Antibiotic Use and Antibiotic Resistance in Animal Production : an Update

M.J. Gwyther 대한수의학회 1999 대한수의학회 학술대회발표집 Vol.1999 No.-

Square arrays of holes and dots patterned from a linear ABC triblock terpolymer.

Choi, Hong Kyoon,Gwyther, Jessica,Manners, Ian,Ross, Caroline A American Chemical Society 2012 ACS NANO Vol.6 No.9

<P>Microphase separation of a polyisoprene-b-polystyrene-b-polyferrocenylsilane (PI-b-PS-b-PFS) triblock terpolymer film during chloroform solvent-annealing formed a 44 nm period square-symmetry array of alternating PI and PFS cylinders in a PS matrix. This nanostructure was converted to either a positive pattern of posts or a negative pattern of holes with tunable diameter by oxygen reactive ion etching or by surface reconstruction in a solvent, respectively, and coexisting post and hole patterns were also formed. Square arrays of silicon posts, pits, and inverted pyramids were fabricated by pattern transfer from the triblock terpolymer film into silicon substrates. The morphology of the triblock terpolymer film varied with the chloroform vapor pressure during solvent annealing, which was explained by selective swelling of the PI block at high vapor pressures. This triblock terpolymer system provides a convenient block copolymer lithography process for generation of nanoscale posts or holes with square symmetry.</P>

Large-Area Nanosquare Arrays from Shear-Aligned Block Copolymer Thin Films

Kim, So Youn,Nunns, Adam,Gwyther, Jessica,Davis, Raleigh L.,Manners, Ian,Chaikin, Paul M.,Register, Richard A. American Chemical Society 2014 NANO LETTERS Vol.14 No.10

<P>While block copolymer lithography has been broadly applied as a bottom-up patterning technique, only a few nanopattern symmetries, such as hexagonally packed dots or parallel stripes, can be produced by spontaneous self-assembly of simple diblock copolymers; even a simple square packing has heretofore required more intricate macromolecular architectures or nanoscale substrate prepatterning. In this study, we demonstrate that square, rectangular, and rhombic arrays can be created via shear-alignment of distinct layers of cylinder-forming block copolymers, coupled with cross-linking of the layers using ultraviolet light. Furthermore, these block copolymer arrays can in turn be used as templates to fabricate dense, substrate-supported arrays of nanostructures comprising a wide variety of elements: deep (>50 nm) nanowells, nanoposts, and thin metal nanodots (3 nm thick, 35 nm pitch) are all demonstrated.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-10/nl502416b/production/images/medium/nl-2014-02416b_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl502416b'>ACS Electronic Supporting Info</A></P>

Development of multiplex PCR for detection of vancomycin resistant enterococci(VRE) and epidemiological application in Korea

Seo, Keun-seok,Song, Deok-jln,Gwyther, M.M.,Park, Yong-ho The Korean Society of Veterinary Science 1999 大韓獸醫學會誌 Vol.39 No.2

Vancomycin resistant enterococci (VRE) have emerged as an important nosocomial pathogen. Since 1989 the Center for Disease Control, United States, has reported a rapid increase in the incidence of enterococcal bacteremia and endocarditis infection by VRE. It was suggested that the use of avoparcin was associated with the appearance of VRE in animal husbandry. To date, several detection methods have been used based on conventional methods of culture and gene detection. However, these methods have some limitations such as time-consuming, laborious and additional differential needs. Therefore, In this study a multiplex PCR method was established to detect and differentiate resistance types of enterococci which specifically amplify the four van genes encoding vancomycin resistance elements. Using the method, we investigated the incidence rates and types of VRE from farms using or not using avoparcin. A total of 1091 animal fecal samples were collected from 70 pig and 32 poultry farms. A total of 425 of enterococci were isolated from samples. Of the 425 isolates, 11 of the them showed a pattern of high-level vancomycin resistance (MIC : $64{\sim}256{\mu}g/ml$) which was associated with the presence of the vanA or vanB gene. Fifty-seven isolates showed a pattern of low-level vancomycin resistance (MIC : $3{\sim}8{\mu}g/ml$) associated with the vanC-1 or vanC-2 gene. Interestingly, all isolates with high-level vancomycin resistance were from farms that have never used avoparcin. Moreover, the high-level VRE isolation rate in Korea (2.58%) was much lower than that of other countries (50% in England, 7% in Belgium) where avoparcin have been used. In conclusion, the multiplex PCR method established in this study could be applied for detection of VRE.

Development of Multiplex PCR for Detection of Vancomycin Resistant Enterococci and Epidemiological Application in Korea

Park, Yong Ho,Seo, Keun Seok,Yoo, Han Sang,Gwyther, M.J. 대한화학요법학회 1999 대한화학요법학회지 Vol.17 No.4

Vancomycin에 저항성을 나타내는 장구균(VRE)은 중요한 병원내 감염 병원균으로 등장하고 있으며 1989년 미국 CDC의 보고에 따르면 VRE에 의한 세균혈증과 심내막염의 감염율이 매우 빠른 속도로 증가하고 있다고 알려져 있다. 이러한 VRE의 축산동물 내에서의 등장은 avoparcin의 사용에 관련이 있을 것이라고 주장되어지고 있다. 본 연구에서는 4가지 형태의 VRE를 유도하는 유전자를 진단하고 구별할 수 있는 multiplex PCR법을 확립하였으며 이를 이용하여 avoparcin을 사용하였던 농장 및 사용하지 않은 농장으로부터의 VRE의 분리율 및 유전자형을 조사하였다. 70개소의 돼지 및 32개소의 닭 농장으로부터 1,091개의 분변 샘플을 수거하여 425주의 장구균을 분리하였으며 그 중 11주가 높은 농도의 vancomycin 저항성(64-256㎍/㎖)을 나타내었으며 PCR 조사결과 vanA, vanB 유전자를 확인할 수 있었다. 57주의 낮은 농도의 vancomycin에 저항성 3-8㎍/㎖)을 나타내는 VRE는 PCR 조사결과 vanC-1 또는 vanC-2의 유전자를 확인할 수 있었다. 국내의 높은 농도의 vancomycin에 저항성을 나타내는 VRE의 분리율(11/425, 2.58%)은 avoparcin을 사용하였던 다른 나라의 분리율(22/55 in England, 7% in Belgium)에 비해 현저히 낮은 것으로 조사되었다. 또한 분리주에 대한 유전적 연관성을 분석하기 위하여 rep-PCR법을 확립하였으며 이를 이용하여 8주의 동물유래 VRE와 31주의 사람유래 VRE의 rep-PCR 양상을 분석한 결과 사람유래 VRE의 경우 6개, 동물유래 VRE의 경우 한 개의 역학적으로 연관성이 있는 그룹이 관찰되었으며 사람유래 VRE의 동물유래 VRE간의 연관성을 관찰할 수 있었다. 결론적으로, 돼지 및 양계농장으로부터 11주의 high-level VRE가 분리되었으며, 이를 사람으로부터 분리된 VRE와 genotype 등을 비교 분석한 결과, 역학적으로 상관관계가 없는 것으로 확인되어 국내에서 동물사료첨가제로 쓰이는 avoparcin에 의한 vancomycin 항생제 유도는 인정되지 않았다. Vancomycin resistant enterococci (VRE) have emerged as an important nosocomial pathogen. Since 1989 the Center for Disease Control, United States, has reported a rapid increase in the incidence of enterococcal bacteremia and endocarditis infection by VRE. It was suggested that the use of avoparcin in animal husbandry was associated with the appearance of VRE. In this study a multiplex PCR method was established to detect and differentiate genotypes of enterococci which specifically amplify the four van genes encoding vancomycin resistance elements. The incidence rates and types of VRE from farms using or not using avoparcin was investigated using this method. From 1,091 animal fecal samples collected from 70 pig and 32 poultry farms, a total of 425 of enterococci were isolated. Of the isolates, 11 of the them showed a pattern of high-level vancomycin resistance (MIC: 64-256 ㎍/㎖) which was associated with the vanA or vanB gene. Fifty-seven isolates showed a pattern of low-level vancomycin resistance (MIC: 3-8 ㎍/㎖) associated with the vanC-1 or vanC-2 gene. The high-level VRE isolation rate in Korea (2.58%) was much lower than that of other countries (50% in England. 7% in Belgium) where avoparcin have been used. A repetitive extragenic palindromic PCR (rep-PCR) method was also established to determine genetic relatedness between animal and human VRE isolates. The repPCR pattern of 31 human VREs isolates with 11 animal isolates was compared. Human isolates generated five different types of group (Group Ⅱ to Ⅳ), whereas animal isolates generated only one group (Group Ⅰ). None of animal isolates had similar rep-PCR pattern of the human isolates. This result suggested that no genetic relatedness was in between animal and human VRE in Korea. In conclusion, the multiplex PCR and rep-PCR methods established in this study could be applied for detection of VRE and might be useful for the epidemiological investigations for their origins.