• Korean Journal of Microbiology
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• v.51 no.1
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• pp.39-47
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• 2015

Secondary metabolism in actinomycetes has been known to be controlled by a small molecule, ${\gamma}$-butyrolactone autoregulator, the binding of which to each corresponding receptor leads to the regulation of the transcriptional expression of the secondary metabolites. We expected that expression of an autoregulator receptor or a pleiotropic regulator in a non-host was to be gained insight of effective production of new metabolic materials. In order to study the function of the receptor protein (seaR), which is isolated from Saccharopolyspora erythraea, we introduced the seaR gene to Streptomyces coelicolor A3(2) as host strains. An effective transformation procedure for S. coelicolor A3(2) was established based on transconjugation by Escherichia coli ET12567/pUZ8002 with a ${\varphi}C31$-derived integration vector, pSET152, which contained int, oriT, attP and $ermEp^*$ (erythromycin promotor). Therefore, the pEV615 was introduced into S. coelicolor A3(2) by conjugation and integrated at the attB locus in the chromosome of the recipients by the ${\varphi}C31$ integrase (int) function. Exconjugant of S. coelicolor A3(2) containing the seaR gene was confirmed by PCR and transcriptional expression of the seaR gene in the transformant was analyzed by RT-PCR. In case of S. coelicolor A3(2), a phenotype microarray was used to analyze the phenotype of transformant compared with wild type by seaR expression. After that, in order to confirm the accuracy of the results obtained from the phenotype microarray, an antimicrobial susceptibility test was carried out. This test indicated that sensitivity of the transformant was higher than wild type in tetracycline case. These results indicated that some biosynthesis genes or resistance genes for tetracycline biosynthesis in transformant might be repressed by seaR expression. Therefore, subsequent experiments, analysis of transcriptional pattern of genes for tetracycline production or resistance, are needed to confirm whether biosynthesis genes or resistance genes for tetracycline are repressed or not.

• Restorative Dentistry and Endodontics
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• v.32 no.2
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• pp.102-110
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• 2007

The purpose of this study was to obtain the basic information for the improvement of dental environment by investigating the presence of methicillin- or vancomycin-resistant Staphylococcus aureus (MRSA or VRSA) isolated from dental health care workers (DHCWs) and environment of the Chosun University Dental Hospital (CUDH) and a private dental clinic (control group). Staphylococcus aureus (S. aureus) was isolated from anterior nares of 42 DHCWS and 38 sites, unit chairss, x-ray devices, computers, etc., at 10 departments of the CUDH and 20 DHCWs and 11 sites at the private dental clinic. S. aureus was isolated on mannitol salt agar plate and confirmed by PCR with S. aureus species-specific primer. Antimicrobial susceptibility test of clinical isolates of S. aureus against several antibiotics including methicillin (oxacillin) was performed by investigating minimum inhibitory concentration (MIC) using broth microdilution assay. In addition, PCR was performed to detect the methicillin- or vancomycin-resistant gene. The data showed that one strain of S. aureus was isolated from DHCWs of the CUDH and three strains of S. aureus was isolated from 3 samples of the private dental clinic, respectively. All of the isolates from the CUDH and the private dental clinic had resistance to penicillin G, amoxicillin and vancomycin and susceptibility to oxacillin and ciprofloxacin. The S. aureus strains were already obtained the resistance to penicillin G and amoxicillin. These results suggest that two dental clinics were under relatively safe environment.

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.210-218
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• 1990

The survival and transfer of chromosomal genes coding for the synthesis of amino acids (threonine, tryptophan, histidine, leucine, methionine) and of plasmid-borne genes coding for resistance to antibiotics (chloramphenicol, kanamycin, erythromycin) by transformation in sterile and nonsterile soil (the soil was amended to 12% vol/vol with the clay mineral, montmorillonite) was studied. In pure culture, the numbers of vegetative cells of the Bacillus subtilis strains decreased by 1 to 1.5 orders of magnitude within one week, but spores of each strain showed lesser decreases. In sterile soil, the populations of vegetative cells and spores decreased by 1.5 to 3 orders of magnitude within 2 to 4 days and then showed little additional decreased. The transformation frequencies (number of transformants/numbers of donors and recipients) of individual amino acid-genes invitro ranged from $1.3{\pm}0.6{\times}10^{-6}$ to $6.0{\pm}2.36{\times}10^{-6}$, of two amino acid-genes from $8.5{\pm}0.7{\times}10^{-8}$ to $3.1{\pm}0.6{\times}10^{-7}$, and of the antibiotic-resistance genes from $1.5{\pm} 0.2{\itmes} 10^{-7}$ to $1.4{\pm} 0.4{\times} 10^{-5}$ . In sterile soil, the frequencies of transfer of individual amino acid-genes ranged from $2.0{\times} 10^{-7}$ to $2.0{\times} 10^{-5}$ and of the antibiotic-resistance genes from $2.0{\times} 10^{-7}$ to $9.4{\pm} 4.7{\times} 10^{-6}$. The transfer of two amino acid-genes in sterile soil was detected at a frequency of $2.0{\times} 10^{-6}$ to $4.5{\times} 10^{-6}$, but only in three instances. The transformation frequencies of antibiotic-resistance genes in nonsterile soil were essentially similar to those in sterile soil. However, to detect transformants in nonsterile soil, higher concentrations of antibiotics were needed, as the result of the large numbers of indigenous soil bacteria resistant to the concentration of antibiotics used in the sterile soil and in vitro studies. The results of these studies show that genes can be transferred by transformation in soil and that this mechanism of transfer must be considered in risk assessment of the release of genetically engineered microorganisms to the environment.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.185-194
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• 2006

The aim of this study was to identify the bacteria isolated from endodontic lesions by cell culture and to determine the antimicrobial susceptibility of them against 8 antibiotics. The necrotic pulpal tissues were collected from 27 infected root canals, which were diagnosed as endodontic infection. Samples were collected aseptically from the infected pulpal tissue of the infected root canals using a barbed broach and a paper point. The cut barbed broaches and paper points were transferred to an eppendorf tube containing $500{\mu}l\;of\;1{\times}PBS$. The sample solution was briefly mixed and plated onto a BHI-agar plate containing 5% sheep blood. The agar plates were incubated in a $37^{\circ}C$ anaerobic chamber for 2 to 5 days. The bacteria grown on the agar plates were identified by comparison of 16S rRNA gene (rDNA) sequencing method at the species level. To test the sensitivity of the bacteria isolated from the infected root canals against 8 antibiotics, minimum inhibitory concentrations (MIC) were determined using broth dilution assay. The data showed that 101 bacterial strains were isolated and were identified. Streptococcus spp. (29.7%) and Actinomyces spp. (21.8%) were predominantly isolated. The 9 strains were excluded in antimicrobial susceptibility test because they were lost during the experiment or were not grown in broth culture. The percentage of bacteria susceptible for each antibiotic in this study was clindamycin, 87.0% (80 of 92); tetracycline, 75.0% (69 of 92); cefuroxime axetil, 75.0% (69 of 92); amoxicillin + clavulanic acid (5:1), 71.7% (66 of 92); penicillin G, 66.3% (61 of 92); erythromycin, 66.3% (61 of 92); amoxicillin, 44.6% (41 of 92); and ciprofloxacin, 31.5% (29 of 92). The susceptibility pattern of 8 antibiotics was dependent on the host of the bacteria strains rather than the kinds of bacterial species. These results indicate that antibiotic susceptibility test should be performed when antibiotics are needed for the treatment of infected root canals.

• Korean Journal of Veterinary Service
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• v.28 no.2
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• pp.121-146
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• 2005

Newcastle disease (ND), infectious bronchitis (IB), low pathogenic avian Influenza (LPAI) and fowl typhoid (FT) have been known as egg drop laying diseases because of the serious layer damage from mass zone layer. In this study, such egg drop laying diseases were investigated. To access this study, we peformed to evaluate antibody titers in serum and isolated bacteria and virus from organs and feces on May, July and September in 2003. The distribution of ND from January to May, IB and LPAI from October to February of the next year, and FT from March to September were inspected by the question survey in 21 farms. ND revealed to be positive rates of 490 to 474 $(96.7\%)$ in May, 510 to 506 $(99.2\%)$ in July and 510 to 510 $(100\%)$ in September with hemagglutination inhibition (HI) test. The mean antibody titers were 10.2, 9.9 and 10.2, respectively. With regard to IB, 484 out of 490 samples $(98.7\%)$ in May, 508 of 510 $(99.6\%)$ in July and 509 of 510 $(99.8\%)$ in September showed positive results and the mean antibody titers were gradually increased with 8.2, 9.0 and 9.4, respectively. According to HI test of LPAI, the positive results were shown in 442 of 480 $(92.1\%)$, 394 of 494 $(79.8\%)$ and 402 of 483 $(83.2\%)$ in May, July and September, respectively The mean antibody titers were decreased with 4.6, 4.3 and 4.0. The distribution of LPAI also elicited the positive rates of 480 to 475 $(99.0\%)$ in May, 494 to 485$(98.2\%)$ in July, 483 to 472 $(97.7\%)$ in September as determined by ELISA and the mean S/P ratio were 2.319, 2.557 and 2.380, respectively. Compared ELISA results with HI test of LPAI the positive results were 480 to 422 $(92.1\%),\;475(99.0\%),\;494\;to\;394 (79.8\%),\;485 (98.2\%)\;and\;483\;to\;402(83.2\%),\;472(97.7\%)$. Therefore, the positive rate determined by ELISA was higher than that of HI test with 6.9, 18.4 and $14.5\%$, respectively. When performed RT-PCR for ND using organ and feces samples, the pathotypes were detected $5(15.6\%)\;in\;May,\; 2(5.3\%) in\;July,\;2(7.1\%)$ in September but there is no samples showing positive band for LPAI. In attempt to isolate Salmonella gallinarum, bacteria were obtained from 4 cases (12.5%) in May, 9 (23.6%) in July, 5 (17.8%) in September. Thus the highest rate for isolation revealed to be shown in July When evaluated the antimicrobial susceptibility to 18 isolated strains of 5. gallinarum, bacteria were sensitive to trimethoprim/sulfamethox$(61.1\%),\;kanamycin\;(55.5\%),\;ampicillin\;(55.5\%)$ and amoxacillin/clavulanic acid $(55.5\%)$, cephalothin $(50.0\%)$, but resistant to penicillin $(88.9\%)$, streptomycin $(88.9\%)$, erythromycin $(83_4\%)$ and tetracycline $(61.1\%)$. According to HI test of ND and LPAI using captured 164 wild Korean tree sparrows (Passer nontanus), the positive rates were $47.6\%\;and\;57.3\%$, and the mean HI titers were 5.32 and 4.02, respectively. 71 $(43.2\%)\;and\;58(35.3\%)$ in captured sparrows also showed more than 4 titers for HI test to ND and LPAI, respectively However, the attempt for isolation of viruses failed in all samples.

• Pediatric Infection and Vaccine
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• v.18 no.2
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• pp.109-116
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• 2011

Purpose : Pneumococcus is one of the most important causes of invasive infection through the childhood period. In January 2008, the Clinical and Laboratory Standards Institute (CLSI) published revised penicillin breakpoints for Streptococcus pneumoniae and penicillin susceptibility rates of S. pneumoniae increased in Korea. This study was performed to determine the probability of oral amoxicillin for the empirical treatment achieving bactericidal exposure against pneumococcus using pharmacodynamics model. Methods : Twenty-three isolates of pneumococci were subjected to determine minimum inhibitory concentration (MIC) for ${\beta}$-lactams and macrolide. For the ${\beta}$-lactams, exposure of fT >MIC (time that free drug concentrations remain above the MIC) for 50% of the administration interval have determined the probability of target attainment (PTA), and regimens that had a PTA >90% were considered optimal. An analysis was performed by applying MIC of 23 isolates to a 5000-patient Monte Carlo simulation model. Results : Among 23 isolates from healthy children, 7 (30.4%) isolates were MIC ${\leq}$1.0 ${\mu}g$/mL and 19 (82.6%) were MIC ${\leq}$2 ${\mu}g$/mL for amoxicillin. Amoxicillin 40 mg/kg/day achieved PTA >90% at MIC ${\leq}$1.0 ${\mu}g$/mL but PTA decreased to 52% at MIC 2 ${\mu}g$/mL, whereas amoxicillin 90 mg/kg/day can predict 97% of PTA at MIC 2 ${\mu}g$/mL. Overall, oral amoxicillin 90 mg/ kg/day for the empirical treatment against pneumococcus can expect more successful response in Korean children. Conclusion : Considering the resistantce pattern of pneumococci in Korean children, we estimate that oral amoxicillin 90 mg/kg/day will provide a pharmacodynamic advantage for the empirical treatment against pneumococcus. And low dose amoxicillin or macrolide are expected to have higher chance of treatment failure than high dose oral amoxicillin.

• 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.

• The Journal of the Korean Society for Microbiology
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• v.8 no.1
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• pp.7-11
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• 1973

The authors identified eighty-eight Shigella cultures among about four thousands specimens collected from all over the country in 1972. Of eighty-eight cultures, seventy-seven cultures belonged to Shigella flexneri and eleven cultures to Shigella sonnei. None of cultures belonging to either subgroup A or C was detected in 1972. Of seventy-seven cultures of Shigella flexneri one was $B_{1b}$, fifty-six were $B_{2a}$, nine were $B_{3a}$, six were $B_{4a}$, three were By and one was each of $B_{3b}$ and $B_{3c}$. Of eleven cultures of Shigella sonnei seven cultures appeared to be phase I and the others phase II. Although there was quite a difference found in the incidence of isolating Shigella organisms between different areas as shown in Table 1, it would not be possible to understand that there might not have been the cases or carriers of Shigella in the areas where the organisms were not isolated in 1972. Concerning the biochemical properties it was not possible to compare the results obtained from the decarboxylase and dihydrolase tests with them obtained in previous years except that of lysine decarboxylase tests since they were not reported individually by the different serotypes in the previous reports. These results obtained in 1972 would be the data for the future comparison. In regards to the antibiotics-sensitivity of Shigella cultures the most of them showed sensitive results to nitrofurantoin, ampicillin, cephalosporin, gentamycin and geopen, and the majority of them appeared to be resistant to cloxacillin, tetracycline and streptomycin by means of the In Vitro tests.

• The Korean Journal of Gastroenterology
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• v.72 no.6
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• pp.325-328
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• 2018

위마비증(gastroparesis)이나 만성 구역 구토 증후군(chronic unexplained nausea and vomiting)으로 인한 구역과 구토에 대한 치료는 일반적으로 사용하는 위장관 촉진제에 만족스럽지 못한 경우가 많고, 여러 부작용으로 인하여 장기적으로 사용하기 어려워 보다 효과적인 치료 방법이 필요하다. 최근 미국에서 발표된 본 연구는 위마비증이나 연관 증후군 환자에서 구역과 구토 증상을 줄이기 위한 aprepitant(neurokinin-1 receptor antagonist) 치료의 효과를 분석한 것으로, 향후 일반적인 치료에 불응성 위마비증 환자에서 새로운 약제 사용을 시도해볼 수 있어 소개하고자 한다. 본 Aprepitant for the Relief of Nausea (APRON) 연구는 기질적 질환을 배제하기 위하여 최근 2년 이내 위내시경이 정상이며, 적어도 6개월 이상 조기 포만감(early satiety), 식후 만복감(postprandial fullness), 팽만감(bloating) 그리고 명치부 통증(epigastric pain)을 유발하는 증상과 함께 만성적인 구역이 있는 18세 이상의 성인 중 4시간의 위배출 검사를 시행받은 환자를 대상으로 하였다. 객관적인 지표로 0점에서 45점까지 보이는 9-증상 Gastroparesis Cardinal Symptom Index(GCSI)가 2주 이상 총 21점 이상이며, 0-100 mm의 visual analog scale (VAS)의 7일간의 구역 증상 평균 25 mm 이상인 환자를 대상으로 하였다. 일주일에 3일 이상 narcotics를 사용하였거나 와파린이나 pimozide, terfenadien, astemizole, cisapride를 복용하였던 환자, 2배 이상으로 간 효소 수치상승을 보이거나 Child-Pugh score 10점 이상, aprepitant에 알레르기를 보이는 환자는 제외되었다. 그렇지만 metoclopramide나 erythromycin을 안정적으로 사용 중인 환자는 제외되지 않았다. 위배출 검사는 2시간에서 60% 이상 남아 있거나 4시간에서 10% 이상 남아 있는 경우에 지연된 것으로 정의되었으며, 지연된 위배출 검사 결과 자체는 환자의 등록 기준에 포함되진 않았다. 등록 기준에 포함된 환자는 1:1로 무작위 배정되어 하루 한 번 125 mg의 aprepitant 복용군과 위약군으로 나누어져 연구가 진행되었으며, 약제 복용 4주간 2주 간격으로, 그리고 복용 후 2주 뒤까지 구역 증상의 호전 정도와 약제 안전성을 확인하였다. 이러한 효과를 판정하기 위하여 환자가 방문하는 동안 GCSI를 포함한 Patient Assessment of Upper GI Symptoms (PAGI-SYM), Gastrointestinal Symptom Rating Scale, daily VAS, daily diary version of the GCSI 그리고 정신 측정 도구와 삶의 질 도구인 Patient health Questionnaire 15와 Short Form 36 version이 측정되었다. 구역에 대한 aprepitant와 위약의 치료 효과의 일차적 판정은 이전 항암 요법에 대한 aprepitant 연구와 같이 28일 평균 VAS 25 mm 미만이거나 치료 전 7일간의 VAS와 비교하여 28일 치료 기간 동안 25 mm 이상 감소한 경우로 정의하였고, 이차 결과는 구역의 매일 시간, 치료 중 구역이 없는 날짜의 퍼센트, PAGI-SYM score의 개선 등으로 확인하였다. 2013년 4월부터 2015년 7월까지 총 126명의 환자가 등록되어 aprepitant군 63명, 위약군 63명으로 무작위 배정되었다. 전체의 57%인 72명에서 위배출 지연이 보였으며, 나머지 43%에서는 정상 또는 빠른 위배출 소견을 보여 만성적으로 설명할 수 없는 구역과 구토에 포함된 환자군으로 확인되었다. 또한 29%에서 당뇨를 가지고 있었으며, 8%에서 수면제를 사용하고 있었다. 최종적으로 aprepitant군은 59명, 위약군은 63명이 연구를 끝까지 종료하였다. 일차 결과에서 aprepitant 군 46%, 위약군 40%의 구역 호전을 보여 두 치료군 간에 통계적으로 의미 있는 차이는 보이지 않았다(상대 위험도 1.2, 95% CI: 0.8-1.7; p=0.43). 그러나 일차 분석의 두 가지 척도(28일 평균 VAS 25 mm 미만과 기저 VAS보다 평균 28일 VAS의 25 mm 이상 감소)를 모두 함께 고려한 민감도 분석에서는 aprepitant군이 37% (22/59)로 위약군의 17%(11/63)에 비하여 통계적으로 의미 있는 구역의 호전을 보였다(상대 위험도 2.1, 95% CI: 1.1-4.1; p=0.01). 또한 이차 분석을 살펴보면 aprepitant군에서 PAGI-SYM 중증도 지수로 확인하였을 때, 구역(1.8 vs. 1.0; p=0.005)과 구토(1.6 vs. 0.5; p=0.001)의 중증도 및 매일 구역 시간의 감소를 보였고, 28일 동안 구역이 없는 날짜의 퍼센트 증가 소견을 보였다. 다른 이차 결과 분석에서 aprepitant군이 PAGI-SYM 중증도 지수의 GCSI 종합 점수(1.3 vs. 0.7; p=0.001), 상당한 증상호전, 구역 구토의 세부 점수, 팽만감 세부 점수 그리고 위식도 역류 증상 점수에서 호전을 보였고, 매일 일기로 표현한 daily diary version of the GCSI에 상복부 통증 중증도, 전체 증상 그리고 Gastrointestinal Symptom Rating Scale의 종합 점수에서 호전을 보였다. 연구 중 발생한 부작용은 주로 경증과 중등도 정도의 부작용이 주로 발생하였지만, aprepitant군(35% vs. 17% 위약군, p=0.04)에서 더 많이 발생하였다. 결론적으로 위마비증 또는 위마비증 유사 증후군으로 인한 만성 구역 및 구토 환자의 무작위 시험에서 aprepitant는 VAS 점수를 통한 주요 결과를 분석하였을 때는 구역의 중증도를 호전시키지 못하였지만 다른 이차적 결과에 대해서는 위약군에 대하여 호전 소견을 보였다. 따라서 aprepitant에 효과적인 반응을 보이는 위마비증 환자를 감별하는 추가 임상시험이 필요할 것으로 판단된다.

• The Journal of the Korean Society for Microbiology
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• v.7 no.1
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• pp.9-15
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• 1972

The authors identified 45 Shigella cultures among 63 suspectable cultures obtained from the cases showing dysentery or the like symptoms in various parts of the country during the period from February to September, 1971. Of 45 cultures, 36 cultures belonged to Subgroup B, 7 cultures to Subgroup C and 2 cultures to Subgroup D. There was none of cultures belonging to Subgroup A in 1971, although the authors detected one culture of that among 41 identified Shigella in 1967. Of 36 cultures belonging to Subgroup B, 27 cultures were $B_{2a}$ and 3 cultures of each $B_{3c},\;B_{4a}$ and $B_y$ were serotyped, respectively. Of 7 cultures beloning to Subgroup C, one was $C_{11}$ and other six cultures were $C_{15}$ and all S. boydii were isolated in Seoul area. It might be possible to suggest that there was a tendency of decreasing prevalence of S. dysenteriae and of increasing prevalence of S. boydii in Korea, although the number of cultures. tested were very much limited to conclude, if it was compared with the results obtained by the authors in 1967 that the fourty-one identified Shigella were composed of one culture of S. dysenteriae, 36 cultures of S. flexneri, 4 cultures of S. sonnei and none of S. boydii. According to the results obtained from the biochemical tests, the positive ratio of Indol tests in Subgroup B was 31/36, which could be higher than 9/36 observed in 1961, but which was nearly correlated with the result published by Ewing and his colleagues in U.S.A. The positive rates of both sorbitol and raffinose were lower than that observed by Ewing and his colleagues in S. flexneri. Regarding with the sensitivity of Shigella cultures to the antibiotics being widely used in the country, 46.2% were sensitive to chloramphenicol, which was very much higher than that observed by Park, and 85.8% were sensitive to ampicillin, which would be the drug of choice according to the results from the In Vitro tests.