• Clinical and Experimental Pediatrics
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• v.57 no.4
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• pp.178-185
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• 2014

Purpose: Blood culture is the most important tool for detecting bacteremia in children with fever. However, blood culture contamination rates range from 0.6% to 6.0% in adults; rates for young children have been considered higher than these, although data are limited, especially in Korea. This study determined the contamination rate and risk factors in pediatric patients visiting the emergency room (ER) or being admitted to the ward. Methods: We conducted a retrospective chart review of blood cultures obtained from children who visited Yonsei Severance Hospital, Korea between 2006 and 2010. Positive blood cultures were labeled as true bacteremia or contamination according to Centers for Disease Control and Prevention/National Healthcare Safety Network definitions for laboratory-confirmed bloodstream infection, after exclusion of cultures drawn from preexisting central lines only. Results: Among 40,542 blood cultures, 610 were positive, of which 479 were contaminations and 131 were true bacteremia (overall contamination rate, 1.18%). The contamination rate in the ER was significantly higher than in the ward (1.32% vs. 0.66%, P<0.001). The rate was higher in younger children (2.07%, 0.94%, and 0.61% in children aged <1 year, 1-6 years, and >6 years, respectively). Conclusion: Overall, contamination rates were higher in younger children than in older children, given the difficulty of performing blood sampling in younger children. The contamination rates from the ER were higher than those from the ward, not accounted for only by overcrowding and lack of experience among personnel collecting samples. Further study to investigate other factors affecting contamination should be required.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.3
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• pp.51-55
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• 2005

This study addresses the contamination sensitivity test of a typical fuel pump for an automotive vehicle. The objective of the study is to find the contamination sensitivity coefficient of a fuel pump on specific contaminant particle sizes so that an optimal fuel filter could be selected. To achieve the objective, the degradation of discharge flow rate of the fuel pump is measured under the experiments of various contaminants size ranges of ISO test dust up to $80\;{\mu}m$. The fundamental theory of contamination sensitivity is introduced and the contamination sensitivity coefficients are estimated using the experimental data. Maximum contamination sensitivity coefficient of $5\chi\;10^{-6}\;L/min{\cdot}Ea$ is found in the contaminant size range of $40\;{\mu}m\~50\;{\mu}m$. The magnified picture of the surface of vane disc reveals that the abrasive wear is the principal cause of discharge flow rate degradation. Hence, this study reveals that a high efficiency filter for contaminant particles especially in the size range of $30\;{\mu}m\~70\;{\mu}m$ especially should be used to maintain the service life of the fuel filter.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.102-108
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• 2004

This study addresses the contamination sensitivity test of a typical fuel pump for automotive vehicle. The objective of the study is to find the contamination sensitivity coefficient of fuel pump on specific contaminant particle sizes so that optimal fuel filter could be selected. To achieve the objective, the degradation of discharge flow rate of fuel pump was measured under the experiments of various contaminants size ranges of ISO test dust up to 80${\mu}{\textrm}{m}$. The fundamental theory of contamination sensitivity was introduced and the contamination sensitivity coefficients were estimated using the experimental data. Maximum contamination sensitivity coefficient of $5{\times}10^{-6}$ L/minㆍEa was found on the contaminant size range of 40${\mu}{\textrm}{m}$∼50${\mu}{\textrm}{m}$. The magnified picture of the surface of vane disc revealed that the abrasive wear was the principal cause of discharge flow rate degradation. Hence, this study revealed that high efficiency filter on the contaminant particle size range of 30${\mu}{\textrm}{m}$∼70${\mu}{\textrm}{m}$ especially should be used to maintain the service lift of the fuel filter.

• Water for future
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• v.6 no.2
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• pp.19-29
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• 1973

The progressive contamination of water resulted from man's activity and the use of fertilizers is not restricted only to surface water, but also the shallow groundwater is affected. This type of groundwater contamination is mainly restricted to areas composed of permeable, nonconsolidated sediments forming a shallow aquifer. The chloride and the sulfate resulted from man's activity and the use of fertilizers were measured to study the variations of the groundwater contamination. In general, (1) When water level rises, the rate of groundwater contamination becomes less and when water level declines, the rate of contamination is increased. (2) The highly contaminated season is the early-summer and the less contaminated season is the winter or after rainy season. (3) The groundwater in weathering zone without covering layer. (4) The degree of contamination of wells is increased with the increase of well depth and lowing the water table, because of increasing contaminated water from enlargement of the area of influence of the well.

• Clinical and Experimental Pediatrics
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• v.52 no.3
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• pp.346-350
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• 2009

Purpose : Since children under two years with suspected urinary tract infections (UTIs) cannot control urination, urine cultures in such children are usually performed via urine bags. This method is noninvasive but has a high contamination rate. We studied the contamination rate of bag urine culture in diagnosing UTI in infants under two years and the factors responsible for contamination. Methods : We examined patients under 2 years in whom urine culture through the urine bag method yielded over 105 colonies of a single pathogen. We defined UTI by referring to the guidelines of The Korean Society of Pediatric Nephrology, 2005. We examined the factors responsible for contamination according to sex, duration of urine collection, and whether diarrhea took place with contamination rate. Results : We examined 717 patients (412 males and 305 females). The contamination rate of one bag urine culture was 37.9%. Gender was not related to the contamination rate (P>0.05). Duration of urine collection showed an association with the contamination rate. The longer the duration of collecting urine, the higher was the contamination rate. Duration of urine collection was divided into three groups: first group, <2 hours; second group, 24 hours; and third group, ${\geq}4$ hours. Contamination rates were 30.0%, 42.2%, and 43.7% for the first, second, and third groups, respectively, with statistical significance (P=0.001). Diarrhea at admission had no impact on the contamination rate (P>0.05). Conclusion : The contamination rate of urine culture in the examined patients was 37.9%. Gender and diarrhea symptoms were not responsible for contamination. In infants with a suspected UTI, urine should be collected within 2 hours through the urine bag method. If urine collection takes >2 hours, the urine bag should be resterilized and reattached to the patient.

• Particle and aerosol research
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• v.14 no.4
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• pp.181-189
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• 2018

In this study, the risk rates of different contamination sources of the contaminant in a minienvironment were analyzed through Computational Fluid Dynamics (CFD) simulation. The airflow pattern characteristics can only predict the qualitative variation of contaminant concentration, but cannot evaluate the quantitative variations in the risk rate of sources. From the results, the ambient contamination sources mainly affect wafers in the Front Opening Unified Pod (FOUP), whereas the internal contamination sources mainly affect wafers laid on the robot arm in the minienvironment. And the purging plenum system is very useful in protecting the wafers in the FOUP from contaminants transferred from the Fan Filter Unit (FFU). However, this system is unable to protect the wafers on the robot arm from internal contaminants and the wafers in the FOUP from sources of the interface between the FOUP and the minienvironment.

• Clinical Endoscopy
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• v.55 no.1
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• pp.33-40
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• 2022

Background/Aims: Multiple outbreaks of multidrug-resistant organisms have been reported worldwide due to contaminated duodenoscopes. In 2015, the United States Food and Drug Administration recommended the following supplemental enhanced surveillance and reprocessing techniques (ESRT) to improve duodenoscope disinfection: (1) microbiological culture, (2) ethylene oxide sterilization, (3) liquid chemical sterilant processing system, and (4) double high-level disinfection. A systematic review and meta-analysis was performed to assess the impact of ESRT on the contamination rates. Methods: A thorough and systematic search was performed across several databases and conference proceedings from inception until January 2021, and all studies reporting the effectiveness of various ESRTs were identified. The pooled contamination rates of post-ESRT duodenoscopes were estimated using the random effects model. Results: A total of seven studies using various ESRTs were incorporated in the analysis, which included a total of 9,084 post-ESRT duodenoscope cultures. The pooled contamination rate of the post-ESRT duodenoscope was 5% (95% confidence interval [CI]: 2.3%-10.8%, inconsistency index [I²]=97.97%). Pooled contamination rates for high-risk organisms were 0.8% (95% CI: 0.2%-2.7%, I²=94.96). Conclusions: While ESRT may improve the disinfection process, a post-ESRT contamination rate of 5% is not negligible. Ongoing efforts to mitigate the rate of contamination by improving disinfection techniques and innovations in duodenoscope design to improve safety are warranted.

• Journal of Environmental Science International
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• v.26 no.2
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• pp.211-220
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• 2017

For areas with the diverse contamination sources, the change of 4-nitrophenol contamination and impact of potential contamination sources have been evaluated using monitoring data and a numerical model (HydroGeoSphere). The model considered several parameters including land cover, precipitation, and flow rate. And, the model has been performed to investigate the effect of decay rate of 4-nitrophenol. The results of the simulations showed that the influence on 4-nitrophenol in downstream was mainly greater than that in upstream, and the tributaries did not significantly affect the mainstream because of their low flow rates. In addition, the effect of contamination sources was simulated for each section, then the measured data were higher than the corresponding simulated data in most sections of the Geumho river. In particular, the impact of the potential contamination sources in the upstream area was much higher than that in the other area, thus more monitoring data for the upstream area is required.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.447-453
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• 2004

The prevalence of Toxocara canis eggs in the public places in the city of Gwangju were studied through examination of 800 soil and 123 fecal specimens. Toxocara canis eggs were found in 15% of soil samples. In 25% parks and 17% residential quarters, these eggs were detected with higher contamination rate than other places. The soil contamination rate of playgrounds in spring and autumn was higher than that of summer and winter, and the variation range of the rate was high in parks and residential quarters. The contamination rate of eggs in 123 samples of dogs' feces was 31%, it was higher than that of soil samples(21%).

• Journal of Korean Academy of Nursing
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• v.16 no.1
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• pp.67-80
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• 1986

The use of intravenous solutions for fluid replacement has become an integral part of patient care, This widespread use of intravenous solutions has increased the risk of contamination that can lead to septicemia and phlebitis. The literature regarding contamination of in use intravenous solutions recommends a standard 24-hour time limit on the use of these fluids. But the desings of these studies did not incorporate a time variable related to contamination. In other studies, however, time was a manipulated variable: but data regarding the onset of contamination were conflicting. Because published reports conflict with regard to a time standard related to the use of intravenous therapy, additional empirical data are needed upon which to base the standards of care regulating use of intravenous therapy. This study investigated rate of contamination in simulated in-use intravenous solutions to obtain data from which to recomend a standard time period for the administration of intravenous solutions. In this study samples were drawn from 60 bottles of 5% D/W solution at predetermined time intervals over 48 hours and samples were inoculated to Thio-glychollate Broth. After 10 days' culturing in that Broth, samples were cultured on blood agar plates for 18∼48 hours to determine the rate of contamination. was found at all time Period, regardless of the presence or absence of nurse's gloving in the preparation of fluids, the location in which the experimentations were performed, the contamination level of surrounding air, or the length of time during which solutions were opened. Data from this study support the use of a 48-hour time period on which to base the standard involved in ready-to-use simple intravenous solutions without additives. In emergency departments and critical care areas where intravenous solutions are prepared in advance, the suggested time standard supported by the data generated from this study is 48 hours, not 24 hour. Data from this study support a 24-hour time standard for changing in-use intravenous solutions when the contamination results from the manipulation of intravenous infusion system by hospital personnel, or from some other exogenous sources during administration. Because contamination that does occur within 48 hours in intravenous solutions must be introduced from some exogenous sources, further empirical studies based on the identification of sources of contamination and factors that affect the rate of contamination, are needed to investigate the currently employed standard of intravenous therapy and to provide the patient with more efficient and safer intravenous thereapy.