Comparative evaluation of the BACTEC MGIT 960 system with solid medium for isolation of mycobacteria.

SETTING: The utilisation of new, rapid methods of diagnosis of tuberculosis is currently of great interest for tuberculosis control. This study was carried out in a teaching hospital in the eastern region of Taiwan. OBJECTIVE: The BACTEC MGIT 960 system was evaluated and compared with Lowenstein-Jensen (LJ) medium and Middlebrook 7H11 plate for recovery rate and time to detection of mycobacteria. DESIGN: A total of 1396 sputum samples were tested for the presence of mycobacteria. Specimens were processed and inoculated separately in the BACTEC MGIT 960 system, on LJ medium and 7H11 for comparative study. RESULTS: The BACTEC MGIT 960 detected 235 isolates (100%), followed by LJ with 205 isolates (87.2%) and 7H11 with 178 isolates (75.7%). The mean time to detection of Mycobacterium tuberculosis complex was 11.6 days with MGIT 960, 20.1 days with LJ, and 18.7 days with 7H11. The contamination rates were 15.1% with MGIT 960, 10.1% with LJ and 9.7% with 7H11. CONCLUSION: The BACTEC MGIT 960 system is a sensitive, rapid mycobacterial culturing system. However, the high contamination rate is a concern that should be carefully evaluated in the clinical setting.     

Differentiation of Mycobacterium tuberculosis from other mycobacteria with rho-nitrobenzoic acid using MGIT960.

SETTING: Mycobacteria growth in media with the addition of inhibitory substances has been used in species identification. Growth of the Mycobacterium tuberculosis complex (MTC) is inhibited by rho-nitrobenzoic acid (PNB), whereas non-tuberculous mycobacteria (NTM) are resistant. OBJECTIVE: To develop a rapid PNB test using the automated BACTEC MGIT960 system and to evaluate its usefulness in the screening of mycobacterial isolates. DESIGN: PNB tests were performed in 93 MTC strains and 61 NTM strains from the Instituto Adolfo Lutz Culture Collection. PNB was added to L?wenstein-Jensen (LJ) medium and to BACTEC MGIT960 medium. RESULTS: The MTC strains were all PNB-susceptible, confirming the original identification. Among 10 NTM species, all were found to be resistant to PNB, except for one strain of M. kansasii and another of M. marinum. The median time to obtain presumptive identification of MTC by inhibition test in the BACTEC MGIT960 system was 6.3 days and for NTM it was 2.5 days. The presumptive identification of MTC in LJ was mostly obtained after day 20. CONCLUSION: The key finding of this analysis was the possibility of combining the traditionally accepted method proposed by Tsukamura and Tsukamura in 1964 with the modern, safe and rapid BACTEC MGIT960 methodology.     

BACTEC960培养阳性530株分枝杆菌的形态学特征探讨

目的探讨分枝杆菌在BACTEC960中的生长特点和涂片抗酸染色形态特征,为菌群鉴定提供初步意见。方法收集福州肺科医院临床标本经BACTEC960培养阳性530例,进行直接涂片抗酸染色、菌群鉴定和药敏试验。结果结核分枝杆菌在MGIT培养管中呈絮状沉淀生长,镜检呈绳索状排列。非结核分枝杆菌（NTM）呈混浊生长,镜检呈散在、团粒状、块状、碎片状和松疏束状等不规则排列。结论结核分枝杆菌在BACTEC960中培养形成有特点的缠结,在显微镜下很容易识别,对鉴定分枝杆菌有初筛作用。     

Is it appropriate to routinely use a nucleic acid amplification test for the diagnosis of tuberculosis?

The purpose of this study was to compare the usefulness of the nucleic acid amplification (NAA) test against conventional tests under normal laboratory operational conditions. The NAA test was performed on the first sputum specimen of all patients. Liquid media culture, solid media culture, and Ziehl-Neelsen stain for an acid-fast bacilli (AFB) smear were performed on three sputum specimens. The results were calculated using the gold standard of either the culture results or the clinical diagnosis. Of the 593 patients tested, 151 (25.5%) were diagnosed with pulmonary tuberculosis. The sensitivity of the first specimen only was 64% for the NAA test, 54% for the AFB smear, 77% for BACTEC MGIT 960 culture, 40% for Lowestain-Jensen (LJ) culture, and 25% for 7H11 culture. The sensitivity when using all three specimens increased to 63% for AFB smear, 87% for BACTEC MGIT 960 culture, 51% for LJ culture, and 40% for 7H11 culture. The specificity was 100% for all culture tests, 99% for the AFB smear, and 99.5% for NAA test. The mean turnaround time was 1.34 days for NAA, 0.59 days for AFB smear, 11 days for BACTEC MGIT 960 culture, 23 days for LJ culture, and 20 days for 7H11 culture. We conclude that the sensitivity of NAA is still far from ideal, and the test is not cost effective. Thus, the COBAS AMPLICOR PCR system is not suitable for routine use in microbiology laboratories.     

Comparison of the BACTEC MGIT 960 with L?wenstein-Jensen medium for recovery of mycobacteria from clinical specimens.

SETTING: Taiwan Provincial Chronic Disease Control Bureau. OBJECTIVE: To evaluate the rate of recovery and the mean time to detection (TTD) of mycobacteria in clinical specimens with two culture systems, the BACTEC MGIT 960 and L?wenstein-Jensen (LJ) medium. DESIGN: We studied 365 specimens, collected from 166 patients. Specimens were processed with standard N-acetyl-L-cysteine (NALC)-NaOH method, then inoculated onto BACTEC MGIT 960 and onto LJ slants. RESULTS: A total of 124 mycobacterial isolates (114 Mycobacterium tuberculosis and 10 non-tuberculous mycobacteria) were detected. The recovery rates were 94% (117/124) with BACTEC MGIT 960 and 75.8% (94/124) with LJ. The rates of contamination for each of the systems were 5.5% with BACTEC MGIT 960 and 4.1% with LJ. The TTDs for mycobacteria were 10.7 days with BACTEC MGIT 960 and 30.6 days with LJ. Excluding the non-tuberculous mycobacteria, the TTDs for M. tuberculosis were 11.1 days with BACTEC MGIT 960 and 30.7 days with LJ. The difference in TTD between smear-positive and smear-negative specimens for either mycobacteria (10.0 vs 12.6 days; P = 0.06) or M. tuberculosis (10.1 vs 12.7 days; P = 0.06) with BACTEC MGIT 960 was not statistically significant. CONCLUSION: The BACTEC MGIT 960 system can expedite the recovery of mycobacteria in culture. Combined with conventional solid medium, it also increases the overall recovery of mycobacteria in culture.     

对BACTEC^TM MGIT960培养报告结果为阴性的培养管中颗粒性物质的研究

目的 探讨使用BACTEC^TM MGIT960进行分枝杆菌培养时,仪器报告结果为阴性的MGIT960培养管中颗粒的性质及成因。 方法 收集北京市结核病胸部肿瘤研究所2010年1月至2010年12月进行分枝杆菌培养的标本中31份仪器报告阴性但有颗粒形成的培养管,分别对颗粒性物质进行抗酸染色、罗氏培养和BACTEC^TM MGIT960传代培养。对培养阳性的标本进行菌种鉴定、药敏试验。选择8株培养阳性的标本进行低细菌载量接种试验来分析颗粒形成的原因,包括2株结核分枝杆菌复合群,3株蟾蜍分枝杆菌和3株胞内分枝杆菌,每株将1个麦氏浓度的菌悬液用生理盐水连续稀释至10^-5、 10^-6、10^-7、 10^-8 倍,各接种到2支培养管。 结果 31份仪器报告阴性但有颗粒形成的培养管,有29份经再次传代培养后获得阳性培养结果,其中24份（24/29）用颗粒直接涂片后进行显微镜抗酸杆菌检查结果为阳性。29份培养阳性的菌株包括7株蟾蜍分枝杆菌,4株胞内分枝杆菌和18株结核分枝杆菌复合群。接种量为10^-6、10^-7、 10^-8 浓度的蟾蜍分枝杆菌培养管中均有颗粒形成,阳性比例分别为4/6、5/6、6/6。 结论 BACTEC^TM MGIT960进行结核分枝杆菌培养时,仪器报告阴性的MGIT960培养管中颗粒多为活的分枝杆菌;BACTEC^TM MGIT960系统颗粒的形成与低细菌载量有关,颗粒形成也有一定的种属特异性,主要集中在蟾蜍分枝杆菌和胞内分枝杆菌。     

Direct identification of mycobacteria from the positive cultures in mycobacteria growth indicator tube (MGIT)

The ability of the AccuProbe (Kyokuto) to identify mycobacteria directly from the positive cultures in an automatic detector for mycobacteria (BACTEC MGIT960, Becton Dickinson) was evaluated. Sputum samples were collected from patients with suspected mycobacteriosis between February and April 1999 and conventionally incubated in MGIT960 (37 degrees C for 42 days). The MGIT-positive cultures were successively incubated for several days and were directly identified with the AccuProbe. Monomycobacterial strains were detected from 93 (93.9%) of the 99 sputum samples and polymycobacterial strains were detected from 6 sputum samples (6.1%). Viable cell counts in the positive cultures in MGIT960 were determined using Middlebrook 7H10 agar. The cell counts of Mycobacterium tuberculosis and Mycobacterium avium-intracellulare complex (MAC) varied greatly among the individual samples; the former, 3.8 x 10(2)-2.5 x 10(6) cfu/ml and the latter 1.5 x 10(3)-1.9 x 10(8) cfu/ml. The great differences in the cell counts were observed among these samples. Although the cultures in MGIT were estimated as positive, the early stage of bacterial growth might be used as the samples for the cell counting. By this method, 96 of the total 101 cases were successfully identified as follows: M. tuberculosis 57 cases (56.4%) and MAC 39 cases (38.6%). In conclusion, the present results indicate that the direct identification of mycobacteria from the positive cultures in MGIT960 using AccuProbe is useful for a rapid diagnosis in microbiological testing for mycobacteriosis which has tended to increase in recent years.     

Comparison of the newly developed MB redox system with mycobacteria growth indicator tube (MGIT) and 2% Ogawa egg media for recovery of mycobacteria in clinical specimens

The rate of recovery and the mean time to detection of mycobacteria in clinical specimens were determined in a newly-developed MB Redox system based on liquid medium, and the results were compared with those of MGIT and 2% Ogawa egg media. From 587 sputum specimens processed, totally 203 mycobacterial isolates were detected, of which 177 (87.2%) with MB Redox, 185 (91.1%) with MGIT and 133 (65.6%) with 2% Ogawa medium. The difference in the percentages of positive cultures between either of the two liquid media and 2% Ogawa medium was significant (p < 0.0001). The mean time to detection of the Mycobacterium tuberculosis complex was 17.5 days with MB Redox, 18.7 days with MGIT, and 26.2 days with 2% Ogawa medium. The contamination rates were 1.5, 1.7, and 4.1% for MB Redox, MGIT, and 2% Ogawa medium, respectively. In conclusion, both MB Redox and MGIT systems, based on liquid medium, are more efficient than 2% Ogawa medium for the recovery of mycobacteria in clinical specimens.     

BACTEC MGIT 960和BACT/ALERT 3D系统快速培养和鉴定痰中抗酸杆菌

目的对抗酸染色阳性痰行分枝杆菌培养和鉴定。方法采用萋一尼氏抗酸染色法对临床诊断肺结核患者的晨痰涂片直接镜检,抗酸染色阳性痰经BACTEC960和BACT/ALERT3D系统进行分枝杆菌培养,分别经对硝基苯甲酸（PNB）和噻吩-2-羧基肼（TCH）培养基生长试验行分枝杆菌菌群和结核分枝杆菌复合群菌种鉴定。结果抗酸染色阳性痰标本的分枝杆菌培养阳性率100％,大多数为结核分枝杆菌（9／10）,少数为非结核分枝杆菌（1／10）,最快6天即可报告分枝杆菌阳性培养。结论BACTEC 960和BACT／ALERT3D系统具有快速培养分枝杆菌作用,抗酸染色阳性痰有必要行分枝杆菌培养和鉴定,有利于肺结核与非结核分枝杆菌病的鉴别诊断、结核分枝杆菌菌种鉴定和抗结核药物敏感性试验。     

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.     

The validity of acid-fast smears of gastric aspirates as an indicator of pulmonary tuberculosis.

SETTING: A tuberculosis referral hospital in Canada. OBJECTIVE: To determine the validity of acid-fast (AFB) smears of gastric aspirates (GA) in the diagnosis of pulmonary tuberculosis, and to assess the prevalence of nontuberculous mycobacteria (NTM) in GA isolates from such patients. DESIGN: A retrospective case review of our experience with AFB smears (Kinyoun) and cultures of GA and sputum over a 3-year period. RESULTS: From 1994 to 1996 inclusive, 1155 GA were performed in 889 patients. Mycobacteria were cultured from 109 (9%) GA. Thirteen of these were positive on smear (sensitivity 19%). All GA that were positive on smear were culture positive for Mycobacterium tuberculosis. There were no false positive smears (specificity 100%). The sensitivity and specificity of the sputum smear were 45% and 99%, respectively. Of the 96 culture positive, smear negative GA, 54 grew M. tuberculosis and 42 grew an NTM. Of 13 patients who had sputum and GA studied coincidentally, and in whom the sputum was both smear and culture positive, the GA culture was positive in 13 and the smear was positive in eight (66%). CONCLUSION: AFB smear of GA is a relatively insensitive but highly specific indicator of pulmonary tuberculosis warranting institution of antituberculosis treatment. Gastric AFB smear positivity appears to reflect a high bacillary burden within the respiratory tract.     

Comparison of the newly developed MYCOACID system with mycobacteria growth indicator tube (MGIT) and newly developed 2% Ogawa medium (S) for recovery of mycobacteria in clinical specimens]

The detection rate of mycobacteria from patients' specimens and the time required to get positive culture were compared among newly developed MYCOACID SYSTEM, MGIT, Ogawa K medium and 2% Ogawa medium (S). A total of 249 sputum samples taken from patients were used as the study subjects and 124 kinds of mycobacteria were isolated. For 135 cases clinically diagnosed as pulmonary tuberculosis, the detection rate was 44.4% for MYCOACID, 47.4% for MGIT and 38.5% for Ogawa K medium, showing that there are no significant differences in the detection rate between MYCOACID and MGIT, and MYCOACID and Ogawa K medium but the differences was significant between MGIT and Ogawa K medium (p = 0.02). The mean days needed for detection of Mycobacterium tuberculosis complex was 12.3 days for MYCOACID, 13.4 days for MGIT, and 26.8 days for Ogawa K medium, indicating significant differences in the time to get positive culture between Ogawa K medium and either of both liquid media (p < 0.001). Furthermore, 2% Ogawa medium (S) was used only for the detection of mycobacteria among previously untreated tuberculosis and there were no significant differences in the detection rate between 2% Ogawa medium (S) and either of both liquid media. The time to get positive culture for 2% Ogawa medium (S) was 18.2 days, which was longer than that for either of liquid media, MYCOACID and MGIT, but it was significantly shorter (7.9 days) than that for Ogawa K medium (p = 0.003). These results demonstrate that the liquid culture systems both MYCOACID and MGIT were very useful for the detection of mycobacteria compared with Ogawa K medium.     

Recovery rates of mycobacterium from suspected extra-pulmonary tuberculosis patients using liquid culture at a tertiary referral centre of India

Tuberculosis still remains a serious public health problem in developing countries. Rapid isolation of mycobacteria is critical for accurate diagnosis and management of tuberculosis. In the present study BACTEC MGIT 960 system was evaluated against Lowenstein Jensen (LJ) medium for isolation of mycobacteria from different extra-pulmonary specimens (N = 371). The samples were processed using NaOH-NALC method and inoculated in BACTEC MGIT and on LJ medium. The BACTEC MGIT 960 system detected 93 (25.06%) samples positive for acid fast bacilli and by LJ only 38 samples (10.24%) was positive. Furthermore, total 99 (26.68%) samples were detected positive by both the culture methods. The mean turnaround time to detection of mycobacteria by MGIT 960 were significantly less (12.4 days) as compared with LJ (22.76 days). In conclusion, BACTEC MGIT 960 system is more sensitive and rapid culture system for isolation of mycobacteria. However LJ culture method also suggested to further increase the detection rate of EPTB cases.     

结核/非结核分枝杆菌核酸快速检测方法临床应用价值

目的 评价结核/非结核分枝杆菌核酸快速检测方法的临床应用价值。 方法 应用实时荧光PCR技术对420例标本进行临床试验研究,并与抗酸杆菌涂片和分枝杆菌培养方法对照比较。 结果 结核分枝杆菌核酸检测灵敏度为48.5%（其中菌阳标本灵敏度为95.8%,菌阴标本灵敏度为14.5%）,特异度99.3%,阳性预测值为99.1%,阴性预测值为55.5%;临床试验388例痰标本中检测出1例非结核分枝杆菌核酸阳性,经测序确认,准确率100%;同时对32例非结核分枝杆菌临床分离株进行核酸检测,并经测序确认,准确率100%。 结论 应用实时荧光PCR技术,能实现在1支管内同时进行结核分枝杆菌/非结核分枝杆菌的核酸检测。该方法具有简单快速、特异性好污染性少的特点。可作为实验室辅助检测结核/非结核分枝杆菌核酸方法之一。     

基因芯片技术在肺结核快速诊断及分枝杆菌菌种鉴定中的应用价值

目的探讨基因芯片技术诊断肺结核及鉴定分枝杆菌菌种的应用价值。方法搜集2017年1-12月在黑龙江省传染病防治院结核科就诊并连续3次痰涂片检测为阳性的1248例疑似肺结核患者为研究对象。每例患者均留取清晨痰液标本3~5ml,对痰液标本分别进行BACTEC MGIT 960(简称"MGIT 960")培养和基因芯片检测。以MGIT 960培养结果作为参照,分析基因芯片法的检测效能。结果1248例患者痰标本经MGIT960培养阳性1224例(98.08%),基因芯片法检测阳性1212例(97.11%)。以MGIT 960培养结果作为参照,基因芯片法检测的敏感度为98.94%(1211/1224),特异度为95.83%(23/24),符合率为98.88%(1234/1248),Kappa值为0.76。1212例基因芯片法检测阳性的患者中非结核分枝杆菌(NTM)感染60例(4.95%),结核分枝杆菌感染1152例(95.05%)。60例NTM感染者中比较常见的菌种是胞内分枝杆菌(43.33%,26/60)。结论基因芯片检测与MGIT 960培养结果的一致性较好,可以快速、准确地区分结核分枝杆菌复合群和NTM,并可进一步进行菌种鉴定。     

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.     

New recommendations for duration of respiratory isolation based on time to detect Mycobacterium tuberculosis in liquid culture.

It was hypothesised that the time to detect Mycobacterium tuberculosis in liquid culture of sputum from patients with pulmonary tuberculosis may be a better indicator for the duration of respiratory isolation than sputum smear status. Pre-treatment and during-treatment sputum acid-fast bacilli (AFB) smear and culture results were reviewed in 284 patients with pulmonary tuberculosis. The time to detect M. tuberculosis in liquid culture (TTD-TB) was the number of days from inoculation of the Mycobacterial Growth Indicator Tube to culture detection and visualisation of AFB. The median (interquartile range) TTD-TB for smear group 0 (no bacilli seen) was 14 (12-20) days. This value was used as the standard at which release from isolation could be permitted. In smear group 4 (>9 AFB per high-power field (hpf) in sputum specimens before treatment) patients, the TTD-TB exceeded 14 days after a median of 25 days of treatment. The current authors recommend that patients in smear groups 1 and 2 (1-9 AFB per 100 hpf and 1-9 AFB per 10 hpf in sputum specimens before treatment, respectively) receive treatment in respiratory isolation for 7 days, provided the risk of drug resistance is low. Smear group 3 (1-9 AFB per hpf) and 4 patients should receive treatment in respiratory isolation for 14 and 25 days, respectively. These criteria would have reduced the duration of respiratory isolation by 1,516 days in the 143 study participants with sputum smear-positive pulmonary tuberculosis. Provided clinical and radiographical criteria are satisfactory, use of the time to detect Mycobacterium tuberculosis in liquid culture could enable the duration of respiratory isolation to be predicted from the pre-treatment sputum smear grade. The recommendations enable isolation to end well before sputum becomes smear negative, with considerable benefits to patients and healthcare providers.     

Evaluation of the Mycobacteria Growth Indicator Tube system for detection and quantification of mycobacteria from clinical specimens

The Mycobacteria Growth Indicator Tube (MGIT) system, a broth system for detection of mycobacterial growth, has been shown to be more sensitive and rapid compared with the egg-based Ogawa solid media, while the lack of ability to quantitate bacterial growth is the problem. We compared mycobacterial growth in the MGIT and the Ogawa systems, and evaluated the relationship between detection time in the MGIT system and bacterial CFU on Ogawa egg medium. A total of 413 respiratory specimens from 245 patients were included in the study, of which Mycobacterium tuberculosis (MTB), M. avium complex (MAC) and M. kansasii were recovered from 127, 42 and 6 specimens, respectively. Recovery rates were significantly higher and detection time was significantly shorter in the MGIT than in the Ogawa for MTB and MAC. Detection time in the MGIT was significantly shorter in smear positive specimens than in smear negative ones for MTB and MAC. There was a significant negative correlation between CFUs on Ogawa egg medium and detection time in the MGIT system for the MTB, therefore, this system may have an ability to quantitate live mycobacteria according to the detection time.     

Non tuberculosis mycobacteria isolates among new and previously treated pulmonary tuberculosis patients in Nigeria

ObjectiveTo determine the prevalence of non tuberculosis mycobacteria (NTM) among new and previously treated tuberculosis (TB) patients in Nigeria.MethodsIt was a retrospective study. A total of 102 sputum smear positive samples/culture isolates from pulmonary TB patients (41 new smear positive and 61 smear positive retreatment cases) were sent to the Institute of Tropical Medicine, Antwerp Belgium between 2007-2009. Data on patients' characteristics were retrieved from their treatment cards.ResultsAmong the 102 samples, 25 isolates results (20 were culture negative while 5 were contaminated) were excluded from the study. Data were available for 77 mycobacterium isolates. 70 (90.9%) were identified as Mycobacterium tuberculosis and 7 (9.1%) as atypical mycobacteria. Among the atypical mycobacteria, three of them were Mycobacterium fortuitum, two Mycobacterium intracellulare and two Mycobacterium chelonae. Of the seven isolates with atypical mycobacteria, 4 (57.1%) were from previously treated patients, while 3 (42.9%) were new sputum positive patients. There was no statistically significant difference in NTM infection between new and previously treated pulmonary TB patients (P =0.97).ConclusionsThe study shows the involvement of atypical mycobacterium in pulmonary infection in both new and previously treated TB patients. Therefore, there is a need to carry out culture and drug susceptibility testing in all pulmonary TB patients especially those who had failed conventional DOTS treatment to rule out NTM infections.     

Characterization of mycobacterium isolates from pulmomary tuberculosis suspected cases visiting Tuberculosis Reference Laboratory at Ethiopian Health and Nutrition Research Institute,Addis Ababa Ethiopia:a cross sectional study

Objective:To characterize mycobaclerium isolates from pulmomary tuberculosis suspected cases visiting National Tuberculosis Reference Laboratory at Ethiopian Health and Nutrition Research Institute,for diagnosis of pulmonary tuberculosis from January 4 to February 22.2010 with total samples of 263.Methods:Sputum specimens were collected and processed:the deposits were cultured.Por culturing Lowenstein Jensen medium(LJ) and Mycobacteria Growth Indicator Tube(BACTEC MGIT 960) were used.Capilia Neo was used for detecting NTM isolates from isolates of BACTEC MGIT960.In Armauer Hansen Research Institute,Addis Ababa Ethiopia,Deletion typing PCR method for species identification(from confirmed Mycobacterium tuberculosis complex(MTBC) isolates by Capilia Neo) uas done.Results:Out of 263 enrolled in the study.124 and 117 ol them were positive for mycobaeterium growth by BACTEC MGIT 960 and 1.1 culture method,respectively.From BACTEC MGIT 960 positive media of 124 isolates.117 were randomly taken to perform Capilia TB Neo lest.From these 7(6%) of them were found to be NTM and 110(94%) were MTBC.From these 110 MTBC isolates,81 of them were randomly taken and run by the deletion typing RD9 PCR method of molecular technique.Out of these 78(96.3%) were found to be species of Mycobacterium tuberculosis and 3(3.7%) were found to be not in the MTBC.Regarding the types of methods of culture media.Mycobacteria Growth Indicator Tube(BACTEC MGIT 960) method was found to have excellent agreement(with kappa value ol 0.78) with the routine method of LJ.Conclusions:Pulmonary tuberculosis suspected cases visiting the National Tuberculosis Reference Laboratory at EHNR1 that were confirmed to be pulmonary tuberculosis are caused by the species of Mycobacterium tuberculosis.hence treatment regimen including pyrazinamide can be applied to the patients as the first choice in the study area in Addis Ababa.Ethiopia.There is indication of the presence of NTM in patients visiting the tuberculosis reference laboratory and this is important because NTM is known lo cause pulmonary disease similar with sign and symptom ol pulmonary tuberculosis but different in treatment.BACTEC MGIT 960 has excellent agreement with LJ media but it has high tendency of having high contamination rale unless a better decontamination method is designed.