Throat Carriage Rate and Antimicrobial Resistance of Streptococcus pyogenes In Rural Children in Argentina

Delpech, Gaston,Sparo, Monica,Baldaccini, Beatriz,Pourcel, Gisela,Lissarrague, Sabina,Allende, Leonardo Garcia The Korean Society for Preventive Medicine 2017 Journal of Preventive Medicine and Public Health Vol.50 No.2

Objectives: The aim of this study was to determine the prevalence of asymptomatic carriers of group A ${\beta}-hemolytic$ streptococci (GAS) in children living in a rural community and to investigate the association between episodes of acute pharyngitis and carrier status. Methods: Throat swabs were collected from September to November 2013 among children 5-13 years of age from a rural community (Maria Ignacia-Vela, Argentina). The phenotypic characterization of isolates was performed by conventional tests. Antimicrobial susceptibility was assayed for penicillin, tetracycline, chloramphenicol, erythromycin, and clindamycin (disk diffusion). The minimum inhibitory concentration was determined for penicillin, cefotaxime, tetracycline, and erythromycin. Results: The carriage of ${\beta}-hemolytic$ streptococci was detected in 18.1% of participants, with Streptococcus pyogenes in 18 participants followed by S. dysgalactiae ssp. equisimilis in 5. The highest proportion of GAS was found in 8 to 10-year-old children. No significant association between the number of episodes of acute pharyngitis suffered in the last year and the carrier state was detected (p>0.05). Tetracycline resistance (55.5%) and macrolide-resistant phenotypes (11.1%) were observed. Resistance to penicillin, cefotaxime, or chloramphenicol was not expressed in any streptococcal isolate. Conclusions: The present study demonstrated significant throat carriage of GAS and the presence of group C streptococci (S. dysgalactiae ssp. equisimilis) in an Argentinian rural population. These results point out the need for continuous surveillance of GAS and non-GAS carriage as well as of antimicrobial resistance in highly susceptible populations, such as school-aged rural children. An extended surveillance program including school-aged children from different cities should be considered to estimate the prevalence of GAS carriage in Argentina.

Throat Carriage Rate and Antimicrobial Resistance of Streptococcus pyogenes In Rural Children in Argentina

Gastón Delpech,Mónica Sparo,Beatriz Baldaccini,Gisela Pourcel,Sabina Lissarrague,Leonardo García Allende 대한예방의학회 2017 Journal of Preventive Medicine and Public Health Vol.50 No.2

Objectives: The aim of this study was to determine the prevalence of asymptomatic carriers of group A β-hemolytic streptococci (GAS) in children living in a rural community and to investigate the association between episodes of acute pharyngitis and carrier status. Methods: Throat swabs were collected from September to November 2013 among children 5-13 years of age from a rural community (Maria Ignacia-Vela, Argentina). The phenotypic characterization of isolates was performed by conventional tests. Antimicrobial susceptibility was assayed for penicillin, tetracycline, chloramphenicol, erythromycin, and clindamycin (disk diffusion). The minimum inhibitory concentration was determined for penicillin, cefotaxime, tetracycline, and erythromycin. Results: The carriage of β-hemolytic streptococci was detected in 18.1% of participants, with Streptococcus pyogenes in 18 participants followed by S. dysgalactiae ssp. equisimilis in 5. The highest proportion of GAS was found in 8 to 10-year-old children. No significant association between the number of episodes of acute pharyngitis suffered in the last year and the carrier state was detected (p>0.05). Tetracycline resistance (55.5%) and macrolide-resistant phenotypes (11.1%) were observed. Resistance to penicillin, cefotaxime, or chloramphenicol was not expressed in any streptococcal isolate. Conclusions: The present study demonstrated significant throat carriage of GAS and the presence of group C streptococci (S. dysgalactiae ssp. equisimilis) in an Argentinian rural population. These results point out the need for continuous surveillance of GAS and non-GAS carriage as well as of antimicrobial resistance in highly susceptible populations, such as school-aged rural children. An extended surveillance program including school-aged children from different cities should be considered to estimate the prevalence of GAS carriage in Argentina.

Validation of 500-kW/1000-s operation of 5-GHz klystron for KSTAR LHCD system

Kim, Jeehyun,Seong, Taesik,Park, Seungil,Bae, Y.S.,Delpech, Lena,Namkung, Won,Cho, Moohyun Elsevier 2019 Fusion engineering and design Vol.139 No.-

<P><B>Abstract</B></P> <P>In this study, a klystron for the KSTAR lower hybrid current drive (LHCD) system was developed as a prototype for a 5 GHz, 500 kW CW operation that is aimed to meet the requirement of the ITER LHCD system as well. Before the 2012 KSTAR campaign, the prototype klystron was validated only for 350 kW CW operation. The weakest part of the klystron for 500 kW CW operation was the RF output window failure due to a thermal stress caused by the temperature gradient. The klystron was equipped with two RF windows, each of which should transmit 250 kW power. Prior to the full performance test of the klystron, the performance of the test RF windows that were identical to those mounted on the klystron was tested with half of the klystron’s full power. The temperature increase in the test RF windows was monitored using an IR camera. The temperature difference, ΔT<SUB>ce</SUB>, between the center and edge of the test window at 250-kW 1000-s transmitting power was predicted to be 23 °C, which is smaller than the safe ΔT<SUB>ce</SUB>, which is 50 °C according to the manufacturer. Based on the result of the test window measurement, 500-kW 1000-s operation of the klystron was conducted successfully. The klystron output power characteristics depending on the phase of load reflection VSWR 1.4:1 were investigated. The klystron generated stable power on a load VSWR of 1.4:1 at various phases. The output power at the worst phase was 380 kW. Details of the IR-imaging setup are discussed and the results obtained are presented.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Validation of 5-GHz 500-kW CW operation of the klystron which is relevant to the ITER LHCD system. </LI> <LI> The weakest part was the RF window damage due to a thermal stress by the temperature gradient. </LI> <LI> The accurate temperature of the test RF window was monitored using IR camera with a calibration. </LI> <LI> The klystron operation at 500 kW for 1000s was successfully. </LI> <LI> The klystron characteristics with reflective load. </LI> </UL> </P>

Design of mid-plane passive active multijunction antenna for 5-GHz KSTAR LHCD system

Kim, Jeehyun,Wang, Sonjong,Hillairet, Julien,Wi, Hyunho,Seon, Sangwon,Han, Jongwon,Delpech, Lena Elsevier 2017 Fusion engineering and design Vol.123 No.-

<P><B>Abstract</B></P> <P>The major upgrade of KSTAR LHCD system to 4MW is planned in 2021. 4-MW RF power will be provided by 8×0.5MW klystrons. Highly oversized circular waveguide transmitting TE<SUB>01</SUB>° mode will be adopted for the low loss transmission line longer than 50m. The design of the 4-MW mid-plane Passive Active Multijunction launcher has been performed. Considering parallel refractive index N<SUB>||</SUB> for the efficient current drive and the maximum power density at the launcher mouth, the launcher is composed of 256 active waveguides whose dimension is 58mm x 7mm and 18mm of spatial period for N<SUB>||0</SUB> =2.5. Multijunction with E<SUB>max <</SUB> 3.5kV/cm and high power waveguide components have been designed using HFSS code. The antenna properties were evaluated using ALOHA. Prototype PAM launcher with 32 active waveguides is under development for 0.5-MW pulsed operation.</P>

Design and tests of 500kW RF windows for the ITER LHCD system

Hillairet, J.,Kim, J.,Faure, N.,Achard, J.,Bae, Y.S.,Bernard, J.M.,Delpech, L.,Goniche, M.,Larroque, S.,Magne, R.,Marfisi, L.,Park, S.,Poli, S.,Dechambre, N.,Vulliez, K. Elsevier 2015 Fusion engineering and design Vol.94 No.-

<P><B>Abstract</B></P> <P>In the frame of a R&D effort conducted by CEA towards the design and the qualification of a 5GHz LHCD system for the ITER tokamak, two 5GHz 500kW/5s windows have been designed, manufactured and tested at high power in collaboration with the National Fusion Research Institute (NFRI). The window design rely on a symmetrical pill-box concept with a cylindrical beryllium oxide ceramic brazed on an actively water cooled copper skirt. The ceramic RF properties have been measured on a test sample to get realistic values for guiding the design. Low power measurements of the manufactured windows show return losses below −32dB and insertion losses between −0.01dB and −0.05dB, with an optimum frequency shifted toward lower frequencies. High power tests conducted at NFRI show unexpected total power loss for both windows. The ceramic temperature during RF pulses has been found to reach unexpected high temperature, preventing these windows to be used under CW conditions. A post-mortem RF analysis of samples taken from one window shows that the dielectric properties of the ceramic were not the ones measured on the manufacturer sample, which partly explain the differences with the reference modelling.</P>

A lower hybrid current drive system for ITER

Hoang, G.T.,Bé,coulet, A.,Jacquinot, J.,Artaud, J.F.,Bae, Y.S.,Beaumont, B.,Belo, J.H.,Berger-By, G.,Bizarro, Joã,o P.S.,Bonoli, P.,Cho, M.H.,Decker, J.,Delpech, L.,Ekedahl, A.,Garcia, J. International Atomic Energy Agency 2009 Nuclear fusion Vol.49 No.7

<P>A 20 MW/5 GHz lower hybrid current drive (LHCD) system was initially due to be commissioned and used for the second mission of ITER, i.e. the <I>Q</I> = 5 steady state target. Though not part of the currently planned procurement phase, it is now under consideration for an earlier delivery. In this paper, both physics and technology conceptual designs are reviewed. Furthermore, an appropriate work plan is also developed. This work plan for design, R&D, procurement and installation of a 20 MW LHCD system on ITER follows the ITER Scientific and Technical Advisory Committee (STAC) T13-05 task instructions. It gives more details on the various scientific and technical implications of the system, without presuming on any work or procurement sharing amongst the possible ITER partners. This document does not commit the Institutions or Domestic Agencies of the various authors in that respect.</P>