Management of opportunist mycobacterial infections: Joint Tuberculosis Committee Guidelines 1999. Subcommittee of the Joint Tuberculosis Committee of the British Thoracic Society

Extrapulmonary nontuberculous mycobacterial infections: a guide for the general physician

Non-tuberculous mycobacteria (NTM) infections predominantly present as pulmonary disease. Although relatively rare, 20-30 % originate from extrapulmonary sites resulting in a wide range of clinical syndromes. Immunocompromised individuals are particularly susceptible. Clinical manifestations include skin and soft-tissue infections, lymphadenitis, musculoskeletal infections and disseminated disease. Diagnosing extrapulmonary NTM is challenging, and management is complex, often involving multiple radiological and microbiological investigations, long courses of combination antibiotic regimens and may require adjuvant surgical interventions. We highlight both the importance of involving NTM experts at an early stage and the role of a multidisciplinary approach in the diagnosis and management of these infections.

Distinguishing nontuberculous mycobacterial lung disease and Mycobacterium tuberculosis lung disease on X-ray images using deep transfer learning

BACKGROUND

Nontuberculous mycobacterial lung disease (NTM-LD) and Mycobacterium tuberculosis lung disease (MTB-LD) have similar clinical characteristics. Therefore, NTM-LD is sometimes incorrectly diagnosed with MTB-LD and treated incorrectly. To solve these difficulties, we aimed to distinguish the two diseases in chest X-ray images using deep learning technology, which has been used in various fields recently.

METHODS

We retrospectively collected chest X-ray images from 3314 patients infected with Mycobacterium tuberculosis (MTB) or nontuberculosis mycobacterium (NTM). After selecting the data according to the diagnostic criteria, various experiments were conducted to create the optimal deep learning model. A performance comparison was performed with the radiologist. Additionally, the model performance was verified using newly collected MTB-LD and NTM-LD patient data.

RESULTS

Among the implemented deep learning models, the ensemble model combining EfficientNet B4 and ResNet 50 performed the best in the test data. Also, the ensemble model outperformed the radiologist on all evaluation metrics. In addition, the accuracy of the ensemble model was 0.85 for MTB-LD and 0.78 for NTM-LD on an additional validation dataset consisting of newly collected patients.

CONCLUSIONS

In previous studies, it was known that it was difficult to distinguish between MTB-LD and NTM-LD in chest X-ray images, but we have successfully distinguished the two diseases using deep learning methods. This study has the potential to aid clinical decisions if the two diseases need to be differentiated.

Improving Antimicrobial Activity and Physico-Chemical Properties by Isosteric Replacement of 2-Aminothiazole with 2-Aminooxazole

Antimicrobial drug resistance is currently one of the most critical health issues. Pathogens resistant to last-resort antibiotics are increasing, and very few effective antibacterial agents have been introduced in recent years. The promising drug candidates are often discontinued in the primary stages of the drug discovery pipeline due to their unspecific reactivity (PAINS), toxicity, insufficient stability, or low water solubility. In this work, we investigated a series of substituted N-oxazolyl- and N-thiazolylcarboxamides of various pyridinecarboxylic acids. Final compounds were tested against several microbial species. In general, oxazole-containing compounds showed high activity against mycobacteria, especially Mycobacterium tuberculosis (best MIC_H37Ra = 3.13 µg/mL), including the multidrug-resistant strains. Promising activities against various bacterial and fungal strains were also observed. None of the compounds was significantly cytotoxic against the HepG2 cell line. Experimental measurement of lipophilicity parameter log k’_w and water solubility (log S) confirmed significantly (typically two orders in logarithmic scale) increased hydrophilicity/water solubility of oxazole derivatives in comparison with their thiazole isosteres. Mycobacterial β-ketoacyl-acyl carrier protein synthase III (FabH) was suggested as a probable target by molecular docking and molecular dynamics simulations.

Distinguishing nontuberculous mycobacteria from Mycobacterium tuberculosis lung disease from CT images using a deep learning framework

Purpose

To develop and evaluate the effectiveness of a deep learning framework (3D-ResNet) based on CT images to distinguish nontuberculous mycobacterium lung disease (NTM-LD) from Mycobacterium tuberculosis lung disease (MTB-LD).

Method

Chest CT images of 301 with NTM-LD and 804 with MTB-LD confirmed by pathogenic microbiological examination were retrospectively collected. The differences between the clinical manifestations of the two diseases were analysed. 3D-ResNet was developed to randomly extract data in an 8:1:1 ratio for training, validating, and testing. We also collected external test data (40 with NTM-LD and 40 with MTB-LD) for external validation of the model. The activated region of interest was evaluated using a class activation map. The model was compared with three radiologists in the test set.

Result

Patients with NTM-LD were older than those with MTB-LD, patients with MTB-LD had more cough, and those with NTM-LD had more dyspnoea, and the results were statistically significant (p < 0.05). The AUCs of our model on training, validating, and testing datasets were 0.90, 0.88, and 0.86, respectively, while the AUC on the external test set was 0.78. Additionally, the performance of the model was higher than that of the radiologist, and without manual labelling, the model automatically identified lung areas with abnormalities on CT > 1000 times more effectively than the radiologists.

Conclusion

This study shows the efficacy of 3D-ResNet as a rapid auxiliary diagnostic tool for NTB-LD and MTB-LD. Its use can help provide timely and accurate treatment strategies to patients with these diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05432-x.

Diagnosing MonoMAC Syndrome in GATA2 Germline Mutated Myelodysplastic Syndrome via Next-Generation Sequencing in a Patient with Refractory and Complex Infection: Case Report and Literature Review

Monocytopenia and mycobacterial infection (MonoMAC) syndrome is a rare disease. Herein, we reported a 65-year-old Asian woman, previously diagnosed with myelodysplastic syndrome (MDS), suffering from recurrent pneumonia, intermittent fever, fatigue, and chest tightness lasting for five months. She was ultimately diagnosed with MonoMAC syndrome with Mycobacterium kansasii (M. kansasii) infection and GATA2 mutation through metagenomic generation sequencing (mNGS) of peripheral blood specimen, for which she was given anti-NTM therapy. Her situation significantly improved within 2 weeks of therapy. We discussed the clinical features, genetic characteristic, and prognosis of this disorder, aiming to further elucidate this rare syndrome. For MDS/AML patient with recurrent mixed infection and pancytopenia (especially with monocyte absence), MonoMAC syndrome should be highly suspected, and germline mutation and pathogen sequencing should be performed.

A case of pulmonary Mycobacterium heckeshornense infection in a healthy Japanese man

A 72-year-old man, healthy, smoker, with long-standing cough, was referred to our hospital and his chest X-ray (CXR) revealed a cavity lesion in the right upper lobe. Direct sputum smears, but not culture in solid medium, were positive for acid-fast bacilli (AFB) without tuberculosis DNA. The preliminary diagnosis was of a non-tuberculosis infection that progressed slowly, and the CXR showed the condition to worsen daily. Four years later, a commercialized mycobacteria growth indicator tube system was used to culture the colonies of AFB successfully in liquid medium, and the species Mycobacterium heckeshornense was identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. The patient responded well to triple therapy with rifampicin, ethambutol, and clarithromycin, the sputum cultures remained negative and the roentgenogram showed minor improvement over the following 6 months.

Prescribing Patterns for Treatment of Mycobacterium avium Complex and M. xenopi Pulmonary Disease in Ontario, Canada, 2001-2013

Surveys suggest that clinicians diverge from guidelines when treating Mycobacterium avium complex (MAC) pulmonary disease (PD). To determine prescribing patterns, we conducted a cohort study of adults >66 years of age in Ontario, Canada, with MAC or Mycobacterium xenopi PD during 2001-2013. Using linked laboratory and health administrative databases, we studied the first treatment episode (>60 continuous days of >1 of a macrolide, ethambutol, rifamycin, fluoroquinolone, linezolid, inhaled amikacin, or, for M. xenopi, isoniazid). Treatment was prescribed for 24% MAC and 15% of M. xenopi PD patients. Most commonly prescribed was the recommended combination of macrolide, ethambutol, and rifamycin, for 47% of MAC and 36% of M. xenopi PD patients. Among MAC PD patients, 20% received macrolide monotherapy and 33% received regimens associated with emergent macrolide resistance. Although the most commonly prescribed regimen was guidelines-recommended, many regimens prescribed for MAC PD were associated with emergent macrolide resistance.

Clinical findings and treatment of disseminated 'Mycobacterium avium subspecies hominissuis' infection in a domestic cat

A cat was referred because of diffuse parenchymal lung disease. Close examinations revealed a swollen abdominal lymph node and multiple nodules of the liver. Mycobacterium avium subspecies hominissuis infection was confirmed by culture and single nucleotide polymorphism analysis of samples recovered from the liver and bronchoalveolar lavage. After administration of combination antibiotics for 6 months, culture results were negative. Though atonic seizures were observed during the treatment, it disappeared after isoniazid discontinuation and pyridoxal phosphate administration. On day 771 of illness, no clinical signs, lung diseases, or obvious swelling of lymph nodes was observed. This is the first report to confirm Mycobacterium avium subspecies hominissuis infection in cats through gene analysis and to completely cure it with combination antibiotics.

Clinical and microbiological characteristics of non-tuberculous mycobacteria diseases in Singapore with a focus on pulmonary disease, 2012-2016

Background

Information on non-tuberculosis mycobacterial (NTM) diseases remains limited in Singapore and other Southeast Asian countries. This study aimed to delineate epidemiological and clinical features of pulmonary NTM disease.

Methods

A retrospective review was performed on all NTM isolates identified in Singapore General Hospital from 2012 to 2016 using the 2007 ATS/IDSA diagnostic criteria.

Results

A total of 2026 NTM isolates from 852 patients were identified. M. abscessus-chelonae group (1010, 49.9%) was the most commonly isolated and implicated in pulmonary NTM disease. Pulmonary cases (352, 76%) had the highest prevalence among patients diagnosed with NTM diseases (465/852, 54.6%) with no gender difference. Male patients were older (68.5 years, P = 0.014) with a higher incidence of chronic obstructive pulmonary disease (COPD) (23.6%, P < 0.001) and recurrent cough with phlegm production (51.6%, P = 0.035). In contrast, more female patients had bronchiectasis (50%, P < 0.001) and haemoptysis (37.6%, P = 0.042). Age and COPD were associated with multiple NTM species isolation per patient.

Conclusions

M. abscessus-chelonae group was the commonest NTM species isolated in Singapore. Pulmonary NTM infection has the highest frequency with male and female patients associated with a higher incidence of COPD and bronchiectasis respectively. Age and COPD were associated with multiple NTM species isolation per patient.

Failure among Patients with Non-Tuberculous Mycobacterial Infections in Skin, Soft Tissue, and Musculoskeletal System in Southern Taiwan, 2012-2015

Background: The incidence of non-tuberculous mycobacterial (NTM) infections of the skin, soft tissue, and musculoskeletal system (SSTI) has increased over the past two decades, however, relatively few studies have documented the reasons for the reported increase. Specifically, no standardized treatment protocols have been adopted, therefore, clinical prognosis of the patients with NTM SSTI has thus far remained uncertain. In our study, we sought to identify risk factors for treatment failure in southern Taiwan. Methods: Patients with NTM SSTI, who received treatment between 2012 and 2015 were included in this retrospective study; detailed medical records, images, tissue specimens for culture, and pathology reports were collected for further analysis. Risk factors for treatment failure were determined using multivariable logistic regression. Results: Forty-two patients (16 females, 26 males; aged 58 ± 14 years) with NTM SSTI were included in the study. Isolated mycobacterial species included Mycobacterium abscessus complex, Mycobacterium marinum, Mycobacterium kansasii, Mycobacterium avium-intracellulare complex (MAC), Mycobacterium fortuitum, Mycobacterium gordonae, Mycobacterium haemophilum, Mycobacterium peregrinum, and Mycobacterium chelonae. The incidence of NTM SSTI was 23.6 per 100,000 inpatients. The sites of infection included the hand/wrist areas, spine, feet, lower legs, femur, knees, shoulders, and elbows, in 15, 6, 5, 5, 4, 3, 2, and 1 patients, respectively. The time interval between culturing the specimens and diagnosis averaged 21.2 ± 11.4 days. The main risk factors for treatment failure included treatment delays exceeding two months and infection with Mycobacterium abscessus complex. Conclusions: Improved clinical outcome of NTM with STI may be achieved by identifying the causative NTM species, and by initializing appropriate pharmacotherapy and surgical intervention. Non-tuberculous mycobacterial infection should be included in the differential diagnosis of SSTI and it is recommended that patients with an increased risk of treatment failure should receive prolonged antibiotic treatment and prompt surgical intervention upon diagnosis or indication of NTM infections.

Current status of MALDI-TOF mass spectrometry in clinical microbiology

Mass spectrometry (MS) is a type of analysis used to determine what molecules make up a sample, based on the mass spectrum that are created by the ions. Mass spectrometers are able to perform traditional target analyte identification and quantitation; however, they may also be used within a clinical setting for the rapid identification of bacteria. The causative agent in sepsis is changed over time, and clinical decisions affecting the management of infections are often based on the outcomes of bacterial identification. Therefore, it is essential that such identifications are performed quickly and interpreted correctly. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometer is one of the most popular MS instruments used in biology, due to its rapid and precise identification of genus and species of an extensive range of Gram-negative and-positive bacteria. Microorganism identification by Mass spectrometry is based on identifying a characteristic spectrum of each species and then matched with a large database within the instrument. The present review gives a contemporary perspective on the challenges and opportunities for bacterial identification as well as a written report of how technological innovation has advanced MS. Future clinical applications will also be addressed, particularly the use of MALDI-TOF MS in the field of microbiology for the identification and the analysis of antibiotic resistance.

Risk factors and secondary care utilisation in a primary care population with non-tuberculous mycobacterial disease in the UK

Prior research has identified risk factors associated with developing non-tuberculous mycobacterial disease (NTMD); we identified risk factors and secondary care utilisation of NTMD patients in the UK. This was a matched case-control study using electronic healthcare records from Clinical Practice Research Datalink from 2006 to 2016. NTMD was defined using prescription data and Read codes, based on international guidelines. Risk factors for NTMD were investigated using conditional logistic regression within a representative general population. All-cause secondary care utilisation (combined inpatient, outpatient, emergency visits) was investigated for participants with linked Hospital Episode Statistics (HES), using incidence rate ratio (IRR) from 2007 to 2015. We identified 1225 individuals with NTMD. A subset of individuals (426 patients) were eligible for linkage with HES. In the adjusted model, risk factors most strongly associated with an increased likelihood of NTMD included previous tuberculosis (OR 69.0; 47.7-99.8); bronchiectasis (OR 23.3; 12.4-43.9); lung cancer (OR 14.9; 3.98-55.7); oral corticosteroids (OCS; OR 7.28; 4.94-10.7); immunosuppressive (excluding corticosteroids) medication (OR 3.05; 1.15-8.10); being underweight (odds ratio (OR) 2.92; 95% CI 1.95, 4.36); and rheumatoid arthritis (OR 2.12; 1.05-4.27). NTMD patients had significantly higher rates of all-cause secondary care utilisation than non-NTMD patients (IRR 5.80; 5.14-6.46). Using a representative adult population, we identified prior TB, bronchiectasis, lung cancer, immunosuppressive medication, and OCS as the risk factors associated with the highest odds of developing NTMD in the UK. Patients with NTMD experienced nearly six times more all-cause secondary care events following their NTMD diagnosis than patients without NTMD.

Nontuberculous mycobacterial disease managed within UK primary care, 2006-2016

Previous UK studies investigating nontuberculous mycobacteria have been limited to reporting isolation from culture, not burden of disease. We assessed the burden of nontuberculous mycobacterial disease (NTMD) in UK primary care from 2006 to 2016. Using electronic healthcare records, we identified patients with NTMD using a strict definition including patients with guideline-directed treatment/monitoring. We described treatment regimens and incidence/prevalence in the general population and in patients with underlying chronic respiratory diseases. Incidence of primary care-managed NTMD in the general population decreased (2006 to 2016 rates per 100,000 person-years, 3.85 to 1.28). Average annual prevalence of NTMD in the general population was 6.38 per 100,000. Around 85% were taking antimycobacterial therapy; 53.2% were taking a guideline-recommended regimen. Incidence of NTMD in patients with respiratory disease decreased (2006 to 2016 rates per 100,000 person-years, 12.5 to 7.40). Average annual prevalence of NTMD in patients with respiratory disease was 27.7 per 100,000. This is the first UK study using nationally representative data to investigate the burden of NTMD managed within primary care. Incidence and prevalence of managed NTMD within primary care is gradually declining. Increasing complexity in the management of NTMD may be driving a shift in care to secondary settings.

Are We Neglecting Nontuberculous Mycobacteria Just as Laboratory Contaminants? Time to Reevaluate Things

OBJECTIVES

Nontuberculous mycobacteria (NTM) incidences are on the rise worldwide, including the tuberculosis endemic areas. They should be identified rapidly to the species level and should be carefully differentiated as contamination, colonization, or disease. This study was aimed at determining the prevalence and clinicoepidemiological profile of mycobacteriosis cases.

MATERIALS AND METHODS

Cultures were made on liquid and solid media. NTM were identified by polymerase chain reaction (PCR) restriction analysis (PRA) and gene sequencing. Data was analyzed using Epi-info 7.

RESULTS

Out of the 1042 processed specimens, 16% were positive for M. tuberculosis complex and 1.2% for clinically significant NTM. M. intracellulare was the commonest species isolated. NTM were treated mainly on outdoor basis (92%), involving more extrapulmonary system (62%) and higher age-group of 41-60 years (69%). No significant factor was seen to be associated clinically, radiologically, and biochemically with the NTM infections.

CONCLUSIONS

Our study highlights the importance of early diagnosis and differentiation among Mycobacterium tuberculosis and NTM so that these NTM are not underestimated in routine diagnostic procedures merely as environmental or laboratory contaminants.

Accurate diagnosis of latent tuberculosis in children, people who are immunocompromised or at risk from immunosuppression and recent arrivals from countries with a high incidence of tuberculosis: systematic review and economic evaluation

BACKGROUND

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB) [(Zopf 1883) Lehmann and Neumann 1896], is a major cause of morbidity and mortality. Nearly one-third of the world's population is infected with MTB; TB has an annual incidence of 9 million new cases and each year causes 2 million deaths worldwide.

OBJECTIVES

To investigate the clinical effectiveness and cost-effectiveness of screening tests [interferon-gamma release assays (IGRAs) and tuberculin skin tests (TSTs)] in latent tuberculosis infection (LTBI) diagnosis to support National Institute for Health and Care Excellence (NICE) guideline development for three population groups: children, immunocompromised people and those who have recently arrived in the UK from high-incidence countries. All of these groups are at higher risk of progression from LTBI to active TB.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, The Cochrane Library and Current Controlled Trials were searched from December 2009 up to December 2014.

REVIEW METHODS

English-language studies evaluating the comparative effectiveness of commercially available tests used for identifying LTBI in children, immunocompromised people and recent arrivals to the UK were eligible. Interventions were IGRAs [QuantiFERON(®)-TB Gold (QFT-G), QuantiFERON(®)-TB Gold-In-Tube (QFT-GIT) (Cellestis/Qiagen, Carnegie, VA, Australia) and T-SPOT.TB (Oxford Immunotec, Abingdon, UK)]. The comparator was TST 5 mm or 10 mm alone or with an IGRA. Two independent reviewers screened all identified records and undertook a quality assessment and data synthesis. A de novo model, structured in two stages, was developed to compare the cost-effectiveness of diagnostic strategies.

RESULTS

In total, 6687 records were screened, of which 53 unique studies were included (a further 37 studies were identified from a previous NICE guideline). The majority of the included studies compared the strength of association for the QFT-GIT/G IGRA with the TST (5 mm or 10 mm) in relation to the incidence of active TB or previous TB exposure. Ten studies reported evidence on decision-analytic models to determine the cost-effectiveness of IGRAs compared with the TST for LTBI diagnosis. In children, TST (≥ 5 mm) negative followed by QFT-GIT was the most cost-effective strategy, with an incremental cost-effectiveness ratio (ICER) of £18,900 per quality-adjusted life-year (QALY) gained. In immunocompromised people, QFT-GIT negative followed by the TST (≥ 5 mm) was the most cost-effective strategy, with an ICER of approximately £18,700 per QALY gained. In those recently arrived from high TB incidence countries, the TST (≥ 5 mm) alone was less costly and more effective than TST (≥ 5 mm) positive followed by QFT-GIT or T-SPOT.TB or QFT-GIT alone.

LIMITATIONS

The limitations and scarcity of the evidence, variation in the exposure-based definitions of LTBI and heterogeneity in IGRA performance relative to TST limit the applicability of the review findings.

CONCLUSIONS

Given the current evidence, TST (≥ 5 mm) negative followed by QFT-GIT for children, QFT-GIT negative followed by TST (≥ 5 mm) for the immunocompromised population and TST (≥ 5 mm) for recent arrivals were the most cost-effective strategies for diagnosing LTBI that progresses to active TB. These results should be interpreted with caution given the limitations identified. The evidence available is limited and more high-quality research in this area is needed including studies on the inconsistent performance of tests in high-compared with low-incidence TB settings; the prospective assessment of progression to active TB for those at high risk; the relative benefits of two-compared with one-step testing with different tests; and improved classification of people at high and low risk for LTBI.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014009033.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Introducing the new BTS Guideline: Management of non-tuberculous mycobacterial pulmonary disease (NTM-PD)

The new BTS Guidelines for the management of non-tuberculous mycobacterial pulmonary disease combine the best available evidence with expert consensus to generate a set of pragmatic Guidelines, published as a supplement to this issue of Thorax, to assist in the management of these challenging infections.

British Thoracic Society Guideline for the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD)

The full guideline for the management of non-tuberculous mycobacterial pulmonary disease is published in Thorax. The following is a summary of the recommendations and good practice points. The sections referred to in the summary refer to the full guideline.

Mycobacterium malmoense pulmonary infection in France: a case report

BACKGROUND

Mycobacterium malmoense infections have frequently been reported in northern Europe since the late 1970s. Factors accounting for this geographically localized epidemiology remain poorly understood.

CASE PRESENTATION

We report the case of a 54-year old man concomitantly diagnosed with non-small cell lung carcinoma and M. malmoense pulmonary infection. We present detailed clinical, microbiological and radiological elements strongly arguing for M. malmoense true pathogenicity. Since M. malmoense infection has rarely been reported in France, we also provide elements of the epidemiological investigation and a literature review of potential acquisition and transmission pathways of M. malmoense. We detail therapeutic interventions and subsequent favorable evolution.

CONCLUSION

Mycobacterium malmoense is a recognized respiratory pathogen for which routes of infection need to be better investigated.

Recovery Rates of Non-Tuberculous Mycobacteria from Clinical Specimens Are Increasing in Korean Tertiary-Care Hospitals

Non-tuberculous mycobacteria (NTM) are being recognized increasingly as the causative agents of opportunistic infections in humans. This study investigated the epidemiologic trends of NTM recovery from various clinical specimens in 2 Korean tertiary-care hospitals. We reviewed the laboratory records of patient samples cultured for mycobacteria between 2009 and 2015 at 2 tertiary-care hospitals in Korea. The medical records for patients with positive NTM samples were also reviewed. During the study period, 144,540 specimens were cultured for mycobacteria. The proportion of NTM-positive samples increased from 23.3% in 2009 to 48.2% in 2015. The 2 most frequently isolated NTM were Mycobacterium intracellulare (38.3%) and M. avium (23.1%). The number of clinically significant diseases caused by NTM in inpatients and outpatients increased from 6.8 to 12.9 per 100,000 patients over the same period. The rates of recovery of NTM from clinical specimens and the number of patients with NTM infections increased significantly (P < 0.001, testing for trend) between 2009 and 2015.

Mycobacterium kansasii

The incidence of Mycobacterium kansasii varies widely over time and by region, but this organism remains one of the most clinically relevant isolated species of nontuberculous mycobacteria. In contrast to other common nontuberculous mycobacteria, M. kansasii is infrequently isolated from natural water sources or soil. The major reservoir appears to be tap water. Infection is likely acquired through the aerosol route, with low infectivity in regions of endemicity. Human-to-human transmission is thought not to occur. Clinical syndromes and radiological findings of M. kansasii infection are mostly indistinguishable from that of Mycobacterium tuberculosis, thus requiring microbiological confirmation. Disseminated disease is uncommon in HIV-negative patients and usually associated with severe immunosuppression. The majority of patients with M. kansasii pulmonary disease have underlying pulmonary comorbidities, such as smoking, chronic obstructive pulmonary disease, bronchiectasis, and prior or concurrent M. tuberculosis infection. Surveys in Great Britain, however, noted higher rates, with 8 to 9% of M. kansasii infections presenting with extrapulmonary disease. Common sites of extrapulmonary disease include the lymph nodes, skin, and musculoskeletal and genitourinary systems. The specificity of gamma interferon release assays (IGRAs) for M. tuberculosis may be reduced by M. kansasii infection, as M. kansasii encodes CFP-10 and ESAT-6, two antigens targeted by IGRAs. A study conducted to evaluate the therapy in rifampin-resistant disease found that patients with acquired rifampin resistance were treated with daily high-dose ethambutol, isoniazid, sulfamethoxazole, and pyridoxine combined with aminoglycoside therapy. Given the potential toxicities, particularly with aminoglycoside therapy, clarithromycin and/or moxifloxacin therapy could be considered as alternatives.

Non-Tuberculous Mycobacteria. An Emerging Threat?

INTRODUCTION AND OBJECTIVE

Non-tuberculous mycobacteria (NTM) isolates are becoming more common. The main objective of our study was to establish the number and diversity of NTM species in our region and their distribution according to the source sample, age and gender of the patients, and to analyse clinically significant isolates.

METHODOLOGY

Prospective study of all NTM isolated in Asturias from 2005 to 2012. Samples were processed following internationally accepted guidelines. Statistical analysis was based on Fisher's exact test for 2×2 contingency tables.

RESULTS

A total of 3,284 mycobacteria were isolated: 1,499 Mycobacterium tuberculosis complex (MTB) and 1,785 NTM.During the study, NTM isolation rates increased while MTB isolation decreased. NTM were more frequent in men (P<.001). M.gordonae was the most frequently isolated species but did not cause disease in any case. NTM isolates from 212 patients were associated with clinically significant disease (17.1%). M.kansasii and M.avium were most commonly associated with disease. The number of M.kansasii isolates from men was statistically significant (P<.01).

CONCLUSIONS

In our study, NTM isolates increased by 35%, compared with a 21% decline in cases of MTB. Both isolation of NTM and clinically significant cases were more common in men. Only 17.1% of NTM isolates were associated with disease, most commonly M.avium complex and M.kansasii.

Pulmonary Mycobacterium kansasii disease in immunocompetent host: Treatment outcomes with short-course chemotherapy

Mycobacterium kansasii, most virulent of all atypical mycobacteria, causes pulmonary disease identical to the disease caused by Mycobacterium tuberculosis. Early identification of the species and prompt initiation of treatment for M. kansasii is necessary to prevent morbidity and mortality due to this disease. This case series highlights the similarity in the clinical presentation of both M. tuberculosis and M. kansasii and response to direct observation of short-course chemotherapy with rifampicin, in the management of pulmonary M. kansasii disease. Larger studies are required to evaluate the long-term effect of short-course chemotherapy, especially use of moxifloxacin, in the management of pulmonary M. kansasii disease.

Factors which influence treatment initiation for pulmonary non-tuberculous mycobacterium infection in HIV negative patients; a multicentre observational study

BACKGROUND

Clinical, radiological and microbiological criteria inform diagnosis of pulmonary Non-Tuberculous Mycobacteria (NTM) disease and treatment decisions. This multicentre, review aims to characterise NTM disease meeting ATS/IDSA criteria and define factors associated with initiation of treatment.

METHODS

Sputum samples growing NTM from 5 London hospitals between 2010 and 2014 were identified. Data for HIV-negative individuals meeting ATS/IDSA guidelines for pulmonary NTM disease were extracted. Associations between clinical variables and treatment decision were investigated using Chi-squared, Fishers-exact or Mann Whitney tests. Factors associated with treatment in univariate analysis (p < 0.150) were included in a multivariate logistic regression model.

RESULTS

NTM were identified from 817 individuals' sputum samples. 108 met ATS/IDSA criteria. 42/108 (39%) were initiated on treatment. Median age was 68 (56-78) in the cohort. On multivariate analysis, factors significantly associated with treatment of pulmonary NTM infection were: Cavitation on HRCT (OR: 6.49; 95% CI: 2.36-17.81), presenting with night sweats (OR 4.18; 95% CI: 1.08-16.13), and presenting with weight loss (OR 3.02; 95% CI: 1.15-7.93). Of those treated, 18(43%) have completed treatment, 9(21%) remain on treatment, 10(24%) stopped due to side effects, 5(12%) died during treatment. Mortality was 31% (n = 13) in treated versus 21% (n = 14) in the non-treated cohort. Subgroup analysis of individual NTM species did not observe any differences in treatment initiation or outcomes between groups.

DISCUSSION

Decision to treat pulmonary NTM infection requires clinical judgement when interpreting clinical guidelines. Factors independently associated with decision to treat in this HIV-negative cohort include cavitation on HRCT and presenting with night sweats or weight loss.

Miliary pulmonary nodules due to Mycobacterium xenopi in a steroid-induced immunocompromised patient successfully treated with chemotherapy: a case report

Background

Mycobacterium xenopi-infected patients have a high prevalence of pulmonary cavities and nodules. However, the clinical course for patients with miliary nodules due to M. xenopi has not yet been reported.

Case presentation

We encountered a case of miliary nodules with gradually worsening coughing and sputum production in a 44-year-old male who had renal dysfunction due to glomerulosclerosis with a decade-long history of steroid therapy. Although we started anti-tuberculosis treatment on clinical suspicion of miliary tuberculosis, cultures of sputum and bronchial lavage were both positive for M. xenopi. The patient was successfully treated with rifampin, ethambutol and clarithromycin, without fibrosis. It was unclear whether the miliary pattern was induced by hematogenous or endobronchial spread of the M. xenopi infection.

Conclusion

Even when clinical and radiological disease manifestations are similar to those of miliary tuberculosis, M. xenopi infection should be considered in the differential diagnosis of miliary nodules.

Pulmonary Disease Caused by Non-Tuberculous Mycobacteria

Non-tuberculous mycobacteria (NTM) include more than 160 ubiquitous, environmental, acid-fast-staining bacterial species, some of which may cause disease in humans. Chronic pulmonary infection is the most common clinical manifestation. Although patients suffering from chronic lung diseases are particularly susceptible to NTM pulmonary disease, many affected patients have no apparent risk factors. Host and pathogen factors leading to NTM pulmonary disease are not well understood and preventive therapies are lacking. NTM isolation and pulmonary disease are reported to rise in frequency in Europe as well as in other parts of the world. Differentiation between contamination, infection, and disease remains challenging. Treatment of NTM pulmonary disease is arduous, lengthy, and costly. Correlations between results of in vitro antibiotic susceptibility testing and clinical treatment outcomes are only evident for the Mycobacterium avium complex, M. kansasii, and some rapidly growing mycobacteria. We describe the epidemiology of NTM pulmonary disease as well as emerging NTM pathogens and their geographical distribution in non-cystic fibrosis patients in Europe. We also review recent innovations for the diagnosis of NTM pulmonary disease, summarize treatment recommendations, and identify future research priorities to improve the management of patients affected by NTM pulmonary disease.

Non-tuberculous mycobacterial lung disease: diagnosis based on computed tomography of the chest

OBJECTIVES

To elucidate the accuracy and inter-observer agreement of non-tuberculous mycobacterial lung disease (NTM-LD) diagnosis based on chest CT findings.

METHODS

Two chest radiologists and two pulmonologists interpreted chest CTs of 66 patients with NTM-LD, 33 with pulmonary tuberculosis and 33 with non-cystic fibrosis bronchiectasis. These observers selected one of these diagnoses for each case without knowing any clinical information except age and sex. Sensitivity and specificity were calculated according to degree of observer confidence. Inter-observer agreement was assessed using Fleiss' κ values. Multiple logistic regression was performed to elucidate which radiological features led to the correct diagnosis.

RESULTS

The sensitivity of NTM-LD diagnosis was 56.4 % (95 % CI 47.9-64.7) and specificity 80.3 % (73.1-86.0). The specificity of NTM-LD diagnosis increased with confidence: 44.4 % (20.5-71.3) for possible, 77.4 % (67.4-85.0) for probable, 95.2 % (87.2-98.2) for definite (P < 0.001) diagnoses. Inter-observer agreement for NTM-LD diagnosis was moderate (κ = 0.453). Tree-in-bud pattern (adjusted odds ratio [aOR] 6.24, P < 0.001), consolidation (aOR 1.92, P = 0.036) and atelectasis (aOR 3.73, P < 0.001) were associated with correct NTM-LD diagnoses, whereas presence of pleural effusion (aOR 0.05, P < 0.001) led to false diagnoses.

CONCLUSIONS

NTM-LD diagnosis based on chest CT findings is specific but not sensitive.

KEY POINTS

• Diagnosis of NTM-LD based on radiological findings showed high specificity. • Sensitivity of NTM-LD diagnosis was around 50 %. • Inter- observer agreement was moderate. • Identification of tree-in-bud pattern, consolidation and atelectasis led to correct diagnoses.

Health-related quality of life is inversely correlated with C-reactive protein and age in Mycobacterium avium complex lung disease: a cross-sectional analysis of 235 patients

Background

Mycobacterium avium complex (MAC) lung diseases generally cause chronic disease in immunocompetent hosts. Although a few studies have examined health-related quality of life (HRQL) in patients with MAC lung disease, there have been no large studies. This study aimed to evaluate HRQL and its correlation with clinical outcomes in MAC lung disease.

Methods

A cross-sectional study was conducted at Keio University Hospital to investigate the factors associated with HRQL in pulmonary nontuberculous mycobacterial diseases. MAC lung diseases were diagnosed according to the 2007 ATS/IDSA guidelines for nontuberculous mycobacterial diseases. The 36-item short form health survey (SF-36) was administered to assess clinical outcomes. Clinical variables included treatment status, latest haematological data, and bacterial smear and culture results.

Results

The SF-36 scores for the 235 patients (median age, 69 years; 45 men and 190 women) with MAC lung disease, except for the bodily pain and mental health subscale scores, were significantly lower than the Japanese population norms. In the multivariable analyses, current treatment for MAC and a positive sputum smear or culture within the past year were significantly associated with lower SF-36 scores. C-reactive protein (CRP) and age showed stronger inverse correlations with SF-36 scores.

Conclusions

HRQL, especially the physical component, was impaired in patients with MAC lung diseases; this appears to be related with current treatment status, positive sputum smear or culture within the previous year, and particularly CRP and age. Further studies including qualitative assessments are needed to investigate the efficacy of CRP as a marker for progression or treatment response in MAC lung disease.

Trial registration

Clinical trial registered with UMIN (UMIN000007964).

Repeated acute kidney injury associated with Mycobacterium gordonae infection

Mycobacterium gordonae is a nontuberculous mycobacterium widely distributed in the environment. Although M. gordonae is not usually pathogenic and glomerular lesions due to M. gordonae are very rare, infection has been reported in both immunocompromised patients and healthy persons. We report a case of acute kidney injury (AKI) in which M. gordonae was ultimately identified as the cause. A 70-year-old man was admitted to our hospital because of fever, polyarthritis, and AKI. He was a hepatitis B virus carrier, suffered from diabetes, and had a past history of erysipelas. No causative bacteria were identified, but coexisting infection was suspected. The patient experienced remission with antibiotic therapy, but the same symptoms recurred eight times. Blood polymerase chain reaction was performed during the 7th recurrence, and M. gordonae was detected. Clarithromycin was initiated, but 2 years after initial hospitalization, the patient died due to M. gordonae infection. In this case, acute kidney injury was a consequence of infection-related glomerulonephritis due to M. gordonae. Mycobacterium is difficult to detect by routine culture methods; therefore, diagnosis remains challenging.

Diagnostic performance of measuring antibodies to the glycopeptidolipid core antigen specific to Mycobacterium avium complex in patients with rheumatoid arthritis: results from a cross-sectional observational study

Introduction

The aim of this study was to investigate the diagnostic performance of measuring antibodies to the glycopeptidolipid (GPL) core antigen specific to Mycobacterium avium complex (MAC) in patients with rheumatoid arthritis (RA).

Methods

We cross-sectionally investigated anti-GPL antibodies and radiographs of 396 patients with RA. A diagnosis of MAC pulmonary disease (MAC-PD) was made according to the criteria by the American Thoracic Society and the Infectious Diseases Society of America. Serum immunoglobulin A antibodies to MAC-specific GPL core antigen were measured by an enzyme immunoassay. All patients with RA with abnormal shadows on chest x-rays underwent chest computed tomography (CT). Bronchoscopy was performed on patients with negative cultures for MAC by expectorated sputum and positive CT findings compatible with MAC-PD.

Results

Ten patients were newly diagnosed with MAC-PD. Eight individuals who already had diagnoses of MAC-PD at the time of enrollment and nineteen who had negative expectorated sputum cultures for MAC and positive CT images compatible with MAC-PD and who refused bronchoscopy were excluded from the following analysis. Anti-GPL antibodies were detected in 12 of 369 patients. Eight of the ten patients with MAC-PD and 4 of 359 patients without MAC-PD tested positive for the anti-GPL antibodies. The specificity and sensitivity were 99 % and 80 %, respectively. Positive and negative predictive values were 67 %, and 97 %, respectively. When we analyzed diagnostic performance of the antibodies in 57 patients with RA who had abnormal shadows on chest x-rays, the positive and negative predictive values were 100 %, and 96 %, respectively. Twelve patients underwent bronchoscopy. Bronchoalveolar lavage fluid (BALF) samples from six patients were positive for MAC, and BALF samples from the remainder were negative. Anti-GPL antibodies were detected in the sera of all six patients with positive results for MAC by BALF sampling, whereas the antibodies were not detected in the sera from the remainder with negative results for MAC by BALF sampling.

Conclusions

The measurement of anti-GPL antibodies is useful as a supplementary diagnostic tool for MAC-PD in patients with RA and may provide a new strategy, in combination with chest x-ray and CT, for differentiating MAC-PD from other pulmonary comorbidities in patients with RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0787-y) contains supplementary material, which is available to authorized users.

Semiquantitative Culture Analysis during Therapy for Mycobacterium avium Complex Lung Disease

RATIONALE

Microbiologically based criteria such as sputum culture conversion to negative have traditionally been used to define treatment success for mycobacterial diseases. There are, however, limited data regarding whether nontuberculous mycobacterial sputum culture conversion or semiquantitative culture analysis correlates with subjective or nonmicrobiologic objective indices of treatment response.

OBJECTIVES

To determine whether a semiquantitative mycobacterial culture scale correlated with clinical disease status and was predictive of long-term sputum mycobacterial culture conversion to negative in a cohort of patients with nodular/bronchiectatic Mycobacterium avium complex lung disease undergoing therapy.

METHODS

One hundred and eighty patients undergoing standard macrolide-based therapy for M. avium complex lung disease were monitored at standard frequent intervals with symptomatic, radiographic, and microbiologic data collected, including semiquantitative mycobacterial culture analysis. Analyses were used to evaluate clinical and microbiologic predictors of long-term sputum conversion to culture negative.

MEASUREMENTS AND MAIN RESULTS

After 12 months of therapy, 148 (82%) patients had sputum conversion to culture negative. Baseline semiquantitative sputum culture scores did not differ between patients with sputum conversion and those without. The change in sputum culture semiquantitative score from baseline to Month 3 was highly predictive of subsequent sputum long-term conversion status indicative of treatment success, as was improvement in cough, and especially early radiographic improvement.

CONCLUSIONS

Early semiquantitative sputum agar plate culture results can be used to predict symptomatic and radiographic improvement as well as long-term sputum culture conversion to negative in this population. We suggest that semiquantitative sputum culture scores can be a useful tool for evaluating new nontuberculous mycobacterial lung disease therapies.

Comparison of Sample Preparation Methods, Instrumentation Platforms, and Contemporary Commercial Databases for Identification of Clinically Relevant Mycobacteria by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

When mycobacteria are recovered in clinical specimens, timely species-level identification is required to establish the clinical significance of the isolate and facilitate optimization of antimicrobial therapy. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been reported to be a reliable and expedited method for identification of mycobacteria, although various specimen preparation techniques and databases for analysis are reported across studies. Here we compared two MALDI-TOF MS instrumentation platforms and three databases: Bruker Biotyper Real Time Classification 3.1 (Biotyper), Vitek MS Plus Saramis Premium (Saramis), and Vitek MS v3.0. We evaluated two sample preparation techniques and demonstrate that extraction methods are not interchangeable across different platforms or databases. Once testing parameters were established, a panel of 157 mycobacterial isolates (including 16 Mycobacterium tuberculosis isolates) was evaluated, demonstrating that with the appropriate specimen preparation, all three methods provide reliable identification for most species. Using a score cutoff value of ≥1.8, the Biotyper correctly identified 133 (84.7%) isolates with no misidentifications. Using a confidence value of ≥90%, Saramis correctly identified 134 (85.4%) isolates with one misidentification and Vitek MS v3.0 correctly identified 140 (89.2%) isolates with one misidentification. The levels of accuracy were not significantly different across the three platforms (P = 0.14). In addition, we show that Vitek MS v3.0 requires modestly fewer repeat analyses than the Biotyper and Saramis methods (P = 0.04), which may have implications for laboratory workflow.

Nontuberculous mycobacteria pathogenesis and biofilm assembly

Nontuberculous mycobacteria (NTM) are emergent pathogens whose importance in human health has been gaining relevance after being recognized as etiological agents of opportunist infections in HIV patients. Currently, NTM are recognized as etiological agents of several respiratory and extra-respiratory infections of immune-competent individuals. The environmental nature of NTM together with the ability to assemble biofilms on different surfaces plays a key role on their pathogenesis. In the present work the ability of three fast-growing NTM (Mycobacterium smegmatis, Mycobacterium fortuitum and Mycobacterium chelonae) to persist within a model of human alveolar macrophages was evaluated. Most often human infections with NTM occur by contact with the environment. Biofilms can work as environmental reservoirs. For this reason, it was decided to evaluate the ability of NTM to assemble biofilms on different surfaces. Scanning electron microscopy was used to elucidate the biofilm structure. The ability to assemble biofilms was connected with the ability to spread on solid media known as sliding. Biofilm assembly and intracellular persistence seems to be ruled by different mechanisms.

Epidemiology of human pulmonary infection with nontuberculous mycobacteria: a review

Population-based data have documented a worldwide increase in the prevalence of human nontuberculous mycobacterial (NTM) infections since 2000. Mycobacterium avium complex is predominant in North America and East Asia, whereas in regions within Europe, M kansasii, M xenopi, and M malmoense are more common. Host factors important to the current epidemiology of NTM pulmonary disease include thoracic skeletal abnormalities, rheumatoid arthritis, and use of immunomodulatory drugs. Clustering of disease within families suggests a heritable genetic predisposition to disease susceptibility. Warm, humid environments with high atmospheric vapor pressure contribute to population risk.

Increase in nontuberculous mycobacteria isolated in Shanghai, China: results from a population-based study

BACKGROUND

In China, the prevalence of nontuberculous mycobacteria (NTM) in isolates from mycobacterial culture-positive patients with pulmonary tuberculosis (TB) is largely unknown.

METHODS

We used conventional biochemical and 16S rRNA gene sequencing to identify species of mycobacteria in specimens from patients suspected of having TB. Drug-susceptibility testing was performed on NTM isolates using the proportion method. We also determined the independent risk factors associated with infection with NTM compared with infection with Mycobacterium tuberculosis.

RESULTS

The overall rate of NTM isolated from mycobacterial culture-positive patients was 5.9% in this population, with a significantly increasing trend from 3.0% in 2008 to 8.5% in 2012 (P for trend <0.001). The organism most frequently identified was M. kansasii (45.0%), followed by M. intracellulare (20.8%) and M. chelonae/abscessus (14.9%). The overall proportion of isolates resistant to the four first-line anti-TB agents were 64.6% for isoniazid, 77.6% for streptomycin, 63.3% for rifampicin and 75.1% for ethambutol. The risk factors most often associated with NTM infection were older age (P for trend <0.001), being a resident of Shanghai (adjusted odds ratio [aOR], 1.48; 95% CI, 1.10-2.00), having been treated for tuberculosis (aOR, 1.64; 95% CI, 1.18-2.29), having a cavity on chest X-ray (aOR, 1.51; 95% CI, 1.16-1.96), and being sputum smear-negative (aOR, 1.59; 95% CI, 1.16-2.18).

CONCLUSIONS

The prevalence of NTM isolated in Shanghai increased between 2008 and 2012, thus clinicians should consider NTM as a possible cause of TB-like disease. Accurate species identification is imperative so that proper treatment can be administered for diseases caused by the diversity of NTM species.

Managing pulmonary nontuberculous mycobacterial infection. time for a patient-centered approach

The incidence of nontuberculous mycobacteria is increasing worldwide. However, the evidence base for clinical management comprises mostly expert opinion, case series, and few randomized clinical trials. Most currently recommended treatment regimens entail prolonged use of multiple antimicrobial agents associated with multiple self-limited and persistent potential adverse effects, including irreversible impairments of hearing, vision, and kidney function. Yet, little is known about how treatment impacts an individual patient's overall health status. Current treatment guidelines, although of undoubted value, are constrained by these limitations. Here we call for new studies that reassess recommendations for medical management of pulmonary nontuberculous mycobacteria infections, in particular Mycobacterium avium-intracellulare complex and Mycobacterium abscessus complex. We propose pragmatic, person-centered outcome measures that might be used in clinical assessments and new research studies, including patient-reported experience measures and patient-reported outcome measures. This will enable patients and their health-care providers to make clinical management decisions that derive from a realistic view of what they can hope to achieve from treatment.

Evidence of mycobacterial disease in COPD patients with lung volume reduction surgery; the importance of histological assessment of specimens: a cohort study

Background

Patients with COPD are at risk of non-tuberculous mycobacterial infection (NTM). This study examined the histology of lung tissue from COPD patients following lung volume reduction with particular focus on evidence of mycobacterial infection.

Methods

Retrospective histological study of 142 consecutive lung volume reduction surgical specimens (126 separate patients) at Royal Brompton Hospital between 2000 – 2013, with prospectively collected preoperative data on exacerbation rate, lung function and body mass index.

Results

92% of patients had at least one other histological diagnosis in addition to emphysema. 10% of specimens had histological evidence of mycobacterial infection, one with co-existent aspergilloma. Mycobacteria were only identified in those patients with granulomas that were necrotising. These patients had higher exacerbation rates, lower TLCO and FEV₁.

Conclusion

A proportion of severe COPD patients will have evidence of mycobacterial infection despite lack of clinical and radiological suspicion. This may have implications for long-term management of these patients.

Drug treatment of pulmonary nontuberculous mycobacterial disease in HIV-negative patients: the evidence

Pulmonary disease (PD) caused by nontuberculous mycobacteria is an emerging infection mainly in countries where the incidence of tuberculosis is in decline. It affects an elderly population, often with underlying chronic lung diseases, but its epidemiology shows significant regional variation. Guidelines and recommendations for treatment of these infections exist, but build strongly on expert opinion, as very few good quality clinical trials have been performed in this field. Only for the most frequent causative agents, the Mycobacterium avium complex, Mycobacterium kansasii and Mycobacterium abscessus, a reasonable number of trials and case series is now available. For the less frequent causative agents of pulmonary nontuberculous mycobacterial (NTM) disease (Mycobacterium xenopi, Mycobacterium malmoense, Mycobacterium fortuitum, Mycobacterium chelonae) data is mostly limited to a few very small case series. Within this review, we have collected and combined evidence from all available trials and case series. From the data of these trials and case series, we reconstruct a more evidence-based overview of possible drug treatment regimens and their outcomes.