in fomites where they constitute a major health hazards as sources of community acquired infections. Therefore, constant and regular disinfection should always be conducted at different concentrations so as to determine the potent concentration against the adhered microorganisms on various surfaces of the laboratory. Keywords : Disinfection, Phenol coefficient, Surface disinfection, Contamination, Inanimate surfaces.

Automated classification of transient contamination in stationary acoustic data

An automated procedure for the classification of transient contamination of stationary acoustic data is proposed and analyzed. The procedure requires the assumption that the stationary acoustic data of interest can be modeled as a band-limited, Gaussian random process. It also requires that the transient contamination be of higher variance than the acoustic data of interest. When these assumptions are satisfied, it is a blind separation procedure, aside from the initial input specifying how to subdivide the time series of interest. No a priori threshold criterion is required. Simulation results show that for a sufficient number of blocks, the method performs well, as long as the occasional false positive or false negative is acceptable. The effectiveness of the procedure is demonstrated with an application to experimental wind tunnel acoustic test data which are contaminated by hydrodynamic gusts.

The method used to dry washed hands affects the number and type of transient and residential bacteria remaining on the skin

Widespread antibiotic resistance has led to fears that we are entering a post-antibiotic era and the relatively simple premise of hand washing to reduce transfer of bacteria and viruses has never been more important. Much of the emphasis has been on hand-washing technique, type of soap, and maintaining compliance but effective drying of the hands is just as important. To compare the efficacy of drying washed hands with a jet air dryer or paper towels to remove transient bacterial contamination and to determine the effect on residential flora. Eighty volunteers were recruited. The entire surfaces of volunteers' hands were artificially contaminated with Escherichia coli before being washed and dried; then bacteria remaining on the skin were recovered and enumerated. In the second part of the study the number and types of bacteria comprising the natural flora remaining on washed and dried hands were determined. Significantly fewer transient and residential bacteria remained on the skin if hands were dried with a jet air dryer (P<0.001). Drying hands with paper towels increased the number of resident bacteria, including potentially pathogenic species, released from the volunteers' skin, compared to a jet air dryer. The number and types of bacteria remaining on washed hands were affected by the drying method. Hands dried with a jet air dryer harboured fewer viable bacteria, reducing the risk of infection transmission via touch. This could be especially important for healthcare workers who are constantly in contact with large numbers of vulnerable patients.

Duodenoscopy: an amplifier of cross-transmission during a carbapenemase-producing Enterobacteriaceae outbreak in a gastroenterology pathway

Carbapenemase-producing Klebsiella pneumoniae (OXA-48 CPE) were identified in five patients who underwent an endoscopy with the same duodenoscope in October 2015. The endoscope was the only epidemiological link between these cases. A transient contamination of the duodenoscope following a failure in the disinfection process may have been the cause of transmission.

Heterogeneous scintillator geometries to maximise energy deposition for waterborne beta particle detection

Here the geometries that maximise detection efficiency of heterogeneous scintillators used to detect beta particles in aqueous solutions by maximising energy deposition are described. The determination of the geometry was achieved with the Monte Carlo code Geant4 using CaF2:Eu scintillator as a pertinent case study, and validated with experimental data using single crystal CaF2:Eu and heterogeneous CaF2:Eu scintillators. Both 2D and 3D structures composed of arrays of primitive unit cells of packed spheres were examined to find the optimal geometry to maximise detection of volumetric sources of tritium and aqueous Carbon 14 and Lead 210. The 2D structures were evaluated relative to a single crystal scintillator and results show the detection efficiency of the 2D structures is maximised when the sphere radius is c.a. 0.46x the maximum track length of the beta particle in the scintillator. Data for the 3D structures show that the efficiency is maximised when the sphere radius is minimised, but it is further shown that practical issues limit the minimum radius that can be used for transient radiological contamination monitoring.

Endosymbionts Differentially Alter Exploratory Probing Behavior of a Nonpersistent Plant Virus Vector.

Insect endosymbionts (hereafter, symbionts) can modify plant virus epidemiology by changing the physiology or behavior of vectors, but their role in nonpersistent virus pathosystems remains uninvestigated. Unlike propagative and circulative viruses, nonpersistent plant virus transmission occurs via transient contamination of mouthparts, making direct interaction between symbiont and virus unlikely. Nonpersistent virus transmission occurs during exploratory intracellular punctures with styletiform mouthparts when vectors assess potential host-plant quality prior to phloem feeding. Therefore, we used an electrical penetration graph (EPG) to evaluate plant probing of the cowpea aphid, Aphis craccivora Koch, an important vector of cucurbit viruses, in the presence and absence of two facultative, intracellular symbionts. We tested four isolines of A. craccivora: two isolines were from a clone from black locust (Robinia pseudoacacia L.), one infected with Arsenophonus sp. and one cured, and two derived from a clone from alfalfa (Medicago sativa L.), one infected with Hamiltonella defensa and one cured. We quantified exploratory intracellular punctures, indicated by a waveform potential drop recorded by the EPG, initiation speed and frequency within the initial 15min on healthy and watermelon mosaic virus-infected pumpkins. Symbiont associations differentially modified exploratory intracellular puncture frequency by aphids, with H. defensa-infected aphids exhibiting depressed probing, and Arsenophonus-infected aphids an increased frequency of probing. Further, there was greater overall aphid probing on virus-infected plants, suggesting that viruses manipulate their vectors to enhance acquisition-transmission rates, independent of symbiont infection. These results suggest facultative symbionts differentially affect plant-host exploration behaviors and potentially nonpersistent virus transmission by vectors.

Performance of constant exhaust ventilation for removal of transient high-temperature contaminated airflows and ventilation-performance comparison between two local exhaust hoods

Transient high-temperature contaminated airflows generated during the pouring of high-temperature materials are widespread in Chinese industrial plants. In this study, the performance of both the local exhaust and the general exhaust with a constant flow rate to remove these transient contaminants was experimentally investigated, and the ventilation performance was compared between two local exhaust hoods. This study focused on the dispersion and removal characteristics of contaminant concentrations under the conditions of high-temperature airflows. The results showed that the cumulative contaminant concentration could be divided into four time slots and that there was a time lag between the cumulative concentration of the local and general exhaust. Additionally, the fitting formula of time-varying concentration decay was discussed to highlight the advantages of the designed hood performance. Finally, the dynamic evaluation index (TCRRt) for evaluating exhaust hoods on removing transient contaminants was proposed, and the connections between the proposed index and the traditional capture efficiency were illustrated. The minimum TCRRt for the improved exhaust hood was invariably greater than that for the existing hood for each hood flow rate. This study demonstrates that increasing the containment volume of the exhaust hood can help to remove transient high-temperature contaminants in industrial plants.