• 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.

• Biomedical Science Letters
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• v.26 no.3
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• pp.170-178
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• 2020

Mycobacterium tuberculosis (MTB) continues to be one of the main causative agents of tuberculosis (TB); moreover, the incidence of nontuberculous mycobacteria (NTM) infections has been rising gradually in both immunocompromised and immunocompetent patients. Precise and rapid detection and identification of MTB and NTM in respiratory specimens are thus important for MTB infection control. Molecular diagnostic methods based on the nucleic acid amplification test (NAAT) are known to be rapid, sensitive, and specific compared to the conventional acid-fast bacilli (AFB) smear and mycobacterial culture methods. In the present study, the clinical performances of three commercial molecular diagnostic assays, namely TB/NTM PCR (Biocore), MolecuTech Real MTB-ID^® (YD Diagnostics), and REBA Myco-ID^® (YD Diagnostics), were evaluated with a total of 92 respiratory specimens (22 AFB smear positives and 67 AFB smear negatives). The sensitivity and specificity of TB/NTM PCR were 100% and 75.81%, respectively. The corresponding values of MolecuTech Real MTB-ID^® and REBA Myco-ID^® were 56.52% and 90.32%, and 56.52% and 82.26%, respectively. TB/NTM PCR showed the highest sensitivity; however, the concordant rate was 10% compared with sequence analysis. Although MolecuTech Real MTB-ID^® showed lower sensitivity, its specificity was the highest among the three methods. REBA Myco-ID^® allowed accurate classification of NTM species; therefore, it was the most specific diagnostic method. Of the three PCR-based methods, MolecuTech Real MTB-ID^® showed the best performance. This method is expected to enable rapid and accurate identification of MTB and NTM.

• Tuberculosis and Respiratory Diseases
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• v.72 no.5
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• pp.409-415
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• 2012

Background: The isolation of non-tuberculous mycobacteria (NTM) has been increasing in South Korea. To date, however, the cause of this increase has not been determined, and it remains unclear whether the use of liquid media has contributed to this increase. The aim of this study was to evaluate the factors associated with NTM isolation and the impact of liquid media on NTM culture. Methods: Mycobacterial smear/culture results of respiratory specimens (sputum and bronchial aspirates), obtained during the years 2002, 2005, and 2010, were retrieved and analyzed retrospectively. Results: During the years 2002, 2005, and 2010, 83,096 sputum specimens were collected from 31,104 patients, and were cultured for mycobacteria, using solid media only in the 2002 and 2005 specimens and both solid and liquid media in the 2010. Of these, 3,516 (4.2%) specimens were smear-positive for acid-fast bacilli (AFB). The annual rate of NTM among positive culture specimens increased from 21% in 2002 to 57.8% in 2010 (p<0.001), as did the proportion of NTM, among AFB smear- and culture-positive specimens, from 12.2% in 2002 to 45.2% in 2010 (p<0.001). In 2010, the NTM culture rate was higher in the liquid than in the solid media (13.9% vs. 8.4%, p<0.001). The NTM rate among AFB-positive specimens was higher in patients aged >50 than ${\leq}$50 years. Conclusion: The rate of NTM isolation has steadily been increasing at the hospital in South Korea, likely due in part to the use of liquid media for the culture.

• Tuberculosis and Respiratory Diseases
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• v.72 no.1
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• pp.55-58
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• 2012

Mycobacterium szulgai is a rare nontuberculous mycobacterium found in Korea. It is an opportunistic pathogen and is usually isolated from patients with a history of alcoholism, chronic pulmonary disease, or an immunocompromising condition. We present here a case of M. szulgai isolated from a patient with a history of pulmonary tuberculosis. A 54-year-old man was admitted with dyspnea and febrile sensation. He had a history of pulmonary tuberculosis which occurred 30 years earlier and treatment with anti-tuberculosis medication. His chest computed tomography scan showed cavitary consolidation in both upper lungs. A sputum acid-fast bacilli (AFB) smear was positive and anti-tuberculous medication was started. However, a polymerase chain reaction for mycobacterium tuberculosis was negative and anti-tuberculous medication was stopped. M. szulgai was isolated on 3 separate sputum and bronchial wash fluid AFB cultures. He was treated with clarithromycin, rifampicin, and ethambutol. After 1 month, a sputum AFB smear and culture became negative and no additional M. szulgai were isolated during a 16-month treatment.

• Tuberculosis and Respiratory Diseases
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• v.67 no.3
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• pp.199-204
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• 2009

Background: To examine the recovery rate of nontuberculous mycobacteria (NTM) from respiratory specimens and the clinical course of NTM pulmonary disease at a 700-bed secondary hospital. Methods: This study analyzed the results of 843 acid-fast bacilli (AFB) culture-positive respiratory specimens from 650 subjects collected between May 2003 and April 2008. In addition, the clinical course of NTM pulmonary disease, diagnosed using criteria established by the American Thoracic Society, was examined. Results: There were 67 (7.9%) NTM isolates recovered from 52 (8.0%) subjects. Among the 535 AFB smear-positive specimens, 34 (6.3%) NTM isolates were recovered. There were 33 (10.7%) NTM isolates were recovered from 308 AFB smear-negative specimens. Of 52 subjects with isolated NTM, M. intracellulare was the most common species at 73.1% (n=33), followed by M. kansassi (n=7), M. abscessus (n=2), M. fortuitum (n=2), and M. avium (n=1). Sixteen (30.8%) patients had NTM pulmonary disease and the most common causative organism was M. intracellulare (n=14, 87.5%). Of these, 6 cases attained negative conversion in culture, 4 cases failed to attain negative conversion because of poor cooperation or expiration from complicated underlying lung disease, and 5 cases were transferred to a higher-grade hospital. Conclusion: The recovery rate of NTM from respiratory specimens was relatively low and the most common species was M. intracellulare. Patients with NTM pulmonary disease showed variable clinical outcomes.

• Tuberculosis and Respiratory Diseases
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• v.64 no.4
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• pp.293-297
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• 2008

Mycobacterium fortuitum usually causes colonization or transient infection in patients with underlying lung disease, such as prior tuberculosis or bronchiectasis. The majority of these patients may not need to receive antibiotic therapy for M. fortuitum isolates. We report here on a patient with M. fortuitum lung disease and who was successfully treated with combination oral antibiotic therapy. A 53-year-old woman was referred to our institution because of purulent sputum and dyspnea. A chest radiograph and computed tomography scan revealed cavitary consolidation in the left upper lobe and multiple small cavities in the left lower lobe. Numerous acid-fast bacilli (AFB) were seen in multiple sputum specimens and M. fortuitum was identified by culture from the sputum specimens. The patient received antibiotic treatment including clarithromycin, ciprofloxacin and sulfamethoxazole, because her symptoms were worsening despite conservative treatment. Sputum conversion was achieved after one month of antibiotic therapy. Both the patient's symptoms and radiographic findings improved after 10 months of antibiotic therapy.

• Tuberculosis and Respiratory Diseases
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• v.62 no.6
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• pp.531-535
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• 2007

The esophagus is a rate site for rarely involved site of tuberculosis. The most common cause of esophageal tuberculosis is secondary involvement from adjacent tuberculous lymphadenitis. Esophago-nodal or esophagobronchial fistulas may be formed when tuberculous lymph nodes erode the adjacent esophageal or bronchial wall. We report a patient diagnosed with esophageal tuberculosis, which was complicated by an esophago-mediastinal fistula, by endoscopy, sputum acid fast bacilli (AFB) stain, chest computed tomography (CT), and an esophagogram. The patient was treated with antituberculous agents and chest CT and endoscopy showed that the fistula had closed completely.

• Pediatric Infection and Vaccine
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• v.13 no.2
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• pp.174-179
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• 2006

Tuberculosis still ranks as one of the three most important infectious diseases in the world in terms of morbidity and mortality. In Korea, an increased incidence of tuberculosis has been observed in recent years. With the resurge of tuberculosis, extrapulmonary tuberculosis has increased, too. From this point of view, tuberculous arthritis affecting knee is rare in all forms of tuberculosis, but we can consider tuberculous arthritis in patients with osteomyelitis. We report the case of a 14-month-old male child who presented with fever and swelling on the left knee joint. Histologic examination of knee joint fluid showed consistent with tuberculosis. Ziehl-Neelsen stain of joint fluid was positive for acid-fast bacilli(AFB). The outcome was favorable after treatment with anti-tuberculosis medication. Because clinical signs and symptoms of musculoskeletal tuberculosis in children is more indolent, we can misdiagnose or delay diagnosis. The diagnosis of tuberculous arthritis can be elusive, necessitating a high index of suspicion.

• Tuberculosis and Respiratory Diseases
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• v.50 no.2
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• pp.222-228
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• 2001

Backgrounds : Recent technological developments have introduced a new method to identifying M. tuberculosis complex DNA in clinical samples directly. The direct amplification test (DAT) is approved for identifying M. tuberculosis complex in respiratory specimens that are smear-positive for acid-fast bacilli (AFB). When there is a discrepancy between the AFB smear and DAT, no information on their clinical utility is currently available. In this study, the diagnostic reliability of DAT was investigated in suspected pulmonary tuberculosis patients whose sputum AFB smear was negative. Methods : From June 1, 1998 through May 30, 1999, 909 patients with presumed active pulmonary tuberculosis were enrolled. A sputum AFB stain, culture, DAT and/or biopsy were performed. Using the criteria of clinical tuberculosis or confirmed tuberculosis, the positive predictive value of DAT in diagnosing pulmonary tuberculosis was investigated. Results : The positive predictive value of DAT was 82.1% by the clinically active tuberculosis criteria. However, it decreased to 61.5% when diagnosis was restricted to only to culture positive or biopsy proven cases. The false positive rate of DAT was 18.0%. Conclusion : The DAT is a valuable diagnostic method in suspected patients whose sputum AFB is was negative.

• Korean Journal of Head & Neck Oncology
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• v.12 no.2
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• pp.169-176
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• 1996

Tuberculous cervical lymphadenitis is still an important cause of neck mass in Korea. Tuberculosis is an important differential diagnosis in patients of cervical lymphadenopathy. Rapid and sensitive test for the diagnosis of tuberculosis is essential for the approapiate treatment. Up to now, conventional diagnostic methods for M. tuberculosis were acid-fast bacilli(AFB) stain and culture of M. tuberculosis. The direct microscopic examination of AFB by Ziehl-Neelsen stain is rapid, but often negative. The culture for M. tuberculosis is time-consuming, taking 4 to 8 weeks. Recently various methods to detect Mycobacterial DNA, including PCR and restriction fragment length polymorphism(RFLP) analysis have been reported. Here we represent a simple method for the confirmation of M. tuberculosis and exclusion of the other Mycobacterial species by RFLP analysis and silver staining of polyacrylamide gel electrophoresis after nested PCR for a repetitive DNA sequence(IS986) specific for M. tuberculosis from fresh or paraffin-embedded biopsy specimens. This result leads us to conclude that this method is simple, rapid and possibly applicable to confirm M. tuberculosis and rule out the other Mycobacteria species from the clinical specimens in the clinical laboratories.