Characterization of Quinolone-Resistant Clinical Isolates of Escherichia coli in Korea

오유정,박서형,하미선,이연희 한국미생물학회 2002 The journal of microbiology Vol.40 No.2

Twenty-eight clinical isolates of Escherichia coli, composed of thirteen norfloxacin resistant isolates (MIC of >16 mg/ml), one intermediately resistant isolate (MIC of 8 mg/ml), and fourteen susceptible isolates (MIC of <4 mg/ml), were randomly selected to study the norfloxacin resistance mechanism and phylogeny in clinical isolates in Korea. Eleven norfloxacin resistant isolates and one susceptible isolate were multi-drug resistant (MDR). Every norfloxacin resistant isolate with MIC higher than 32 mg/ml had the same three mutations Ser83Leu and Asp87Asn or Tyr in GyrA and Ser80Ile in ParC. Whereas a resistant isolate with MIC of 16 mg/ml had three mutations but Asp87 in GyrA was replaced with Gly instead of Asn. The intermediately resistant isolate had the same two mutations in GyrA but a different mutation in ParC, Glu84Lys. Among the susceptible isolates, two isolates with MIC of 4 mg/ml had one mutation Ser83Leu in GyrA, and no mutation was found in the susceptible isolates. Resistant isolates showed higher efflux activity than the susceptible ones, with random amplification of polymorphic DNA (RAPD), six susceptible isolates form a separate group from the rest of the isolates.

Synergistic Antibacterial Activity of an Active Compound Derived from Sedum takesimense against Methicillin-Resistant Staphylococcus aureus and Its Clinical Isolates

( Eun-tak Jeong ),( Seul-ki Park ),( Du-min Jo ),( Fazlurrahman Khan ),( Tae Ho Choi ),( Tae-mi Yoon ),( Young-mog Kim ) 한국미생물 · 생명공학회 2021 Journal of microbiology and biotechnology Vol.31 No.9

There are a growing number of reports of hospital-acquired infections caused by pathogenic bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). Many plant products are now being used as a natural means of exploring antimicrobial agents against different types of human pathogenic bacteria. In this research, we sought to isolate and identify an active molecule from Sedum takesimense that has possible antibacterial activity against various clinical isolates of MRSA. NMR analysis revealed that the structure of the HPLC-purified compound was 1,2,4,6-tetra-Ogalloyl- glucose. The minimum inhibitory concentration (MIC) of different extract fractions against numerous pathogenic bacteria was determined, and the actively purified compound has potent antibacterial activity against multidrug-resistant pathogenic bacteria, i.e., MRSA and its clinical isolates. In addition, the combination of the active compound and β-lactam antibiotics (e.g., oxacillin) demonstrated synergistic action against MRSA, with a fractional inhibitory concentration (FIC) index of 0.281. The current research revealed an alternative approach to combating pathogenesis caused by multi-drug resistant bacteria using plant materials. Furthermore, using a combination approach in which the active plant-derived compound is combined with antibiotics has proved to be a successful way of destroying pathogens synergistically.

A Comparison of the Ability of Fungal Internal Transcribed Spacers and D1/D2 Domain Regions to Accurately Identify Candida glabrata Clinical Isolates Using Sequence Analysis

Min-Ji Kang,Yoon-Sung Choi,Sunghyun Kim 대한의생명과학회 2018 Biomedical Science Letters Vol.24 No.4

Candida glabrata is the second most prevalent causative agent for candidiasis following C. albicans. The opportunistic yeast, C. glabrata, is able to cause the critical bloodstream infections in hospitalized patients. Conventional identification methods for yeasts are often time consuming and labor intensive. Therefore, recent studies on sequence-based identification have been conducted. Recently, sequencing the D1/D2 domain of the large subunit ribosomal RNA gene and the internal transcribed spacers (ITS) 1 and ITS2 regions of the ribosomal DNA has proven useful for DNA-based identification of most species of fungi. In the present study, therefore, fungal ITS and D1/D2 domain regions were targeted and analyzed by DNA sequencing for the accurate identification of C. glabrata clinical isolates. A total of 102 C. glabrata clinical isolates from various clinical samples including bloodstream, catheterized urine, bile and other body fluids were used in the study. The results of the DNA sequence analysis showed that the mean standard deviation of species identity percent score between ITS and D1/D2 domain regions was 97.8% ± 2.9 and 99.7% ± 0.46, respectively. These results revealed that the D1/D2 domain region might be a better target for identifying C. glabrata clinical isolates based on DNA sequences than the ITS1 and ITS2 regions. However, in order to evaluate the usefulness of D1/D2 domain region for species identification of all Candida species, other Candida species such as C. albicans, C. tropicalis, C. dubliniensis, and C. krusei should be verified in further studies additionally.

MIC Distribution of Isoniazid, Rifampicin, Ethambutol, Pyrazinamide, and Levofloxacin in cPMTb Cohort Mycobacterium Tuberculosis Isolates

( Yumi Park ),( Sun-young Lee ),( Eun-soon Son ),( Jeong Seong Yang ),( Jake Whang ),( Tae Won Jang ),( Je Hun Kim ),( Jee Youn Oh ),( Hyn Kuk Kim ),( Hyo-jung Kim ),( Yong-soon Cho ),( Jae-gook Shin 대한결핵 및 호흡기학회 2020 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.128 No.-

Background Minimum inhibitory concentration (MIC) of antibiotics has been widely conducted for drug susceptibility tests (DST) of most bacterial infectious diseases, except tuberculosis (TB). Current phenotypic DST for TB uses one or two critical concentrations to determine the resistance of anti-TB drugs. The MIC test would be necessary not only for therapeutic drug monitoring-based precision medicine but also for detecting borderline resistance of anti-TB drugs. Here, we present the distribution of MIC of 4 first-line drugs and levofloxacin in cPMTb cohort Mycobacterium tuberculosis (Mtb) isolates. Methods From 2019-2020, 108 Mtb strains were collected in the cPMTb cohort. Broth microdilution Method in 96 well plates was used for the MIC test of anti-TB drugs, except for pyrazinamide (PZA). MGIT960 system was used for PZA MIC determination. Results The proportions of drug-resistant (DR) and drug-susceptible (DS) strains were 15.7% and 84.3%, respectively. Most of the DS MIC were distributed below the critical concentration of the drug. Three discordances between phenotypic DST and MIC were found in isoniazid, which is 2.8% in total. We observed 2 cases (1.9%) of low-level resistance (MIC 0.5 ug/ml), determined as DS for rifampicin in phenotypic DST but DR in genotypic DST. Conclusion MIC of cPMTb cohort 108 strains were distributed mostly below the critical concentration of all drugs. There are 6 cases of discordance between MIC and DST (phenotypic or genotypic). The MIC test could be utilized to overcome the limitation of phenotypic DST using critical concentration and fill the gap between genotypic and phenotypic DST.

Lab on a fabric: Mass producible and low-cost fabric filters for the high-throughput viable isolation of circulating tumor cells

Bu, Jiyoon,Kang, Yoon-Tae,Lee, Yong-Seok,Kim, Jeongsuk,Cho, Young-Ho,Moon, Byung-In Elsevier 2017 Biosensors & Bioelectronics Vol.91 No.-

<P><B>Abstract</B></P> <P>Circulating tumor cells (CTCs) play an important role in estimating the presence and the metastatic relapse of tumor. Despite of their importance, isolation of viable CTCs is still struggling, since chemical or mechanical damages are unavoidable when separating less than 1000 of CTCs out of billions of other blood components. Furthermore, the current CTC isolation devices show low productivity, since they are produced after a series of complicated fabrication processes. Here, we present a low-cost and mass-producible fabric filters for the viable CTC isolation and the further molecular assay for profiling cancer-associated markers. The fabric filter, produced by polyester monofilament yarns, can be massively produced at extremely low-cost, by showing productivity of ~22filters/s at ~59filters/USD. By utilizing size-based sorting method, the fabric filter is capable to isolate both epithelial and mesenchymal CTCs, while slots with curved walls are beneficial for preventing the cell rupture by reducing 21.6% of mechanical stress compared to the conventional straight-walled slots. We applied our filter to 11 human blood samples and found that the number of CTCs was closely related to the expression level of Ki-67, which is highly overexpressed in proliferative tumors. The fabric filter might be an appropriate caner-screening tool in developing countries, where people suffer from insufficient healthcare services.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We present a mass producible and low-cost fabric filter for viable CTC isolation. </LI> <LI> Curved walls in the fabric filter is beneficial for minimizing the cellular damage. </LI> <LI> The fabric filter is capable for viable capture and efficient retrieval. </LI> <LI> CTCs were detected from all patients, while none was found among healthy donors. </LI> <LI> The number of CTCs was closely related with the expression level of Ki-67. </LI> </UL> </P>

녹농균 임상균주의 쿼럼 센싱 관련 표현형 분석

정경주,최유상,하창완,신정환,이준희,Jung, Kyung-Ju,Choi, Yu-Sang,Ha, Chang-Wan,Shin, Jeong-Hwan,Lee, Joon-Hee 한국미생물학회 2010 미생물학회지 Vol.46 No.3

그람음성 간균인 녹농균(Pseudomonas aeruginosa)은 비뇨기, 결막(conjunctiva), 호흡기(respiratory system), 화상부위 등에 광범위하게 감염하며, 병원성의 발현에 세균의 세포밀도 인식기전인 쿼럼 센싱이 매우 중요하다고 알려진 기회감염성 병원균이다. 국내의 환자들에게 감염하는 녹농균에서 쿼럼 센싱의 중요성을 알아보기 위해 부산 백병원의 환자들로부터 189종의 녹농균을 분리 동정하였다. 이 임상 균주들에서 쿼럼 센싱 신호 물질의 발현을 리포터 균주를 이용한 고체 배지 확산법으로 조사하였다. 전체 임상 균주의 79.4%가 녹농균 야생형균주와 비슷하게 쿼럼 센싱 조절의 가장 상위 신호인식-조절단백질인 LasR을 충분히 활성화 시키는 수준으로 쿼럼 신호물질을 생성하였다. 반면 4.2% 정도는 신호물질을 합성하지 못하는 녹농균 돌연변이주와 비슷하게 LasR을 활성화 시키지 못하는 수준으로 쿼럼 신호물질을 생성하였다. 한편, 전체의 72.5%가 또 다른 쿼럼 신호인식-조절 단백질인 QscR을 충분히 활성화 시킬 수 있는 야생형 수준으로 신호물질을 생성한 반면, 9%가 QscR을 활성화 시키지 못하는 수준으로 신호물질을 생성하였다. 임상 균주들 중 특히 녹농균 감염이 의심되는 환자들에게서 유래한 74종을 선정하여 병독인자로 중요한 프로테아제 활성을 조사한 결과, 44.6%에서 프로테아제 활성이 낮아져 있었으며, 12.2%에서는 프로테아제 활성이 관찰되지 않았다. 같은 균들을 대상으로 만성감염에 중요한 역할을 하는 것으로 알려진 생물막 형성 능력을 확인하였을 때, 대부분이 야생형보다 생물막 형성능력이 떨어져 있었다. 또한 이 균주들의 운동성을 살펴본 결과 많은 균주들이 swarming과 twitching 능력이 저해되어 있었으며(전체의 51.4%가 reduced swarming activity, 전체의 41.9%가 reduced twitching activity), 관찰되지 않는 수준의 균주도 상당부분 있었다(전체의 28.4%가 swarming negative, 전체의 28.4%가 twitching negative). 본 연구결과는 쿼럼 센싱을 정상적으로 하는 임상 균주들 중에서도 상당 부분은 프로테아제 생성, 생물막 형성, 운동성 등의 특징들이 저해될 수 있음을 의미하며, 일부 임상 균주들은 그들의 쿼럼 활성과는 상관관계가 없는 독특한 패턴의 프로테아제 생성능과 생물막 형성능 및 운동성을 보여주고 있음을 확인하였다. Pseudomonas aeruginosa is a Gram (-) opportunistic human pathogen causing a wide variety of infections on lung, urinary tract, eyes, and burn wound sites and quorum sensing (QS), a cell density-sensing mechanism plays an essential role in Pseudomonas pathogenesis. In order to investigate the importance of QS in the Pseudomonas infections of Korean patients, we isolated 189 clinical strains of P. aeruginosa from the patients in Pusan Paik Hospital, Busan, South Korea. The QS signal production of these clinical isolates was measured by signal diffusion assay on solid media using reporter strains. While most clinical strains (79.4%) produced the QS signals as similar level as a wild type strain, PAO1 did, where LasR, the initial QS signal sensor-regulator was fully activated, a minority of them (4.2%) produced much less QS signals at the level to which LasR failed to respond. Similarly, while 72.5% of the clinical isolates produced QS signals enough to activate QscR, an another QS signal sensor-regulator, some few of them (9%) produced the QS signals at much lower level where QscR was not activated. For further analysis, we selected 74 clinical strains that were obtained from the patients under suspicion of Pseudomonas infection and investigated the total protease activity that is considered important for virulence. Interestingly, significant portion of them showed very low protease activity (44.6%) or no detectable protease activity (12.2%). When the biofilm-forming ability that is considered very important in chronic infection was examined, most isolates showed lower biofilm-forming activity than PAO1. Similarly, significant portion of clinical isolates showed reduced motility (reduced swarming activity in 51.4% and reduced twitching activity in 41.9%), or non-detectable motility (swarming-negative in 28.4% and twitching-negative in 28.4%). Our result showed that the clinical isolates that produced QS signals at the similar level to wild type could have significantly reduced activities in the protease production, biofilm formation, and motility, and some clinical isolates had unique patterns of motility, biofilm formation, and protease production that are not correlated to their QS activity.

우안의 시력 저하를 주소로 내원한 10세 여자에서 진단된 Clinically isolated 증후군 1례

권세호,이병국,이흔지,문지영,민성주,박철용,박수연 동국대학교 의학연구소 2008 東國醫學 Vol.15 No.1

Clinically isolated 증후군은 염증성 탈수초가 원인으로 추정되는 중추신경계 증상이 급성으로 처음 발현하는 경우를 일컫는다. 이 때 뇌 또는 전척수 자기 공명 영상에서 무증상적 다발성 병변이 있을 경우 추후 다발성 경화증으로 진행될 가능성이 높아진다. 다발성 경화증은 시신경을 포함한 중추신경계의 여러 부위에 발생하는 탈수초성 질환으로 시간 간격을 두고 다양한 형태의 임상 양상을 보이며 호전과 재발을 반복하는 질환이다. 이 질환은 성인기에 주로 발병한다고 알려져 있으나 소아에서도 드물게 발생하며 발병 후 다양한 정도의 합병증 및 후유증을 남길 수 있다. 저자들은 우안의 시력 저하를 주소로 내원하여 시행한 자기 공명 영상 검사에서 중추신경계의 다발성 병변을 보여 clinically isolated syndrome (CIS)으로 진단된 1례를 경험하였고 이 경우 다발성 경화증으로 이행할 가능성이 있기에 문헌 고찰과 함께 보고하는 바이다. A clinically isolated syndrome is a first acute clinical episode of CNS symptoms with a presumed inflammatory demyelinating cause for which there is no prior history of a demyelinating event. MRI evidence of multiple clinically silent lesions may be associated with an increased risk of multiple sclerosis. Multiple sclerosis is a demyelinating disorders that affects discrete areas of the CNS, including the optic nerve, in a quite variable relapsing-remitting fashion over a prolonged period of time. Although usually considered to be a disease that affects people in early to middle adulthood, children develop multiple sclerosis and may account for up to 4% to 5% of all reported cases. We present a case of clinically isolated syndrome in 10 year-old girl with decreased right visual acuity. She was admitted due to decreased unilateral visual acuity that known incidentally. We founded abnormal finding on brain and whole spine magnetic resonance imaging and treated her with steroid.

Development of Broad-range and Specific 16S rRNA PCR for Use in Routine Diagnostic Clinical Microbiology

Hyun-Chul Kim(김현철),Yun-Tae Kim(김윤태),Hyogyeong Kim(김효경),Sanghoo Lee(이상후),Kyoung-Ryul Lee(이경률),Young-Jin Kim(김영진) 한국생명과학회 2014 생명과학회지 Vol.24 No.4

16S rRNA gene PCR법은 환자 검체로부터 병원성 미생물을 검출 및 동정에 사용되어진다. 본 연구는 대량의 임상미생물 진단을 위해 bacterial 16S rRNA 부위 유전자 서열을 이용하여 광대한 범위와 높은 특이도를 가지는 primer을 포함한 PCR법을 개발하였다. 10개 표준 균주 16S rRNA 보존 부위의 유전자 서열을 기반으로 primer set를 구축하였다. 98명 환자 검체에서 임상 미생물을 분리하였다. 98개 균주는 phenotypic 방법을 이용하여 확인하고, 개발된 primer set와 universal primer set를 이용한 PCR법으로 확인하였다. 획득한 PCR 산물은 forward primer, reverse primer, 그리고 자동화 DNA 분석기를 이용하여 각 균주의 16S rRNA 유전자 서열을 분석 및 확인하였다. 본 연구에서 개발된 primer set와 universal primer set의 임상미생물 검출에 대한 효율성을 평가하였고, 또한 phenotypic 방법과 분자생물학적 방법을 비교했다. 분리된 98개 균주를 대상으로 개발된 primer set로 16S rRNA PCR을 진행하여 778 bp 크기의 단일밴드로 증폭 되었음을 확인했다. 총 98개중 94개 균주(95.9%)는 phenotypic 결과와 동일함을 확인했다. 새로 개발된 primer set를 이용한 결과는 universal primer set를 이용한 98개 균주(100%)의 결과와 동일함을 확인하였다. 개발된 16S rRNA gene PCR법은 임상미생물 검출 및 동정에서 신속성, 정확성, 그리고 검사 비용 절감의 장점을 가진다. 개발된 primer set는 병원성 미생물 동정에서 효율성을 확인했다. Broad-range and specific 16S rRNA gene PCR is used for detection and identification of bacterial pathogens in clinical specimens from patients with a high suspicion for infection. We describe the development of a broad-range and specific PCR primer, based on bacterial 16S rRNA, for use in routine diagnostic clinical microbiology services. The primers were designed by using conservative regions of 16S rRNA sequences from 10 strains. Ninety-eight clinical strains were isolated from clinical patient specimens. A total of 98 strains of bacteria were identified by phenotypic methods; PCR with newly designed primers and universal primers. All purified PCR products were sequenced using both forward and reverse primers on an automated DNA analyzer. In this study, we evaluated the usefulness of the newly designed primers and the universal primers for the detection of bacteria, and both these techniques were compared with phenotypic methods for bacteria detection. When we also tested 98 strains of clinical isolates with newly designed primers, about 778 bp DNA fragments were amplified and identified from all strains. Of the 98 strains, 94 strains (95.9%) correspond in comparison with phenotypic methods. The newly designed primers showed that the identities of 98 (100%) strains were the same as those obtained by universal PCR primers. The overall agreement between the newly designed primers and universal primers was 100%. The primer set was designed for rapid, accurate, and cheap identification of bacterial pathogens. We think the newly designed primer set is useful for the identification of pathogenic bacteria.

Genetic Variations of Aspergillus fumigatus Clinical Isolates from Korea

Sunghyun Kim,Pan-Gon Ma,Young-Seok Park,Young-Bin Yu,Kyu Jam Hwang,Young Kwon Kim 대한의생명과학회 2017 Biomedical Science Letters Vol.23 No.3

Fungal infections by human pathogenic fungi are increasing globally in elderly, children and immune suppressed or deficient patients. Aspergillus fumigatus is one of the well-known pathogenic fungi and causes aspergilloses in human world widely. However, current identification and classification methods based on its phenotypic characteristics still have limitations. Therefore, currently, molecular biological tools using their DNA sequences are used for genotype identification and classification. In the present study, in order to analyze genetic variations of A. fumigatus clinical isolates, a total of six housekeeping genes were amplified by PCR using specific primer pairs and multi-locus sequence typing (MLST) assay. Results from phylogenetic tree analysis showed that most A. fumigatus strains (88.9%) from respiratory specimens were classified into cluster A and B, and approximately half of A. fumigatus strains (46%) from non-respiratory specimens were classified into cluster C and D. Although the sample size was limited, genetic characteristics of A. fumigatus clinical isolates according to their origins were very similar and well-correlated with other clinical data.

서울지역 유아원 어린이들에게 분리된 Streptococcus pneumoniae의 항균제 내성 조사

강은숙,이수연,홍기숙,김경효 대한임상병리학회 2000 대한임상병리학회지 Vol.20 No.2