Recovery rate of NTM from AFB smear-positive sputum specimens at a medical centre in South Korea.

OBJECTIVE: To investigate the recovery rate of non-tuberculous mycobacteria (NTM) from acid-fast bacilli (AFB) smear-positive sputum specimens at a tertiary care medical centre in South Korea with a high pulmonary tuberculosis (PTB) burden. DESIGN: Retrospective analysis of data from AFB smear- and culture-positive sputum specimens collected between January 1998 and December 2001. RESULTS: Over 4 years, 1328 sputum specimens collected from 616 patients were AFB smear- and culture-positive. NTM were recovered from 9.1% (121/1328) of the smear-positive sputum specimens, and from 8.1% (50/616) of patients with smear-positive sputum. NTM were isolated at least twice in 94% (47/50) of the patients from whom NTM was recovered. The most common organism found was Mycobacterium avium complex, followed by M. abscessus. CONCLUSION: These results suggest that a substantial proportion of patients at a tertiary care medical centre in South Korea with AFB smear-positive sputum specimens may have NTM lung disease rather than PTB.     

Regional differences of nontuberculous mycobacteria species in Ulsan,Korea

Background

In Korea recently, nontuberculous mycobacteria (NTM) have been more frequently isolated in respiratory specimens, while Mycobacterium tuberculosis (MTB) isolations have decreased. The major NTM lung disease species in Korea are M. intracellulare, M. avium, and M. abscessus, whereas M. kansasii is a rare species. This retrospective study was performed to determine if there are region-specific characteristics of lung disease-causing NTM species in Ulsan, a highly industrialized city in Korea.

Methods

Between January 2010 and July 2013, the results of all acid-fast bacilli (AFB) cultures of respiratory specimens performed at Ulsan University Hospital (Ulsan, Korea) were collected. NTM were identified and regional differences of NTM species were compared.

Results

AFB cultures were performed on 33,567 respiratory specimens, obtained from 10,208 patients, during the study period. Further, 10% of the specimens (3,287/33,567) were AFB culture-positive [MTB, 2,288/3,287 (70%); NTM 999/3,287 (30%)]. The proportion of NTM isolations gradually increased between 2010 and 2013, at 25% and 38%, respectively. The most common NTM species was M. intracellulare (356/999, 36%), followed by M. kansasii (295/999, 30%), M. avium (161/999, 16%), M. abscessus (117/999, 12%) and M. fortuitum (39/999, 4%). This trend was maintained throughout the study period.

Conclusions

In Ulsan, NTM isolation from respiratory specimens is increasing, consistent with previous studies performed in Korea. The distribution of respiratory NTM species, however, differed from previous studies that were performed in other regions of Korea: M. kansasii was the second most common NTM species in Ulsan. In Ulsan, there is a regional difference in the NTM species isolated.     

Evaluation of 120 mycobacterial strains isolated from clinical specimens to the species level by polymerase chain reaction-restriction enzyme analysis

In this study, a total of 120 mycobacterial strains isolated from clinical specimens in Hacettepe University Hospital Clinical Pathology Laboratories were evaluated by polymerase chain reaction-restriction enzyme analysis (PRA), which analyses the common mycobacterial heat shock protein gene (hsp65). 95 of 120 strains (79.1%) were identified as Mycobacterium tuberculosis and 25 (20.8%) were identified as non-tuberculous mycobacteria (NTM). M. gordonae I and IV were the most common NTM species (3.3% each) followed by M. chelonae (2.5%). Other NTM species isolated were M. gordonae III, M. avium, M. peregrinum (1.6%), M. fortuitum, M. flavescens, M. malmoense and M. mucogenicum (0.8%). Four isolates had PRA patterns that did not match any patterns previously described. The patients who had NTM had underlying diseases; the most frequent clinical diagnosis among these was chronic obstructive pulmonary disease (COPD) and chronic renal failure. AIDS and pulmonary carcinoma were the other underlying diseases detected.     

Emergence of Mycobacterium simiae in respiratory specimens

Temporal changes in epidemiology of non-tuberculous mycobacteria (NTM) infections have hardly been explored. Frequency of isolation of different NTM species varies geographically. We aimed to determine whether the distribution of Mycobacteria species isolated from respiratory specimens had changed from 1996 to 2003. We analysed data on 484 patient mycobacterial isolates from 23,483 respiratory specimens submitted to the Laboratory of Microbiology in a tertiary medical centre. The proportion of patients with Mycobacterium tuberculosis isolates decreased from 44.6% in period I (1996-1999) to 20.6% in period II (2000-2003). Among the NTM, the proportion of some species increased significantly (Mycobacterium simiae: 8.4% to 31.6%; Mycobacterium fortuitum 12% to 20%; and Mycobacterium chelonae 4.8% to 11.3%), while others decreased (Mycobacterium avium complex 31.3% to 17.3%; Mycobacterium kansasii 28.9% to 7.5%; and Mycobacterium haemophilum 1.2% to 0%). These findings disclose major temporal changes in the distribution of mycobacterial species in respiratory specimens with an impressive emergence and takeover of M. simiae.     

Superior sensitivity of MGIT method in identification of specimens culture-positive for acid-fast bacilli (AFB) and individuals with positive AFB cultures]

To investigate the superiority of the Mycobacteria Growth Indicator Tube (MGIT) over Ogawa medium in the detection of acid-fast bacilli (AFB), we surveyed all specimens for AFB culture using Ogawa medium in 1999 and MGIT in 2000. The MGIT method increased the culture-positive rate from 23.1% (Ogawa medium) to 34.5% (p < 0.01). The culture-positive rate in smear-negative specimens was greatly increased (from 9.5% to 16.9%) (p < 0.01). The culture-negative rate in smear-positive specimens was decreased to 19.5% from 27.7% (p < 0.01). More individuals with positive M. tuberculosis cultures were found by the MGIT method than with Ogawa medium. Many more individuals with nontuberculous mycobacteria (NTM), notably those with NTM other than M. avium complex, were detected by the MGIT method than with Ogawa medium. The use of the MGIT method in the clinical laboratory will improve sensitivity in the detection of AFB.     

Direct detection and identification of Mycobacterium tuberculosis in smear-positive sputum samples by fluorescence in situ hybridization (FISH) using peptide nucleic acid (PNA) probes.

SETTING: Peptidenucleic acid (PNA) probesdesigned for specific detection of mycobacteria of the Mycobacterium tuberculosis complex (MTC) and other non-tuberculous mycobacterium species (NTM) are shown to be able to penetrate the mycobacterial cell wall and subsequently hybridize in situ to complementary rRNA. OBJECTIVE: To demonstrate the use of fluorescein-labelled PNA probes for detection and identification of M. tuberculosis in smear-positive sputum samples. DESIGN: The sensitivity and specificity of the PNA probes were investigated by fluorescence in situ hybridization (FISH) using cultures of mycobacterium strains representing species of the MTC and NTM, respectively. RESULTS: M. tuberculosis strains were detected by FISH using specific fluorescein-labelled PNA probes directly in smear-positive sputum samples without changing the morphology of the cells. CONCLUSION: PNA probes allow for rapid diagnosis of tuberculosis in smear-positive cases.     

PCR-荧光探针法检测临床痰标本结核分枝杆菌的可靠性研究

目的 评价PCR-荧光探针法快速检测Mtb和非结核分枝杆菌（NTM）的临床应用价值。方法 应用分枝杆菌核酸检测试剂对1015 例痰标本和56株临床分离株进行检测,与Mtb核酸扩增（PCR）荧光（目前临床上认可惟一同类产品）检测结果进行比较。采用SPSS 11.5统计软件进行数据统计处理,采用χ²检验,以P＜0.05为差异有统计学意义。结果 PCR-荧光探针法检测痰标本分枝杆菌灵敏度50.3%（373/741）,特异度98.9%（271/274）;菌阳肺结核标本检测灵敏度97.0%（257/265）,菌阴肺结核标本检测灵敏度24.4%（116/476）;1015份痰标本中检测出11例非结核分枝杆菌（NTM）核酸阳性标本（占1.1%）,经16S rDNA 测序确认,准确率100.0%。随机数字量表法抽取138例标本重复进行第2次检测,符合率100.0%。对56株临床分离株（1株Mtb临床分离株,55株NTM临床分离株）检测,准确率100.0%。对临床需要的226份标本同时与达安公司试剂盒检测结果比较,总体符合率95.1%（215/226）,经统计学分析,两者之间差异无统计学意义（χ²=2.98,P=0.226）。结论 PCR-荧光探针法可快速检测和区分痰标本Mtb与NTM,具有临床推广应用价值。     

Changing epidemiology of nontuberculous mycobacterial lung disease in South Korea

Abstract Objectives: Pulmonary nontuberculous mycobacteria (NTM) are increasing worldwide, but data from regions with an intermediate tuberculosis (TB) burden are insufficient, and the reason for the changing epidemiology of NTM lung disease is unclear. We investigated the trends of NTM lung disease at a tertiary hospital in Korea and evaluated the contribution of liquid culture systems. Methods: We conducted a retrospective observational study of mycobacterial cultures of respiratory specimens from 26,793 patients at Severance Hospital in South Korea from January 2006 to December 2010. Results: The recovery percent of Mycobacterium tuberculosis isolates was 5.9% in 2006 and 7.1% in 2010, and the recovery percent of NTM isolates was 2.0% in 2006 and 6.3% in 2010. The annual percent of NTM isolation has increased steadily every year (p for trend 相似文献   

Non-tuberculous mycobacteria in China

Infection with non-tuberculous mycobacteria (NTM) is relatively rare in areas that are high-endemic for tuberculosis. We identified 126 strains of NTM in respiratory specimens collected by the Chinese Nationwide Survey in 2000, the Beijing Tuberculosis and Thoracic Tumour Institution, and the Guangzhou Thoracic Hospital. Species diagnosis was attained by sequencing of 16S-rDNA complemented by phenotypic characterization when necessary. Mycobacterium avium-intracellulare-complex - well known as a potential pulmonary pathogen - was diagnosed in all 3 surveys. Potentially pathogenic rapid growing strains of M. abscessus, M. chelonae and M. fortuitum were also detected. Moreover, species non-pathogenic in the airways such as M. nonchromogenicum, M. terrae and M. gordonae were encountered. Also, single strains of rare NTM species were isolated. Thus, several potentially pathogenic species of NTM were isolated from pulmonary specimens in China, and molecular techniques made possible exact species diagnosis.     

Clinical significance of nontuberculous mycobacteria isolated from respiratory specimens in Korea

STUDY OBJECTIVES: Precise epidemiologic data regarding nontuberculous mycobacterial (NTM) lung infection in many Asian countries have been relatively unavailable. In order to determine the clinical significance of NTM isolated from respiratory specimens, we reviewed medical records from all patients from whom NTM isolates were recovered within a 2-year period. MATERIALS AND METHODS: We identified all NTM isolates from respiratory specimens at the Samsung Medical Center (Seoul, South Korea) obtained from January 2002 to December 2003. We then reviewed the clinical and radiologic characteristics of the patients from whom NTM was isolated. Patients were classified as having either definite, probable, or unlikely NTM lung disease, as defined by the guidelines of both the American Thoracic Society and the British Thoracic Society. RESULTS: During the study period, 1,548 NTM isolates were recovered from 794 patients. Of these 794 patients, 131 patients (17%) were determined to have definite NTM lung disease, and 64 patients (8%) were designated as probable disease candidates. The most commonly involved organisms in the definite and probable NTM lung disease cases were Mycobacterium avium complex (n = 94, 48%) and Mycobacterium abscessus (n = 64, 33%). In 195 patients with NTM lung disease, 82 patients (42%) manifested the upper lobe cavitary form, 101 patients (52%) exhibited the nodular bronchiectatic form, and 12 patients (6%) exhibited the unclassifiable form. CONCLUSIONS: About one fourth of the patients in whom NTM was isolated from respiratory specimens were found to have clinically significant NTM lung infections. The spectrum of organisms responsible for the NTM lung disease in these Korean patients differed from those reported in other regions of the world. However, the estimates of clinical significance in this study may be underestimates due to the retrospective analysis. Some of the patients might have "true" NTM lung disease that could be diagnosed with continued evaluation and follow-up.     

Nontuberculous mycobacterial lung disease in patients without HIV infection: a retrospective analysis over 3 years

Introduction: Nontuberculous mycobacterial lung infections are relatively common in immunocompromised patients but are now increasingly being diagnosed in immunocompetent individuals. These organisms are not always pathogenic bacteria when isolated from human samples. The identification of which isolates are contaminants or colonizers is based on internationally accepted criteria. The clinical significance of the isolation of nontuberculous mycobacteria (NTM) from respiratory specimens in Italy is unknown. Objective: study was performed to evaluate the local epidemiology of NTM pulmonary infection in Naples in patients with positive respiratory specimens, and also to describe the clinical and radiological features of NTM pulmonary disease in immunocompetent patients with or without pre‐existing lung disease. Methods: Between December 2006 and September 2009, the clinical records and radiological examinations of 39 patients with 55 positive cultures for NTM species by sputum or bronchial wash or lavage were reviewed. Results: According to microbiological, clinical and radiological criteria, our study identified 16 patients with NTM lung infection as a ‘disease’ group and 23 patients in a ‘contamination’ group but without disease. M. intracellulare (n = 7, 41.2%), followed by M. kansasii (n = 5, 29.4%) were the most common NTM found in the ‘disease’ group. We detected a high number of M. gordonae isolates in respiratory samples obtained by fibrobronchoscopy. Conclusions: We evaluated the clinical significance of isolations in our reference centre in Naples. Forty‐one of all patients have ‘disease’, M. intracellulare and M. kansasii are mainly responsible. NTM species were analyzed in relation to their frequency. Assumptions were made about low pathogenic NTM isolations. Please cite this paper as: Del Giudice G, Iadevaia C, Santoro G, Moscariello E, Smeraglia R and Marzo C. Nontuberculous mycobacterial lung disease in patients without HIV infection: a retrospective analysis over 3 years. Clin Respir J 2011; 5:203–210.     

Tuberculosis in east timorese refugees: implications for health care needs in East Timor.

SETTING: East Timorese refugees evacuated to Darwin, Australia, September 1999. OBJECTIVE: Presentation of the process and results of tuberculosis (TB) screening in a previously unscreened refugee population. DESIGN: Screening for TB by clinical examination (all persons) and chest X-ray (CXR) (persons over 12 years of age and those of any age with respiratory symptoms) and sputum microscopy and mycobacterial culture (abnormal CXR). RESULTS: Seventy-six patients were diagnosed with TB (38 culture-positive for Mycobacterium tuberculosis, including 11 sputum smear-positive). Of 89 positive mycobacterial cultures, 51 were non-tuberculous mycobacteria (NTM). Of the M. tuberculosis isolates, 82.2% were fully sensitive, 17.2% were resistant to isoniazid and 8.6% were resistant to isoniazid and streptomycin. Fifty-three consecutively diagnosed patients with TB were HIV-negative. The TB burden in this population was very high (point prevalence of 542/100,000 for smear-positive and 2,060/100,000 for culture-positive cases). Rates of culture for NTM were also high. Information from this study assisted the implementation of a National TB Control Programme for East Timor in February 2000. CONCLUSION: The challenges for public health authorities in East Timor to provide a successful TB control programme are enormous. The apparently low prevalence of drug resistance and HIV co-infection in the population is encouraging.     

Utilización de diferentes técnicas de biología molecular integradas en un algoritmo de identificación de micobacterias no tuberculosas

Introduction

The aim of the present work was to demonstrate the utility of a non-tuberculous mycobacteria (NTM) identification algorithm, which integrates different PCR-based techniques and basic phenotypic features. Moreover, the algorithm for pattern restriction analysis of hsp65 (hsp65 PRA) interpretation has been updated.

Methods

The workflow chosen consisted of the identification by a DNA hybridization probe method, followed by PCR-restriction enzyme analysis of hsp65 (hsp65 PRA) in those isolates that cannot be identified by hybridization probes. If necessary, 16S rRNA gene and hsp65 gene sequencing were used for speciation.

Results

A total of 236 NTM were collected, in which 102 (43.2%) isolates were identified by DNA specific probes and 76 (32.2%) isolates were identified with hsp65 PRA. Partial sequencing of the 16S rRNA gene was used for species identification of the remaining 58 (24.5%) isolates. Fifty-three (22.4%) were identified using this method. Five isolates (2.1%) were submitted for partial sequencing of hsp65 gene and one isolate was identified with this method. Four strains (1.7%) could not be identified at species level. Three new PRA patterns were found. Seven isolates tested positive with the AccuProbe Mycobacterium avium complex identification test but did not test positive with the M. avium or Mycobacterium intracellulare specific probes. Five and two of these isolates were identified as M. intracellulare and Mycobacterium colombiense, respectively.

Conclusion

This approach allowed us to identify almost all NTM isolates found in this study, including some recently described species.     

Species level identification of non-tuberculous mycobacteria from South Indian BCG trial area during 1981

In 1981, non-tuberculous mycobacteria (NTM) were obtained from 8.6% of 16 907 sputum specimens in a trial in the Chingleput district of Madras state to test the efficacy of BCG vaccination in the prevention of tuberculosis, but from only 0.6% of 672 autoclaved specimens cultured as part of a quality control procedure. This finding suggested that the NTM were truly derived from the sputum of the BCG trial subjects. The mycobacterial species could be identified in 966 (96.6%) of the first 1000 isolates of NTM: 54.6% were potential pathogens and 73.0% were slow growing. The species isolated most frequently were M. avium/intracellulare (22.6% of all NTM), M. terrae (12.5%) and M. scrofulaceum (10.5%). Those species accounting for 8-5% of all NTM were M. fortuitum, M. chelonei, M. flavescens, M. gordonae and M. vaccae.     

Diagnosis,differentiating colonization,infection, and disease

Nontuberculous mycobacteria (NTM) are found commonly in respiratory specimens. In many clinical laboratories, the majority of mycobacteria recovered from respiratory samples are NTM. Perhaps this is because NTM are common in the environment. The water that we drink or shower in often contains NTM; consequently, we often find NTM in respiratory secretions. The term colonization has been used when NTM are recovered more than once even though a specific disease cannot be demonstrated. Under these circumstances, it is never quite clear whether a low-grade infection exists or if secretions are simply contaminated by environmental organisms; however, colonization can be discerned from infection by focusing on the elements of making the diagnosis of an NTM-related disease, rather than simply finding the organism in respiratory samples.     

Respiratory infections associated with nontuberculous mycobacteria in non-HIV patients.

The incidence of nontuberculous mycobacteria (NTM) pulmonary diseases in HIV-negative patients was studied prospectively from January 1, 2001 to December 31, 2003 by 32 sentinel sites distributed throughout France. In total, 262 patients who yielded NTM isolates from respiratory clinical specimens, met the bacteriological, radiological and clinical criteria established by the American Thoracic Society for NTM respiratory disease. Among the 262 NTM isolates, 234 were slow-growing mycobacteria (125 Mycobacterium avium-intracellulare complex (MAC), 66 M. xenopi, 34 M. kansasii) and 28 were rapidly growing mycobacteria (25 M. abscessus complex). In the Paris area, M. xenopi was the most frequently isolated species, followed by MAC. Most patients (>50%), except those with M. kansasii, had underlying predisposing factors such as pre-existing pulmonary disease or immune deficiency. Asthenia, weight loss, chronic cough and dyspnoea were the most common clinical symptoms. The classical radiological appearance of NTM infections was indistinguishable from that observed in patients with pulmonary tuberculosis. In summary, the incidence of nontuberculous mycobacteria pulmonary infections in HIV-negative patients was estimated at 0.74, 0.73 and 0.72 cases per 100,000 inhabitants in 2001, 2002 and 2003, respectively.     

Epidemiology and clinical significance of mycobacterial respiratory infections in Central Greece

SETTING: A 750-bed tertiary referral hospital in Central Greece. OBJECTIVE: To determine the incidence of non-tuberculous mycobacteria (NTM) respiratory infection based on the isolation of NTM in respiratory specimens, to study their clinical significance and to evaluate the differences in clinical, radiological and demographic characteristics between patients with lung disease caused by NTM and that caused by Mycobacterium tuberculosis complex (MTC). DESIGN: A 3-year period prospective study to identify patients with positive NTM and MTC respiratory specimens. RESULTS: Between January 2004 and December 2006, 564 positive NTM cultures from 214 patients and 118 MTC cultures from the same number of patients were collected. The incidence rate of clinically significant NTM lung infection was 0.67, 0.54 and 0.94 cases per 100,000 population, and that of MTC infection of the lung was respectively 5.70, 5.28 and 5.10 cases/100,000 in the three study years. Smoking habits and chronic obstructive pulmonary disease were significant risk factors for NTM disease (P < 0.05 and P < 0.001, respectively). CONCLUSIONS: NTM incidence rates were lower than those reported in the rest of Europe and the USA. Further studies are needed to determine the prevalence and the significant geographic variability of NTM and their clinical significance at the national level.     

Mikrobiologie und Diagnostik nichttuberkul?ser Mykobakterien

In recent years, several new techniques for the diagnostic workup of nontuberculous mycobacteria (NTM) have been introduced into laboratories. The use of nucleic acid amplification techniques for species identification has replaced the conventional biochemical methods. The detection of NTM directly from specimens is difficult because of the low bacterial load in the specimens and no standardized method is available yet. Thus, despite the recent improvements the microscopic and the cultural investigation of the specimens is still the reference standard in the diagnosis of NTM.     

The epidemiology of nontuberculous mycobacterial diseases in the United States. Results from a national survey

During the 2-yr period 1981-83, demographic, clinical, and laboratory information was collected for 5,469 patients from whom nontuberculous mycobacteria (NTM) had been isolated. Among the potential NTM pathogens, isolates of Mycobacterium avium complex were most frequent, followed by M. kansasii, M. fortuitum, M. scrofulaceum, and M. chelonae. Almost 90% of the isolates were obtained from respiratory specimens. Prevalence rates for NTM disease, as calculated by a diagnostic algorithm, were highest for M. avium complex (1.3/10(5)), M. fortuitum-M. chelonae (0.2/10(5)). The data suggest a changing epidemiologic picture of NTM disease due perhaps to the decreasing incidence of tuberculosis, the increasing prevalence of chronic lung disease, and increased culturing of diagnostic specimens, as well as possibly a change in the ecology of these organisms.     

Nontuberculous mycobacteria. I: multicenter prevalence study in cystic fibrosis

Nontuberculous mycobacteria (NTM) are potential respiratory pathogens in cystic fibrosis (CF). To assess the species-specific prevalence and risk factors for acquisition, we conducted a prospective, cross-sectional study of the prevalence of NTM and clinical features of patients at 21 U.S. centers. Almost 10% of patients with CF who were 10 years or older were included (n = 986). The overall prevalence of NTM in sputum was 13.0% (range by center, 7-24%). Mycobacterium avium complex (72%) and Mycobacterium abscessus (16%) were the most common species. When compared with patients with CF without NTM, culture-positive subjects were older (26 vs. 22 years, p < 0.001), had a higher FEV1 (60 vs. 54%, p < 0.01), higher frequency of Staphylococcus aureus (43 vs. 31%, p < 0.01), and lower frequency of Pseudomonas aeruginosa (71 vs. 82%, p < 0.01). Molecular typing revealed that almost all patients within each center had unique NTM strains. In summary, NTM are common in patients with CF, but neither person-to-person nor nosocomial acquisition explained the high prevalence. Older age was the most significant predictor for isolation of NTM. The clinical significance of NTM in CF is incompletely defined, but patients with these organisms should be monitored with repeat cultures.