• Tuberculosis and Respiratory Diseases
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• 제85권3호
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• pp.264-272
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• 2022

Background: The current conventional drug susceptibility test (DST) for Mycobacterium tuberculosis (Mtb) takes several weeks of incubation to obtain results. As a rapid method, molecular DST requires only a few days to get the results but does not fully cover the phenotypic resistance. A new rapid method based on the ability of viable Mtb bacilli to hydrolyze fluorescein diacetate to free fluorescein with detection of fluorescent mycobacteria by flow cytometric analysis, was recently developed. Methods: To evaluate this cytometric method, we tested 39 clinical isolates which were susceptible or resistant to isoniazid (INH) or rifampin (RIF), or ethambutol (EMB) by phenotypic or molecular DST methods and compared the results. Results: The susceptibility was determined by measuring the viability rate of Mtb and all the isolates which were tested with INH, RIF, and EMB showed susceptibility results concordant with those by the phenotypic solid and liquid media methods. The isolates having no mutations in the molecular DST but resistance in the conventional phenotypic DST were also resistant in this cytometric method. These results suggest that the flow cytometric DST method is faster than conventional agar phenotypic DST and may complement the results of molecular DST. Conclusion: In conclusion, the cytometric method could provide quick and more accurate information that would help clinicians to choose more effective drugs.

• Tuberculosis and Respiratory Diseases
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• 제82권2호
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• pp.143-150
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• 2019

Background: The purpose of this study was to analyze the relationship between the gene mutation patterns by the GenoType MTBDRplus (MTBDRplus) assay and the phenotypic drug susceptibility test (pDST) results of isoniazid (INH) and prothionamide (Pto). Methods: A total of 206 patients whose MTBDRplus assay results revealed katG or inhA mutations were enrolled in the study. The pDST results were compared to mutation patterns on the MTBDRplus assay. Results: The katG and inhA mutations were identified in 68.0% and 35.0% of patients, respectively. Among the 134 isolated katG mutations, three (2.2%), 127 (94.8%) and 11 (8.2%) were phenotypically resistant to low-level INH, high-level INH, and Pto, respectively. Among the 66 isolated inhA mutations, 34 (51.5%), 18 (27.3%) and 21 (31.8%) were phenotypically resistant to low-level INH, high-level INH, and Pto, respectively. Of the 34 phenotypic Pto resistant isolates, 21 (61.8%), 11 (32.4%), and two (5.9%) had inhA, katG, and both gene mutations. Conclusion: It is noted that Pto may still be selected as one of the appropriate multidrug-resistant tuberculosis regimen, although inhA mutation is detected by the MTBDRplus assay until pDST confirms a Pto resistance. The reporting of detailed mutation patterns of the MTBDRplus assay may be important for clinical practice, rather than simply presenting resistance or susceptibility test results.

• BMB Reports
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• 제42권2호
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• pp.81-85
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• 2009

Early and accurate detection of drug resistant Mycobacterium tuberculosis can improve both the treatment outcome and public health control of tuberculosis. A number of molecular-based techniques have been developed including ones using probe molecules that target drug resistance-related mutations. Although these techniques are highly specific and sensitive, mixed signals can be obtained when the drug resistant isolates are mixed with drug susceptible isolates. In order to overcome this problem, we developed a new drug susceptibility test (DST) for one of the most effective anti-tuberculosis drug, isoniazid. This technique employed a microplate hybridization assay that quantified signals from each probe molecule, and was evaluated using clinical isolates. The evaluation analysis clearly showed that the microplate hybridization assay was an accurate and rapid method that overcame the limitations of DST based on conventional molecular techniques.

• 미생물학회지
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• 제45권3호
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• pp.281-285
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• 2009

본 연구에서는 객담 내 결핵균의 배양시험과 약제 감수성 시험 방법으로서 BacT/Alert 액체 배지, Ogawa 배지 및 $L\ddot{o}wenstein$-Jensen 배지 배양법을 비교하였다. 신속 액체배양시스템은 기존의 Egg-based media (Ogawa, $L\ddot{o}wenstein$-Jensen 배지)에 비해 높은 민감도와 빠른 배양으로 결핵환자의 초기 객담 검사와 약제 감수성 시험에 널리 사용되어 왔다. 객담은 N-Acetyl-L-cystine과 4% NaOH로 처리한 후 BacT/Alert 액체 배지 시스템과 Ogawa 배지에 접종하고 배양하여 비교하였다. 결핵환자 객담 검체 135개 중 도말검사결과 양성은 95개였고, Ogawa 배지 배양결과 양성으로 확인된 수는 89개(65.9%)였으며, BacT/Alert 액체 배지에서는 97개(71.9%)가 양성으로 확인되었다. 결핵균 배양 양성 검체의 평균배양일은 Ogawa 배지에서 22.4일, BacT/Alert 액체 배지는 11.3일로 단축되는 것을 확인하였다. 약제 감수성 시험에는 32개 결핵균주를 이용하였으며, isoniazid를 첨가한 BacT/Alert 액체 배지와 $L\ddot{o}wenstein$-Jensen 배지에서의 약제 감수성 시험 검사결과 일치률은 87.5%를 보였고, rifampicin에서의 일치률은 90.6%로 나타났다.

• Tuberculosis and Respiratory Diseases
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• 제84권3호
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• pp.237-244
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• 2021

Background: The emergence of drug-resistant tuberculosis (TB), is a major menace to cast off TB worldwide. Line probe assay (LPA; GenoType MTBDRplus ver. 2) and Xpert MTB/RIF assays are two rapid molecular TB detection/diagnostic tests. To compare the performance of LPA and Xpert MTB/RIF assay for early diagnosis of rifampicin-resistant (RR) TB in acid-fast bacillus (AFB) smear-positive and negative sputum samples. Methods: A total 576 presumptive AFB patients were selected and subjected to AFB microscopy, Xpert MTB/RIF assay and recent version of LPA (GenoType MTBDRplus assay version 2) tests directly on sputum samples. Results were compared with phenotypic culture and drug susceptibility testing (DST). DNA sequencing was performed with rpoB gene for samples with discordant rifampicin susceptibility results. Results: Among culture-positive samples, Xpert MTB/RIF assay detected Mycobacterium tuberculosis (Mtb) in 97.3% (364/374) of AFB smear-positive samples and 76.5% (13/17) among smear-negative samples, and the corresponding values for LPA test (valid results with Mtb control band) were 97.9% (366/374) and 58.8% (10/17), respectively. For detection of RR among Mtb positive molecular results, the sensitivity of Xpert MTB/RIF assay and LPA (after resolving discordant phenotypic DST results with DNA sequencing) were found to be 96% and 99%, respectively. Whereas, specificity of both test for detecting RR were found to be 99%. Conclusion: We conclude that although Xpert MTB/RIF assay is comparatively superior to LPA in detecting Mtb among AFB smear-negative pulmonary TB. However, both tests are equally efficient in early diagnosis of AFB smear-positive presumptive RR-TB patients.

• Tuberculosis and Respiratory Diseases
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• 제60권4호
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• pp.404-411
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• 2006

목적 : 지난 3년간 전국적으로 항결핵제에 대한 감수성검사를 시행 받은 환자의 실제 수를 파악함으로 국내 다제내성 결핵의 현황을 파악하고자 하였다. 방법 : 2000년 1월부터 2002년 12월까지 3년간 국내의 결핵 약제감수성검사를 시행하고 있는 7개 국립 및 민간검사기관에서 시행된 검사결과들을 후향적으로 조사하여 이를 근거로 국내 결핵환자 중 다제내성 결핵환자의 연도별 현황 및 추이 등 다제내성 결핵환자의 실제현황을 조사 분석하였다. 결과 : 6개의 검사기관은 절대농도법을 사용하였고 한 개의 기관에서 비율법을 사용하였다. 2000년부터 2002년까지 매년 18,071, 19,950, 그리고 21,919건의 검사가 시행되었다. 한 가지 이상의 약제에 내성으로 진단된 내성결핵 환자의 수는 2000년 6,338명에서 2002년 7,409명으로 16.9% 증가하였다. 약제감수성검사가 시행된 전체 환자들 중 내성결핵으로 진단된 환자의 비율은 2000년 35.1%, 2001년 34.5%, 그리고 2002년 33.8%이었다. 다제내성 결핵으로 확인된 환자는 2000년에 3,708명에서 2002년 4,245명으로 14.5% 증가하였다. 결론 : 2002년에 약 4,000여건의 새로운 다제내성 결핵이 약제감수성검사에 의해 확인되었으며 매년 증가하는 경향을 보였다. 검사실간의 약제감수성검사의 표준화 작업과 보다 효과적인 다제내성 결핵의 관리가 요구 된다.

• 대한임상검사과학회지
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• 제54권2호
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• pp.125-132
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• 2022

다제내성결핵과 광범위내성결핵은 결핵 치료의 문제가 되고 있으며 발생빈도 역시 증가하고 있다. 본 연구는 2010년 1월부터 2019년 12월까지 녹십자의료재단 의뢰된 환자를 대상으로 Löwenstein-Jensen 고체배지와 pyrazinamide for pyrazinamidase를 이용하여 약물감수성시험(DST)을 시행하여 내성으로 전환되는 항결핵제 패턴과 평균 추적 기간을 분석하였다. 항결핵제 중 1개 이상의 항결핵제 내성을 보인 증례들에서 초기 의뢰 시 INH 항결핵제에 내성인 경우가 55명(33.1%)으로 가장 높은 비율로 나타났으며, 내성으로 전환된 항결핵제는 EMB 17명(26.6%), RFP 14명(21.9%), QUI 14명(21.9%), PZA 12명(10.9%) 순으로 조사되었다. 10개의 항결핵제에 모두 감수성인 증례들에서는 INH 항결핵제에 대한 내성 전환은 43명(7.2%)으로 가장 빈도가 높았으며, 평균 추적 기간은435.6일로 조사되었으며, 내성으로 전환되는 항결핵제의 내성전환율은 INH 43명(7.2%), RFP 23명(3.9%), SM 11명(1.9%), QUI 4명(0.7%), AMK 3명(0.5%), EMB 3명(0.5%)이었다. 이에 본 연구는 항결핵제에 대한 감수성에서 내성으로의 전환은 특히 다제내성결핵과 광범위 내성결핵의 전환되는 환자에게 매우 중요한 자료가 될 것으로 보이며, 결핵 치료에서 환자 치료에 도움이 될 것으로 사료된다.

• Tuberculosis and Respiratory Diseases
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• 제64권6호
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• pp.414-421
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• 2008

연구배경: 최근 광역내성 결핵은 공공보건에 중대한 문제가 되고 있다. 본 연구의 목적은 국립의료원에 내원한 폐결핵 환자들 중 광역내성 폐결핵 환자와 다제내성 폐결핵 환자의 임상적 특성을 비교 연구 하여 광역내성 및 다제내성 폐결핵에 대한 관심을 높이고 폐결핵 퇴치에 이바지하고자 하였다. 방 법: 2000년 1월부터 2007년 8월까지 객담 결핵균배 양양성 및 항결핵 약제에 대한 감수성검사가 행해진 환자를 대상으로 하였다. 감수성결과에 따라 광역내성군과 다제내성군으로 나눈 뒤, 의무기록을 토대로하여 임상적 특성을 후향적으로 비교분석 하였다. 결 과: 총 314명의 환자들 중 18명(5.7%)이 광역내성, 69명(22%)이 다제내성이었고 광역내성을 다제내성에 포함시켰을 때 광역내성이 다제내성에서 차지하는 비율은 20.69%였다. 연구된 임상적 특성들 중, 광역내성 또는 다제내성이 진단될 당시 결핵치료를 위한 폐절제술의 과거력이 광역내성군에서 더 많았으며(OR, 3.974; 95% CI, 1.052~15.011; p value, 0.032), 광역내성이나 다제내성으로 진단되기 전 복용중단기간을 포함한 이전 항결핵약제 복용기간의 평균도 광역내성군에서 더 길었다(광역내성군: 72.67개월, 다제내성군: 13.09개월, 평균복용기간의차이, 59.582개월; 95% CI, 31.743~87.420; p value, 0.000). 또한 복용기간이 길수록 광역내성 발생과 유의한 관계가 있었다(OR, 1.076; 95% CI, 1.038~1.117; p value, 0.000). 그 외 남성의 비율, 당뇨병의 빈도, 45세 미만의 연령, 2개월 이상 항결핵약제 복용을 중단한 경력, 다제내 성이나 광역내성으로 진단될 당시 흉부방사선사진에서 공동의 존재 빈도와 내성 진단 당시 객담 항산성균 도말 양성 검사 비율은 전체적으로 광역내성군에서 더 높았으나 통계적으로 유의하지는 않았다. 결 론: 광역내성 폐결핵 환자들에서 광역내성으로 진단될 당시 결핵치료를 위한 폐절제술의 과거력의 비율이 더 높았으며, 내성 진단 전 더 긴 항결핵약제 복용기간을 보여주었다. 또한 긴 복용기간은 유의하게 광역내성의 발생과 관련되어 있었다.

• Tuberculosis and Respiratory Diseases
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• 제72권1호
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• pp.44-49
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• 2012

Background: Multidrug-resistant tuberculosis (MDR-TB) is an increasing public health problem and poses a serious threat to global TB control. Fluoroquinolone (FQ) and aminoglycoside (AG) are essential anti-TB drugs for MDR-TB treatment. REBA MTB-FQ$^{(R)}$ and REBA MTB-KM$^{(R)}$ (M&D, Wonju, Korea) were evaluated for rapid detection of FQ and kanamycin (KM) resistance in MDR-TB clinical isolates. Methods: M. tuberculosis (n=67) were isolated and cultured from the sputum samples of MDR-TB patients for extracting DNA of the bacilli. Mutations in genes, gyrA and rrs, that have been known to be associated with resistance to FQ and KM were analyzed using both REBA MTB-FQ$^{(R)}$ and REBA MTB-KM$^{(R)}$, respectively. The isolates were also utilized for a conventional phenotypic drug susceptibility test (DST) as the gold standard of FQ and KM resistance. The molecular and phenotypic DST results were compared. Results: Sensitivity and specificity of REBA MTB-FQ$^{(R)}$ were 77 and 100%, respectively. Positive predictive value and negative predictive value of the assay were 100 and 95%, respectively, for FQ resistance. Sensitivity, specificity, positive predictive value and negative predictive value of REBA MTB-KM$^{(R)}$ for detecting KM resistance were 66%, 94%, 70%, and 95%, respectively. Conclusion: REBA MTB-FQ$^{(R)}$ and REBA MTB-KM$^{(R)}$ evaluated in this study showed excellent specificities as 100 and 94%, respectively. However, sensitivities of the assays were low. It is essential to increase sensitivity of the rapid drug resistance assays for appropriate MDR-TB treatment, suggesting further investigation to detect new or other mutation sites of the associated genes in M. tuberculosis is required.

• 대한의생명과학회지
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• 제22권1호
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• pp.24-28
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• 2016

Tuberculosis (TB) remains an unsolved community health problem since identification of its causing microorganism called Mycobacterium tuberculosis (MTB) by Robert Koch in 1882. Annually, eight million TB cases are newly reported and 2~3 million patients die from TB. Pulmonary TB is highly infectious and untreated pulmonary TB patients are believed to infect >10 people in a year. The conventional methods for diagnosis of TB are chest X-ray and isolation of the causing microorganisms from patient specimens. Screening of TB is conducted with smeared sputum in slides, and TB is confirmed by identification of MTB in cultured specimens. One of the fatal pitfalls of screening detection for smeared sputum is that it is impossible to distinguish MTB and other acid-fast bacilli (AFB) because they are stained equally with Ziehl-Neelsen (ZN) stain. Culture of MTB is the most reliable method for diagnosis of TB but it takes 4~8 weeks. In this report, we suggest a fast and highly-reliable MTB detection method that distinguishes AFB in sputum samples. Purified DNA from the AFB stained slide samples offered by The Korean Institute of Tuberculosis were used to detect infected MTB in patients. PCR, real-time PCR and reverse blot hybridization assay (REBA) methods were applied to purified DNA. Conclusively, the real-time PCR method was confirmed to produce high sensitivity and we were able to further detect drug-resistant MTB with REBA.