Nontuberculous Mycobacterial Lung Infections in Ontario, Canada: Clinical and Microbiological Characteristics

Identification and Antimicrobial Susceptibilities for Patients with Non-tuberculous Mycobacteria Infection in Jeju Island: Single-Center Retrospective Study

BACKGROUND

The distribution of species and characteristics of non-tuberculous mycobacteria (NTM) differ, and surveillance data for changes in antimicrobial susceptibilities of NTM is insufficient. This study analyzed the changes in antimicrobial susceptibility trends across NTM species and assessed the appropriateness of empirical antimicrobial drugs for NTM.

MATERIALS AND METHODS

We retrospectively analyzed the clinical characteristics, including demographics, distribution of NTM species, antimicrobial drug susceptibilities, and outcomes, at a teaching hospital in Jeju Island from 2009 - 2022.

RESULTS

Overall, 342 patients were included in the analysis; 93.0% were classified into the pulmonary group (PG) and 7.0% into the extrapulmonary group (EPG). The isolation rate of Mycobacterium avium was significantly higher in PG (36.8% vs. 0%, P = 0.001), while that of Mycobacterium fortuitum was significantly higher in EPG (4.5% vs. 31.3%, P = 0.001). The antimicrobial susceptibility rate is higher against clarithromycin (89.9%) and amikacin (83.3%) and lower against rifampin (54.7%) and ethambutol (28.1%). The susceptibility rate to clarithromycin was over 80%, but those to rifampin and ethambutol showed decreasing annual trends. Of the 162 patients who received empirical antimicrobial therapy, actual antimicrobial susceptibility rates were high (90.1%) using empirical macrolide, and relatively low using ethambutol and rifampin (28.0% and 58.8%, respectively).

CONCLUSION

This is the first study of analysis of the distribution, baseline characteristics, and antimicrobial susceptibility of isolated NTM species in pulmonary and extrapulmonary patients in Jeju Island over 10 years. Policies that continuously monitor changes in susceptibility rate are required to ensure effective treatment strategies.

Global Epidemiology of Nontuberculous Mycobacterial Pulmonary Disease: A Review

Nontuberculous mycobacterial (NTM) isolation and pulmonary disease (NTM-PD) have continued to increase in most regions of the world, driven mainly by Mycobacterium avium. Single-center studies also support increasing trends as well as a persistent burden of undiagnosed NTM among persons suspected of having tuberculosis (TB), in countries with moderate-to-high TB prevalence. Cumulative exposure to water and soil presents an increased risk to susceptible hosts, and trace metals in water supply are recently recognized risk factors. Establishing standard case definitions for subnational and national surveillance systems with mandatory notification of NTM-PD are needed to allow comparisons within and across countries and regions.

Nontuberculous mycobacterial (NTM) infections in bronchiectasis patients: A retrospective US registry cohort study

RATIONALE

Longitudinal epidemiological and clinical data are needed to improve the management of patients with bronchiectasis developing nontuberculous mycobacterial (NTM) pulmonary disease.

OBJECTIVES

To describe the epidemiology, patient management, and treatment outcomes of NTM infections in patients with bronchiectasis enrolled in the United States Bronchiectasis and NTM Research Registry (US BRR).

METHODS

This was a retrospective cohort study of patients with bronchiectasis and NTM infections enrolled with follow-up in the US BRR in 2008-2019. The study included patients with ≥1 positive NTM respiratory culture in the 24-month baseline period (baseline NTM cohort) and/or during the annual follow-up visits (incident NTM cohort). Incidence, prevalence, baseline patient characteristics, treatment exposure, treatment outcomes, and respiratory clinical outcomes were described in the baseline NTM cohort, incident NTM cohort, and both cohorts combined (prevalent NTM cohort).

RESULTS

Between 2008 and 2019, 37.9% (1457/3840) of patients with bronchiectasis in the US BRR met the inclusion criteria for this study and were reported to have Mycobacterium avium complex (MAC) and/or Mycobacterium abscessus complex (MABSC) infections. MAC prevalence increased steadily in the US BRR during 2009-2019; incidence was relatively stable, except for a peak in 2011 followed by a slow decrease. MABSC and mixed MAC/MABSC infections were rare. Most patients with bronchiectasis and NTM infections in the registry were female, White, and aged >65 years. The antibiotics administered most commonly reflected current guidelines. In the prevalent cohort, 44.9% of MAC infections and 37.1% of MABSC infections remained untreated during follow-up, and MAC treatment was initiated with delay (>90 days after positive NTM respiratory culture) twice as frequently as promptly (≤90 days after positive NTM respiratory culture) (68.6% vs 31.4%, respectively). The median time from diagnosis to treatment was shorter for MABSC versus MAC infections (194.0 days [interquartile range (IQR) 8.0, 380.0] vs 296.0 days [IQR 35.0, 705.0], respectively). Among patients with MAC infections who completed treatment, 27.6% were classified as cured and 29.6% as treatment failure during the annual follow-up visit window. For MABSC, these proportions were 25.0% and 28.0%, respectively.

CONCLUSIONS

A considerable proportion of MAC and MABSC infections were untreated or treated after initial delay/observation. MABSC infections were more likely to be treated and start treatment sooner than MAC infections. Further longitudinal studies are warranted to evaluate the monitor-with-delay approach and inform clinical guidelines.

TNF inhibitors increase the risk of nontuberculous mycobacteria in patients with seropositive rheumatoid arthritis in a mycobacterium tuberculosis endemic area

The aim of this study is to examine the impact of tumor necrosis factor inhibitors (TNFI) on nontuberculous mycobacterium (NTM) infection in rheumatoid arthritis (RA) patients in a mycobacterium tuberculosis (MTB) endemic area. We selected 1089 TNFI-treated RA patients and 4356 untreated RA patients using propensity-matching analysis according to age, gender, and Charlson comorbidity index using the Korean National Health Insurance Service database from July 2009 to December 2010. Both groups were followed-up until the end of 2016 to measure the incidence of mycobacterial diseases. The incidence rate of NTM in TNFI-treated RA group was similar to those of MTB (328.1 and 340.9 per 100,000 person-years, respectively). The adjusted hazard ratio (aHR) of NTM for TNFI-treated RA compared to untreated RA was 1.751(95% CI 1.105-2.774). The risk of TNFI-associated NTM in RA was 2.108-fold higher among women than men. The age-stratified effects of TNFI on NTM development were significantly high in RA patients aged 50-65 years (aHR 2.018). RA patients without comorbidities had a higher incidence of NTM following TNFI treatment (aHR 1.742). This real-world, observational study highlights the need to increase awareness of NTM in TNFI-treated RA patients in an MTB endemic area.

The clinical features of pulmonary artery involvement in Takayasu arteritis and its relationship with ischemic heart diseases and infection

Background

Pulmonary artery involvement (PAI) in Takayasu arteritis (TAK) can lead to severe complications, but the relationship between the two has not been fully clarified.

Methods

We retrospectively investigated 166 consecutive patients with TAK who attended Kyoto University Hospital from 1997 to 2018. The demographic data, clinical symptoms and signs, comorbidities, treatments, and imaging findings were compared between patients with and without PAI. TAK was diagnosed based on the American College of Rheumatology Classification Criteria (1990) or the Japanese Clinical Diagnostic Criteria (2008). PAI was identified using enhanced computed tomography, magnetic resonance imaging, or lung scintigraphy.

Results

PAI was detected in 14.6% (n = 24) of total TAK patients. Dyspnea (25.0% vs. 8.6%; p = 0.043), pulmonary arterial hypertension (PAH) (16.7% vs. 0.0%; p < 0.001), ischemic heart disease (IHD) (29% vs. 9.3%; p = 0.018), respiratory infection (25.0% vs. 6.0%; p = 0.009), and nontuberculous mycobacteria (NTM) infection (20.8% vs. 0.8%; p < 0.001) were significantly more frequent, and renal artery stenosis (0% vs. 17%; p = 0.007) was significantly less frequent in TAK patients with PAI than in those without PAI. PAI and biologics were risk factors for NTM.

Conclusions

TAK patients with PAI more frequently have dyspnea, PAH, IHD, and respiratory infection, including NTM, than TAK patients without PAI.

Mycobacterial biofilms as players in human infections: a review

The role of biofilms in pathogenicity and treatment strategies is often neglected in mycobacterial infections. In recent years, the emergence of nontuberculous mycobacterial infections has necessitated the development of novel prophylactic strategies and elucidation of the mechanisms underlying the establishment of chronic infections. More importantly, the question arises whether members of the Mycobacterium tuberculosis complex can form biofilms and contribute to latent tuberculosis and drug resistance because of the long-lasting and recalcitrant nature of its infections. This review discusses some of the molecular mechanisms by which biofilms could play a role in infection or pathological events in humans.

Incidence of nontuberculous mycobacterial disease and coinfection with tuberculosis in a tuberculosis-endemic region: A population-based retrospective cohort study

Nontuberculous mycobacteria (NTM) infection may interfere in the diagnosis and treatment of tuberculosis (TB) in TB-endemic regions. However, the population-based incidence of NTM disease and NTM-TB coinfection remains unclear.We used Taiwan's National Health Insurance Research Database to identify new diagnoses of NTM disease and TB from 2005 to 2013 and calculated the incidence rate and the proportion of NTM-TB coinfection. The patients with NTM disease or TB were determined by the use of disease codes from International Classification of Diseases, Ninth Revision, Clinical Modification, laboratory mycobacterium examination codes, and antimycobacterial therapy receipts.From 2005 to 2013, the age-adjusted incidence rate of NTM disease increased from 5.3 to 14.8 per 100,000 people per year and the age-adjusted incidence rate of NTM-TB coinfection was around 1.2 to 2.2 per 100,000 people per year. The proportion of NTM-TB coinfection among patients with confirmed TB was 2.8%. Male and older patients had a significantly higher incidence of NTM disease. The effects of urbanization and socioeconomic status (SES) on the incidences of TB and NTM disease were different. Rural living and lower SES were significantly associated with increasing the incidence of confirmed TB but not with that of NTM disease. For NTM disease, those living in the least urbanized area had significantly lower incidence rate ratio than in the highest urbanized area. The incidence of NTM-TB coinfection was higher in older patients and compared with patients aged < 45 years, the incidence rate ratio of the patients aged> 74 years was 12.5.In TB-endemic Taiwan, the incidence of NTM disease increased from 2005 to 2013. Male gender and old age were risk factors for high incidence of NTM disease. SES did not have a significant effect on the incidence of NTM disease, but rural living was associated with lower incidence of NTM disease. In TB-endemic areas, NTM-TB coinfection could disturb the diagnosis of TB and treatment, especially in elderly patients.

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.

Prevalence of nontuberculous mycobacteria in a tertiary hospital in Beijing, China, January 2013 to December 2018

BACKGROUND

To investigate the species distribution of non-tuberculous mycobacteria (NTM) among tuberculosis (TB) specimens collected from January 2013 to December 2018 at Peking Union Medical Hospital (Beijing), China. NTM species identification was carried out by DNA microarray chip.

RESULTS

Mycobacterial species were detected in 1514 specimens from 1508 patients, among which NTM accounted for 37.3% (565/1514), increasing from a proportion of 15.6% in 2013 to 46.1% in 2018 (P < 0.001). Among the 565 NTM positive specimens, the majority (55.2%) were from female patients. Furthermore, patients aged 45-65 years accounted for 49.6% of the total patients tested. Among 223 NTM positive specimens characterized further, the majority (86.2%) were from respiratory tract, whilst 3.6 and 3.1% were from lymph nodes and pus, respectively. Mycobacterium intracellulare (31.8%) and Mycobacterium chelonae / Mycobacterium abscessus (21.5%) were the most frequently detected species, followed by M. avium (13.5%), M. gordonae (11.7%), M. kansasii (7.6%), and others.

CONCLUSION

The proportion of NTM among mycobacterial species detected in a tertiary hospital in Beijing, China, increased rapidly from year 2013 to 2018. Middle-aged patients are more likely to be infected with NTM, especially females. Mycobacterium intracellulare and Mycobacterium chelonae/ Mycobacterium abscessus were the most frequently detected NTM pathogens. Accurate and timely identification of NTM is important for diagnosis and treatment.

B Cell-Based Vaccine Transduced With ESAT6-Expressing Vaccinia Virus and Presenting α-Galactosylceramide Is a Novel Vaccine Candidate Against ESAT6-Expressing Mycobacterial Diseases

Early secretory antigenic target-6 (ESAT6) is a potent immunogenic antigen expressed in Mycobacterium tuberculosis as well as in some non-tuberculous mycobacteria (NTM), such as M. kansasii. M. kansasii is one of the most clinically relevant species of NTM that causes mycobacterial lung disease, which is clinically indistinguishable from tuberculosis. In the current study, we designed a novel cell-based vaccine using B cells that were transduced with vaccinia virus expressing ESAT6 (vacESAT6), and presenting α-galactosylceramide (αGC), a ligand of invariant NKT cells. We found that B cells loaded with αGC had increased levels of CD80 and CD86 after in vitro stimulation with NKT cells. Immunization of mice with B/αGC/vacESAT6 induced CD4⁺ T cells producing TNF-α and IFN-γ in response to heat-killed M. tuberculosis. Immunization of mice with B/αGC/vacESAT6 ameliorated severe lung inflammation caused by M. kansasii infection. We also confirmed that immunization with B/αGC/vacESAT6 reduced M. kansasii bacterial burden in the lungs. In addition, therapeutic administration of B/αGC/vacESAT6 increased IFN-γ⁺ CD4⁺ T cells and inhibited the progression of lung pathology caused by M. kansasii infection. Thus, B/αGC/vacESAT6 could be a potent vaccine candidate for the prevention and treatment of ESAT6-expressing mycobacterial infection caused by M. kansasii.

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.

Epidemiology of nontuberculous mycobacterial infections in the U.S. Veterans Health Administration

Objective

We identified patients with non-tuberculous mycobacterial (NTM) disease in the US Veterans Health Administration (VHA), examined the distribution of diseases by NTM species, and explored the association between NTM disease and the frequency of clinic visits and mortality.

Methods

We combined mycobacterial isolate (from natural language processing) with ICD-9-CM diagnoses from VHA data between 2008 and 2012 and then applied modified ATS/IDSA guidelines for NTM diagnosis. We performed validation against a reference standard of chart review. Incidence rates were calculated. Two nested case-control studies (matched by age and location) were used to measure the association between NTM disease and each of 1) the frequency of outpatient clinic visits and 2) mortality, both adjusted by chronic obstructive pulmonary disease (COPD), other structural lung diseases, and immunomodulatory factors.

Results

NTM cases were identified with a sensitivity of 94%, a specificity of >99%. The incidence of NTM was 12.6/100k patient-years. COPD was present in 68% of pulmonary NTM. NTM incidence was highest in the southeastern US. Extra-pulmonary NTM rates increased during the study period. The incidence rate ratio of clinic visits in the first year after diagnosis was 1.3 [95%CI 1.34–1.35]. NTM patients had a hazard ratio of mortality of 1.4 [95%CI 1.1–1.9] in the 6 months after NTM identification compared to controls and 1.99 [95%CI 1.8–2.3] thereafter.

Conclusions

In VHA, pulmonary NTM disease is commonly associated with COPD, with the highest rates in the southeastern US. After adjustment, NTM patients had more clinic visits and greater mortality compared to matched patients.

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.

Pulmonary Nontuberculous Mycobacteria-Associated Deaths, Ontario, Canada, 2001-2013

Survival implications of nontuberculous mycobacterial pulmonary disease (NTM-PD) and NTM pulmonary isolation without disease (NTM-PI) are unclear. To study deaths associated with NTM-PD and NTM-PI and differences in survival between them, we conducted a population-based cohort study of persons with microbiologically defined NTM-PD or NTM-PI diagnosed during 2001–2013 in Ontario, Canada. We used propensity score matching and Cox proportional hazards models to compare survival. Among 9,681 NTM-PD patients and 10,936 NTM-PI patients, 87% and 91%, respectively, were successfully matched with unexposed controls. Both NTM-PD and NTM-PI were associated with higher rates of death for all species combined and for most individual species. Compared with NTM-PI, NTM-PD was associated with higher death rates for all species combined, Mycobacterium avium complex, and M. xenopi. NTM-PD and NTM-PI were significantly associated with death, NTM-PD more so than NTM-PI.

On the Reportability of Nontuberculous Mycobacterial Disease to Public Health Authorities

Nontuberculous mycobacteria (NTM) are environmental pathogens that are an increasingly common cause of pulmonary and extrapulmonary disease. Electronic laboratory-based reporting is a straightforward mechanism for identifying NTM infections and for monitoring trends in disease. Oregon was the first state to make NTM reportable, although at this time the reporting requirement is limited to extrapulmonary infection. This has assisted authorities in detecting outbreaks and healthcare-related infections. However, further consideration should be given to the reportability of pulmonary NTM disease. Pulmonary NTM disease is more common than tuberculosis in the United States and is of emerging public health concern. Although the direct public health action that would be triggered by a pulmonary NTM disease report is not clear, without surveillance, public health is missing an opportunity to better understand pulmonary NTM disease trends and reasons for its increasing recognition within our population. We believe state health authorities should conduct surveillance for pulmonary NTM, either by mandating reporting of laboratory isolates or by other mechanisms as we have done in Oregon.

Notification of Nontuberculous Mycobacteria: An Australian Perspective

In Queensland, Australia, all cases of mycobacterial infection (tuberculosis [TB] and nontuberculous mycobacteria [NTM]) are notifiable under the Queensland Public Health Act (2005). This process originally emerged to avoid NTM confounding with notification of cases of TB, but has facilitated awareness of the increasing incidence and changing epidemiology of NTM. Although initially not a public health priority, the notification process has facilitated research that has led to an appreciation of both public health and environmental health issues associated with these pathogens. When reports of NTM infections were low in frequency, reporting was managed largely by clinicians specializing in TB. However, as reports of NTM isolates surpassed those for TB, the workload associated with clinical reporting exceeded resources. The Communicable Diseases Branch transitioned to digital reporting of laboratory isolates of mycobacteria, thereby enabling weekly and quarterly reporting of data, and generation of more detailed annual reports. The reports now include species and geographic distributions by health service district, allowing identification of clusters requiring further investigation and systematic reviews of different species. With ecological and climate change, the distribution and virulence of these emerging pathogens are evolving. Evidence of transmission of highly virulent and antibiotic-resistant clones of Mycobacterium abscessus among patients with cystic fibrosis internationally heightens the need for timely reporting to public health authorities. Ongoing systematic monitoring by public health authorities will be crucial to our understanding of NTM diseases.

Nontuberculous mycobacterial infection in rheumatoid arthritis patients: a single-center experience in South Korea

BACKGROUND/AIMS

Nontuberculous mycobacteria (NTM) infection has been increasing worldwide in both general population and immunocompromised patients, which has also been reported in rheumatoid arthritis (RA) patients. This study aimed to identify the incidence and clinical characteristics of NTM infection in RA patients living in tuberculosis (TB) infection endemic area.

METHODS

We performed a retrospective analysis of NTM infection cases in our RA registry at a tertiary referral center from January 1995 to December 2013. The clinical features of them were compared to those of 52 TB infection patients from same registry.

RESULTS

Among 1,397 patients with RA, NTM infection was newly developed in 26 patients and the incidence of NTM infection was 164.8 per 100,000 patient-years. The Mycobacterium avium complex was the most frequent isolate (76.9%). None of the NTM infections had extrapulmonary involvement, which was rather common in TB infection (26.9%). Patients with NTM infection were older, received higher cumulative steroid doses, and had higher rates of past TB infection history and concomitant interstitial lung disease (ILD) than cases with TB infection.

CONCLUSIONS

In South Korea, NTM infection is not rare in RA patients, and infection rates are growing. Physicians should be cautious about NTM infection in patients with a history of TB infection or concomitant ILD, even living in TB endemic area.

Gender susceptibility to mycobacterial infections in patients with non-CF bronchiectasis

Non-tuberculous mycobacteria (NTM) are environmental microbes that cause a variety of diseases both in immunocompromised and immunocompetent patients. Epidemiologic data indicate that there has been a global rise in the incidence of NTM infections. It has also been noted that NTM infections have a predilection to occur in postmenopausal women. In a recent study, it was demonstrated that in patients with non-CF bronchiectasis the probability of NTM isolation was significantly higher in elderly female patients and in those with a low body mass index. However, the mechanisms of causality of these gender differences and morpho-phenotypes remain enigmatic. The present study reviews the data and plausible mechanisms which might provide clues to this gender susceptibility and morpho-phenotypes of patients with bronchiectasis and NTM.

Health-related quality of life, comorbidities and mortality in pulmonary nontuberculous mycobacterial infections: A systematic review

Nontuberculous mycobacterial (NTM) infections are increasing in disease frequency worldwide. This systematic review examines health-related quality of life (HRQOL), comorbidities and mortality associated with pulmonary NTM disease. We searched MEDLINE, EMBASE, CINAHL, Scopus Life Sciences, conference proceedings and Google (earliest date available to February 2015) for primary studies. Eligible studies compared populations with and without pulmonary NTM disease in high-income jurisdictions. We excluded studies on HIV/AIDS. All languages were accepted. Two reviewers followed MOOSE and PRISMA reporting guidelines and independently appraised quality using STROBE. All studies were summarized qualitatively regardless of quality. Of 3193 citations screened, we included 17 studies mostly from Taiwan (n = 5) and the USA (n = 4). Two studies assessed HRQOL; one assessed comorbidities, 11 assessed mortality, and three assessed multiple outcomes. Populations with pulmonary NTM reported significantly worse or similar HRQOL than the general population, depending on the instruments used. Some suggested greater prevalence of having bronchiectasis (n = 2) and greater risk of developing pulmonary tuberculosis (n = 1). Most (n = 7) suggested no difference in mortality, although only one was age-matched and gender-matched to the general population. Four suggested NTM populations had higher mortality-two of which compared with the general population and were deemed of high quality, while two compared with non-NTM patients from hospital. High clinical heterogeneity in study design may explain discordant results. Bias assessments and controlling for confounding were carried out poorly. No consistent trends were observed although there is suggestion of an increased health burden from respiratory diseases and increased mortality associated with pulmonary NTM disease.

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.

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.

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.

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.

Highlight on advances in nontuberculous mycobacterial disease in North America

Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and exist as an important cause of pulmonary infections in humans. Pulmonary involvement is the most common disease manifestation of NTM and the incidence of NTM is growing in North America. Susceptibility to NTM infection is incompletely understood; therefore preventative tools are not well defined. Treatment of pulmonary nontuberculous mycobacterial (NTM) infection is difficult and entails multiple antibiotics and an extended treatment course. Also, there is a considerable variation in treatment management that should be considered before initiating treatment. We highlight the new findings in the epidemiology diagnosis and treatment of mycobacterial infections. We debate new advances regarding NTM infection in cystic fibrosis patients and solid organ transplant recipients. Finally, we introduce a new epidemiologic model for NTM disease based on virulence-exposure-host factors.

Comparison of the Spectrum of Radiologic and Clinical Manifestations of Pulmonary Disease Caused by Mycobacterium avium Complex and Mycobacterium xenopi

Aim

Mycobacterium xenopi is described with upper lobe cavitation (“fibrocavitary” pattern), whereas the Mycobacterium avium complex (MAC) is described with bronchiectasis and centrilobular nodules (“nodular bronchiectasis”). We retrospectively described and compared computed tomography (CT) chest manifestations of disease caused by MAC and M xenopi.

Materials and Methods

We reviewed patients who had either MAC or M xenopi lung disease and who had CTs between January 2002 and December 2003. Clinical data were recorded, and the patterns on chest CTs were categorized as “fibrocavitary,” “nodular bronchiectatic,” and “unclassified.”

Results

There were 74 patients; 50 with MAC and 24 with M xenopi. The patients with MAC were older (mean 69 vs 58 years; P = .007). Patients with M xenopi more often had emphysema (50% vs 20%; P = .02), cavities (46% vs 16%; P = .01), and nodules ≤5 mm (88% vs 58%; P = .02). M xenopi cases more commonly had a fibrocavitary radiologic pattern (33% vs 18%), with no statistically significant difference ( P = .24). MA C was more often associated with a nodular bronchiectatic pattern (68% MAC vs 4% M xenopi; P < .0001). Sixty-three percent of patients with M xenopi had a pattern that was predominantly randomly distributed nodules (11/15 [73%]) or consolidation and/or ground-glass opacities (4/15 [27%]).

Conclusion

Compared with MAC, patients with M xenopi infection develop more cavities and more nodules, and they less often have a predominant nodular bronchiectatic pattern. Although a predominantly cavitary pattern appears to be more common with M xenopi, the majority of patients with M xenopi had CT patterns of random nodules or consolidation and/or ground-glass opacities rather than classically described findings.

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.

Chest computed tomography predicts microbiological burden and symptoms in pulmonary Mycobacterium xenopi

BACKGROUND AND OBJECTIVE

The development of computed tomography (CT) findings usually precedes the diagnosis of pulmonary nontuberculous mycobacterial infection. The utility of specific CT scan features, although often available long before respiratory sample cultures, is not fully understood. We sought to assess associations among CT features, symptoms and microbiological disease criteria in pulmonary Mycobacterium xenopi isolation.

METHODS

We reviewed 70 consecutive immunocompetent patients with pulmonary M. xenopi isolation and classified them according to the American Thoracic Society (ATS) diagnostic criteria for disease. 'Definite disease' patients (n = 16) met modified ATS criteria. 'Possible disease' patients (n = 10) met microbiological criteria, had abnormal CT scans, but data regarding symptoms were unavailable. 'No disease' patients (n = 44) had only one positive sputum culture, or were asymptomatic or had no relevant CT findings. Two radiologists, without knowledge of the clinical or microbiological information, independently reviewed the scans.

RESULTS

The mean (standard deviation) age of all patients was 63 (16) years, and 39% were women. Patients with 'definite disease' usually had nodules (88%) and cavities (63%), but less often bronchiectasis (50%) and tree-in-bud (50%). Patients with 'possible' or 'no disease', respectively, had nodules (100% or 80%), bronchiectasis (40% or 18%) or tree-in-bud (40% or 11%). Cavitation (P ≤ 0.0001) and nodules ≥ 5 mm (P = 0.0002) were associated with fulfilled microbiological criteria for disease. Bronchiectasis (P = 0.02) and nodules <5 mm (P = 0.002) were associated with symptoms of infection.

CONCLUSIONS

Among immunocompetent patients with pulmonary M. xenopi isolation, cavitation and large nodules predict fulfilling microbiological disease criteria, while bronchiectasis and small nodules predict symptoms.

Clinical significance of a single isolation of pathogenic nontuberculous mycobacteria from sputum specimens

A single sputum culture positive for nontuberculous mycobacteria (NTM) could be an early sign of NTM lung disease. We found that 14% of patients with a single sputum culture positive for pathogenic NTM were diagnosed with NTM lung disease during the median follow-up period of 16 months.

Prevalence of nontuberculous mycobacterial lung disease in U.S. Medicare beneficiaries

RATIONALE

Pulmonary nontuberculous mycobacteria (PNTM) are an important cause of morbidity among older adults in the United States, but national prevalence estimates are lacking.

OBJECTIVES

To describe the prevalence and trends of PNTM disease among adults aged 65 years or older throughout the United States.

METHODS

A nationally representative 5% sample of Medicare Part B beneficiaries was analyzed from 1997 to 2007. Demographic and medical claims data were compiled and prevalence estimates for PNTM and selected comorbidities were calculated and trends over time evaluated. Logistic regression was used to identify demographic and geographic factors associated with PNTM.

MEASUREMENTS AND MAIN RESULTS

From 1997 to 2007, the annual prevalence significantly increased from 20 to 47 cases/100,000 persons, or 8.2% per year. The period prevalence was 112 cases/100,000 persons, although prevalence was twofold higher among Asians/Pacific Islanders than among whites (228 vs. 116 cases/100,000 persons). Western states had the highest period prevalence at 149 cases/100,000 persons, with Hawaii having the highest prevalence at 396 cases/100,000 persons, followed by southeastern states, which had a period prevalence of 131 cases/100,000 persons. PNTM cases had more comorbid conditions than noncases and were 40% more likely to die than noncases. Women were 1.4 times more likely to be a PNTM case than men. Relative to whites, Asians/Pacific Islanders were twice as likely to be a case, whereas blacks were half as likely.

CONCLUSIONS

The prevalence of PNTM is increasing across all regions of the United States and among both men and women. Significant racial/ethnic and geographic differences suggest important gene-environment interactions.

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.

The reliability of diagnostic coding and laboratory data to identify tuberculosis and nontuberculous mycobacterial disease among rheumatoid arthritis patients using anti-tumor necrosis factor therapy

PURPOSE

Anti-tumor necrosis factor-alpha (anti-TNF) therapies are associated with severe mycobacterial infections in rheumatoid arthritis patients. We developed and validated electronic record search algorithms for these serious infections.

METHODS

The study used electronic clinical, microbiologic, and pharmacy records from Kaiser Permanente Northern California (KPNC) and the Portland Veterans Affairs Medical Center (PVAMC). We identified suspect tuberculosis and nontuberculous mycobacteria (NTM) cases using inpatient and outpatient diagnostic codes, culture results, and anti-tuberculous medication dispensing. We manually reviewed records to validate our case-finding algorithms.

RESULTS

We identified 64 tuberculosis and 367 NTM potential cases, respectively. For tuberculosis, diagnostic code positive predictive value (PPV) was 54% at KPNC and 9% at PVAMC. Adding medication dispensings improved these to 87% and 46%, respectively. Positive tuberculosis cultures had a PPV of 100% with sensitivities of 79% (KPNC) and 55% (PVAMC). For NTM, the PPV of diagnostic codes was 91% (KPNC) and 76% (PVAMC). At KPNC, ≥ 1 positive NTM culture was sensitive (100%) and specific (PPV, 74%) if non-pathogenic species were excluded; at PVAMC, ≥1 positive NTM culture identified 76% of cases with PPV of 41%. Application of the American Thoracic Society NTM microbiology criteria yielded the highest PPV (100% KPNC, 78% PVAMC).

CONCLUSIONS

The sensitivity and predictive value of electronic microbiologic data for tuberculosis and NTM infections is generally high, but varies with different facilities or models of care. Unlike NTM, tuberculosis diagnostic codes have poor PPV, and in the absence of laboratory data, should be combined with anti-tuberculous therapy dispensings for pharmacoepidemiologic research.