全自动半巢式实时荧光定量PCR技术检测 BALF诊断肺结核的价值

目的 探讨全自动半巢式实时荧光定量PCR技术（GeneXpert MTB/RIF）检测肺胞灌洗液（BALF）诊断肺结核的价值。方法 采集2016年6月~2018年6月滨州市结核病防治院已经确诊的住院菌阴肺结核269例设为实验组,另收集其他肺部疾病患者87例设为对照组。利用支气管镜术收集肺胞灌洗液;肺胞灌洗液采用涂片法、培养法和GeneXpert MTB/RIF法3种方法检测结核分枝杆菌,分别对其阳性率及检测菌量进行比较。结果 BALF经涂片、培养和GeneXpert MTB/RIF3种方法检测,敏感度分别为23.05%、33.83%和62.08%,特异度分别为97.70%、97.70%和100.00%。GeneXpert MTB/RIF法分别与涂片法和培养法结果比较,差异均有统计学意义（P＜0.05）;涂片法与培养法结果比较,差异有统计学意义（P＜0.05）;对照组涂片和培养均出现2例阳性者,而GeneXpert MTB/RIF为阴性;涂片和培养相同的2例阳性者,经基因芯片检测确定为NTM。269例菌阴肺结核BALF涂片阴性者207例,207例涂片阴性者经GeneXpert MTB/RIF法检测呈阳性者105例,其中GenXpert MTB/RIF 法“极低”量级50例,占47.62%。269例菌阴肺结核BALF培养阴性者178例,178例涂片阴性者经GeneXpert MTB/RIF法检测呈阳性者76例,其中GenXpert MTB/RIF 法“极低”量级37例,占48.68%。结论 GeneXpert MTB/RIF技术结核分枝杆菌阳性检出率高于涂片和培养法,对早期诊断肺结核具有一定的临床应用价值,且操作简单、快速,值得推广。     

肺泡灌洗液mNGS技术在痰菌阴性肺结核患者诊断中的应用

目的:分析肺泡灌洗液宏基因组二代测序(Metagenomic next-generation sequencing,mNGS)技术在痰菌阴性肺结核患者诊断中的应用价值.方法:选取 2020 年 1 月至2023 年12 月我院收治的60 例痰菌阴性疑似肺结核患者作为研究对象,所有患者均采集肺泡灌洗液标本,并行抗酸染色及mNGS技术检查,以临床诊断结果为金标准,分析两种检查手段的诊断效能.结果:临床诊断结果显示,60 例痰菌阴性疑似肺结核患者中,48 例痰菌阴性肺结核患者,12 例非肺结核患者;所有患者中被确诊为痰菌阴性肺结核患者 48 例,以男性(60.42%)、年龄＜50 岁(68.75%)、有吸烟史(52.08%)、病灶累及右肺上叶(47.92%)、形态为肺叶/段实变(72.92%)等为主;肺泡灌洗液mNGS技术诊断痰菌阴性肺结核的准确度、敏感度分别为 90.00%、87.50%,高于抗酸染色诊断的 73.33%、68.75%(P＜0.05).结论:肺泡灌洗液mNGS技术对痰菌阴性肺结核具有较高的诊断效能,相较于抗酸染色能提高诊断的准确度及敏感度.     

结核杆菌伽马干扰素释放试验联合NK细胞及炎症因子变化检测在肺结核诊断及预后中的应用价值分析

目的研究结核杆菌伽马干扰素释放试验(TB-IGRAs)联合NK细胞及炎症因子变化检测在肺结核诊断及预后中的应用价值。方法回顾性分析2015年12月至2017年12月我院收治的疑似肺结核患者600例,选择同期于我院体检正常的健康对照200例。所有受试者均行TB-IGRAs,并检测NK细胞及炎症因子变化情况,评价各指标单独及联合检测在肺结核诊断和预后中的应用价值。结果 600例患者中肺结核共355例,非肺结核共245例,非肺结核患者主要疾病为肺部感染(165例,67.35%)。3组受试者NK细胞、炎症因子水平以及TB-IGRAs阳性率差异显著,其中肺结核组IP-10、MIP-1α、IL-8水平以及TB-IGRAs阳性率显著高于非肺结核组和健康组,而NK细胞水平显著低于非肺结核组和健康组(P0.05)。TB-IGRAs、NK细胞以及所有细胞因子联合诊断的敏感性、特异性以及准确度均显著高于单项检测(P0.05)。IL-8、MIP-1α以及联合检测的ROC曲线下面积分别为0.713、0.784、0.898,差异具有统计学意义(P0.05)。肺结核患者经6个月治疗后,死亡38例(10.70%),其中死亡组患者NK细胞水平显著低于生存组,而IL-2、IL-8、IL-15、IP-10、MIP-1α水平显著高于生存组,联合诊断阳性组患者死亡率(11.24%)显著高于TB-IGRAs阳性组(6.51%),差异有统计学意义(P0.05)。结论 TB-IGRAs联合NK细胞及炎症因子变化可提高活动性肺结核诊断的灵敏度、准确度,以及有效反应患者预后进展,值得临床推广。     

Xpert结核分枝杆菌/利福平试验对结核病及耐多药结核病诊断价值的Meta分析

目的 评估Xpert结核分枝杆菌/利福平（MTB/RIF）试验对结核病的诊断价值.方法 检索PubMed、Medline、中国知网、万方数据库等,收集Xpert MTB/RIF试验对结核病诊断价值的文献,检索起止时间均为建库至2012年6月.2名研究者独立进行资料提取和文献质量评估.采用Meta-Disc 1.4软件进行Meta分析.结果 共纳入26篇文献,其中2篇文献涉及儿童病例,包含了13 270例来自临床患者的检测标本.Meta分析结果显示,Xpert MTB/RIF试验诊断结核病的汇总敏感度为87%（95%CI：86%～88%）、特异度为97%（95%CI：97%～97%）.按照结核病的类型和患者年龄进行亚组分析,Xpert MTB/RIF试验诊断肺结核的敏感度高于肺外结核病,90%（95%CI：89%～91%） vs 76%（95%CI：72%～79%）;诊断涂阴菌阳性和涂阳菌阳性结核病的敏感度分别为74%（95%CI：71%～76%）和99%（95%CI：98%～99%）;对儿童肺结核的诊断敏感度比成人肺结核低,74%（95%CI：65%～83%） vs 90%（95%CI：89%～92%）.Xpert MTB/RIF试验诊断耐多药结核病的敏感度为96%（95%CI：94%～97%）,特异度为98%（95%CI：98%～99%）.结论 Xpert MTB/RIF试验诊断结核病的价值较高,尤其是成人结核病及耐多药结核病.Xpert MTB/RIF试验在儿童结核病中的诊断价值由于纳入文献较少,尚待进一步研究.     

2013~2017年南昌市学生肺结核流行特征及防制措施

目的 分析南昌市学生结核病流行特征,为制定南昌市学校结核病防控策略提供科学依据。方法 采用描述性流行病学方法,对南昌市2013~2017年《结核病管理信息系统》登记报告的学生结核病患者的发病数据进行分析。结果 南昌市2013~2017年累计报告学生肺结核1093例,年均报告发病率为15.58/10 万,各年学生肺结核报告发病率比较,差异有统计学意义（P＜0.05）;2013~2017年南昌市学生肺结核登记发病率从17.47/10万上升至17.54/10万。男生发病数是女生的2.26倍,15~20岁病例数最多（50.32%）,每年以第二季度为结核病发病高峰期（28.82%）。患者以因症就诊、推荐方式为主（71.27%）,绝大多数是初治肺结核（99.63%）。学生涂阳肺结核患者治愈率为94.62%,涂阴肺结核患者治愈率为97.57%。结论 近5年来南昌市学生结核病疫情呈上升趋势,建议进一步重视学生健康,优化校园生态环境,健全学校结核病综合防制网络。     

肺结核患者外周血CD4~+和CD8~+记忆性T细胞亚群、IL-17、IL-27表达的初步探讨

目的:探讨肺结核患者外周血CD4+和CD8+记忆性T细胞亚群及白细胞介素17(Interleukin-17,IL-17),IL-27的表达。方法:采用流式细胞术检测肺结核患者组外周血CD4+和CD8+记忆性T细胞,患者组按治疗史分为初治组,复治组;按痰涂片抗酸染色分为痰涂阳性组,痰涂阴性组。初治组8例为凡既往未用过抗结核药物治疗或用药时间少于一个月的新发病例;复治组22例为凡既往应用抗结核药物一个月以上的新发病例、复发病例、初治治疗失败病例等;痰涂阳组9例为痰涂片抗酸染色阳性;痰涂阴组21例为痰涂片抗酸染色阴性。ELISA法检测IL-17,IL-27。结果:①与健康对照组比较:患者组CD4+效应型记忆性T细胞均显著增高(P<0.05),初治组与涂阴组CD8+效应型记忆性T细胞均显著降低(P<0.05),复治组IL-17显著降低(P<0.05),而IL-27显著增高(P<0.05)。②与初治组比较:复治组CD4+中央型记忆性T细胞显著降低(P<0.05),而CD8+效应型记忆性T细胞显著增高(P<0.05),IL-17显著降低(P<0.05),IL-27显著增高(P<0.05)。③与涂阴组比较:涂阳组CD4+中央型记忆性T细胞显著降低(P<0.05),CD8+效应型记忆性T细胞显著增高(P<0.05),CD8+中央型记忆性T细胞显著降低(P<0.05)。④Spearman相关性分析显示:IL-17与IL-27呈正相关(P<0.05),记忆性T细胞亚群与IL-17,IL-27水平无显著相关性(P>0.05)。结论:肺结核患者外周血CD4+效应型记忆性T细胞的表达可望作为TB初步诊断的观察指标,CD4+中央型记忆性T细胞和CD8+效应型记忆性T细胞的表达均可望作为TB患者的临床分组依据,TB外周血IL-17、IL-27水平可望用于判断TB的炎症程度。     

华支睾吸虫感染对诊断活动性肺结核的影响分析

目的 通过对华支睾吸虫感染者与非感染者有关资料的对比分析，了解华支睾吸虫感染后对活动性肺结核的影响情况。方法 收集2004～2005年间呼吸科病房以呼吸系疾病收治的并有进行粪便找华支睾吸虫虫卵、结核菌素皮试（PPD皮试）和血清抗结核抗体（PPD-IgG）检测结果的139份病案资料分为：初治涂阳肺结核组56例（简称初治涂阳组）、初治玲，阴肺结核组53例（简称初治涂阴组）、肺部非结核疾病组30例（简称肺部疾病组）作为回顾性分析的对象。结果 ①三组患者的粪便华支睾吸虫虫卵阳性率分别为：初治涂阳组26．8％（15／56）、初治涂阴组11．3％（6／53）和肺部疾病组6.7％（2／30）。初治涂阳组与肺部疾病组比较，x^2=4．986，P〈0．05。②各组的华支睾吸虫感染者PPD皮试阳性率只达20％以下，而非感染者PPD皮试阳性率却可达到50．0～67．9％。二组肺结核患者与肺部疾病组患者比较x^2=42．423，P〈0．005。③二组肺结核患者与肺部疾病组患者PPD皮试、PPD-IgG二项阳性结果的比较，x^2=11．631，P〈0．005。结论 华支睾吸虫感染者可能为肺结核发病的危险因素和PPD皮试、PPD—IgG检测阳性率的影响因素。     

新疆塔城地区结核病控制项目经济与社会效益分析

目的：通过分析我国结核病控制项目经济与社会效益,取长补短、查漏补缺为今后的结核病控制的持续发展提供查考意见;方法采用回顾性方法对2010年~2012年实行的结核病控制项目资料进行分析,通过成本-效果、成本-效益、成本-效益对这些资料中的控制项目进行经济学评价;结果2010年~2012年,抽样地区共诊断可疑结核病患者12271例,发现2535例活动性肺结核患者,其中初治涂阳患者1894例,占74.7%,初治涂阴患者1219例,占48.1%,复治涂阳患者600例,占23.6%;结论有效控制了抽样地区的结核病疫情,保护了易感人群,促进了当地经济发展,取得了巨大的经济与社会效益。     

结核分枝杆菌多抗原蛋白芯片对儿童结核病的诊断价值

目的探讨结核分枝杆菌（MTB）多抗原蛋白芯片对儿童结核病的诊断价值。方法选取2005年4月至2006年4月在首都医科大学附属北京儿童医院诊断为结核病的住院患儿作为结核病组。选取同期住院，患感染性疾病，同时除外结核病的患儿作为非结核病组；选取体检纯化蛋白衍生物（PPD）试验阳性，既往无结核病史，无明显结核中毒症状，胸部影像学及腹部B超检查未见结核病灶的儿童作为结核感染组；选取同期行健康体检，卡疤试验阳性，无基础疾病，无结核接触史的儿童为健康对照组。各组留取血清标本。计算结核病组PPD试验阳性率及细菌学检查阳性率。应用MTB多抗原蛋白芯片同时检测标本中脂阿拉伯甘露糖（LAM）、相对分子质量16000和38000蛋白IgG抗体，通过蛋白芯片阅读仪判断结果，其中任意1种或1种以上抗体检测阳性，即判为蛋白芯片检测阳性。分别计算各组抗体检测阳性率，并计算该方法检测儿童结核病的灵敏度、特异度、阳性预测值和阴性预测值等指标。应用Logistic回归及，检验分析蛋白芯片检测阳性率与患儿年龄、病程、抗结核治疗时间、激素使用以及结核病类型的关系。结果研究期间共纳入结核病组79例，非结核病组33例，结核感染组15例，健康对照组30例。蛋白芯片检测结核病组的阳性率为34．2％（27／79），低于PPD试验阳性率（84．8％，67／79），高于细菌学检查阳性率（12．7％，10／79）。在非结核病组阳性率为6．1％（2／33），结核感染组和健康对照组阳性率为0。蛋白芯片检测结核病组的灵敏度为34．2％，特异度为97．4％。阳性预测值93．1％，阴性预测值58．5％。Logistic回归发现蛋白芯片检测阳性率仅与病程相关，且随病程延长而阳性率升高。病程〈1个月，蛋白芯片检测阳性率为18．8％（6／32），病程在～3个月，蛋?     

实时荧光PCR与BACTEC MGIT 960快速培养在初治痰涂片阴性未受抗结核治疗的肺结核诊断中的应用

目的:探讨实时荧光PCR与BACTEC MGIT 960分枝杆菌快速培养(快速培养法)准确诊断初治痰涂片阴性(涂阴)且未经受抗结核治疗的肺结核可能性。方法:实验组:368份临床诊断活动性肺结核患者的初治涂片阴性痰标本;对照组:55份非结核性肺部疾病患者的痰液标本。用FQ-PCR技术、快速培养法及改良罗氏培养参考法对两组标本进行分析,观察指标为TB-DNA和结核菌阳性率。结果:实验组和对照标本中FQPCR技术、快速培养法和改良罗氏培养参考法检测的TB-DNA或结核菌阳性率分别为:16.85%、23.37%、22.01%和1%、0%、0%。三种方法分别平均耗时3h、9.6d和28d。以改良罗氏培养参考法为参照,FQ-PCR法和快速培养法的敏感性分别为69.1%和100%;特异性分别为91.2%和98.6%。结论:FQ-PCR和快速培养法均能提高初治涂阴肺结核患者的早期确诊率,但FQ-PCR的敏感性尚需进一步提高。     

The validity of acid-fast smears in the diagnosis of pulmonary tuberculosis.

The acid-fast smear remains an important tool in the diagnosis of tuberculosis. Some reports have questioned the validity of this stain in situations of low prevalence. We examined the relationship between prevalence and predictive value of sputum smears in one laboratory during periods of both low and high laboratory prevalence of Mycobacterium tuberculosis. Smears were examined by fluorescence and confirmed by Kinyoun stain. The number of samples positive for mycobacteria increased from 128 (4.3%) of 2956 during the 1975 through 1978 study period to 197 (8.4%) of 2347 during the 1979 through 1982 study period. Of 47 positive smears during the first study period, only one was a false-positive. None of 96 positive smears during the second period was a false-positive. The positive predictive value of acid-fast microscopy was 97.9% and 100% for the two periods examined. We have demonstrated in practice the small effect of a shift in prevalence on the positive predictive value of an acid-fast smear when specificity is maintained.     

GeneXpertMTB/RIF Assay对肺部结核的临床诊断及治疗价值

目的:探究GeneXpertMTB/RIF Assay对临床诊断及治疗肺部结核的应用价值.方法:收集2019年1月至2019年12月在甘孜藏族自治州人民医院住院的肺结核患者的痰液标本148份,同时选取50份非结核肺部感染患者的痰液标本作为对照.分别采用涂片抗酸杆菌检查、MGIT960检测MTB及药敏法和GeneXper...     

Clinical evaluation of the Roche AMPLICOR PCR Mycobacterium tuberculosis test for detection of M. tuberculosis in respiratory specimens.

The reliability of the Roche AMPLICOR Mycobacterium tuberculosis test (AMPLICOR MTB) for the diagnosis of pulmonary tuberculosis was evaluated by testing 956 respiratory specimens from 502 patients and comparing results with results by culture and medical history. Of those 135 specimens that were culture positive for mycobacteria, 61 specimens from 31 patients grew M. tuberculosis. Fifty-two specimens were smear positive for acid-fast bacteria (AFB); M. tuberculosis was isolated from 41 of these specimens. On initial testing, the sensitivity and specificity of the AMPLICOR MTB assay, compared with culture, were 78.7 and 99.3%, respectively. After resolution of discrepancies (by review of medical history), the sensitivity, specificity, and positive and negative predictive values of the AMPLICOR MTB assay were 79.4, 99.6, 92.6, and 98.6%, respectively. Two specimens from two patients with no clinical evidence of tuberculosis were AMPLICOR MTB positive and culture positive for Mycobacterium avium complex. For AFB smear-positive specimens, the sensitivity, specificity, and positive and negative predictive values of AMPLICOR MTB were 97.6, 100, 100, and 90.9%, respectively. For AFB smear-negative specimens, the sensitivity, specificity, and positive and negative predictive values of AMPLICOR MTB were 40.0, 99.5, 69.2, and 98.7%, respectively. Our results support the use of AMPLICOR MTB for rapid diagnosis of tuberculosis in patients whose respiratory specimens are AFB smear positive. Further studies are needed to determine the most clinically relevant and cost-effective use of this assay with AFB smear-negative specimens.     

Rapid diagnosis by buffy coat smear of disseminated Mycobacterium avium complex infection in patients with acquired immunodeficiency syndrome.

A smear of the buffy coat of peripheral blood for acid-fast bacilli was assessed for sensitivity and specificity in the diagnosis of disseminated Mycobacterium avium complex (MAC) infection in acquired immunodeficiency syndrome (AIDS) patients. Seventeen AIDS patients with blood cultures positive for MAC had simultaneous quantitative blood cultures and buffy coat smears performed, as did 4 patients later proven not to have disseminated MAC. The sensitivity of the buffy coat smear for the detection of MAC was 35%, the specificity was 100%, the positive predictive value was 100%, and the negative predictive value was 22%. We conclude that the buffy coat smear is a rapid, simple, and specific method of diagnosis of disseminated MAC infection in AIDS patients, although it is not very sensitive.     

Evaluation of the semiautomated Abbott LCx Mycobacterium tuberculosis assay for direct detection of Mycobacterium tuberculosis in respiratory specimens.

Five hundred twenty processed respiratory specimens from 326 patients received for the diagnosis of tuberculosis or other mycobacterial infections were tested by means of the LCx Mycobacterium tuberculosis Assay from Abbott Laboratories, which uses ligase chain reaction technology for the direct detection of M. tuberculosis complex in respiratory specimens. The results of the LCx M. tuberculosis Assay were compared with the results of culture and staining techniques. After a combination of culture results and the patient's clinical data, a total of 195 specimens were collected from 110 patients who were positively diagnosed as having pulmonary tuberculosis. Twenty-three of these 195 specimens which corresponded to 10 patients with a history of pulmonary tuberculosis (TB) and anti-TB treatment ranging from 1 to 6 months were culture negative. The other 172 specimens were culture positive for M. tuberculosis. With an overall positivity rate of 37.5% (195 of 520 specimens), the sensitivity, specificity, and positive and negative predictive values were 90.8, 100, 100, and 94.7%, respectively, for the LCx M. tuberculosis Assay; 88.2, 100, 100, and 93.4%, respectively, for culture; and 82.6, 92, 72.9, and 97.6%, respectively, for acid-fast staining. For 161 specimens (82.6%) from patients smear positive for the disease and 34 specimens (17.4%) from patients smear negative for the disease, the sensitivity values for the LCx M. tuberculosis Assay were 98.8 and 53%, respectively. There were no statistically significant differences in the sensitivities and specificities between the LCx M. tuberculosis Assay and culture (P > 0.05). Conclusively, the LCx M. tuberculosis Assay has proved to have an acceptable sensitivity and a high specificity in detecting M. tuberculosis and has the potential of reducing the diagnosis time to an 8-h working day.     

Evaluation of Amplicor MTB test as adjunct to smears and culture for direct detection of Mycobacterium tuberculosis in the French Caribbean.

A total of 784 specimens collected from 370 individuals between January and August 1995 were analyzed by using the Amplicor Mycobacterium tuberculosis test (Roche Diagnostic System, Basel, Switzerland), a PCR-based test for the direct detection of organisms of the M. tuberculosis complex. The PCR results were compared with standard bacteriological data, including those obtained by acid-fast microscopy, culture, and biochemical identification as well as final clinical diagnosis for each patient. Several parallel controls were used: the kit DNA positive control, 10(3) CFU of M. tuberculosis, and three negative controls for each independent assay. No false-positive PCR results were obtained, and overall, M. tuberculosis was detected in 20 of 370 individuals screened. Five additional patients during the same time were found to be infected with mycobacteria other than tubercle bacilli; their specimens gave positive smear and/or culture test results, but Amplicor tests were always negative. The sensitivity, specificity, positive predictive value, and negative predictive value for the Amplicor MTB test compared with culture per specimen were 76.7, 97.7, 66.0, and 98.6%, respectively. For resolved cases, these values were, respectively, 69.4, 100, 100, and 96.8%; however, the sensitivity and negative predictive value increased to 90.9 and 99.2%, respectively, if PCR-negative nonrespiratory specimens (gastric washings) were not considered. When only specimens from proven tuberculosis patients were considered (n = 114) and the sum of PCR-positive and/or culture-positive samples from proven tuberculosis patients was considered the total number of positive samples, PCR had a sensitivity of 83.3% compared with 71.6% for culture. Results per patient (about three samples each) yielded 100% sensitivity and 100% specificity. We conclude that the Amplicor MTB test is highly specific and rapid for routine use in a clinical laboratory. However, in order to obtain a higher degree of sensitivity, it should be run as an adjunct to smears and culture with at least three samples for each patient, and a single-sample PCR-negative results must be considered carefully because of potential false-negatives.     

Q-beta replicase-amplified assay for detection of Mycobacterium tuberculosis directly from clinical specimens.

We report the results of a study conducted to evaluate the performance of manual Q-Beta replicase-amplified Mycobacterium tuberculosis complex assay compared with that of culture for detecting M. tuberculosis directly from digested sputum pellets. A total of 261 specimens submitted to three tuberculosis testing laboratories were analyzed. Culture and acid-fast bacillus smear results were provided by the tuberculosis testing laboratories. Of these 261 specimens, 34 (13% prevalence rate) were positive for M. tuberculosis by culture. The samples were digested and decontaminated by the testing laboratories by using their standard digestion and decontamination procedures. An aliquot of the digested and decontaminated pellet was sent to GENE-TRAK. The digested and decontaminated pellet was neutralized by washing it with 0.067 M phosphate buffer (pH 6.8), and the bacteria present in the washed pellet were heat inactivated at 100 degrees C for 15 min. The samples were combined with sample processing buffer containing GuSCN and were treated for 6 min in the GENE-TRAK Sample Processing Instrument to release the nucleic acids. The release rRNA was analyzed in a manual Q-Beta replicase assay format which incorporates elements of sandwich hybridization, reversible target capture, and Q-beta replicase signal amplification technologies. In comparison with culture, the overall assay sensitivity and specificity were 97.1 and 96.5%, respectively. The positive predictive value was 80.5%, and the negative predictive value was 99.5%. After analysis of discrepant results, the assay sensitivity and specificity were 97.3 and 97.8, respectively, and the prevalence rate was 14%. The positive predictive value and the negative predictive value were 87.8 and 99.5%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Usefulness of a new mycobacteriophage-based technique for rapid diagnosis of pulmonary tuberculosis

A new mycobacteriophage-based technique (PhageTek MB) was compared with standard culture and staining techniques for diagnosis of pulmonary tuberculosis. A total of 2,048 respiratory specimens from 1,466 patients collected from February 2000 to March 2001 were studied by both (i) conventional methods (direct microscopic examination [auramine-rhodamine fluorochrome], and culture in BacT/ALERT 3D and solid media) and (ii) the PhageTek MB assay. This phenotypic test utilizes specific mycobacteriophages to detect the presence of live Mycobacterium tuberculosis complex organisms within a decontaminated clinical sample. Overall, 205 (10%) specimens were positive for mycobacteria (134 patients): 144 (70.2%) M. tuberculosis isolates and 61 (29.8%) nontuberculous mycobacterium isolates (30 Mycobacterium kansasii, 12 Mycobacterium xenopi, 9 Mycobacterium gordonae, 7 Mycobacterium avium complex, 2 Mycobacterium chelonae, and 1 Mycobacterium fortuitum isolate). PhageTek MB was more likely to give a positive result with specimens in which high numbers of acid-fast bacilli were observed on the smear. The sensitivity, specificity, and positive and negative predictive values of this mycobacteriophage-based technique versus culture for M. tuberculosis were 58.3, 99.1, 83.2, and 96.9%, respectively. PhageTek MB is a rapid (48-h), specific, safe, and easy-to-perform test. According to the prevalence of the disease in the population studied, the test would require improved sensitivity in order to be used as a screening test for routine diagnosis of respiratory tuberculosis in our setting.     

Are three sputum acid-fast bacillus smears necessary for discontinuing tuberculosis isolation?

To evaluate the efficacy of three sputum acid-fast bacillus (AFB) smears to rule out pulmonary tuberculosis, sputum AFB smear and culture results were analyzed at two university-affiliated teaching hospitals. The negative predictive value of the smear increased by only 0.2% on days 2 and 3 each, indicating that in low-prevalence populations, there is limited value in requiring three negative sputum AFB smears before discontinuing tuberculosis isolation.