• Korean Journal of Clinical Laboratory Science
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• v.52 no.4
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• pp.335-341
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• 2020

This study investigates the association of the AFB stain with the cycle threshold (Ct) value of the Cobas TaqMan MTB test (CTM test, Roche Diagnostics, Basel, Switzerland), and it establishes the base data for semi-quantitative identification of M. tuberculosis by the Ct value. CTM test were simultaneously conducted on 8,389 specimens submitted to the Samsung Medical Center from January 2015 to December 2015, and the results were analyzed and compared retrospectively investigates the association of the AFB stain with the Ct value of the CTM test, and it establishes the base data for semi-quantitative identification of M. tuberculosis by the Ct value. The Ct values for 135 positive specimens of the CTM were inversely correlated with the AFB stain (rs=-0.545, P<0.01). When the Ct value of the CTM test and the time to positivity (TTP) of the mycobacteria cultures were verified based on the AFB stain, they were found to have a positive correlation (rs=0.136, P<0.01). The negative correlation between the CTM test and the AFB stain grade was demonstrated. The clinical significance was verified by applying these criteria to the clinical results. The semi-quantitative criteria of this study can be used to facilitate the rapid isolation of patients with active tuberculosis and infection control in the hospital.

• Korean Journal of Clinical Laboratory Science
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• v.45 no.2
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• pp.48-53
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• 2013

Recently, the isolation rate of nontuberculous mycobacteria (NTM) in clinical laboratories and the incidence of NTM infections are on the increase in Korea, but there have been only a few studies that reveal the general aspect of NTM isolation or species distribution. Therefore, this study was performed to examine the species identification by PCR-restriction fragment length polymorphism analysis (PRA, PCR-RFLP), and the clinical significance of mycobacterial cultures. PRA was used during the novel region of the rpoB gene and was developed for rapid and precise identification of mycobacteria to the species level. From January 2012 to April 2012, we examined pre-identified nontuberculous mycobacteria (60 species in 3 hospital of Busan-Kyeongnam area). We confirmed 4 (6.6%) Mycobacterium tuberculosis (MTB) and 56 (93.4%) NTM from 60 pre-identified NTM species by multiplex PCR (MolecuTech $MTB-ID^R$ V3, YD Diagnostics, Korea) and PRA (Myco-ID, YD Diagnostics, Korea). The distribution of 56 NTM species were M. intracellulare type I 15 (26.7%), M. avium 14 (25%), M. abscessus 11 (19.5%), M. kansasii type I 3 (5.4%), M. pulveris 2 (3.6%), M. intracellulare type, M. chelonae, M. kansasii type V, M. gallinarum, M. wolinskyi. Respectively, 1 (1.8%) and 6 (10.7%) species were not identified.

• Biomedical Science Letters
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• v.24 no.2
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• pp.138-142
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• 2018

The incidence of tuberculosis (TB) in the Republic of Korea remains high when compared to the incidence in other Organization for Economic Cooperation and Development (OECD) countries. The prompt diagnosis and effective treatment of latent TB infection (LTBI) are very important in terms of controlling the burden of TB. The tuberculin skin test (TST) has long been the "gold standard" assay for the diagnosis of LTBI. However, it can show false positive results due to Bacille Calmette-$Gu{\acute{e}}rin$ (BCG) vaccination and infection with many environmental nontuberculous mycobacteria (NTM). The interferon gamma release assay (IGRA) using Mycobacterium tuberculosis (MTB)-specific antigens, was developed for the detection of LTBI. The QuantiFERON-TB Gold In-Tube assay is one of the most commonly used forms of the IGRA. In order to compare the diagnostic efficacy of the TST and IGRA in relation to LTBI among BCG-vaccinated healthy donors, whole blood samples were collected from 51 participants, and the results of the TST and IGRA were compared. Of the 51 cases, 18 cases (35.3%) were positive and 33 cases (64.7%) were negative when using the TST, while four cases (7.8%) were positive and 47 cases (92.2%) negative when using the IGRA. There was no correlation between the size of the induration in the TST and the $IFN-{\gamma}$ protein level. In conclusion, the TST showed higher cross-reactivity among the BCG-vaccinated healthy participants, therefore, the IGRA might be the most suitable assay for the rapid screening of LTBI in BCG-vaccinated healthy population, or for TB contact investigation.

• Tuberculosis and Respiratory Diseases
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• v.61 no.1
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• pp.54-59
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• 2006

Background: Although there have been several studies regarding the clinical value of an automated TB-PCR study using sputum, bronchial washing, and other body fluid samples for the detection of pulmonary tuberculosis, there are only a few reports on the use of fresh tissue samples. Materials and methods: The acid-fast bacilli stain(AFB), tuberculosis culture, automated TB-PCR study, and histopathology examination were performed in 42 fresh tissue samples. Results: Among the 42 cases, 18 cases were diagnosed with tuberculosis based on the clinical findings. Sixteen of the 18 cases were TB-PCR positive and of these 16 cases, only 2 cases were positive in the AFB stain or culture study. However, all 18 cases showed the histopathology findings of chronic granulomatous inflammation that was compatible with tuberculosis. Based on the clinical findings, the sensitivity, specificity, positive predictability, and negative predictability of the automated TB-PCR study were 88.9%, 100%, 100%, and 92.3% respectively. Conclusion: An automated TB-PCR assay is an important diagnostic tool for diagnosing tuberculosis in fresh tissue samples.

• Tuberculosis and Respiratory Diseases
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• v.40 no.5
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• pp.483-494
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• 1993

Cell surface antigenic relationships between pathogenic mycobacteria have been investigated by the enzyme-linked immunosorbent assay using phenolkilled cells and their rabbits antisera. Homologous and heterologous reactions of Mycobacterium avium-intracellulare antisera before and after homologous and heterologous absorption revealed a close antigenic relationship between strains of the same species and between species if they were members of M. avium(MA)-intracellulare(MI)-scrofulaceum(MG) complex. MAI sera showed a considerable reaction with M. kansasii(MK) and tuberculosis(MTB), but not with the other species. MA(K40004) antiserum reacted with other mycobacteria except few strains of MI and 50~89% of homologous reaction was reduced by heterologous absorption with cells of MI or MS. Intraspecific reaction of MI antisera was natural1y stronger than interspecific reaction and different in extent due to a magnitude of antigenic sharing. Antigenic relationships between N-260D, N-260R, N-260T, and K41014 was somewhat closer than that with N-242D, N-257T, N-28ID, and N-275T. M. nonchromogenicum(MNC) antisera showed a strong interspecific reaction with exception of M. chelonei(MC) and triviale(MTV) to which they reacted weakly or none. Antigenic sharing with M. terrae(MTR) and MG(K30003) was next to intraspecific sharing. NC-3 shared antigens considerably with MA, MC, and M. fortuitum(MF) while NC-11 did not. MTR antisera showed a strong cross-reaction with MI but their homologous reaction was not reduced by MI absorption indicating a paucity of shared antigen of MTR surface. Intraspecific antigenic sharing of course was large with on exception between T-8 and T-13. A considerable amount of antigenic sharing was also found with MNC, MC and MF. Unlike T-8 serum, T-13 antiserum strongly cross-reacted with MA, MG, MK, and MTB. In general, antigenic relationships of mycobacteria, that have been elucidated in this study, well conformed to taxons delineated by the various biological and biochemical means.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.3
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• pp.289-297
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• 2019

Objectives: To identify the positive rate of and the risk factors associated with latent tuberculosis infection(LTBI) in mine workers, the objectives of the present study evaluated those among former mine workers. Methods: Between January 2015 and May 2017, former male mine workers who had been subjects for epidemiology research for work-related chronic obstructive pulmonary disease(COPD) and had received QuantiFERON-$TB^{(R)}$ Gold In-Tube(QFT-GIT) from the Institute of Occupation and Environment(IOE) under Korea Workers' Compensation and Welfare Service(KCOMWEL) were selected as the study subjects. To identify significant variables for increased risk of LTBI, logistic regression analysis was performed. Results: A total of 736 male former mine workers were selected as study subjects. The positive rate of LTBI among subjects was 69.2%(509/736). The current smoking[odds ratio(OR), 2.3; 95% confidence interval(CI), 1.1-4.9], COPD(OR, 1.4; 95% CI, 0.9-2.3), department loading(OR, 1.8; 95% CI, 0.9-3.4) and mining(OR, 1.5; 95% CI, 0.9-2.5), and working duration of over 20(OR, 1.6; 95% CI, 0.9-3.1) and over 30 years(OR, 2.2; 95% CI, 0.9-4.9) were associated with increased risk of LTBI. The interferon-gamma(IFN-${\gamma}$) level after stimulation with Mycobacterium tuberculosis(MTB)-specific antigens showed a significantly negative correlation with age(r=-0.126). Conclusions: The present study determined that the high positive rate of LTBI among mine workers was associated with not only the host factors but also the occupational exposure to mine dust.

• Tuberculosis and Respiratory Diseases
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• v.42 no.5
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• pp.646-653
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• 1995

Background: The confirmative diagnosis of pulmonary tuberculosis(Tb) can be made by the isolation of Mycobacterium Tuberculosis(MTb) in the culture of the sputum, respiratory secretions or tissues of the patients, but positive result could not always be obtained in pulmonary Tb cases. Although there are many indirect ways of the diagnosis of Tb, clinicians still experience the difficulty in the diagnosis of Tb because each method has its own limitation. Therefore development of a new diagnostic tool is clinically urgent. It was reported that silica cause some lysosomal enzymes to be released from macrophages in vitro and one of these enzymes is elevated in workers exposed to silica dust and in silicotic subjects. In pulmonary Tb, alveolar macrophages are known to be activated after ingestion of MTb. Activated macrophages can kill MTb through oxygen free radical species and digestive enzymes of lysosome. But if macrophages allow the bacilli to grow intracellularly, the macrophages will die finally and local lesion will enlarge. Then it is assumed that the lysosomal enzymes would be released from the dead macrophages. The goal of this investigation was to determine if there are differences in the plasma activities of lysosomal enzymes, ($\beta$-glucuronidase(GLU) and $\beta$-N-acetyl glucosaminidase(NAG), among the groups of active and inactive pulmonary Tb and healthy control, and to see if there is any possibility that the plasma activity of GLU and NAG can be used as diagnostic indicies of active pulmonary Tb. Methods: The plasma were obtained from 20 patients with bacteriologically proven active pulmonary Tb, 15 persons with inactive Tb and 20 normal controls. In 10 patients with active pulmonary Tb, serial samples after 2 months of anti-Tb medications were obtained. Plasma GLU and NAG activities were measured by the fluorometric methods using 4-methylumbelliferyl substrates. All data are expressed as the mean $\pm$ the standard error of the mean. Results: The activites of GLU and NAG in plasma of the patients with active Tb were $21.52{\pm}3.01$ and $325.4{\pm}23.37$(nmol product/h/ml of plasma), respectively. Those of inactive pulmonary Tb were $24.87{\pm}3.78$, $362.36{\pm}33.92$ and those of healthy control were $25.45{\pm}4.05$, $324.44{\pm}28.66$(nmol product/h/ml of plasma), respectively. There were no significant differences in the plasma activities of both enzymes among 3 groups. The plasma activities of GLU at 2 months after anti-Tb medications were increased($42.18{\pm}5.94$ nmol product/h/ml of plasma) in the patients with active pulmonary Tb compared with that at the diagnosis of Tb(P-value <0.05). Conclusion: The results of the present investigation suggest that the measurement of the plasma activities of GLU and NAG in the patients with active pulmonary Tb could not be a useful method for the diagnosis of active Tb. Further investigation is necessary to define the reasons why the plasma activities of the GLU was increased in the patients with active pulmonary Tb after Tb therapy.

• Journal of Yeungnam Medical Science
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• v.32 no.2
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• pp.71-79
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• 2015

Background: Recent studies have shown that the nontuberculosis mycobacterium (NTM) recovery rate in clinical cultures has increased within Korea. However, another study conducted by a secondary hospital within Daegu reported different results. Therefore, the purpose of this study is to understand and evaluate the microbiological distribution and clinical features of NTM in Daegu. Methods: A retrospective study was conducted on 11,672 respiratory specimens undergoing acid fast bacilli (AFB) culture from 6,685 subjects who visited Yeungnam University Respiratory Center from January 2012 to December 2013. Results: Of the 11,672 specimens undergoing AFB culture, 1,310 specimens (11.2%) showed positive results. Of these specimens, NTM was recovered from 587 specimens, showing a recovery rate of 44.8%. Identification test for NTM was performed on 191 subjects; the results were as follows: M. avium-intracellulare complex (MAC) 123 (64.4%), M. abscessus 20 (10.5%), M. kansasii 12 (6.3%), and 33 other NTM germ strains. Of the 382 subjects with NTM, 167 were diagnosed with pulmonary NTM disease (43.7%), however virulence differed depending on NTM strain. Multivariate analysis showed that nodular bronchiectasis, the nodules, and finding consistent with cavity under imaging study were statistically significant for triggering pulmonary NTM disease. AFB culture showing MAC and M. abscessus was statistically significant as well. Positive predictive value for NTM polymerase chain reaction (NTM-PCR) was 88.6%. Conclusion: Results for NTM recovery rate within the Daegu area were similar to those for the Seoul metropolitan area. We can assume that NTM infection is increasing in our community, therefore AFB-positive subjects (1) should undergo NTM-PCR, (2) should have their culture results checked for differentiation of mycobacterium tuberculosis complex (MTB) from NTM, and (3) undergo NTM identification test to confirm its type. Administration of treatment with the above results should be helpful in improving the patients' prognosis.