Distinguish Mycobacterium Tuberculosis Research Articles

Specific Cytokines Analysis Incorporating Latency-Associated Antigens Differentiates Mycobacterium tuberculosis Infection Status: An Exploratory Study.

Current immunologic methods cannot distinguish Mycobacterium tuberculosis (Mtb) infection statuses, especially to discriminate active tuberculosis (ATB) from latent tuberculosis infection (LTBI). This study explored the potential of latency-associated antigens (Rv1733cSLP and Rv2028c) and multifactorial cytokine detection to distinguish tuberculosis infection states. ATB patients (20), LTBI healthcare workers (25), fever patients (11), and healthy controls (10) were enrolled. Cytokine levels (IFN-γ, TNF-α, IL-2, IL-6, IP-10, IL-1Ra, CXCL-1, and MCP-1) were measured using Luminex with/without MTB-specific virulence factor and latency-associated antigens stimulation. Without antigen stimulation, IL-6, IP-10, MCP-1, and IL-1Ra were higher in the ATB group than in the LTBI group (p<0.05), but no significant differences between the ATB group and the fever group. Stimulated with the four antigens, respectively, the cytokines, including IP-10Esat-6, IP-10CFP-10, IFN-γRv1733cSLP, IFN-γRv2028c, IL-6Esat-6, IL-6Rv1733cSLP, IL-6Rv2028c, IL-2Rv1733cSLP, IL-2 Rv2028c, IL-1RaEsat-6, IL-1RaCFP-10, IL-1RaRv2028c, CXCL-1Esat-6, CXCL-1CFP-10, CXCL-1Rv1733cSLP, CXCL-1Rv2028c, MCP-1Esat-6 and MCP-1CFP-10, demonstrated accurate discrimination between ATB and LTBI (p<0.05). Additive concentrations demonstrated significant secretion differences of IFN-γ, IP-10 and IL-2, primarily by virulence factors in ATB and latency-associated antigens in LTBI. Latency-associated antigens synergized with virulence factors, enhancing TH1-type cytokine diagnostic efficacy for discriminating ATB from LTBI, the AUC for TNF-α increased from 0.696 to 0.820 (p=0.038), IFN-γ increased from 0.806 to 0.962 (p=0.025), and IL-2 increased from 0.565 to 0.868 (p=0.007). Model selected by forward likelihood method indicated combined detection of IFN-γCFP-10, IFN-γRv1733cSLP, IP-10Rv1733cSLP, and CXCL-1Rv1733cSLP achieved ATB diagnosis (AUC=0.996) and ATB-LTBI differentiation (AUC=0.992). Combined detection of IFN-γCFP-10 and IFN-γRv1733cSLP achieved tuberculosis infection diagnosis (AUC=0.943). Latency-associated antigens enhance multiple cytokine discriminatory ability, particularly TH1-type cytokines, for differentiating Mtb infection statuses.

Hematological profiles of patients with tuberculosis and nontuberculous mycobacteria infections in Bamako, Mali.

Pulmonary tuberculosis (TB) remains one of the main causes of morbidity and mortality in Mali. Nontuberculous mycobacteria (NTM) infections are very common but are often cofounded with TB because of the similarity of symptoms, which makes the diagnosis difficult. Hematological abnormalities associated with TB have been described, but not with NTM. Therefore, the goal of this study was to compare the hematological parameters of patients infected with TB and NTM infections. A cross-sectional study enrolling TB and NTM participants was conducted in 2018-2020. Five milliliters of venous blood and sputum samples were collected from each participant to determine the hematological parameters using the RUBY CELL-DYN Ruby Version 2.2 ML. A BACTEC MGIT 960 and multiplex reverse transcription-polymerase chain reaction were used to distinguish Mycobacterium tuberculosis from NTM, respectively. Of the total 90 patients enrolled, there was a decrease in hemoglobin and hematocrit levels in both the groups (P = 0.05). In addition, we found that the percentages of basophil cells (P = 0.01) and mean values of platelets (P = 0.04) were significantly higher in TB patients than those of NTMs. Moreover, the mean of absolute values of eosinophil cells of TB patients was significantly lower than those of NTMs (P = 0.03). We found significant statistical differences in basophils, platelets, and eosinophils in differentiating TB and NTM in this pilot study. Future studies with patients at different clinical stages are needed to confirm the hematological profiles of TB and NTM patients.

Development of diagnostic algorithm using machine learning for distinguishing between active tuberculosis and latent tuberculosis infection

BackgroundThe discrimination between active tuberculosis (ATB) and latent tuberculosis infection (LTBI) remains challenging. The present study aims to investigate the value of diagnostic models established by machine learning based on multiple laboratory data for distinguishing Mycobacterium tuberculosis (Mtb) infection status.MethodsT-SPOT, lymphocyte characteristic detection, and routine laboratory tests were performed on participants. Diagnostic models were built according to various algorithms.ResultsA total of 892 participants (468 ATB and 424 LTBI) and another 263 participants (125 ATB and 138 LTBI), were respectively enrolled at Tongji Hospital (discovery cohort) and Sino-French New City Hospital (validation cohort). Receiver operating characteristic (ROC) curve analysis showed that the value of individual indicator for differentiating ATB from LTBI was limited (area under the ROC curve (AUC) < 0.8). A total of 28 models were successfully established using machine learning. Among them, the AUCs of 25 models were more than 0.9 in test set. It was found that conditional random forests (cforest) model, based on the implementation of the random forest and bagging ensemble algorithms utilizing conditional inference trees as base learners, presented best discriminative power in segregating ATB from LTBI. Specially, cforest model presented an AUC of 0.978, with the sensitivity of 93.39% and the specificity of 91.18%. Mtb-specific response represented by early secreted antigenic target 6 (ESAT-6) and culture filtrate protein 10 (CFP-10) spot-forming cell (SFC) in T-SPOT assay, as well as global adaptive immunity assessed by CD4 cell IFN-γ secretion, CD8 cell IFN-γ secretion, and CD4 cell number, were found to contribute greatly to the cforest model. Superior performance obtained in the discovery cohort was further confirmed in the validation cohort. The sensitivity and specificity of cforest model in validation set were 92.80% and 89.86%, respectively.ConclusionsCforest model developed upon machine learning could serve as a valuable and prospective tool for identifying Mtb infection status. The present study provided a novel and viable idea for realizing the clinical diagnostic application of the combination of machine learning and laboratory findings.

Genotyping of Mycobacterium tuberculosis in Liaoning with variable number of tandem repeats method

Objective To explore the genotype distribution and transmission patterns of 81 Mycobacterium tuberculosis (MTB) clinical isolates from Liaoning province with the variable number tandem repeats (VNTR). Methods The 81 strains were isolated from each city of the province in 2018, the p-nitrobenzoic acid (PNB) was used to identify the flora, so as to distinguish Mycobacterium tuberculosis complex from non-tuberculous mycobacteria. The solid ratio method was used to conduct drug susceptibility tests on four first-line anti-tuberculosis drugs using Roche's medium. Based on PCR, the standard 24 sites were detected and analyzed, and the Beijing genotype was identified by the RD105 gene deletion method. Microsoft Excel software was used for polymorphism analysis, and website ( https://www.miru-vntrplus.org/MIRU/index ) was used to get the VNTR genotyping results, the locus polymorphism and clustering rate at the same time was calculated. SPSS 23.0 software was used for statistical description of data, and χ 2 test carried out on count data or drug resistance in each year; when the theoretical frequency is less than 5, the Fisher exact probability method is used to calculate the two-sided P value, and the test level is α=0.05. Results The clustering analysis of genotype showed that 81 strains were categorized into 3 gene clusters (genogroup I, II and III), in which 1.23% (1/81) was belong to genogroup I, 4.94% (4/81) was genogroup II, and 93.83% (76/81), one of the largest group of genes for III group. The clustering rate was 4.94% (4/81) and the least estimated proportion of the recent infection rate was 2.47% (2/81). The polymorphism of 5 in 24 VNTR loci was better, 3 loci was acceptable, the remaining 16 loci was less polymorphic. Conclusion The drug resistant Mycobacterium tuberculosis shows obvious gene polymorphisms in Liaoning province and Beijing genotype is the predominant prevalent strain (III group). 摘要 ：目的了解辽宁省81例结核分枝杆菌多位点数目可变串联重复序列分析(variable number of tandem repeats. VNTR)的基因多态性及近期传播情况。 方法 对2018年辽宁省内送至辽宁省疾病预防控制中心实验室的菌株进行传 代后米用对硝基苯甲酸(p-nitrobenzok: acid, PNB)培养基进行菌群鉴定, 以区分结核分枝杆菌复合体和非结核分枝杆 菌。采用固体比例法利用罗氏培养基对4种一线抗结核药物进行药敏实验。以PCR为基础对标准24位点进行检测分 析, 利用RD105基因缺失法鉴定北京基因型。利用Microsoft Excel软件进行多态性分析, 利用 https://www.miru-vntrplus.org/MIRU/index 网站得到VNT R基因分型结果, 同时进行位点多态性和成簇率的计算。采用SPSS 23.0软件进行数据的 统计描述 , 对计数资料或各年度耐药情况进行 χ 2 检验；当理论频数<5时 , 采用Fisher确切概率法计算双侧 P 值, 检验水 准α=0.05。 结果 经分析81株菌株可分为3个基因群（I、Ⅱ、Ⅲ), 菌株数分别为1(1.23%)、4(4.94%)和76(93.83%), 其中最大的基因群为Ⅲ群。成簇率为4.94%(4/81)。近期感染率最小估计值为2.47%(2/81)。24个VNTR位点中有5 个位点的多态性较好, 3个位点的多态性尚可, 16个位点的多态性较差。 结论 初步证实辽宁省耐药结核分枝杆菌菌 株存在明显的基因多态性, 其主要流行型为北京基因型（Ⅲ群）。

High degree of fluoroquinolone resistance among pulmonary tuberculosis patients in New Delhi, India.

Background & objectives:The fluoroquinolones (FQs) group of antibiotics is the backbone drugs for the management of drug-resistant tuberculosis (TB). In routine clinical practice, drug susceptibility testing (DST) for FQs is not performed, and the patients are empirically treated. A limited information exists regarding FQs resistance among pulmonary TB cases. The present study was conducted to determine the FQs resistance among drug sensitive and drug-resistant pulmonary TB patients in a tertiary care centre in north India.Methods:A total of 1619 sputum/smear-positive specimens of pulmonary TB patients were subjected to DST for first-line drugs (FLDs) and second-line drugs. In addition, FQs DST was also performed using automated Mycobacterial Growth Indicator Tube-960 liquid culture technique. The immuno-chromatographic assay was performed to distinguish Mycobacterium tuberculosis complex (MTBC) from non-MTBC.Results:Mycobacterium tuberculosis (Mtb) was isolated in 1499 sputum specimens; 1099 culture specimens were sensitive to FLDs, 249 grew as multidrug-resistant (MDR) Mtb and the remaining 151 isolates revealed any drug resistance to FLDs. While FQs monoresistance among the FLD sensitive isolates was 3.1 per cent (35/1099), 27.3 per cent (68/249) among MDR Mtb isolates had additional FQs resistance.Interpretation & conclusions:FQs resistance among drug sensitive and MDR Mtb isolates was high in Delhi, India. Based on these findings, it is recommended that the DST for FQs should be routinely performed to avoid further amplification of drug resistance.

Update on trends in childhood tuberculosis.

Although tuberculosis (TB) causes much morbidity and mortality in children, diagnosis and treatment remain challenging. Recently, children have gained increasing attention in research and clinical trials driving improved contact management, case identification and treatment of both drug-susceptible and drug-resistant TB. This review highlights some recent advances. The tuberculin skin test is the most widely used test to distinguish Mycobacterium tuberculosis (M. tuberculosis) infection from active TB, however, using M. tuberculosis-specific, antigenic stimulation of CD4 and CD8 cells appear more effective. The use of Xpert MTB/RIF to identify M. tuberculosis in clinical samples, together with novel sampling methods have in part, overcome the difficulty of sampling and increased case identification capacity. Advances in treating both drug-susceptible and drug-resistant childhood TB show promise in being more paediatric friendly and improving adherence. Dosing strategies for drug-sensitive TB have improved with dispersible fixed drug combinations now available. In the treatment and prevention of drug-resistant TB, however, research involving the use of newer and more effective drugs currently recommended for adults, are still ongoing in children. The World Health Organization aims to end the TB epidemic by 2035 whereas the United Nations' Sustainable Developmental Goals sets this ambitious target for 2030. Therefore, adequate funding and implementing effective national TB programs must be prioritized, particularly in high-burden, low-income settings.

Antigen 85B peptidomic analysis allows species-specific mycobacterial identification

BackgroundNontuberculous mycobacteria (NTM)-mediated infections are a growing cause of worldwide morbidity, but lack of rapid diagnostics for specific NTM species can delay the initiation of appropriate treatment regimens. We thus examined whether mass spectrometry analysis of an abundantly secreted mycobacterial antigen could identify specific NTM species.MethodsWe analyzed predicted tryptic peptides of the major mycobacterial antigen Ag85B for their capacity to distinguish Mycobacterium tuberculosis and three NTM species responsible for the majority of pulmonary infections caused by slow-growing mycobacterial species. Next, we analyzed trypsin-digested culture supernatants of these four mycobacterial species by liquid chromatography–tandem mass spectrometry (LC–MS/MS) to detect candidate species-specific Ag85B peptides, the identity of which were validated by LC–MS/MS performed in parallel reaction monitoring mode.ResultsTheoretical tryptic digests of the Ag85B proteins of four common mycobacterial species produced peptides with distinct sequences, including two peptides that could each identify the species origin of each Ag85B protein. LC–MS/MS analysis of trypsinized culture supernatants of these four species detected one of these species-specific signature peptides in each sample. Subsequent LC–MS/MS analyses confirmed these results by targeting these species-specific Ag85B peptides.ConclusionsLC–MS/MS analysis of Ag85B peptides from trypsin-digested mycobacterial culture supernatants can rapidly detect and identify common mycobacteria responsible for most pulmonary infections caused by slow-growing mycobacteria, and has the potential to rapidly diagnose pulmonary infections caused by these mycobacteria through direct analysis of clinical specimens.

Identification of Mycobacteria isolated from AIDS patients

Obstract: To identify Mycobacteria isolated from AIDS patients and to evaluate the diagnostic value of MBP64 antigen Colloidal Gold Diagnostic Kit in distinguishing Mycobacterium tuberculosis(MTB) and Nontuberculous mycobacteria (NTM). Methods: A total of 140 Mycobacteria isolates from AIDS patients were collected and identified by using 16SrDNA PCR assay as well as immune colloidal gold technique (MBP64 antigen Colloidal Gold Diagnostic Kit). The sensitivity and specificity of Colloidal Gold method was analyzed. Results: With the results of 16SrDNA PCR assay as gold standard, the sensitivity and specificity of Colloidal Gold method in distinguishing MTB and NTM were 96.00% and 96.84%, respectively. Among 140 samples, 114 were identified by 16SrDNA PCR assay, among which 50 (43.86%) were identified as MTB, and 63 (55.26%) were identified as NTM. The most popular NTM in AIDS patients were Mycobacterium gordonae, Mycobacterium avium and Mycobacterium kansasii. Conclusion: NTM is of high prevalence in AIDS patients, and MBP64 antigen Colloidal Gold Diagnostic Kit can be used as an effective technique in distinguishing NTM and MTB.

Identification and application of ssDNA aptamers against H₃₇Rv in the detection of Mycobacterium tuberculosis.

Microscopy of direct smear with the Ziehl-Neelsen stain is still broadly used in tuberculosis diagnosis. However, this method suffers from low specificity and is difficult to distinguish Mycobacterium tuberculosis (MTB) from nontuberculosis mycobacterial (NTM), since all mycobacterial species are positive in Ziehl-Neelsen stain. In this study, we utilized whole cell SELEX to obtain species-specific aptamers for increasing the specificity of MTB detection. Whole cell SELEX was performed in MTB reference strain H37Rv by two selection processes based on enzyme-linked plate or Eppendorf tube, respectively. To increase success rate of generating aptamers, the selection processes were systematically monitored to understand the dynamic evolution of aptamers against complex structure of target bacteria. Two preponderant groups and ten high-affinity aptamers were obtained by analyzing the dynamic evolution. Preponderant aptamer MA1 from group I showed relatively high binding affinity with apparent dissociation constant (KD value) of 12.02 nM. Sandwich ELISA assay revealed five aptamer combinations effectively bound MTB strains in preliminary evaluation, especially the combination based on aptamer MA2 (another preponderant aptamer from group II) and MA1. Further evaluated in many other strains, MA2/MA1 combination effectively identified MTB from NTM or other pathogenic bacteria, and displayed the high specificity and sensitivity. Binding analysis of aptamer MA1 or MA2 by fluorescence microscopy observation showed high binding reactivity with H37Rv, low apparent cross-reactivity with M. marinum, and no apparent cross-reactivity with Enterobacter cloacae. Taken together, this study provides attractive candidate species-specific aptamers to effectively capture or discriminate MTB strains.

Evaluation of Mycobacterium tuberculosis Early Secreted Antigenic Target 6 Recombinant Protein as a Diagnostic Marker in Skin Test

ObjectivesTuberculosis (TB) is the leading infectious disease in the developing world. Delayed-type hypersensitivity skin test diagnoses TB using tuberculin purified protein derivative (PPD), but this test is incapable of distinguishing Mycobacterium tuberculosis (MTB) infection from bacillus Calmette–Guérin (BCG) vaccination or an infection caused by nontuberculous mycobacteria (NTM). This study was performed to evaluate the use of recombinant early secretory antigenic target 6 (rESAT-6), a secretory protein found only in MTB, Mycobacterium bovis, and few other mycobacterial species, as a skin marker for MTB in guinea pigs. MethodsWe prepared recombinant MTB ESAT-6 and evaluated its use as a specific antigen for MTB in guinea pigs. ResultsOur results show that the purified MTB rESAT-6 antigen is capable of inducing a positive reaction only in guinea pigs sensitized to MTB. No such reaction was observed in the animals sensitized to M. bovis, BCG vaccination, or NTM (Mycobacterium avium). ConclusionOur study results confirm that the ESAT-6 antigen is more specific to MTB infection than PPD and could be used in more specific skin tests for detection of MTB in large animals and in humans.

Validation of Biomarkers for Distinguishing Mycobacterium tuberculosis from Non-Tuberculous Mycobacteria Using Gas Chromatography−Mass Spectrometry and Chemometrics

Tuberculosis (TB) remains a major international health problem. Rapid differentiation of Mycobacterium tuberculosis complex (MTB) from non-tuberculous mycobacteria (NTM) is critical for decisions regarding patient management and choice of therapeutic regimen. Recently we developed a 20-compound model to distinguish between MTB and NTM. It is based on thermally assisted hydrolysis and methylation gas chromatography-mass spectrometry and partial least square discriminant analysis. Here we report the validation of this model with two independent sample sets, one consisting of 39 MTB and 17 NTM isolates from the Netherlands, the other comprising 103 isolates (91 MTB and 12 NTM) from Stellenbosch, Cape Town, South Africa. All the MTB strains in the 56 Dutch samples were correctly identified and the model had a sensitivity of 100% and a specificity of 94%. For the South African samples the model had a sensitivity of 88% and specificity of 100%. Based on our model, we have developed a new decision-tree that allows the differentiation of MTB from NTM with 100% accuracy. Encouraged by these findings we will proceed with the development of a simple, rapid, affordable, high-throughput test to identify MTB directly in sputum.

Specific Antigens to Distinguish &amp;lt;i&amp;gt;M. tuberculosis&amp;lt;/i&amp;gt; from &amp;lt;i&amp;gt;M. avium&amp;lt;/i&amp;gt;

To distinguish Mycobacterium tuberculosis from Mycobacterium avium, specific M. tuberculosis antigens had been studied for improving the early differential diagnosis effect of tuberculosis caused by different Mycobacterium. The rabbit anti-M. avium sera and anti-M. tuberculosis sera were analyzed for antibody-based reactivity by matrix-assisted laser desorption-ionization mass spectrometry (MALDI-TOF Mass) against M. tuberculosis proteins. The immunoreactive spots, which were attributed to the proteins HspX, GroES and CFP-10, were mostly located at 10 - 60 kDa and PI 4 - 6, subsequently Western blotting result proved that HspX and CFP-10 were specific to M. tuberculosis and ELISA testing result of 30 M. avium positive sera showed that GroES were cross-reactive to M. avium. Lastly, positive and negative tuberculosis reference sera and based on the mechanism of indirect ELISA, the specificity and the sensitivity of the methods targeting the antibodies HspX, GroES or CFP-10 were evaluated at 37% and 26%, 12% and 97%, 81% and 98%, respectively. The combination of these three antibody detection methods allowed to reached a specificity of 42%, and of 39% without taken into account of the method targeting the GroES antibody. Using proteomics approach, we found three M. tuberculosis specific antigens showed good potential in tuberculosis diagnosis, providing basic study for serodiagnosis of tuberculosis.

Nontuberculous Mycobacterial Infections

Abstract Context.—Nontuberculous mycobacteria include numerous acid-fast bacilli species, many of which have only recently been recognized as pathogenic. The diagnosis of mycobacterial disease is based on a combination of clinical features, microbiologic data, radiographic findings, and histopathologic studies. Objective.—To provide an overview of the clinical and pathologic aspects of nontuberculous mycobacteria infection, including diagnostic laboratory methods, classification, epidemiology, clinical presentation, and treatment. Data Sources.—Review of the pertinent literature and published methodologies. Conclusions.—Nontuberculous mycobacteria include numerous acid-fast bacilli species, many of which are potentially pathogenic, and are classified according to the Runyon system based on growth rates and pigment production. Their slow growth hinders cultures, which require special medium and prolonged incubation. Although such methods are still used, newer nucleic acid–based technologies (polymerase chain reaction and hybridization assays) can rapidly detect and speciate some mycobacteria—most notably, distinguishing Mycobacterium tuberculosis from other species. Infections caused by these organisms can present as a variety of clinical syndromes, not only in immunocompromised patients but also in immunocompetent hosts. Most common among these are chronic pulmonary infections, superficial lymphadenitis, soft tissue and osteoarticular infections, and disseminated disease. Treatment of nontuberculous mycobacterial infections is difficult, requiring extended courses of multidrug therapy with or without adjunctive surgical intervention.

The capacity of MTD method for distinguishing Mycobacterium tuberculosis and nontuberculosis mycobacteria

目的 应用结核分枝杆菌直接检测(MTD)试剂盒对临床痰液样本及分离的结核分枝杆菌复合群,进行检出率和常规菌型鉴定法符合率的比较和评价.方法 将10株标准菌种(其中1株为H37Rv、9株为非结核分枝杆菌)、94株临床分离菌株(其中48株经常规生化方法分型鉴定为结核分枝杆菌,46株分型法鉴定为非结核分枝杆菌)和40份临床痰标本分别用法国生物梅里埃公司生产的AMPLIFIED-MTD试剂盒进行检测.结果 结核分枝杆菌复合群检测均呈阳性,非结核分枝杆菌检测均呈阴性,符合率均达到100%.临床痰标本用MTD检测的阳性检出率为65%(26/40),明显高于直接涂片法的12%(5/40)、培养方法的12%(5/40)、集菌涂片法的25%(10/40).结论 MTD试验是一套新的生物学检测技术,具有快速、灵敏的特点。

New method for detection of Mycobacterium tuberculosis Direct Test inhibitors in clinical specimens

Existing protocols for the detection of Mycobacterium tuberculosis Direct Test (MDT) inhibitors require substantial quantities of specimen and cannot distinguish Mycobacterium tuberculosis complex from other mycobacteria if inhibitors are present. We describe a preliminary evaluation of a simple and practical protocol for MTD inhibitor testing that circumvents these difficulties.

Diagnosis of abdominal tuberculosis * Authors' reply

We agree with the argument presented by Mr Rai and Mr Thomas (December 2003 JRSM1) for earlier use of diagnostic laparoscopy in suspected abdominal tuberculosis (TB). However, even in the hands of experienced operators the risk is not negligible (though under 1%). The complications, apart from those of general anaesthesia, include damage to blood vessels, bowel and bladder. In Rai and Thomas's series, seemingly, a polymerase chain reaction (PCR) test was not used on the 11 ascitic fluids when acid-fast bacilli were not found. A positive result might have avoided the need for laparoscopy;2,3 furthermore, PCR can help to distinguish Mycobacterium tuberculosis from M. avium in immunocompromised patients.3 In addition, although in 9 of 28 patients ultrasound showed evidence of TB, it seems that fine needle aspiration was not attempted in those with lymph node abnormalities, or colonoscopy in those with an ileocaecal mass. An ultrasound-guided biopsy4 or colonoscopy5 is indicated in the presence of lymphadenopathy, abscess or a focal lesion in the viscera. Finally, Rai and Thomas refer to low haemoglobin and raised C-reactive protein as a consistent feature but say nothing about Ca-125, which can be high in abdominal tuberculosis.6 In our opinion, diagnostic laparoscopy should be used only when less invasive investigations yield no positive results.

Rapid and sensitive identification of Mycobacterium tuberculosis.

The fatty acid constituents of 14 species of Mycobacterium (14 isolates) and one isolate each of Corynebacterium xerosis, Nocardia asteroides, and Streptomyces albus were examined with the purpose of distinguishing Mycobacterium tuberculosis from other acid-fast bacilli. Combined thin-layer chromatography (TLC) of methyl mycolates and gas-liquid chromatography (GLC) of shorter-chain fatty acid esters provided an unequivocal identification of M. tuberculosis in a matter of 2 to 3 days. The methodology included rapid and simplified procedures for methanolysis and extraction of bacterial lipids with equally facilitated GLC and TLC analyses. These studies were performed with 0.5 to 1.0 mg of dry bacterial cells (approximately 2.5 X 10(7) CFU). When applied to 100 unknown cultures, the methodology with combined TLC-GLC correctly identified all 49 of the M. tuberculosis-Mycobacterium bovis cultures and a variety of other mycobacterium taxa. It was also interesting to note that 28 of 39 (72%) of the nontuberculous mycobacteria were correctly identified. An additional five species were tentatively identified as belonging to either of two species (Mycobacterium malmoense, Mycobacterium terrae), but in all cases, the two species belonged to the same Runyon group. All six nonmycobacterial species were differentiated from the mycobacteria studied.