Levels of anti-cytokine antibodies may be elevated in patients with pulmonary disease associated with non-tuberculous mycobacteria

Pulmonary disease due to non-tuberculous mycobacteria (NTM) is caused by several species (particularly Mycobacterium avium, Mycobacterium intracellulare) that are abundant in the environment. Th1 cytokines such as interferon (IFN)-γ are important in the control of mycobacteria, but in vitro production of IFN-γ is not deficient in adult patients with pulmonary NTM disease. Antibodies reactive with IFN-γ have been described in patients with disseminated NTM disease, but it is not clear whether they are common in pulmonary disease. Here we show that patients with pulmonary NTM have a higher level of anti-IFN-γ and anti-GM-CSF antibodies than healthy controls, although some controls also have high levels. Levels of anti-IFN-γ antibodies did not correlate with levels of total immunoglobulin. Longitudinal studies are required to determine whether anti-cytokine autoantibodies are consequence rather than a cause of pulmonary NTM disease.     

Atypical mycobacterial infection in patients with cystic fibrosis: update on clinical microbiology methods

While patients with cystic fibrosis (CF) have had dramatic improvement in their survival rates, this has been accompanied by the emergence of more virulent pathogens such as Pseudomonas aeruginosa and Burkholderia cepacia complex organisms. In addition, there has been emergence of organisms of increasing clinical significance such as the nontuberculous mycobacterial (NTM). Although TB infection in patients with CF is extremely uncommon, there is growing concern with regard to atypical Mycobacterium spp, in particular Mycobacterium abscessus. Many methods of decontamination of sputum, which have been adapted from TB methodologies, are ineffective; as shown by the overgrowth of P. aeruginosa, it is essential that decontamination methods are optimized to overcome this. Establishing optimal methods of isolation and determining accurate levels of prevalence is of importance as, although NTM may be isolated relatively infrequently in CF populations, their clinical status in pulmonary disease is now beginning to emerge.     

Non‐Tuberculosis mycobacterium speciation using HPLC under Revised National TB Control Programme (RNTCP) in India

Aims

Non‐Tuberculous Mycobacteria (NTM) are ubiquitous in nature. The data on prevalence of NTM under the RNTCP is scarce. Many NTM species have clinical significance, and hence their identification and speciation are important.

Methods and Results

It is a cross‐sectional study conducted at the five RNTCP accredited culture and drug susceptibility testing (CDST) laboratory. The culture isolates from AFB positive but Immunochromatographic test negative samples were taken for identification and speciation using HPLC. Of the total 266 isolates only 164 isolates had a second sample received at the laboratory. The speciation was done using HPLC for those isolates. The type of species identified are: 26·8% (44) were Mycobacterium chelonae, 12·8% (21) were Mycobacterium fortuitum, 9% (15) were Mycobacterium gordonae, 9% (15) were Mycobacterium tuberculosis complex, 6·1% (10) were Mycobacterium kansasii, 4·9% (8) were Mycobacterium simiae, 2·4% (4) were Mycobacterium thermophile, 1·2% (2) were Mycobacterium gastri, 0·6% (1) were Mycobacterium scrofulaceum, 0·6% (1) were Mycobacterium avium and 4·9% (8) isolates had chromatogram which was un‐interpretable.

Conclusion

Identification and its speciation of NTM are not routinely done under TB control programme. Since HPLC could identify 95% of isolates belonging to 10 species, the speciation of NTM using HPLC should gain importance in the diagnosis of disease caused by NTM.

Significance and Impact of Study

NTM are emerging as important causative agents of pulmonary and extra pulmonary disease, the ability to recognize disease caused by NTM and subsequently treat such disease has become increasingly important. The identification of NTM up to its species level should gain importance in all TB reference Laboratories.     

Nontuberculous mycobacteria in respiratory samples from patients with pulmonary tuberculosis in the state of Rond?nia, Brazil

The main cause of pulmonary tuberculosis (TB) is infection with Mycobacterium tuberculosis (MTB). We aimed to evaluate the contribution of nontuberculous mycobacteria (NTM) to pulmonary disease in patients from the state of Rondônia using respiratory samples and epidemiological data from TB cases. Mycobacterium isolates were identified using a combination of conventional tests, polymerase chain reaction-based restriction enzyme analysis of hsp65 gene and hsp65 gene sequencing. Among the 1,812 cases suspected of having pulmonary TB, 444 yielded bacterial cultures, including 369 cases positive for MTB and 75 cases positive for NTM. Within the latter group, 14 species were identified as Mycobacterium abscessus, Mycobacterium avium, Mycobacterium fortuitum, Mycobacterium intracellulare, Mycobacterium gilvum, Mycobacterium gordonae, Mycobacterium asiaticum, Mycobacterium tusciae, Mycobacterium porcinum, Mycobacterium novocastrense, Mycobacterium simiae, Mycobacterium szulgai, Mycobacterium phlei and Mycobacterium holsaticum and 13 isolates could not be identified at the species level. The majority of NTM cases were observed in Porto Velho and the relative frequency of NTM compared with MTB was highest in Ji-Paraná. In approximately half of the TB subjects with NTM, a second sample containing NTM was obtained, confirming this as the disease-causing agent. The most frequently observed NTM species were M. abscessus and M. avium and because the former species is resistant to many antibiotics and displays unsatisfactory cure rates, the implementation of rapid identification of mycobacterium species is of considerable importance.     

HMGN2 regulates non‐tuberculous mycobacteria survival via modulation of M1 macrophage polarization

Non‐tuberculous mycobacteria (NTM), also known as an environmental and atypical mycobacteria, can cause the chronic pulmonary infectious diseases. Macrophages have been suggested as the main host cell to initiate the innate immune responses to NTM infection. However, the molecular mechanism to regulate the antimicrobial immune responses to NTM is still largely unknown. Current study showed that the NTM clinical groups, Mycobacterium abscessus and Mycobacterium smegmatis, significantly induced the M1 macrophage polarization with the characteristic production of nitric oxide (NO) and marker gene expression of iNOS, IFNγ, TNF‐α, IL1‐β and IL‐6. Interestingly, a non‐histone nuclear protein, HMGN2 (high‐mobility group N2), was found to be spontaneously induced during NTM‐activated M1 macrophage polarization. Functional studies revealed that HMGN2 deficiency in NTM‐infected macrophage promotes the expression of M1 markers and the production of NO via the enhanced activation of NF‐κB and MAPK signalling. Further studies exhibited that HMGN2 knock‐down also enhanced IFNγ‐induced M1 macrophage polarization. Finally, we observed that silencing HMGN2 affected the survival of NTM in macrophage, which might largely relevant to enhanced macrophage polarization into M1 phenotype under the NTM infection. Collectively, current studies thus suggested a novel function of HMGN2 in regulating the anti‐non‐tuberculous mycobacteria innate immunity of macrophage.     

Mycobacteria mobility shift assay: a method for the rapid identification of Mycobacterium tuberculosis and nontuberculous mycobacteria

The identification of mycobacteria is essential because tuberculosis (TB) and mycobacteriosis are clinically indistinguishable and require different therapeutic regimens. The traditional phenotypic method is time consuming and may last up to 60 days. Indeed, rapid, affordable, specific and easy-to-perform identification methods are needed. We have previously described a polymerase chain reaction-based method called a mycobacteria mobility shift assay (MMSA) that was designed for Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) species identification. The aim of this study was to assess the MMSA for the identification of MTC and NTM clinical isolates and to compare its performance with that of the PRA-hsp65 method. A total of 204 clinical isolates (102 NTM and 102 MTC) were identified by the MMSA and PRA-hsp65. For isolates for which these methods gave discordant results, definitive species identification was obtained by sequencing fragments of the 16S rRNA and hsp65 genes. Both methods correctly identified all MTC isolates. Among the NTM isolates, the MMSA alone assigned 94 (92.2%) to a complex or species, whereas the PRA-hsp65 method assigned 100% to a species. A 91.5% agreement was observed for the 94 NTM isolates identified by both methods. The MMSA provided correct identification for 96.8% of the NTM isolates compared with 94.7% for PRA-hsp65. The MMSA is a suitable auxiliary method for routine use for the rapid identification of mycobacteria.     

Focus: Rare Disease: Histopathologic Analysis of Surgically Resected Lungs of Patients with Non-tuberculous Mycobacterial Lung Disease: a Retrospective and Hypothesis-generating Study

Non-tuberculous mycobacterial lung disease (NTM-LD) is most commonly due to species within the Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex (MAbC). Surgical lung resection, typically a lobectomy or segmentectomy, is occasionally undertaken for individuals with recalcitrant but localized NTM-LD. Since the growth characteristics of MAC (slow growers) and MAbC (rapid growers) as well as their drug susceptibility patterns are significantly different, the objective of this study is to characterize and compare the histopathologic features of the resected lungs due to these two major NTM groups. From 1996 to 2017, 356 patients with NTM-LD due to MAC (n=270), MAbC (n=54), or both (n=32) underwent a total of 404 lobar resections (with the lingula counted as a separate lobe) at the University of Colorado Hospital. We analyzed by microscopy the existing surgical lung tissue sections for bronchiolitis, bronchiolectasis, bronchiectasis, non-necrotizing granuloma (airway, parenchymal, and total), necrotizing granuloma (airway, parenchymal, and total), peri-airway fibrosis, fibrous pleuritis, and lymphoid follicles. There were no significant differences in the presence or absence of most of the histopathologic features of surgically removed lungs due to MAC, MAbC, or both MAC + MAbC. However, there were significantly more necrotizing granulomas (airway, parenchymal, and total) and fibrous pleuritis in MAC compared to MAbC lung diseases. Since necrotizing granulomas may be a sign of inadequate control of the infection, we posit that their presence may be an indication of increased chronicity, increased virulence of MAC compared to MAbC, and/or impaired host immunity against the NTM. Futures studies to determine the root cause of such differences in histopathologic findings in MAC versus MAbC lung disease may spawn new leads on differential pathogenic mechanisms with different NTM, with the goal of aiming for more targeted therapy against both the NTM and the lung damage induced by them.     

非结核分枝杆菌肺病临床分离株的菌种鉴定及临床特征分析

为探究非结核分枝杆菌（nontuberculous mycobacterium,NTM）肺病临床分离株的菌种分布及临床特征, 对2017年5月―2018年10月就诊于复旦大学附属中山医院的90例NTM肺病患者的样本进行分析。采用快速全自动分枝杆菌培养和药物敏感检测系统（BACTEC MGIT960 System）或改良罗氏培养法对90例患者的采集样本进行培养,利用基质辅助激光解析/电离飞行时间质谱（matrix assisted laser desorption/ionization time of flight mass spectrometry,MALDI-TOF MS）进行菌种鉴定,并对回顾性分析收集的90例患者的临床资料进行分析。结果NTM菌种鉴定为9种,其中慢速生长分枝杆菌65例,以胞内分枝杆菌（54.4%,49/90）占多数;快速生长分枝杆菌25例,以脓肿分枝杆菌（22.2%,20/90）占多数。90例患者中确诊67例、疑似23例。确诊患者中少见菌种所占比例较低（6.0% vs 26.1%,P = 0.016）。确诊与疑似患者在临床表现方面未见显著差异,但确诊患者有抗NTM治疗史的比例显著高于疑似患者（85.1% vs 4.3%,P < 0.001）。确诊患者中,快速生长NTM肺病患者既往抗结核治疗史的比例显著高于慢速生长组（52.9% vs 24.0%,P = 0.036）。本研究结果为NTM肺病的临床诊治提供了数据参考。     

供水系统非结核分枝杆菌生长因素及控制措施研究进展

近年来,非结核分枝杆菌感染在世界范围内日益普遍,严重威胁公众健康。供水系统是非结核分枝杆菌重要环境来源和主要传播途径,但目前对供水系统非结核分枝杆菌生长因素及控制措施的认识仍有较多不足。本文介绍了供水系统非结核分枝杆菌的生长传播特征,探讨了多个工程环境因素(如消毒剂、有机碳、管材和温度)和生物因子(如生物膜、阿米巴原虫和细菌)对非结核分枝杆菌丰度和物种多样性特征的影响,分析了供水全流程不同阶段控制措施对非结核分枝杆菌的控制效用,提出了深化认识供水系统非结核分枝杆菌的研究需求。     

Targeting the rpoB gene using nested PCR-restriction fragment length polymorphism for identification of nontuberculous mycobacteria in hospital tap water

Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and can cause nosocomial infections in immunocompromised patients. Recently the presence of NTM in public drinking water and hospital water distribution systems has been reported. Their ability to form biofilms and their resistance to chlorine both contribute to their survival and colonization in water distribution systems. Here we analyzed thirty-two hospital tap water samples that were collected from different locations in three hospitals so as to evaluate the prevalence of NTM species. The water samples were concentrated by membrane filtration and then eluted with sterilized water following sonication. Two-step direct PCR targeting the rpoB gene, restriction fragment length polymorphism (RFLP) using the MspI restriction enzyme, and sequence analysis were performed for identification of NTM to the species level. The sequences of each PCR product were analyzed using BLASTN. Seven samples (7/32, 21.9%) were positive for NTM as determined by nested-PCR. The PCR-RFLP results indicated five different patterns among the seven positive PCR samples. The water-born NTM were identified, including M. peregrinum, M. chelonae (2 cases), M. abscessus, M. gordonae (2 cases), and Mycobacterium sp. JLS. The direct two-step PCR-RFLP method targeting the rpoB gene was effective for the detection and the differentiation of NTM species from hospital tap water.     

Development of multiplex PCR assays based on the 16S-23S rRNA internal transcribed spacer for the detection of clinically relevant nontuberculous mycobacteria

Aims: To accelerate the identification and differentiation of clinically relevant nontuberculous mycobacteria (NTM) with two sets of multiplex PCR (mPCR) targeting the 16S–23S rRNA internal transcribed spacer (ITS) region for timely patient management. Methods and Results: Two mPCR assays were developed: Slow‐Growers (SG) mPCR was used for the detection of slow‐growing mycobacteria, which included Mycobacterium avium complex, Mycobacterium kansasii, Mycobacterium gordonae and Mycobacterium xenopi whilst the other mPCR assay labelled as Fast‐Growers (FG) mPCR was used for the detection of Mycobacterium fortuitum complex, Mycobacterium abscessus and Mycobacterium chelonae. In these assays, a common forward primer based on a conserved section of the 16S rRNA region was used in conjunction with species‐specific reverse primers. The mPCRs were tested against 247 clinical mycobacterial isolates and demonstrated 100% specificity and sensitivity. Identification of the mycobacterial species was also validated by DNA sequencing of the 16S–23S ITS region and when further confirmation was needed, hsp65 sequencing was performed. Conclusions: The mPCR assays could be a potentially useful diagnostic tool for the rapid and accurate identification of clinically relevant NTM. Significance and Impact of the Study: In this study, we looked at the frequency of hospital isolated NTM over the last 5 years (2005–2010), and an mPCR targeting the ITS region was developed for NTM species that appeared to be more prevalent in the context of Singapore.     

Distribution of non-tuberculosis mycobacteria strains from suspected tuberculosis patients by heat shock protein 65 PCR–RFLP

The genus Mycobacterium contains more than 150 species. Non-tuberculosis mycobacteria (NTM) often cause extrapulmonary and pulmonary disease. Mycobacteria detection at species level is necessary and provides useful information on epidemiology and facilitates successful treatment of patients. This retrospective study aimed to determine the incidence of the NTM isolates and Mycobacterium tuberculosis (Mtb) in clinical specimens collected from Iranian patients during February 2011–December 2013, by PCR–restriction fragment length polymorphism analysis (PRA) of the hsp65 gene. We applied conventional biochemical test and hsp65–PRA identification assay to identify species of mycobacteria in specimens from patients suspected of having mycobacterial isolates. This method was a sensitive, specific and effective assay for detecting mycobacterial species and had a 100% sensitivity and specificity for Mtb and Mycobacterium avium complex (MAC) species. Using PRA for 380 mycobacterial selected isolates, including 317 Mtb, four Mycobacterium bovis and of the 59 clinical isolates, the most commonly identified organism was Mycobacterium kansasii (35.6%), followed by Mycobacterium simiae (16.9%), Mycobacterium gordonae (16.9%), Mycobacterium fortuitum (5.1%), Mycobacterium intracellulare (5.1%), Mycobacterium avium (5.1%), Mycobacterium scrofulaceum (3.4%), Mycobacterium gastri (3.4%), Mycobacterium flavescens (3.4%), Mycobacterium chelonae (3.4%) and Mycobacterium nonchromogenicum (1.7%). PRA method, in comparison with classical methods, is rapid, useful and sensitive for the phylogenetic analysis and species detection of mycobacterial strains. Mycobacterium kansasii is the most common cause of infection by NTM in patients with non-HIV and HIV which demonstrated a high outbreak and diversity of NTM strains in our laboratory.     

Profiling serum antibodies to Mycobacterium tuberculosis proteins in rhesus monkeys with nontuberculous Mycobacteria

Recent evidence indicates that the prevalence of diseases caused by nontuberculous mycobacteria (NTM) has been increasing in both human and animals. In this study, antibody profiles of NTM in rhesus monkeys (Macaca mulatta) were determined and compared with those of monkeys infected with Mycobacterium tuberculosis complex (MTBC). Antibodies against 10 M. tuberculosis proteins, purified protein derivative (PPD), and mammalian old tuberculin (MOT) were detected in 14 monkeys naturally infected with NTM by indirect ELISA. Sera from 10 monkeys infected with MTBC and 10 healthy monkeys were set as controls. All antigens showed high serological reactivities to MTBC infections and low reactivities in healthy monkeys. NTM infections showed strong antibody responses to MOT and PPD; moderate antibody responses to 16kDa, U1, MPT64L, 14kDa, and TB16.3; and low antibody responses to 38kDa, Ag85b, CFP10, ESAT-6, and CFP10-ESAT-6. According to the criteria of MTBC, only CFP10, ESAT-6, and CFP10-ESAT-6 showed negative antibody responses in all NTM infections. Taken together, these results suggest that positive results of a PPD/MOT-based ELISA in combination with results of antibodies to M. tuberculosis-specific antigens, such as CFP10 and ESAT-6, could discriminate NTM and MTBC infections. Two positive results indicate an MTBC infection, and a negative result for an M. tuberculosis-specific antigen may preliminarily predict an NTM infection.     

2018—2020年平顶山地区非结核分枝杆菌菌种鉴定及耐药性分析

本文旨在观察2018—2020年河南省平顶山地区非结核分枝杆菌(nontuberculous mycobacteria,NTM)的菌种分布及耐药情况。收集2018年1月—2020年12月平顶山市传染病医院分离到的326株NTM,采用DNA微阵列芯片鉴定菌种,改良罗氏培养基比例法进行药敏试验。结果显示,从61～80岁患者中分离的NTM菌株最多,其次是41～60岁患者。共鉴定出8个NTM菌种,分别为胞内分枝杆菌(35.28%)、龟/脓肿分枝杆菌(24.85%)、鸟分枝杆菌(18.40%)、偶然分枝杆菌(5.21%)、戈登分枝杆菌(1.23%)、堪萨斯分枝杆菌(12.58%)、浅黄分枝杆菌(1.53%)、瘰疬分枝杆菌(0.92%)。NTM对异烟肼的耐药率最高,为97.85%。除戈登分枝杆菌外,其他NTM菌种对异烟肼的耐药率均＞94%;胞内分枝杆菌对丙硫异烟胺的耐药率(8.70%)相对较低,鸟分枝杆菌对丙硫异烟胺的耐药率为10.00%;龟/脓肿分枝杆菌对异烟肼、利福平、链霉素、乙胺丁醇、阿米卡星的耐药率均＞95%;偶然分枝杆菌对左氧氟沙星的耐药率为35.29%,堪萨斯分枝杆菌对左氧氟沙星的耐药率最低(7.32%);戈登分枝杆菌对异烟肼、乙胺丁醇、链霉素、对氨基水杨酸的耐药率均≥50%;浅黄分枝杆菌对乙胺丁醇、左氧氟沙星、阿米卡星、卡那霉素的耐药率均＜50%;瘰疬分枝杆菌对阿米卡星和丙硫异烟胺的耐药率为0。结果提示,2018—2020年河南省平顶山地区鉴定出的8个NTM菌种中,胞内分枝杆菌占比最高,不同菌种对不同抗结核药物的耐药性差异较大,因此菌种鉴定对临床治疗有重要意义。     

Surrounded by mycobacteria: nontuberculous mycobacteria in the human environment

A majority of the Mycobacterium species, called the nontuberculous mycobacteria (NTM), are natural inhabitants of natural waters, engineered water systems, and soils. As a consequence of their ubiquitous distribution, humans are surrounded by these opportunistic pathogens. A cardinal feature of mycobacterial cells is the presence of a hydrophobic, lipid-rich outer membrane. The hydrophobicity of NTM is a major determinant of aerosolization, surface adherence, biofilm-formation, and disinfectant- and antibiotic resistance. The NTM are oligotrophs, able to grow at low carbon levels [>50 μg assimilable organic carbon (AOC) l⁻¹], making them effective competitors in low nutrient, and disinfected environments (drinking water). Biofilm formation and oligotrophy lead to survival, persistence, and growth in drinking water distribution systems. In addition to their role as human and animal pathogens, the widespread distribution of NTM in the environment, coupled with their ability to degrade and metabolize a variety of complex hydrocarbons including pollutants, suggests that NTM may be agents of nutrient cycling.     

Occurrence of Nontuberculous Mycobacterial Pulmonary Infection in an Endemic Area of Tuberculosis

The majority of investigations of the epidemiology of nontuberculous mycobacteria (NTM) have focused on highly developed nations with a low prevalence of tuberculosis. In contrast, the Para state of north Brazil represents an area of high tuberculosis prevalence and increasing NTM incidence. Toward the goal of understanding the dynamics of infection by all Mycobacterium species, we report patient characteristics and the identification of NTM strains isolated from sputum samples from patients that were residents of Para, a state in the Amazon region, Northern of Brazil, over the period January 2010 through December 2011 (2 years). The 29 NTM patients comprised 13.5% of positive mycobacterial cultures over the 2-year period. A major risk factor for NTM pulmonary disease was previous tuberculosis (76%). Further, the average age of NTM patients (52 years) was significantly higher than that of tuberculosis patients (39 years) and more were female (72.4% vs. 37.4%). Unlike other Brazilian states, NTM pulmonary patients in Para were infected with a different spectrum of mycobacteria; primarily the rapidly growing Mycobacterium massiliense and Mycobacterium simiae complex.     

Environmental Nontuberculous Mycobacteria in the Hawaiian Islands

Lung disease caused by nontuberculous mycobacteria (NTM) is an emerging infectious disease of global significance. Epidemiologic studies have shown the Hawaiian Islands have the highest prevalence of NTM lung infections in the United States. However, potential environmental reservoirs and species diversity have not been characterized. In this cross-sectional study, we describe molecular and phylogenetic comparisons of NTM isolated from 172 household plumbing biofilms and soil samples from 62 non-patient households and 15 respiratory specimens. Although non-uniform geographic sampling and availability of patient information were limitations, Mycobacterium chimaera was found to be the dominant species in both environmental and respiratory specimens. In contrast to previous studies from the continental U.S., no Mycobacterium avium was identified. Mycobacterium intracellulare was found only in respiratory specimens and a soil sample. We conclude that Hawai’i’s household water sources contain a unique composition of Mycobacterium avium complex (MAC), increasing our appreciation of NTM organisms of pulmonary importance in tropical environments.     

Slender,Older Women Appear to Be More Susceptible to Nontuberculous Mycobacterial Lung Disease

Background: Nontuberculous mycobacteria (NTM) are environmental microbes that are associated with a variety of human diseases, particularly chronic lung infections. Over the past several decades, NTM lung disease has been increasingly seen in postmenopausal women with slender body habitus.Objective: This article reviewed the clinical and experimental evidence that supports the observation that thin older women (aged 50–80 years) are predisposed to NTM lung disease. We posited 3 potential pathways for this predisposition: relative estrogen deficiency, abnormal levels of adipokines that alter immune responses, and abnormal expression of transforming growth factor-β (TGF-β) related to fibrillin anomalies similar to Marfan syndrome (MFS).Methods: Using the PubMed database, a literature search was performed (all publications up to July 2009) by pairing the key phrase nontuberculous mycobacteria with weight, malnutrition, female gender, body habitus, leptin, adipokines, estrogen, menopause, postmenopausal, or body mass index. Non-English-language articles were included if their abstracts were in English. Relevant articles were also identified from the abstracts.Results: Published case reports and series indicate that in the past 20 years, NTM lung disease has been recognized in disproportionately increased numbers in postmenopausal women. Among these patients, slender body habitus and thoracic cage abnormalities, such as pectus excavatum and scoliosis, are commonly described. Notably, no long-term prospective clinical studies exist to corroborate that low weight is an independent risk factor for NTM lung disease. However, based on the findings of a limited number of experimental studies, we hypothesize that decreased leptin, increased adiponectin, and/or decreased estrogen in older women with slender body habitus may account for their increased susceptibility to NTM infections. We further speculate that in some patients with features mindful of MPS (slender, scoliosis, pectus excavatum, or mitral valve prolapse), there may be anomalies of fibrillin, similar to MFS, that lead to the expression of the immunosuppressive cytokine TGP-β further increasing their susceptibility to NTM.Conclusions: It is likely that both sufficient environmental exposure and host susceptibility are required for the establishment of NTM lung disease. The observation that NTM lung infections are more common in slender, older women without any overt immune defects suggests that abnormal expression of adipokines, sex hormones, and/or TGF-β may play an important role in their susceptibility.     

The identification of biomarkers differentiating Mycobacterium tuberculosis and non-tuberculous mycobacteria via thermally assisted hydrolysis and methylation gas chromatography–mass spectrometry and chemometrics

Infections with non-tuberculous mycobacteria (NTM) are increasing, particularly among immune-compromised patients and those with damaged lungs. Mycobacterium tuberculosis complex (MTB) strains, however, remain the most common cause of mycobacterial infection. A rapid method of distinguishing MTB from NTM is required for correct diagnosis and tuberculosis management. We have developed an automated procedure based on thermally-assisted hydrolysis and methylation followed by gas chromatography–mass spectrometry (THM–GC–MS) and advanced chemometrics to differentiate MTB from NTM. We used early cultures of mycobacteria in this first step towards the direct identification of these bacteria in sputum using a hand-held portable device. To build a classification model, we used 44 strains including 15 MTB and 29 NTM. A matrix of the aligned dataset containing ~45,700 features (retention time/mass pairs) for the 44 observations was submitted to partial least squares discriminant analysis (PLS–DA). We could reduce the number of features down to 250 without compromising the accuracy of the model. Twenty different compounds were found through mass spectral interpretation of these 250 features. Some of these compounds have not been linked to tuberculosis before, others have been proposed previously as diagnostic biomarkers for this disease. We have built a final model based on our proposed biomarkers that performed with 95 % accuracy in distinguishing MTB from NTM in early cultures. Since all these biomarkers have been chemically identified, work can proceed towards the development of simpler, bed-side diagnostic tests to differentiate MTB from NTM in sputum.