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Serotype Distribution of Invasive Group B Streptococcal Diseases in Infants at Two University Hospitals in Korea (영아에서의 침습 B군 사슬알균 감염증 및 혈청형 분석: 2개 대학병원 연구)

  • Cho, Hye-Kyung;Nam, Hye Na;Cho, Hye Jung;Son, Dong Woo;Cho, Yong Kyun;Seo, Yiel-Hea;Kim, Yae-Jean;Eun, Byung Wook
    • Pediatric Infection and Vaccine
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    • v.24 no.2
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    • pp.79-86
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    • 2017
  • Purpose: This study was aimed at analyzing the serotypes of group B streptococcus (GBS) isolated from Korean infants with invasive disease and evaluating their association with disease manifestation. Methods: Data were retrospectively collected from invasive GBS infections at Gachon University Gil Medical Center from January 2006 to June 2012 and at Samsung Medical Center from April 2010 to November 2012. Serotypes were determined by slide agglutination test. Results: A total of 37 cases were identified, which included 22 full-term infants and 15 preterm infants. Fifteen cases (40.5%) were early-onset, 19 (51.4%) was late-onset, and three (8.1%) was very late-onset. Early-onset diseases among preterm infants were higher than those among full-term infants (60.0% [9/15] vs. 27.3% [6/22], P=0.17). The most common manifestation was bacteremia (70.3%), followed by meningitis and septic arthritis. Among 24 isolates retrievable for serotyping, serotype III (41.7%) was most common, followed by V (16.7%), Ia, Ib, and II (12.5%, respectively), and non-typeable (4.2%). Serotype III was more common in isolates from full-term infants (10/22) than from preterm infants (0/15), whereas serotype V was more common in isolates from preterm infants (4/15) than from full-term infants (0/22) (P=0.002). No penicillin-resistant strain was detected, and resistance to erythromycin and clindamycin were both 64.9%. Conclusions: GBS is an important pathogen in both preterm and full-term infants, and serotype distribution of GBS causing invasive diseases can differ between preterm and full-term infants. It is necessary to monitor the nationwide epidemiology of GBS diseases, including in preterm infants, in order to prepare preventive measures without underestimating early-onset diseases.

Etiology of Bacteremia in Children with Hemato-oncologic Diseases from a Single Center from 2011 to 2015 (단일 기관에서의 소아 혈액종양 환자에서 발생한 균혈증의 원인균 및 임상 양상: 2011-2015년)

  • Park, Ji Young;Yun, Ki Wook;Kang, Hyoung Jin;Park, Kyung Duk;Shin, Hee Young;Lee, Hoan Jong;Choi, Eun Hwa
    • Pediatric Infection and Vaccine
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    • v.24 no.2
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    • pp.71-78
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    • 2017
  • Purpose: The aim of this study was to identify the pathogens of blood stream infection (BSI) in children with hemato-oncologic disorders, to analyze susceptibility patterns of microorganisms to guide empirical antimicrobial therapy, and to compare temporal trends of the pathogen and antimicrobial susceptibility with those of previous studies. Methods: We retrospectively analyzed the medical records of children with hemato-oncologic disorders whose blood culture grew pathogens at the Seoul National University Children's Hospital between 2011 and 2015. Results: A total of 167 patients developed 221 episodes of bacteremia. Among 229 pathogens, gram-negative bacteria (GNB) accounted for 69.0% (64.0% in 2002 to 2005, 63.4% in 2006 to 2010); gram-positive bacteria (GPB) accounted for 28.8% (31.3% in 2002 to 2005, 34.6% in 2006 to 2010); and fungus accounted for 2.2%. Among GNB, Klebsiella species (53.2%, 84/158) and Escherichia coli (19.6%, 31/158) were common. Staphylococcus aureus (48.5%, 32/66) and viridans streptococci (21.2%, 14/66) were frequently isolated among GPB. The susceptibilities of oxacillin and vancomycin in GPB were 54.8% and 96.9% (51.5% and 95.5% in 2002 to 2005; 34.1% and 90.5% in 2006 to 2010), respectively, whereas in GNB, the susceptibilities of cefotaxime, piperacillin/tazobactam, and imipenem were 73.2%, 77.2%, and 92.6% (75.9%, 82.8%, and 93.4% in 2002 to 2005; 62.8%, 82.9%, 93.8% and in 2006 to 2010), respectively. There were no significant differences in the proportion of etiologic agents or the antimicrobial susceptibilities between the current study and that of the previous two studies from 2002 to 2010. Overall fatality rate was 13.1%. Conclusions: GNB predominated in BSI among children with hemato-oncologic disorders. The etiology of bacteremia and antimicrobial susceptibility were comparable to those of the previous studies. Thus, piperacillin/tazobactam can be used as the initial empirical antimicrobial agent in febrile neutropenia.

Epidemiology and Clinical Severity of the Hospitalized Children with Viral Croup (바이러스성 크루프로 입원하는 소아 환자의 역학적 특성과 임상적 중증도 평가)

  • Jeon, In Soo;Cho, Won Je;Lee, Jeongmin;Kim, Hwang Min
    • Pediatric Infection and Vaccine
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    • v.25 no.1
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    • pp.8-16
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    • 2018
  • Purpose: In this study, the clinical and epidemiological characteristics of patients admitted for viral croup were analyzed to evaluate disease severity based on the organism that caused the infection. Methods: We retrospectively reviewed the medical records of 302 patients who were admitted to the Department of Pediatrics at the Wonju Severance Hospital between May 2013 and December 2016 for viral croup. Patients who showed positive results on multiplex polymerase chain reaction were subsequently diagnosed with respiratory virus infection. The Westley scoring system was used to evaluate the severity of viral croup. Results: Of the 302 patients, 149 were admitted due to severe viral croup, including 88 boys and 61 girls, with a boy-to-girl ratio of 1.44:1. About 110 cases of parainfluenza virus infection have been reported, which accounted for almost half of the total cases. The other identified viruses included influenza virus, human rhinovirus, and respiratory syncytial virus. Analysis of the association between severe viral croup and causative pathogen revealed that only parainfluenza type 2 virus showed a significantly high risk. Parainfluenza type 2 virus did not show an age-based difference in frequency but showed relatively a higher frequency of infections during the summer and fall. Conclusions: In this study, parainfluenza virus type 2 was the only virus associated with severe viral croup. To facilitate proper preventive management, treatment, and prognosis evaluation of viral croup, prospective and multicenter studies should assess the additional variables and the severity of the virus. Additionally, further studies should be conducted to assess age-dependent influences, as well as the regional and seasonal incidence of viral infection.

Recent Progress in Air Conditioning and Refrigeration Research - A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2004 and 2005 - (공기조화, 냉동 분야의 최근 연구 동향 -2004년 및 2005년 학회지 논문에 대한 종합적 고찰-)

  • Choi, Yong-Don;Kang, Yong-Tae;Kim, Nae-Hyun;Kim, Man-Hoe;Park, Kyoung-Kuhn;Park, Byung-Yoon;Park, Jin-Chul;Hong, Hi-Ki
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.1
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    • pp.94-131
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    • 2007
  • A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2004 and 2005 has been done. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD and flow visualization(PIV, PTV and LDV methods) technologies were widely applied for developing facilities and their systems. (2) The research trends of the previous two yews are surveyed as groups of natural convection, forced convection, electronic cooling, heat transfer enhancement, frosting and defrosting, thermal properties, etc. New research topics introduced include natural convection heat transfer enhancement using nanofluid, supercritical cooling performance or oil miscibility of $CO_2$, enthalpy heat exchanger for heat recovery, heat transfer enhancement in a plate heat exchanger using fluid resonance. (3) The literature for the last two years($2004{\sim}2005$) is reviewed in the areas of heat pump, ice and water storage, cycle analysis and reused energy including geothermal, solar and unused energy). The research on cycle analysis and experiments for $CO_2$ was extensively carried out to replace the Ozone depleting and global warming refrigerants such as HFC and HCFC refrigerants. From the year of 2005, the Gas Engine Heat Pump(GHP) has been paid attention from the viewpoint of the gas cooling application. The heat pipe was focused on the performance improvement by the parametric analysis and the heat recovery applications. The storage systems were studied on the performance enhancement of the storage tank and cost analysis for heating and cooling applications. In the area of unused energy, the hybrid systems were extensively introduced and the life cycle cost analysis(LCCA) for the unused energy systems was also intensively carried out. (4) Recent studies of various refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and of alternative refrigerants including carbon dioxide. Efficiency of various compressors and expansion devices are also dealt with for better modeling and, in particular, performance improvement. Thermoelectric module and cooling systems are analyzed theoretically and experimentally. (5) According to the review of recent studies on ventilation systems, an appropriate ventilation systems including machenical and natural are required to satisfied the level of IAQ. Also, an recent studies on air-conditioning and absorption refrigeration systems, it has mainly focused on distribution and dehumidification of indoor air to improve the performance were carried out. (6) Based on a review of recent studies on indoor environment and building service systems, it is noticed that research issues have mainly focused on optimal thermal comfort, improvement of indoor air Quality and many innovative systems such as air-barrier type perimeter-less system with UFAC, radiant floor heating and cooling system and etc. New approaches are highlighted for improving indoor environmental condition as well as minimizing energy consumption, various activities of building control and operation strategy and energy performance analysis for economic evaluation.

Error Analysis of Image Velocimetry According to the Variation of the Interrogation Area (상관영역 크기 변화에 따른 영상유속계의 오차 분석)

  • Kim, Seojun;Yu, Kwonkyu;Yoon, Byungman
    • Journal of Korea Water Resources Association
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    • v.46 no.8
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    • pp.821-831
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    • 2013
  • Recently image velocimetries, including particle image velocimetry (PIV) and surface image velocimetry (SIV), are often used to measure flow velocities in laboratories and rivers. The most difficult point in using image velocimetries may be how to determine the sizes of the interrogation areas and the measurement uncertainties. Especially, it is a little hard for unskilled users to use these instruments, since any standardized measuring techniques or measurement uncertainties are not well evaluated. Sometimes the user's skill and understanding on the instruments may make a wide gap between velocity measurement results. The present study aims to evaluate image velocimetry's uncertainties due to the changes in the sizes of interrogation areas and searching areas with the error analyses. For the purpose, we generated 12 series of artificial images with known velocity fields and various numbers and sizes of particles. The analysis results showed that the accuracy of velocity measurements of the image velocimetry was significantly affected by the change of the size of interrogation area. Generally speaking, the error was reduced as the size of interrogation areas became small. For the same sizes of interrogation areas, the larger particle sizes and the larger number of particles resulted smaller errors. Especially, the errors of the image velocimetries were more affected by the number of particles rather than the sizes of them. As the sizes of interrogation areas were increased, the differences between the maximum and the minimum errors seemed to be reduced. For the size of the interrogation area whose average errors were less than 5%, the differences between the maximum and the minimum errors seemed a little large. For the case, in other words, the uncertainty of the velocity measurements of the image velocimetry was large. In the viewpoint of the particle density, the size of the interrogation area was small for large particle density cases. For the cases of large number of particle and small particle density, however, the minimum size of interrogation area became smaller.

Post-exposure Prophylaxis against Varicella Zoster Virus in Hospitalized Children after Inadvertent Exposure (수두-대상포진 바이러스에 노출된 소아 환자의 예방 조치)

  • Yang, Song I;Lim, Ji Hee;Kim, Eun Jin;Park, Ji Young;Yun, Ki Wook;Lee, Hoan Jong;Choi, Eun Hwa
    • Pediatric Infection and Vaccine
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    • v.23 no.3
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    • pp.180-187
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    • 2016
  • Purpose: This study described the post-exposure prophylaxis (PEP) and secondary varicella infection in children inadvertently exposed to varicella zoster virus (VZV) in the hospital. Methods: We retrospectively analyzed data from patients with VZV infection who were initially not properly isolated, as well as children exposed to VZV at the Seoul National University Children's Hospital between January 2010 and December 2015. The PEP measures were determined by the presence of immunity to VZV and immunocompromising conditions. Patient clinical information was reviewed via medical records. Results: Among 147 children hospitalized between 2010 and 2015, 13 inadvertent exposures were notified due to VZV infection. Five index children had a history of VZV vaccination. Eighty-six children were exposed in multi-occupancy rooms and 62.8% (54/86) were immune to VZV. The PEP measures administered to 27 exposed patients included varicella zoster immunoglobulin and VZV vaccination. Four children developed secondary varicella, which was linked to a single index patient, including one child who did not receive PEP and three of the 27 children who received PEP. The rates of secondary varicella and prophylaxis failure were 4.7% (4/85) and 11.1% (3/27), respectively. The secondary varicella rates were 1.9% (1/54) and 9.7% (3/31) among immunocompetent and immunocompromised children, respectively. Conclusions: Delayed diagnosis of VZV infection can lead to unexpected exposure and place susceptible children and immunocompromised patients at risk for developing varicella. The appropriateness of the current PEP strategy based on VZV immunity may require re-evaluation.

Real-time Reverse Transcription Polymerase Chain Reaction Using Total RNA Extracted from Nasopharyngeal Aspirates for Detection of Pneumococcal Carriage in Children (소아에서 폐렴구균 집락률 측정을 위해 비인두 흡인 물의 총 RNA를 이용한 실시간 중합효소 연쇄반응법)

  • Kim, Young Kwang;Lee, Kyoung Hoon;Yun, Ki Wook;Lee, Mi Kyung;Lim, In Seok
    • Pediatric Infection and Vaccine
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    • v.23 no.3
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    • pp.194-201
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    • 2016
  • Purpose: Monitoring pneumococcal carriage rates is important. We developed and evaluated the accuracy of a real-time reverse transcription polymerase chain reaction (RT-PCR) protocol for the detection of Streptococcus pneumoniae. Methods: In October 2014, 157 nasopharyngeal aspirates were collected from patients aged <18 years admitted to Chung-Ang University Hospital. We developed and evaluated a real-time PCR method for detecting S. pneumoniae by comparing culture findings with the results of the real-time PCR using genomic DNA (gDNA). Of 157 samples, 20 specimens were analyzed in order to compare the results of cultures, real-time PCR, and real-time RT-PCR. Results: The concordance rate between culture findings and the results of real-time PCR was 0.922 (P<0.01, Fisher exact test). The 133 culture-negative samples were confirmed to be negative for S. pneumoniae using real-time PCR. Of the remaining 24 culture-positive samples, 21 were identified as S. pneumonia -positive using real-time PCR. The results of real-time RT-PCR and real-time PCR from 20 specimens were consistent with culture findings for all S. pneumoniae -positive samples except one. Culture and real-time RT-PCR required 26.5 and 4.5 hours to perform, respectively. Conclusions: This study established a real-time RT-PCR method for the detection of pneumococcal carriage in the nasopharynx. Real-time RT-PCR is an accurate, convenient, and time-saving method; therefore, it may be useful for collecting epidemiologic data regarding pneumococcal carriage in children.

Occurrence Pattern of Intussusception according to the Introduction of Rotavirus Vaccine: An Observational Study at a University Hospital (로타바이러스 백신 도입에 따른 장겹침증 발생 경향: 한 대학병원 관찰 연구)

  • Nam, Hye Na;Lim, Kyung In;Tchah, Hann;Ryoo, Eell;Sun, Yong Han;Cho, Hye-Kyung
    • Pediatric Infection and Vaccine
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    • v.23 no.3
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    • pp.202-208
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    • 2016
  • Purpose: Rotavirus vaccine (RV) was introduced in Korea since 2007, and intussusception (IS) remains an important safety concern. This study investigated the trend of IS occurrence related to RV as well as the temporal relevance between vaccination and IS in children. Methods: We collected data of the patient aged ${\leq}18$ years with IS admitted to Gachon University Gil Medical Center, 2003 to 2015. For the patients that have occurred since 2008, the immunization records of RV were collected. The proportion of cases <1 year was calculated by the year and the temporal relationship between vaccination and IS occurrence was analyzed. Results: A total of 696 IS cases were noted. The cases <1 year were 30.7% (214/696). Although the incidence of all IS has increased over the 13-year period (from 74.1 in 2003 to 89.5 in 2015, linear by linear association, P=0.003), the incidence of IS <1 year has not increased (from 56.9 in 2003 to 53.3 in 2015, P=0.910), and the proportion of cases <1 year has decreased (from 35.4 in 2003 to 18.8 in 2015, P=0.000). Of 128 cases <1 year since 2008, 53.9% received RV. In the vaccinated group, 10 cases of IS occurred within 30 days, and eight cases did within 31 to 60 days. Numbers of IS after first, second, and third dose were three, 10, and five cases, respectively. Conclusions: Occurrence of IS in children <1 year of age did not increase since the introduction of RV. Further monitoring is essential for evaluation of vaccine safety.

Human Parechovirus as an Important Cause of Central Nervous System Infection in Childhood (소아청소년기 중추신경 감염의 주요 원인으로서 Human Parechovirus의 의의)

  • Jung, Hyun Joo;Choi, Eun Hwa;Lee, Hoan Jong
    • Pediatric Infection and Vaccine
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    • v.23 no.3
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    • pp.165-171
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    • 2016
  • Purpose: Human parechovirus (HPeV) is an increasingly recognized pathogenic cause of central nervous system (CNS) infection in neonates. However, HPeV infections have not been studied in older children. This study determined the prevalence and clinical features of HPeV CNS infection in children in Korea. Methods: Reverse transcription polymerase chain reaction assays were performed using HPeV-specific, 5' untranslated, region-targeted primers to detect HPeV in cerebrospinal fluid (CSF) samples from children presenting with fever or neurologic symptoms from January 1, 2013, to July 31, 2014. HPeV genotyping was performed by sequencing the viral protein 3/1 region. Clinical and laboratory data were retrospectively abstracted from medical records and compared with those of enterovirus (EV)-positive patients from the same period. Results: Of 102 CSF samples, six (5.9%) were positive for HPeV; two of 21 EV-positive samples were co-infected with HPeV. All samples were genotype HPeV3. Two HPeV-positive patients were <3 months of age and four others were over 1 year old. While HPeV-positive infants under 1 year of age presented with sepsis-like illness without definite neurologic abnormalities, HPeV-positive children over 1 year of age presented with fever and neurologic symptoms such as seizures, loss of consciousness, and gait disturbance. The CSF findings of HPeV-positive patients were mostly within the normal range, whereas most (73.7%) EV-positive patients had pleocytosis. Conclusions: Although HPeV is typically associated with disease in young infants, the results of this study suggest that HPeV is an emerging pathogen of CNS infection with neurologic symptoms in older childhood.

Molecular Epidemiology of Bacillus cereus in a Pediatric Cancer Center (소아 암 환자에서 발생한 Bacillus cereus 균혈증의 분자역학 분석에 관한 연구)

  • Kim, Jong Min;Park, Ki-Sup;Lee, Byung-Kee;Kim, Soo Jin;Kang, Ji-Man;Kim, Yanghyun;Yoo, Keon Hee;Sung, Ki Woong;Koo, Hong Hoe;Lee, Nam Yong;Kim, Yae-Jean
    • Pediatric Infection and Vaccine
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    • v.23 no.3
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    • pp.172-179
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    • 2016
  • Purpose: Bacillus cereus has been reported as the cause of nosocomial infections in cancer patients. In our pediatric cancer ward, a sudden rise in the number of patients with B. cereus bacteremia was observed in 2013 to 2014. This study was performed to investigate the molecular epidemiology of increased B. cereus bacteremia cases in our center. Methods: Pediatric cancer patients who developed B. cereus bacteremia were identified from January 2001 to June 2014. The B. cereus bacteremia in this study was defined as a case in which at least one B. cereus identified in blood cultures, regardless of true bacteremia. Available isolates were further tested by multilocus sequence typing (MLST) analysis. A retrospective chart review was performed. Results: Nineteen patients developed B. cereus bacteremia during the study period. However, in 2013, a sudden increase in the number of patients with B. cereus bacteremia was observed. In addition, three patients developed B. cereus bacteremia within 1 week in July and the other three patients within 1 week in October, respectively, during emergency room renovation. However, MLST analysis revealed different sequence types without consistent patterns. Before 2013, five tested isolates were ST18, ST26, ST177, and ST147-like type, and ST219-like type. Isolates from 2013 were ST18, ST73, ST90, ST427, ST784, ST34-like type, and ST130-like type. Conclusions: MLST analyses showed variable ST distribution of B. cereus isolates. Based on this study, there was no significant evidence suggesting a true outbreak caused by a single ST among patients who developed B. cereus bacteremia.