Isolation prevalence of pulmonary nontuberculous mycobacteria in Ontario in 2007

Prevalence of Mycobacterium kansasii in clinical and environmental isolates, a systematic review and meta-analysis

Background

Mycobacterium kansasii infection is one of the most common causes of non-tuberculosis mycobacterial (NTM) disease worldwide. However, accurate information on the global prevalence of this bacterium is lacking. Therefore, this study was conducted to investigate the prevalence of M. kansasii in clinical and environmental isolates.

Methods

Databases, including PubMed, Scopus, and the Web of Science, were utilized to gather articles on the prevalence of M. kansasii in clinical and environmental isolates. The collected data were analyzed using Comprehensive Meta-Analysis software.

Results

A total of 118 and 16 studies met the inclusion criteria and were used to analyze the prevalence of M. kansasii in clinical and environmental isolates, respectively. The prevalence of M. kansasii in NTM and environmental isolates were 9.4 and 5.8%, respectively. Subsequent analysis showed an increasing prevalence of M. kansasii over the years. Additionally, the results indicated a significant difference in the prevalence of this bacteria among different regions.

Conclusion

The relatively high prevalence of M. kansasii among NTM isolates suggests the need for further implementation of infection control strategies. It is also important to establish appropriate diagnostic criteria and management guidelines for screening this microorganism in environmental samples in order to prevent its spread, given its high prevalence in environmental isolates.

Increasing and More Commonly Refractory Mycobacterium avium Pulmonary Disease, Toronto, Ontario, Canada

In mid-2014, Public Health Ontario Laboratories identified coincident increasing Mycobacterium avium isolation and falling M. xenopi isolation in the Toronto, Ontario, Canada, area. We performed a retrospective cohort of all patients in a Toronto clinic who began treatment for either M. avium or M. xenopi pulmonary disease during 2009–2012 (early period) or 2015–2018 (late period), studying their relative proportions and sputum culture conversion. We conducted a subgroup analysis among patients who lived in the Toronto-York region. The proportion of patients with M. avium was higher in the late period (138/146 [94.5%] vs. 82/106 [77.4%]; p<0.001). Among M. avium patients, conversion was lower in the late period (26.1% vs. 39.0%; p = 0.05). The increase in the proportion of patients with M. avium pulmonary disease and the reduction in the frequency of sputum culture conversion is unexplained but could suggest an increase in environmental M. avium exposure.

Non-tuberculous mycobacteria pulmonary disease: A review of trends, risk factors, diagnosis and management

Non-tuberculous mycobacteria (NTM) reports have been on the rise globally, with increasing incidence and prevalence accompanied by poor outcomes. The rise has been attributed to an ageing population with increasing comorbid illnesses, and improved laboratory techniques in diagnosing the disease. However, despite the increase, some parts of the world still lack data, especially sub-Saharan African countries. The lack of data in our setting is difficult to explain, as we have a significant burden of NTM risk factors (i.e. HIV, tuberculosis and bronchiectasis). This review therefore serves as a reminder and a challenge to start searching, and reporting on our experiences. The review will highlight the rising incidence, important risk factors, diagnosis and management of NTM pulmonary disease.

Nontuberculous Mycobacteria

Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and 193 species of NTM have been discovered thus far. NTM species vary in virulence from benign environmental organisms to difficult-to-treat human pathogens. Pulmonary infections remain the most common manifestation of NTM disease in humans and bronchiectasis continues to be a major risk factor for NTM pulmonary disease (NTM PD). This article will provide a useful introduction and framework for clinicians involved in the management of bronchiectasis and NTM. It includes an overview of the epidemiology, pathogenesis, diagnosis, and management of NTM PD. We will address the challenges faced in the diagnosis of NTM PD and the importance of subspeciation in guiding treatment and follow-up, especially in Mycobacterium abscessus infections. The treatment of both Mycobacterium avium complex and M. abscessus, the two most common NTM species known to cause disease, will be discussed in detail. Elements of the recent ATS/ERS/ESCMID/IDSA NTM guidelines published in 2020 will also be reviewed.

Mycobacteria: Selection of Transplant Candidates and Post-lung Transplant Outcomes

Mycobacterium is a large, clinically relevant bacterial genus made up of the agents of tuberculosis and leprosy and hundreds of species of saprophytic nontuberculous mycobacteria (NTM). Pathogenicity, clinical presentation, epidemiology, and antimicrobial susceptibilities are exceptionally diverse between species. Patients with end-stage lung disease and recipients of lung transplants are at a higher risk of developing NTM colonization and disease and of severe manifestations and outcomes of tuberculosis. Data from the past three decades have increased our knowledge of these infections in lung transplant recipients. Still, there are knowledge gaps to be addressed to further our understanding of risk factors and optimal treatments for mycobacterial infections in this population.

Role of Soluble T-Cell Immunoglobulin Mucin Domain-3 in Differentiating Nontuberculous Mycobacterial Lung Disease from Pulmonary Colonization

BACKGROUND

Differentiating between nontuberculous mycobacterial lung disease (NTM-LD) and pulmonary NTM colonization (NTM-Col) is difficult. Compared with healthy controls, patients with NTM-LD generally present immune tolerance along with increased expressions of T-cell immunoglobulin mucin domain-3 (TIM-3) and programmed cell death-1 (PD-1) on T lymphocytes. However, the role of soluble TIM-3 (sTIM-3) and soluble PD-1 (sPD-1) in differentiating NTM-LD from NTM colonization (NTM-Col) remains unclear.

METHODS

Patients with NTM-positive respiratory samples and controls were enrolled from 2016 to 2019. Patients were classified into NTM-Col and NTM-LD groups. Levels of sTIM-3, sPD-1, soluble PD-ligand-1 (sPD-L1), and TIM-3 expression were measured. Factors associated with NTM-LD were analyzed by logistical regression.

RESULTS

TIM-3 expression on CD4+ and CD8+ T lymphocytes were highest in NTM-LD group, followed by NTM-Col, and control (P=.017 and P=.011 for trend). sTIM-3 elevated in the NTM-Col group compared with the NTM-LD and control groups (856.3±518.7 vs. 595.3±352.6pg/mL, P=.009; vs. 437.0±267.4pg/mL, P<.001). Levels of sPD-1 and sPD-L1 were similar among groups. Among the 79 NTM-positive patients, sTIM-3 was associated with NTM-LD (100-pg/mL increase, adjusted odds ratio (aOR) 0.658 [95% CI, 0.502-0.864], P=.003). Patients with ≥2 risk factors (sTIM-3≤530pg/mL, BMI≤22.5, and radiographic score ≥5) were 13 times more likely to exhibit NTM-LD than those without (aOR 13.234 [2.983-58.709], P=.001).

CONCLUSIONS

sTIM-3 was an independent factor for differentiating NTM-LD from NTM-Col, suggesting the immunologic role of sTIM-3 in NTM-LD pathogenesis. By assessing sTIM-3 levels and other risk factors, physicians may be able to identify NTM-LD cases in a simplified manner.

Identification of the Mycobacterial Strains Isolated From Clinical Specimens Using hsp65 PCR-RFLP Method

Objectives

It is important to identify mycobacteria at the species level, to distinguish pathogen from non-pathogenic species, to choose the appropriate treatment regimen and to collect epidemiological data. For the identification of mycobacteria, which are time-consuming and laborious with traditional methods, faster, more sensitive and reliable methods are needed. This study aims to investigate the suitability of the hsp65 Polymerase chain reaction-restriction fragment polymorphism (PCR-RFLP) method for routine laboratory use.

Methods

In this study, 141 mycobacterial isolates were obtained from 1632 samples, which were sent to the Medical Microbiology Laboratory.

Results

In the culture, mycobacteria were identified as 138 M. tuberculosis complex (MTBC) and three non-tuberculosis mycobacteria (NTM) by conventional methods. Using the hsp65 PCR-RFLP method, 137 isolates were identified as MTBC, four isolates as NTM. An isolate that was evaluated as MTBC because it was PNB sensitive by the conventional method was determined as NTM with the hsp65 method. In the identification of non-tuberculosis mycobacteria with the hsp65 PCR-RFLP method, one isolate was identified as M. abcessus and three isolates were identified as M. avium complex.

Conclusion

In our study, it was concluded that the hsp65 PCR-RFLP method, which allows identification of mycobacteria, including NTMs, is a method that is cheap, easy and suitable for routine use to provide rapid information to the clinic. The scope of the agar and database used in the method is effective in the definition of the correct species.

Costs Associated with Nontuberculous Mycobacteria Infection, Ontario, Canada, 2001-2012

To determine incidence-based healthcare costs attributable to nontuberculous mycobacterial (NTM) pulmonary disease (PD) and NTM pulmonary isolation (PI), from the healthcare payer perspective, we conducted a population-based matched cohort study in Ontario, Canada. We established cohorts of patients with incident NTM-PD and NTM-PI during 2001–2012 by using individually linked laboratory data and health administrative data, matched to unexposed persons from the general population. To estimate attributable costs for acute and long-term illness, we used a phase-of-care approach. Costs were stratified by age, sex, and healthcare resource, and reported in 2018 Canadian dollars (CAD) and US dollars (USD), standardized to 10 days. Costs were highest during the before-death phase (NTM-PD CAD $1,352 [USD $1,044]; NTM-PI CAD $731 [USD $565]). The cumulative mean attributable 1-year costs were CAD $14,953 (USD $11,541) for NTM-PD and CAD $8,729 (USD $6,737) for NTM-PI. Costs for patients with NTM-PD and NTM-PI were higher than those for unexposed persons.

Impact of different subspecies on disease progression in initially untreated patients with Mycobacterium avium complex lung disease

OBJECTIVE

Disease progression is a strong indicator of treatment for Mycobacterium avium complex lung disease (MAC-LD). The impact of MAC subspecies on the risk of disease progression remains uncertain in MAC-LD patients.

METHODS

In this cohort study, we included MAC-LD patients from 2013 to 2018 and classified them into M. intracellulare, M. avium, M. chimaera and other subspecies groups by genotype. We observed the disease progression of MAC-LD, indicated by antibiotic initiation and/or radiographic progression. We used Cox regression analysis to assess predictors for disease progression.

RESULTS

Of 105 MAC isolates from unique MAC-LD patients, 35 (33%) were M. intracellulare, 41 (39%) M. avium, 16 (15%) M. chimaera and 13 (12%) other subspecies. After a mean follow-up time of 1.3 years, 56 (53%) patients developed disease progression: 71% (25/35), 54% (22/41), 31% (4/13) and 31% (5/16) in patients with M. intracellulare, M. avium, others and M. chimaera, respectively. The independent predictors for disease progression were M. chimaera subspecies (HR 0.356, 95% CI (0.134-0.943)), compared with the reference group of M. intracellulare, body mass index ≤20 kg/m² (HR 1.788 (1.022-3.130)) and initial fibrocavitary pattern (HR 2.840 (1.190-6.777)) after adjustment for age, sex and sputum smear positivity. Among patients without fibrocavitary lesions (n = 94), the risk of disease progression significantly decreased in patients with other subspecies (HR 0.217 (0.050-0.945)) and remained low in those with M. chimaera (HR 0.352 (0.131-0.947)).

CONCLUSIONS

Mycobacterium chimaera was not uncommon in this study; unlike M. intracellulare, it was negatively correlated with disease progression of MAC-LD, suggesting a role of MAC subspecies identification in prioritizing patients.

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.

Non-tuberculous mycobacteria in lung transplant recipients: Prevalence, risk factors, and impact on survival and chronic lung allograft dysfunction

BACKGROUND

Non-tuberculous mycobacteria (NTM) are environmental organisms that colonize or infect lung transplant recipients. Because of differences in populations studied and geographical diversity of species, risk factors for infection and its impact on patient outcomes post transplant are conflicting in the literature.

METHODS

We reviewed the charts of 375 lung transplant recipients at the University of Alberta Hospital (Edmonton, Canada) between 2005 and 2014 to assess NTM epidemiology and risk factors. NTM positivity was determined from a laboratory database. The impact of NTM on patient and graft survival was tested by multivariate Cox regression analysis.

RESULTS

Non-tuberculous mycobacteria were cultured from 26 patients before and 17 patients after transplant. The most commonly isolated species were Mycobacterium avium complex (55%) and Mycobacterium abscessus (20%). Five-year mortality was significantly higher in those infected with NTM after transplant (P = .016), but there was no difference in chronic lung allograft dysfunction (CLAD) at 5 years (P = .999). Cystic fibrosis and lower body mass index were associated with pre-transplant but not post-transplant NTM.

CONCLUSIONS

Isolation of NTM occurred in 7% of patients before and 4.5% of patients after transplant. In this cohort, NTM isolation was associated with increased risk of death but not CLAD onset at 5 years.

Association between Inhaled Corticosteroid Use and Pulmonary Nontuberculous Mycobacterial Infection

RATIONALE

Nontuberculous mycobacterial (NTM) pulmonary disease prevalence is increasing.

OBJECTIVES

To determine the association between the use of inhaled corticosteroids and the likelihood of NTM pulmonary infection among individuals with treated airway disease.

METHODS

We conducted a case-control study of subjects with airway disease with and without NTM pulmonary infection (based on mycobacterial respiratory cultures) between 2000 and 2010 in northern California. We quantified the use of inhaled corticosteroids, other airway disease medications, and healthcare use within 6 months of NTM pulmonary infection identification. We used 1:10 case-control matching and conditional logistic regression to evaluate the association between the duration and cumulative dosage of inhaled corticosteroid use and NTM pulmonary infection.

RESULTS

We identified 248 cases with NTM pulmonary infection with an estimated rate of 16.4 cases per 10,000 subjects treated for airway disease. The median interval between treated airway disease cohort entry (defined as date of patient filling the third airway disease treatment prescription) and NTM case identification was 1,217 days. Compared with control subjects, subjects with NTM pulmonary infection were more likely to use airway disease medications including systemic steroids; they were also more likely to use health care. Any inhaled corticosteroids use between 120 days and 2 years before cohort entry was associated with substantially increased odds of NTM infection. For example, the adjusted odds ratio for NTM infection among inhaled corticosteroid users in a 2-year interval was 2.51 (95% confidence interval, 1.40-4.49; P < 0.01). Increasing cumulative inhaled corticosteroid dose was also associated with greater odds of NTM infection.

CONCLUSIONS

Inhaled corticosteroid use, and particularly high-dose inhaled corticosteroid use, was associated with an increased risk of NTM pulmonary infection.

Nontuberculous mycobacteria isolated from specimens of pulmonary tuberculosis suspects, Northern Tunisia: 2002-2016

Background

Reports on the worldwide ascending trend of pulmonary nontuberculous mycobacteria (NTM) isolation rates and their effective role in respiratory tract infections are compelling. However, as yet, there are no such data relating to Tunisia.

Methods

Here we carried out a retrospective review of mycobacterial cultures originating from Northern Tunisia, which have been processed in the laboratory of mycobacteria of the Institut Pasteur de Tunis, during the time period 2002–2016. All pulmonary NTM (PNTM) isolates available for culture were characterized phenotypically and their taxonomic status was further established based on polymorphisms in rpoB, 16S rRNA, hsp65, and sodA DNA gene sequences.

Results

Of the 10,466 specimens collected from HIV-negative Tunisian patients with presumptive clinical pulmonary TB, 60 (0.6%) yielded PNTM isolates. An overall annual PNTM isolation prevalence of 0.2/100,000 was estimated. As far as could be ascertained, this isolation rate accounts amongst the lowest reported hitherto throughout the world. Among the 30 NTM isolates that were available for culture, 27 (90.0%) have been identified to the species level. The most commonly encountered species was Mycobacterium kansasii (23.3%) subtype 1. Strikingly, all M. kansasii cases were male patients originating from Bizerte, an industrialized region particularly known for iron industry. The remaining NTM species were M. fortuitum (16.6%), M. novocastrense (16.6%), M. chelonae (10.0%), M. gordonae (6.6%), M. gadium (6.6%), M. peregrinum (3.3%), M. porcinum (3.3%), and M. flavescens (3.3%). There were no bacteria of the M. avium complex, the most frequently isolated NTM globally, and the main driver of the rise of NTM-lung diseases.

Conclusions

This study uncovered an exceptional low prevalence of PNTM isolation among HIV-negative TB suspects in Northern Tunisia, suggesting a very low burden of NTM pulmonary disease. However, the frequent isolation of M. kansasii subtype 1, the most pathogenic subtype, particularly from the industrialized region of Bizerte, strongly suggests its effective involvement in a typical pulmonary disease.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12879-019-4441-1.

MAV_4644 Interaction with the Host Cathepsin Z Protects Mycobacterium avium subsp. hominissuis from Rapid Macrophage Killing

Mycobacterium avium subspecies hominissuis (MAH) is an opportunistic pathogen that is ubiquitous in the environment and often isolated from faucets and showerheads. MAH mostly infects humans with an underlying disease, such as chronic pulmonary disorder, cystic fibrosis, or individuals that are immunocompromised. In recent years, MAH infections in patients without concurrent disease are increasing in prevalence as well. This pathogen is resistant to many antibiotics due to the impermeability of its envelope and due to the phenotypic resistance established within the host macrophages, making difficult to treat MAH infections. By screening a MAH transposon library for mutants that are susceptible to killing by reactive nitrogen intermediaries, we identified the MAV_4644 (MAV_4644:Tn) gene knockout clone that was also significantly attenuated in growth within the host macrophages. Complementation of the mutant restored the wild-type phenotype. The MAV_4644 gene encodes a dual-function protein with a putative pore-forming function and ADP-ribosyltransferase activity. Protein binding assay suggests that MAV_4644 interacts with the host lysosomal peptidase cathepsin Z (CTSZ), a key regulator of the cell signaling and inflammation. Pathogenic mycobacteria have been shown to suppress the action of many cathepsins to establish their intracellular niche. Our results demonstrate that knocking-down the cathepsin Z in human macrophages rescues the attenuated phenotype of MAV_4644:Tn clone. Although, the purified cathepsin Z by itself does not have any killing effect on MAH, it contributes to bacterial killing in the presence of the nitric oxide (NO). Our data suggest that the cathepsin Z is involved in early macrophage killing of MAH, and the virulence factor MAV_4644 protects the pathogen from this process.

Simultaneous diagnosis of tuberculous and non-tuberculous mycobacterial diseases: Time for a better patient management

Tuberculosis (TB) is the deadliest infectious disease in the world which disproportionately affects low-and-middle-income countries (LMICs) where diagnostic resources and treatment options are limited. The incidence of pulmonary non-tuberculous mycobacteria (NTM) disease is also rapidly increasing in these regions traditionally dominated by TB infections. This poses significant diagnostic and treatment challenges, since these two diseases are often indistinguishable clinically or by sputum smear microscopy (SSM), the most commonly used TB diagnostic tool in LMICs. Consequently, NTM-infected patients usually receive unnecessary TB treatment for months. TB patients with NTM co-infections may also be treated incorrectly due to inaccurate SSM and Xpert™ MTB/RIF (M. tuberculosis./rifampin) results. These issues complicate the management of patients and contribute to the worsening of the current TB and NTM epidemiological features including development of drug resistant strains. It is therefore critical to develop improved diagnostic tools to accurately distinguish these two different pathogens that have many similar clinical and epidemiological features but have different treatment regimens. In this review, we will discuss limitations with current diagnostic tools and the need to develop novel techniques that can accurately and simultaneously diagnose TB and NTM disease._.

Mycobacterium xenopi systemic infection in a domestic fiery-shouldered conure bird (Pyrrhura egregia)

Introduction

Mycobacterium xenopi is a rare opportunistic pathogen mainly causing infections in immunocompromised human patients or those with underlying chronic structural lung disease. Cases of disease in veterinary medicine remain scarce. Few animal species, including birds, are suspected of being vectors of the disease and there has not yet been a report of clinical disease in birds. We report the first case, to our knowledge, of systemic infection in a domestic bird.

Case presentation

A female fiery-shouldered conure was submitted after death for necropsy following episodes of heavy breathing. The necropsy revealed multiple granulomatous lesions within the liver, air sacs and kidneys. Ziehl–Neelsen stains demonstrated the presence of numerous intralesional acid-fast bacilli. PCR assays and culture confirmed the presence of M. xenopi.

Conclusion

Through this case we hope to describe the characteristics of M. xenopi disease in birds and the possible close relationship between animal and human infections.

Pulmonary versus Nonpulmonary Nontuberculous Mycobacteria, Ontario, Canada

In Ontario, Canada, during 1998–2010, nontuberculous mycobacteria (NTM) from pulmonary sites comprised 96% of species/patient combinations isolated; annual rates of isolation and cases increased steadily. NTM isolates from nonpulmonary sites comprised 4% of species/patient combinations; annual rates and cases were temporally stable. NTM increases were driven exclusively by pulmonary isolates and disease.

Microbiological Persistence in Patients With Mycobacterium avium Complex Lung Disease: The Predictors and the Impact on Radiographic Progression

Background

Persistent growth of Mycobacterium avium complex (MAC) in the lungs indicates continuous infection in MAC lung disease (MAC-LD), but its clinical significance has not been investigated. We aimed to evaluate the predictors of persistent culture-positivity for MAC (MAC-PP) and its impact on radiographic deterioration in MAC-LD.

Methods

Patients with MAC-LD at multiple medical centers from 2011 to 2016 were enrolled retrospectively. Microbiological persistence of MAC-LD was defined as MAC-PP exceeding 1 year, in contrast with the negative-conversion group. The outcome was radiographic progression, namely, increased number of involved lung areas or cavitary formation.

Results

Among 126 patients with MAC-LD, 75 (60%) were in the MAC-PP group; these patients had a higher proportion of radiographic progression (54%) than patients in the negative-conversion group (odds ratio [OR], 3.318; 95% confidence interval, 1.146-9.612). Independent predictors of MAC-PP were low body mass index (BMI), radiographic nodular-bronchiectatic (NB) pattern, and increase in the highest grade of acid-fast bacilli smear (AFS). Patients with BMI <21 kg/m2, NB pattern, and positive AFS had an OR of 17.7 for MAC-PP, and those with ≥2 of the factors had a 4.5-fold increased OR for MAC-PP relative to the comparison group. Other than MAC-PP, the highest AFS grade and no anti-MAC treatment were correlated with radiographic progression.

Conclusion

Microbiological persistence in patients with MAC-LD is not uncommon and leads to an increased risk of radiographic progression. The predictors of MAC-PP are low BMI, NB pattern, and high AFS grade; if these risk factors are present, anti-MAC treatment should be seriously considered.

Practice Guidelines for Clinical Microbiology Laboratories: Mycobacteria

Mycobacteria are the causative organisms for diseases such as tuberculosis (TB), leprosy, Buruli ulcer, and pulmonary nontuberculous mycobacterial disease, to name the most important ones. In 2015, globally, almost 10 million people developed TB, and almost half a million patients suffered from its multidrug-resistant form. In 2016, a total of 9,287 new TB cases were reported in the United States. In 2015, there were 174,608 new case of leprosy worldwide. India, Brazil, and Indonesia reported the most leprosy cases. In 2015, the World Health Organization reported 2,037 new cases of Buruli ulcer, with most cases being reported in Africa. Pulmonary nontuberculous mycobacterial disease is an emerging public health challenge. The U.S. National Institutes of Health reported an increase from 20 to 47 cases/100,000 persons (or 8.2% per year) of pulmonary nontuberculous mycobacterial disease among adults aged 65 years or older throughout the United States, with 181,037 national annual cases estimated in 2014. This review describes contemporary methods for the laboratory diagnosis of mycobacterial diseases. Furthermore, the review considers the ever-changing health care delivery system and stresses the laboratory's need to adjust and embrace molecular technologies to provide shorter turnaround times and a higher quality of care for the patients who we serve.

Pulmonary Cavity From Mycobacterium malmoense in an HIV-Infected Patient: Complicated by Bronchopleural Fistula

We present a case of M. malmoense and HIV co-infection complicated by aspergilloma leading to bronchopleural fistula with intractable pneumothorax and pleural aspergillosis, ultimately requiring surgical intervention. Treatment guidelines for M. malmoense are reviewed, literature regarding M. malmoense and HIV co-infection is reviewed, and the epidemiology of M. malmoense in North America is discussed.

A Laboratory-based Analysis of Nontuberculous Mycobacterial Lung Disease in Japan from 2012 to 2013

RATIONALE

Since 2010, mycobacterial examination results have been used widely to survey nontuberculous mycobacteria (NTM) lung disease.

OBJECTIVES

To reveal the clinical and epidemiological status of NTM lung disease in Japan.

METHODS

All data on the isolation and identification of mycobacteria in 2012 and 2013 were obtained from three dominant commercial laboratories in Japan. Pulmonary NTM disease was defined on the basis of bacteriological diagnostic criteria issued by the American Thoracic Society/Infectious Diseases Society of America. The coverage population was estimated using the ratio between national tuberculosis registration data and laboratory results for each of the eight regions of Japan.

MEASUREMENTS AND MAIN RESULTS

A total of 113,313 mycobacterial specimens from 4,710 institutes were collected, and specimens from 26,059 patients tested positive for NTM cultures at least once. Among patients with positive cultures, 7,167 (27.5%) satisfied the American Thoracic Society/Infectious Diseases Society of America criteria for NTM lung disease, resulting in a 2-year prevalence rate of 24.0 per 100,000. Mycobacterium avium complex (MAC) was the most commonly isolated species (93.3%), and 29.0% of the patients from whom MAC was isolated satisfied the criteria for NTM lung disease. Individuals older than 70 years of age accounted for the majority of cases, and 65.5% of cases involved females. After MAC, Mycobacterium kansasii and Mycobacterium abscessus exhibited the highest (43.6%) and second-highest (37.1%) incidence per isolation, respectively. The prevalence of M. kansasii was highest in the Kinki region (P < 0.05), and M. abscessus had the greatest prevalence in the Kyushu-Okinawa region (P < 0.005). The proportion of Mycobacterium intracellulare in MAC cases was higher in the southwestern part of Japan than in other regions. The period prevalence was highest in the southwestern part of Japan, and the standardized prevalence ratio was highest in central regions. Evaluations of clarithromycin susceptibility revealed a clear binomial distribution.

CONCLUSIONS

This investigation is the first laboratory-based study in which a large number of NTM isolated from clinical samples in Japan have been assessed. Although the calculated prevalence of NTM disease might be underestimated, the approach may prove useful for monitoring relative epidemiological data for NTM lung disease.

Mortality after Respiratory Isolation of Nontuberculous Mycobacteria. A Comparison of Patients Who Did and Did Not Meet Disease Criteria

RATIONALE

The mortality of patients with respiratory tract isolates of nontuberculous mycobacteria (NTM) and their risk factors for death are not well described.

OBJECTIVES

To determine age-adjusted mortality rates for patients with respiratory NTM isolates and their causes of death and to examine whether American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) diagnostic criteria identify those at higher risk of death after NTM isolation.

METHODS

We linked vital records registries with a previously identified Oregon population-based cohort of patients with NTM respiratory isolation. We excluded patients with Mycobacterium gordonae (n = 33) and those who died (n = 21) at the time of first isolation. We calculated 5-year age-adjusted mortality rates. We used Kaplan-Meier and Cox proportional hazards analysis to examine the association of ATS/IDSA criteria and other risk factors with death.

RESULTS

Of 368 subjects with respiratory NTM isolates in 2005-2006, 316 were included in the survival analysis. Most (84%) of their cultures isolated Mycobacterium avium complex. 35.1% died in the 5 years following respiratory isolation. Five-year age-adjusted mortality rates were slightly higher for those meeting (28.7/1,000) versus not meeting (23.4/1,000) ATS/IDSA criteria. In multivariate analysis, older age (adjusted hazard ratio [aHR], 1.06; 95% confidence interval [CI], 1.04-1.07) and lung cancer (aHR, 2.77; 95% CI, 1.51-5.07) were associated with an increased risk of death. A trend was noted between meeting ATS/IDSA criteria and subsequent death (aHR, 1.37; 95% CI, 0.95-1.97). Among cases, male sex, older age, and immunosuppressive therapy use were independent risk factors for death.

CONCLUSIONS

In the State of Oregon, patients with NTM respiratory isolates have high mortality, regardless of whether they meet ATS/IDSA criteria for pulmonary NTM disease. Most patients die as a result of causes other than NTM infection.

Nontuberculous Mycobacteria in Saudi Arabia and Gulf Countries: A Review

Nontuberculous Mycobacteria (NTM) are causing growing health problems worldwide. This is indicated by an increasing amount of scientific reports showing not only well-identified species reemerging but also emergence of new species. The emergence and reemergence of NTM are particularly worrying in developing countries due to scarce published data and improper identification. Here we aimed to examine the main epidemiological aspects and diagnostic challenges associated with NTM in countries of the Gulf Cooperation Council (GCC) and compare these findings to the international arena findings. Data revealed that countries of the GCC are largely dominated by rapidly growing mycobacteria species such as M. fortuitum (29%) and M. abscessus (17%) with high rate of definitive respiratory diseases. On the other hand, most of the developed countries are dominated by slowly growing mycobacteria such as MAC, M. kansasii, and M. gordonae. More efforts are needed, however, to gain insights into NTM issues in countries of the GCC.

Nucleic Acid Amplification Testing and Sequencing Combined with Acid-Fast Staining in Needle Biopsy Lung Tissues for the Diagnosis of Smear-Negative Pulmonary Tuberculosis

Background

Smear-negative pulmonary tuberculosis (PTB) is common and difficult to diagnose. In this study, we investigated the diagnostic value of nucleic acid amplification testing and sequencing combined with acid-fast bacteria (AFB) staining of needle biopsy lung tissues for patients with suspected smear-negative PTB.

Methods

Patients with suspected smear-negative PTB who underwent percutaneous transthoracic needle biopsy between May 1, 2012, and June 30, 2015, were enrolled in this retrospective study. Patients with AFB in sputum smears were excluded. All lung biopsy specimens were fixed in formalin, embedded in paraffin, and subjected to acid-fast staining and tuberculous polymerase chain reaction (TB-PCR). For patients with positive AFB and negative TB-PCR results in lung tissues, probe assays and 16S rRNA sequencing were used for identification of nontuberculous mycobacteria (NTM). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of PCR and AFB staining were calculated separately and in combination.

Results

Among the 220 eligible patients, 133 were diagnosed with TB (men/women: 76/57; age range: 17–80 years, confirmed TB: 9, probable TB: 124). Forty-eight patients who were diagnosed with other specific diseases were assigned as negative controls, and 39 patients with indeterminate final diagnosis were excluded from statistical analysis. The sensitivity, specificity, PPV, NPV, and accuracy of histological AFB (HAFB) for the diagnosis of smear-negative were 61.7% (82/133), 100% (48/48), 100% (82/82), 48.5% (48/181), and 71.8% (130/181), respectively. The sensitivity, specificity, PPV, and NPV of histological PCR were 89.5% (119/133), 95.8% (46/48), 98.3% (119/121), and 76.7% (46/60), respectively, demonstrating that histological PCR had significantly higher accuracy (91.2% [165/181]) than histological acid-fast staining (71.8% [130/181]), P < 0.001. Parallel testing of histological AFB staining and PCR showed the sensitivity, specificity, PPV, NPV, and accuracy to be 94.0% (125/133), 95.8% (46/48), 98.4% (125/127), 85.2% (46/54), and 94.5% (171/181), respectively. Among patients with positive AFB and negative PCR results in lung tissue specimens, two were diagnosed with NTM infections (Mycobacterium avium-intracellulare complex and Mycobacterium kansasii).

Conclusion

Nucleic acid amplification testing combined with acid-fast staining in lung biopsy tissues can lead to early and accurate diagnosis in patients with smear-negative pulmonary tuberculosis. For patients with positive histological AFB and negative tuberculous PCR results in lung tissue, NTM infection should be suspected and could be identified by specific probe assays or 16S rRNA sequencing.

Epidemiology of nontuberculous mycobacteria isolations among central North Carolina residents, 2006-2010

BACKGROUND

Nontuberculous mycobacteria (NTM) are environmental mycobacteria associated with a range of infections. Reports of NTM epidemiology have primarily focused on pulmonary infections and isolations, however extrapulmonary infections of the skin, soft tissues and sterile sites are less frequently described.

METHODS

We comprehensively reviewed laboratory reports of NTM isolation from North Carolina residents of three counties during 2006-2010. We describe age, gender, and race of patients, and anatomic site of isolation for NTM species.

RESULTS

Among 1033 patients, overall NTM isolation prevalence was 15.9/100,000 persons (13.7/100,000 excluding Mycobacterium gordonae). Prevalence was similar between genders and increased significantly with age. Extrapulmonary isolations among middle-aged black males and pulmonary isolations among elderly white females were most frequently detected. Most isolations from pulmonary sites and blood cultures were Mycobacterium avium complex; rapidly growing NTM (e.g. Mycobacterium chelonae, Mycobacterium fortuitum) were most often isolated from paranasal sinuses, wounds and skin.

CONCLUSIONS

We provide the first characterization of NTM isolation prevalence in the Southeastern United States (U.S.). Variation in isolation prevalence among counties and races likely represent differences in detection, demographics and risk factors. Further characterization of NTM epidemiology is increasingly important as percentages of immunocompromised individuals and the elderly increase in the U.S.

Update on pulmonary disease due to non-tuberculous mycobacteria

Non-tuberculous mycobacteria (NTM) are emerging worldwide as significant causes of chronic pulmonary infection, posing a number of challenges for both clinicians and researchers. While a number of studies worldwide have described an increasing prevalence of NTM pulmonary disease over time, population-based data are relatively sparse and subject to ascertainment bias. Furthermore, the disease is geographically heterogeneous. While some species are commonly implicated worldwide (Mycobacterium avium complex, Mycobacterium abscessus), others (e.g., Mycobacterium malmoense, Mycobacterium xenopi) are regionally important. Thoracic computed tomography, microbiological testing with identification to the species level, and local epidemiology must all be taken into account to accurately diagnose NTM pulmonary disease. A diagnosis of NTM pulmonary disease does not necessarily imply that treatment is required; a patient-centered approach is essential. When treatment is required, multidrug therapy based on appropriate susceptibility testing for the species in question should be used. New diagnostic and therapeutic modalities are needed to optimize the management of these complicated infections.

Clinical and radiographic differentiation of lung nodules caused by mycobacteria and lung cancer: a case-control study

Background

Lung nodules caused by mycobacteria can resemble lung cancer on chest imaging. The advent of lung cancer screening with low-dose Computed Tomography is accompanied by high false-positive rates, making it necessary to establish criteria to differentiate malignant from benign nodules.

Methods

We conducted a retrospective case–control study of 52 patients with mycobacterial lung nodules and 139 patients with lung cancer, diagnosed between 2010 and 2012. We compared clinical and radiographic characteristics to identify predictors of disease by univariate and multivariate analysis. The discriminatory power of maximum Standardized Uptake Values from Positron-Emission-Tomography was also evaluated.

Results

Several variables were correlated with a diagnosis of mycobacterial infection or lung cancer on univariate analysis. Such variable include smoking status and history, lesion size and imaging evidence of tree-in-bud opacities, lymphadenopathy or emphysema on computed tomography. Upon author consensus, the most clinically-relevant variables were selected to undergo multivariate analysis. A history of current or former smoking [OR 4.4 (95 % CI 1.2–15.6) and 2.7 (95 % CI 1.1–6.8), respectively P = 0.04] was correlated with diagnoses of lung cancer. Contrarily, the presence of tree-in-bud opacities was less likely to be correlated with a diagnosis of malignancy [OR 0.04 (95 % CI 0.0–1.0), P = 0.05]. Additionally, higher maximum standardized uptake values from positron emission tomography were associated with malignancy on multivariate analysis [OR 1.1 (95 % CI 1.0–1.2), P = 0.04]; but the accuracy of the values in differentiating between diseases was only 0.67 as measured by the area under the curve. Lesion size was not independently associated with diagnosis [OR 0.5 (95 % CI 0.2–1.2), (P = 0.12)].

Conclusions

Establishing the likelihood of malignancy for lung nodules based on isolated clinical or radiographic criteria is difficult. Using the variables found in this study may allow clinicians to stratify patients into groups of high and low risk for malignancy, and therefore establish efficient diagnostic strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1185-4) contains supplementary material, which is available to authorized users.

Genetic diversity of clinical Mycobacterium avium subsp. hominissuis and Mycobacterium intracellulare isolates causing pulmonary diseases recovered from different geographical regions

Mycobacterium avium complex (MAC) infections are increasing annually in many countries. MAC strains are the most common nontuberculous mycobacterial pathogens isolated from respiratory samples and predominantly consist of two species, Mycobacterium avium and Mycobacterium intracellulare. The aim of this study was to analyze the molecular epidemiology and genetic backgrounds of clinical MAC isolates collected from The Netherlands, Germany, United States, Korea and Japan. Variable numbers of tandem repeats (VNTR) analysis was used to examine the genetic relatedness of clinical isolates of M. avium subsp. hominissuis (n=261) and M. intracellulare (n=116). Minimum spanning tree and unweighted pair group method using arithmetic averages analyses based on the VNTR data indicated that M. avium subsp. hominissuis isolates from Japan shared a high degree of genetic relatedness with Korean isolates, but not with isolates from Europe or the United States, whereas M. intracellulare isolates did not show any specific clustering by geographic origin. The findings from the present study indicate that strains of M. avium subsp. hominissuis, but not M. intracellulare, exhibit geographical differences in genetic diversity and imply that MAC strains may have different sources, routes of transmission and perhaps clinical manifestations.

Epidemiology and Ecology of Opportunistic Premise Plumbing Pathogens: Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa

BACKGROUND

Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa are opportunistic premise plumbing pathogens (OPPPs) that persist and grow in household plumbing, habitats they share with humans. Infections caused by these OPPPs involve individuals with preexisting risk factors and frequently require hospitalization.

OBJECTIVES

The objectives of this report are to alert professionals of the impact of OPPPs, the fact that 30% of the population may be exposed to OPPPs, and the need to develop means to reduce OPPP exposure. We herein present a review of the epidemiology and ecology of these three bacterial OPPPs, specifically to identify common and unique features.

METHODS

A Water Research Foundation-sponsored workshop gathered experts from across the United States to review the characteristics of OPPPs, identify problems, and develop a list of research priorities to address critical knowledge gaps with respect to increasing OPPP-associated disease.

DISCUSSION

OPPPs share the common characteristics of disinfectant resistance and growth in biofilms in water distribution systems or premise plumbing. Thus, they share a number of habitats with humans (e.g., showers) that can lead to exposure and infection. The frequency of OPPP-infected individuals is rising and will likely continue to rise as the number of at-risk individuals is increasing. Improved reporting of OPPP disease and increased understanding of the genetic, physiologic, and structural characteristics governing the persistence and growth of OPPPs in drinking water distribution systems and premise plumbing is needed.

CONCLUSIONS

Because broadly effective community-level engineering interventions for the control of OPPPs have yet to be identified, and because the number of at-risk individuals will continue to rise, it is likely that OPPP-related infections will continue to increase. However, it is possible that individuals can take measures (e.g., raise hot water heater temperatures and filter water) to reduce home exposures.

Distribution System Water Quality Affects Responses of Opportunistic Pathogen Gene Markers in Household Water Heaters

Illustrative distribution system operation and management practices shaped the occurrence and persistence of Legionella spp., nontuberculous mycobacteria (NTM), Pseudomonas aeruginosa, and two amoebae host (Acanthamoeba spp., Vermamoeba vermiformis) gene markers in the effluent of standardized simulated household water heaters (SWHs). The interplay between disinfectant type (chlorine or chloramine), water age (2.3-5.7 days) and materials (polyvinyl chloride (PVC), cement or iron) in upstream simulated distribution systems (SDSs) profoundly influenced levels of pathogen gene markers in corresponding SWH bulk waters. For example, Legionella spp. were 3-4 log higher in SWHs receiving water from chloraminated vs chlorinated SDSs, because of disinfectant decay from nitrification. By contrast, SWHs fed with chlorinated PVC SDS water not only harbored the lowest levels of all pathogen markers, but effluent from the chlorinated SWHs were even lower than influent levels in several instances (e.g., 2 log less Legionella spp. and NTM for PVC and 3-5 log less P. aeruginosa for cement). However, pathogen gene marker influent levels correlated positively to effluent levels in the SWHs (P < 0.05). Likewise, microbial community structures were similar between SWHs and the corresponding SDS feed waters. This study highlights the importance and challenges of distribution system management/operation to help control opportunistic pathogens.

Increased risk of mycobacterial infections associated with anti-rheumatic medications

RATIONALE

Anti-tumour necrosis factor (TNF) agents and other anti-rheumatic medications increase the risk of TB in rheumatoid arthritis (RA). Whether they increase the risk of infections with nontuberculous mycobacteria (NTM) is uncertain.

OBJECTIVES

To determine the effect of anti-TNF therapy and other anti-rheumatic drugs on the risk of NTM disease and TB in older patients with RA.

METHODS

Population-based nested case-control study among Ontario seniors aged ≥67 years with RA who were prescribed at least one anti-rheumatic medication between 2001 and 2011. We identified cases of TB and NTM disease microbiologically and identified drug exposures using linked prescription drug claims. We estimated ORs using conditional logistic regression, controlling for several potential confounders.

MEASUREMENTS AND MAIN RESULTS

Among 56 269 older adults with RA, we identified 37 cases of TB and 211 cases of NTM disease; each case was matched to up to 10 controls. Individuals with TB or NTM disease were both more likely to be using anti-TNF therapy (compared with non-use); adjusted ORs (95% CIs) were 5.04 (1.27 to 20.0) and 2.19 (1.10 to 4.37), respectively. Exposure to leflunomide and other anti-rheumatic drugs with high immunosuppressing potential also were associated with both TB and NTM disease, while oral corticosteroids and hydroxychloroquine were associated with NTM disease.

CONCLUSIONS

Anti-TNF use is associated with increased risk of both TB and NTM disease, but appears to be a relatively greater risk for TB. Several other anti-rheumatic drugs were also associated with mycobacterial infections.

Variable agreement among experts regarding Mycobacterium avium complex lung disease

Data regarding many clinical aspects of pulmonary Mycobacterium avium complex (pMAC) are lacking. Guidelines rely substantially upon expert opinion, integrated through face-to-face meetings, variably weighting individual opinions. We surveyed North American non-tuberculous mycobacteria experts regarding clinical aspects of pMAC using Delphi methods. Nineteen of 26 invited experts (73%) responded, with extensive variability. Convergence could not be reached for most questions. Respondents described extensive uncertainty around specific issues. Findings underscore urgent need for more research.

Risk of mycobacterial infections associated with rheumatoid arthritis in Ontario, Canada

OBJECTIVE

Patients with rheumatoid arthritis (RA) are at increased risk of TB. Little is known about the risk of nontuberculous mycobacteria (NTM) disease in these patients. We sought to ascertain the rate of NTM infection and TB in all residents of Ontario, Canada, with and without RA.

METHODS

In a cohort study, all Ontarians aged ≥ 15 years in January 2001 were followed until December 2010. Individuals with RA were identified using a validated algorithm to search hospitalization and physician billing claims. We linked Public Health Ontario Laboratory data to identify all cases of laboratory-confirmed TB and NTM disease. Analysis was performed using Cox proportional hazards regression.

RESULTS

We identified 113,558 Ontarians with RA and 9,760,075 Ontarians without RA. Relative to the non-RA group, adjusted hazard ratios (HRs) and 95% CIs for TB (1.92, [1.50-2.47]) and NTM disease (2.07, [1.84-2.32]) demonstrated increased risks in the RA group. Among those with RA, per 100,000 person-years, NTM disease (HR, 41.6; 95% CI, 37.1-46.5) was more common than TB (HR, 8.5; 95% CI, 6.5-10.8). After full adjustment, people with RA who developed NTM disease were 1.81 times as likely to die than uninfected people with RA.

CONCLUSIONS

Mycobacterial infections are more common in Ontarians with RA, with NTM disease more likely than TB. NTM disease is associated with an increased risk of death in patients with RA. Given the rising rates of NTM disease worldwide, determining whether this risk is due to the use of immunosuppressive medications vs RA itself is an important objective for future research.

Risk factors for mortality in patients with pulmonary infections with non-tuberculous mycobacteria: a retrospective cohort study

BACKGROUND

Infections with non-tuberculous mycobacteria (NTM) represent an increasing problem. Their clinical relevance is still largely unknown as well as predictors for mortality in affected patients. The objective was to describe prevalence and clinical relevance of different NTM and to identify risk factors for mortality.

METHODS

Retrospective cohort study of 124 patients with NTM detection between January 2001 and December 2011. Clinical characteristics like symptoms and radiological appearance were assessed at presentation. The primary outcome was all cause mortality during the follow-up period. Univariate and multivariate survival analyses using Cox proportional hazard models were employed for statistical analysis.

RESULTS

Over the study period, the frequency of NTM isolation varied from 4 to 12 patients per year. Twenty-nine out of 124 patients (23%) had a clinically relevant infection, according to the criteria of the American Thoracic Society (ATS). Mycobacterium avium was isolated most frequently, but Mycobacterium kansasii, Mycobacterium malmoense and Mycobacterium xenopi had the highest clinical relevance. Symptoms were mostly diverse and non-specific. On radiology, cavities were observed more frequently than a nodular-bronchiectatic variant or consolidation. In 75% of all patients, follow up time was more than two years. Median survival was 6.5 years (95%CI = 2.7-10.3). Factors significantly influencing survival time were haemoptysis (HR = 0.2, 95%CI = 0.1-0.6) and a consolidation on imaging (HR = 5.1, 95%CI 1.4-18.2).

CONCLUSIONS

The presentation of an infection with NTM can be diverse and depends mainly on the causative NTM pathogen. The most important predictor for increased mortality is the radiological appearance of a consolidation.

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.

Opinions differ by expertise in Mycobacterium avium complex disease

RATIONALE

Pulmonary Mycobacterium avium complex treatment guidelines rely largely on expert opinion. The extent to which nonexperts agree with recommendations of experts in this clinical area is unknown.

OBJECTIVES

We sought to compare practices and perceptions of prognosis between experts and nonexperts.

METHODS

We surveyed respirologists (Ontario, Canada, "nonexperts") and experts from nontuberculous mycobacterial disease centers of excellence (Canada and United States).

MEASUREMENTS AND MAIN RESULTS

Forty-six Ontario respirologists (29% of 160) and 19 experts (73% of 26) participated. There was agreement between nonexperts and experts regarding disease duration before diagnosis (2 yr), likelihood of spontaneous remission (7-15%), typical duration of treatment (18 mo), first choice of therapy (guideline regimens), a subgroup of patients for whom less-intensive regimens are favored (10% after recurrence), likelihood of recurrence (30%), and median survival (10 yr in most patients). Noted differences were that nonexperts estimated fewer patients with a positive culture had disease (30% vs. 50%, P = 0.02), used intensive guidelines therapy less often in new cases (50% vs. 79%, P = 0.02), and perceived a slightly lower success rate with guidelines therapy (65% vs. 75%, P = 0.047). Response ranges were wider for nonexperts, significantly so for selection of intensive guidelines therapy in new (P = 0.01) and recurrent (P = 0.04) cases.

CONCLUSION

Experts and nonexperts agreed on many issues. However, nonexperts perceived lower rates of disease among patients with isolates, tended to use less aggressive treatment approaches, and perceived lower success rates. Significant variability was observed in responses-often wider among nonexperts. Although these results are likely biased by referral, they may identify important areas for targeted education.

The epidemiology of pulmonary nontuberculous mycobacteria: data from a general hospital in Athens, Greece, 2007-2013

Background. The epidemiology of pulmonary nontuberculous mycobacteria (NTM) in Greece is largely unknown. Objectives. To determine the incidence and the demographic, microbiological, and clinical characteristics of patients with pulmonary NTM infection and pulmonary NTM disease. Methods. A retrospective review of the demographic, microbiological, and clinical characteristics of patients with NTM culture-positive respiratory specimens from January 2007 to May 2013. Results. A total of 120 patients were identified with at least one respiratory NTM isolate and 56 patients (46%) fulfilled the microbiological ATS/IDSA criteria for NTM disease. Of patients with adequate data, 16% fulfilled the complete ATS/IDSA criteria for NTM disease. The incidence of pulmonary NTM infection and disease was 18.9 and 8.8 per 100.000 inpatients and outpatients, respectively. The spectrum of NTM species was high (13 species) and predominated by M. avium-intracellulare complex (M. avium (13%), M. intracellulare (10%)), M. gordonae (14%), and M. fortuitum (12%). The ratio of isolation of NTM to M. tuberculosis in all hospitalized patients was 0.59. Conclusions. The first data on the epidemiology of pulmonary NTM in Athens, Greece, are presented. NTM infection is common in patients with chronic respiratory disease. However, only a significantly smaller proportion of patients fulfill the criteria for NTM disease.

Pulmonary nontuberculous mycobacterial disease, Ontario, Canada, 1998-2010

We measured the prevalence and temporal trends of pulmonary nontuberculous mycobacterial disease among residents of Ontario, Canada, during 1998–2010. Five-year prevalence increased from 29.3 cases/100,000 persons in 1998–2002 to 41.3/100,000 in 2006–2010 (p<0.0001). Improved laboratory methods did not explain this increase, suggesting a surge in disease prevalence.

Host response to nontuberculous mycobacterial infections of current clinical importance

The nontuberculous mycobacteria are a large group of acid-fast bacteria that are very widely distributed in the environment. While Mycobacterium avium was once regarded as innocuous, its high frequency as a cause of disseminated disease in HIV-positive individuals illustrated its potential as a pathogen. Much more recently, there is growing evidence that the incidence of M. avium and related nontuberculous species is increasing in immunocompetent individuals. The same has been observed for M. abscessus infections, which are very difficult to treat; accordingly, this review focuses primarily on these two important pathogens. Like the host response to M. tuberculosis infections, the host response to these infections is of the TH1 type but there are some subtle and as-yet-unexplained differences.

Management of nontuberculous mycobacterial infection in the elderly

The incidence of nontuberculous mycobacteria (NTM) has increased over the last decades. Elderly people are more susceptible to NTM and experience increased morbidities. NTM incidence is expected to rise due to an increasing elderly population at least up to 2050. Given the importance of NTM infection in the elderly, an increasing interest exists in studying NTM characteristics in the aged population. In this review, we summarize the characteristics of NTM infection among elderly patients. We focus on epidemiology, clinical presentation, and treatment options of NTM in this age group. We highlight the differences in the diagnosis and treatment between rapid and slow growing mycobacterial infections. The current recommendation for treatment of NTM is discussed. We debate if in vitro susceptibility testing has a role in the treatment of NTM. Drug-drug interaction between antibiotics used to treat NTM and other medications, particularly warfarin, is another important issue that we discuss. Finally, we review the prognosis of NTM disease in elderly patients.

Burden and trends of hospitalisations associated with pulmonary non-tuberculous mycobacterial infections in Germany, 2005-2011

BACKGROUND

Representative population-based data on the epidemiology of pulmonary non-tuberculous mycobacterial (PNTM) infections in Europe are limited. However, these data are needed in order to optimise patient care and to facilitate the allocation of healthcare resources. The aim of the present study was to investigate the current burden and the trends of PNTM infection-associated hospitalisations in Germany.

METHODS

International Classification of Diseases, 10th revision (ICD-10) discharge diagnosis codes were extracted from the official nationwide diagnosis-related groups (DRG) hospital statistics in order to identify PNTM infection-associated hospitalisations (ICD-10 code A31.0) between 2005 and 2011. Poisson log-linear regression analysis was used to assess the significance of trends.

RESULTS

Overall, 5,959 records with PNTM infection as any hospital discharge diagnosis were extracted from more than 125 million hospitalisations. The average annual age-adjusted rate was 0.91 hospitalisations per 100,000 population. Hospitalisation rates increased during the study period for both males and females, with the highest rate of 3.0 hospitalisations per 100,000 population among elderly men, but the most pronounced average increase of 6.4%/year among females, particularly those of young and middle age, and hospitalisations associated with cystic fibrosis. Overall, chronic obstructive pulmonary disease (COPD) was the most frequent PNTM infection-associated condition in 28.9% of hospitalisations and also showed a significant average annual increase of 4.8%.

CONCLUSIONS

The prevalence of PNTM infection-associated hospitalisations is steadily increasing in Germany. COPD is currently the most important associated condition. Our population-based study provides evidence of a changing epidemiology of PNTM infections and highlights emerging clinical implications.

HSP65-PRA identification of non-tuberculosis mycobacteria from 4892 samples suspicious for mycobacterial infections

Various molecular methods have been used for the rapid identification of mycobacterial species. In this survey, evaluation of antibiotic resistance and PCR-restriction fragment length polymorphism analysis (PRA) of the hsp65 gene was carried out for identification of non-tuberculosis mycobacteria (NTM) isolates from different clinical specimens. Forty-eight different mycobacterial isolates were selected and followed by the conventional and PRA of hsp65 for species identification. The antibiotic susceptibility test was carried out according to standard methods. A 439 bp PCR product of hsp65 in all selected isolates was amplified and digested with the BstEII and HaeIII restriction enzymes. The restriction fragment length polymorphism (RFLP) patterns were analyzed for species identification. Using PRA for 48 mycobacterial selected isolates, including 15 M. tuberculosis, one M. bovis and all 32 isolates of NTM, revealed 11 different species among the NTM isolates. The most frequent NTM isolates were M. kansasii, M. gordonae III, M. marinum, M. chelonae, M. scrofluaceum and M. gastri. In most cases, the PRA results were perfectly in accordance with the classical biochemical method. Combination of resistance to rifampin and isoniazid was present among M. kansasi, M. gordoniae III, M. scrofluaceum, M. chelonae, M. marinum, M. gastri, M. gordoniae II and M. trivale isolates. A high incidence of co-resistance to six, five, four and three anti-TB drugs was observed in 18.5%, 9.1%, 6.6% and 11.7% of all NTM isolates, respectively. Our results showed that PRA, in comparison with classical methods, is rapid and accurate enough for the identification of mycobacterial species from LJ medium. Additionally, we found that in Iran we have a highly diverse population of NTM isolates among patients suspected of having TB.

Aging, COPD, and other risk factors do not explain the increased prevalence of pulmonary Mycobacterium avium complex in Ontario

BACKGROUND

The cause of observed increases in pulmonary Mycobacterium avium complex (pMAC) isolation and disease is unexplained. To explore possible causes of the increase in pMAC isolation and disease prevalence in Ontario, Canada, we studied age and other population-level risk factors.

METHODS

We determined age and sex of patients with pMAC disease between 2003 and 2008. We then estimated whether the potential effect of population aging and changes in prevalence of HIV infection, solid organ transplant, COPD, and tumor necrosis factor-α (TNF-α) inhibition have contributed to the observed increase in pMAC disease.

RESULTS

During 2003 to 2008, pMAC isolation and disease prevalence (per 100,000) both increased (8.44 to 12.62 and 4.35 to 6.81, respectively). The total number of cases of disease increased by 348 (2.46 per 100,000). Based on actual contemporary population changes, aging could explain 70 additional cases (increase of 0.57 per 100,000). The increase in self-reported COPD prevalence could potentially explain 11 (95% CI, 0-42) additional cases (increase of 0.09 per 100,000 [95% CI, 0-0.34 per 100,000]). HIV infection, solid organ transplant, and TNF-α inhibition combined could potentially explain no more than 73 additional cases (increase of 0.60 per 100,000).

CONCLUSIONS

Although population aging appears to be a major risk factor, the increase in pMAC disease in Ontario could be only partly explained by aging, increases in COPD, HIV, solid organ transplantation, and TNF-α inhibition therapy. The increase in pMAC is likely multifactorial and may be affected by environmental or pathogen factors not addressed in this study.