Nontuberculous mycobacteria testing and culture positivity in the United States.

BACKGROUND: Nontuberculous mycobacteria (NTM) are environmental bacteria which may cause chronic lung disease. The prevalence of NTM pulmonary infection and disease has been increasing in the United States and globally. The predominant clinically relevant species of NTM in the United States are Mycobacterium avium complex (MAC) species and Mycobacterium abscessus. With the development of rapid species identification methods for NTM (e.g. PCR probes), more testing for NTM is being conducted through commercial labs, such as Laboratory Corporation of America (Labcorp), which provides deidentified real-time testing data to the Centers for Disease Control (CDC) pursuant to a data sharing agreement. Because NTM lung infections are not reportable in most states, other data sources are key to understanding NTM testing patterns, positivity rates, and species distributions to track infection trends and identify clinical care needs. METHODS: We obtained national Labcorp data for the period January 2019 through mid-April 2022. We subset the data to only respiratory samples sent for Acid Fast Bacilli (AFB) cultures. NTM positive results were defined as those which identified an NTM species and are not Mycobacterium tuberculosis, Mycobacterium bovis, or Mycobacterium gordonae. RESULTS: Overall, 112,528 respiratory samples were sent for AFB testing during the study period; 26.3% were from the Southeast U.S., identified as HSS Region IV in the Labcorp dataset, and 23.0% were from the Pacific and South Pacific region (Region IX). The culture positive prevalence ranged from 20.2% in the Southeast to 9.2% in the East North Central region (Region V). In the Southeast US, M. abscessus prevalence was 4.0%. For MAC, the highest prevalence was observed in the Mountain region (Region VII) (13.5%) and the lowest proportion was in the East South Central region (7.3%, Region III). Among positive tests, the proportion which was MAC varied from 61.8% to 88.9% and was highest in the Northeast U.S. The proportion of positive samples which were M. abscessus ranged from 3.8% to 19.7% and was highest in the Southeast. CONCLUSIONS: The Southeastern region of the U.S. has the highest rate of culture positivity in Labcorp tests for total NTM and, of all positive tests, the highest proportion of M. abscessus. These estimates may underrepresent the true number of M. abscessus infections because M. absesscus-specific probes are not commercially available and not all NTM testing in the United States is done by Labcorp. Analysis of real-time testing data from commercial laboratories may provide insights into risk factors for NTM culture positivity in 'hotspot' areas.

Incidence of nontuberculous mycobacteria infections among persons with cystic fibrosis in the United States (2010-2019).

BACKGROUND: Nontuberculous mycobacteria (NTM) are ubiquitous, environmental bacteria that can cause chronic lung disease. Persons with cystic fibrosis (pwCF) are at high risk for NTM. Approximately 1 in 5 pwCF in the United States (U.S.) is affected by pathogenic NTM species, and incidence rates of NTM have been increasing among pwCF as well as in the general population. Prevalence of NTM pulmonary infections (PI) varies widely across the United States because of geographic variation in environmental exposures. This study will present updated region-level incidence of NTM infections in the cystic fibrosis (CF) population in the U.S. METHODS: We used the Cystic Fibrosis Foundation Patient Registry (CFFPR) data for the period 2010 through 2019. Our study population comprised persons with CF ≥ 12 years of age who had been tested for NTM PI. We included only registry participants with NTM culture results. We defined incident cases as persons with one positive mycobacterial culture preceded by ≥ two negative mycobacterial cultures. We defined non-cases as persons with ≥ two negative mycobacterial cultures. We estimated average annual NTM PI incidence by region. Using quasi-Poisson models, we calculated annual percent change in incidence by region. RESULTS: We identified 3,771 incident NTM infections. Of these cases, 1,816 (48.2%) were Mycobacterium avium complex (MAC) infections and 960 (25.5%) were Mycobacterium abscessus infections. The average annual incidence of NTM PI among pwCF in the U.S. was 58.0 cases per 1,000 persons. The Northeast had the highest incidence of MAC (33.5/1,000 persons tested) and the South had the highest incidence of M. abscessus (20.3/1,000 persons tested). From 2010 to 2019, the annual incidence of total NTM PI increased significantly by 3.5% per year in the U.S. CONCLUSIONS: NTM PI incidence is increasing among pwCF. Identifying high risk areas and increasing trends is important for allocating public health and clinical resources as well as evaluating interventions.

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.

Detecting clusters of high nontuberculous mycobacteria infection risk for persons with cystic fibrosis - An analysis of U.S. counties.

Nontuberculous mycobacteria are ubiquitous environmental bacteria that frequently cause disease in persons with cystic fibrosis (pwCF). The risks for NTM infection vary geographically. Detection of high-risk areas is important for focusing prevention efforts. In this study, we apply five cluster detection methods to identify counties with high NTM infection risk. Four clusters were detected by at least three of the five methods, including twenty-five counties in five states. The geographic area and number of counties in each cluster depended upon the detection method used. Identifying these clusters supports future studies of environmental predictors of infection and will inform control and prevention efforts.

Methods of isolation and identification of nontuberculous mycobacteria from environmental samples: A scoping review.

Nontuberculous mycobacteria (NTM) are ubiquitous in the environment. Some species of NTM are pathogenic and cause lung disease in susceptible persons. Epidemiologic studies of environmental NTM infection risk rely on both culture-dependent and culture-independent techniques for NTM isolation and identification. In this review, we summarized current methods used to isolate and identify NTM from the environment. We searched PubMed, Embase, Scopus, Web of Science: Core Collection, and Global Health (CAB Direct) for peer-reviewed studies from the last 12 years. We identified 1685 unique citations and 110 studies met our inclusion and exclusion criteria. Approximately half (55%) of the studies identified in this review used a combination of culture-independent and culture-dependent methods. The most common environmental substrate analyzed was water (n = 90). Identification of current, common methods for the isolation and identification of NTM from environmental samples may contribute to the development of standard methodological practices in the future. The choice of isolation method is based on the research question, environment, and species. A summary of common methods may contribute to the development of standard practices for isolation and identification of NTM from environmental samples, which may lead to more robust and comparable results.

The risk of pulmonary NTM infections and water-quality constituents among persons with cystic fibrosis in the United States, 2010-2019.

Rationale: The prevalence of nontuberculous mycobacterial (NTM) pulmonary disease varies geographically in the United States. Previous studies indicate that the presence of certain water-quality constituents in source water increases NTM infection risk. Objective: To identify water-quality constituents that influence the risk of NTM pulmonary infection in persons with cystic fibrosis in the United States. Methods: We conducted a population-based case-control study using NTM incidence data collected from the Cystic Fibrosis Foundation Patient Registry during 2010-2019. We linked patient zip code to the county and associated patient county of residence with surface water data extracted from the Water Quality Portal. We used logistic regression models to estimate the odds of NTM infection as a function of water-quality constituents. We modeled two outcomes: pulmonary infection due to Mycobacterium avium complex (MAC) and Mycobacterium abscessus species. Results: We identified 484 MAC cases, 222 M. abscessus cases and 2816 NTM-negative cystic fibrosis controls resident in 11 states. In multivariable models, we found that for every 1-standardized unit increase in the log concentration of sulfate and vanadium in surface water at the county level, the odds of infection increased by 39% and 21%, respectively, among persons with cystic fibrosis with MAC compared with cystic fibrosis-NTM-negative controls. When modeling M. abscessus as the dependent variable, every 1-standardized unit increase in the log concentration of molybdenum increased the odds of infection by 36%. Conclusions: These findings suggest that naturally occurring and anthropogenic water-quality constituents may influence the NTM abundance in water sources that supply municipal water systems, thereby increasing MAC and M. abscessus infection risk.

Environmental risk of nontuberculous mycobacterial infection: Strategies for advancing methodology.

The National Institute of Allergy and Infectious Diseases organized a symposium in June 2022, to facilitate discussion of the environmental risks for nontuberculous mycobacteria exposure and disease. The expert researchers presented recent studies and identified numerous research gaps. This report summarizes the discussion and identifies six major areas of future research related to culture-based and culture independent laboratory methods, alternate culture media and culturing conditions, frameworks for standardized laboratory methods, improved environmental sampling strategies, validation of exposure measures, and availability of high-quality spatiotemporal data.

Antimicrobial activity of ruthenium-based intercalators.

Multidrug resistance of bacterial pathogens is a major problem and there is a clear need for the development of new types of antibiotics. Here we investigated the antimicrobial activity of ruthenium(II) based DNA-intercalating complexes. These complexes were found to have no activity in vitro against the Gram-negative bacterium Escherichia coli, but the complexes were clearly active against the Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus. In vivo activity has also been demonstrated for one of the compounds using a simple infection model, the nematode Caenorhabditis elegans. Importantly, this also showed that the compound tested was not toxic to the nematodes.