Epidemiology of Non-Tuberculous Mycobacteria isolated from clinical specimens in Madrid, Spain, from 2013 to 2017

Prescription habits and drugs accessibility for the treatment of non-tuberculous mycobacteria infections in Italy: a multicentric survey from the IRENE study group

PURPOSE

Non-tuberculous mycobacteria (NTM) account for high clinical burden, and treatment can be challenging. Moreover, accessibility of NTM medications varies across centers. These challenges may lead to unplanned therapeutic changes, discontinuations, potentially affecting patient outcomes. Aim of this survey was to evaluate the accessibility of NTM-targeting drugs in Italy (with a particular focus on clofazimine) in centers associated with the IRENE Registry, a collaborative network of healthcare professionals.

METHODS

A cross-sectional, internet-based, questionnaire-survey on the use and availability of clofazimineand other NTM-targeting drugs was sent to 88 principal investigators of the IRENE network in Italyin 2020. The questionnaires were designed with closed-ended and open-ended questions and distributed using the SurveyMonkey® platform.

RESULTS

The surveys underscore the more frequent involvement of pulmonologists (42%) and infectious disease specialists (34%) in NTM treating strategies. Respondents were distributed across 18 out of20 Italian regions, with a significant concentration in the north, encompassing university hospitalsand outpatient clinics. Molecular testing is available in 40% of the involved centers, while phenotypic in 30% of the centers. Centers have a multidisciplinary team and an appointed pharmacy service for NTM drugs distribution in 10 and 75% of the cases, respectively. Substantial variability was observed in drug availability and accessibility, drug regimen composition, and drug dosage, particularly for medications like clofazimine.

CONCLUSIONS

This study shows the high heterogeneity of anti-NTM drug availability in Italy and prompts toward a harmonization in antibiotic prescription and access; it also emphasizes the challenges in determining the optimal therapeutic strategies for treating NTM-infections.

Nontuberculous Mycobacteria Isolates in Respiratory Samples and Mycobacterial Pulmonary Disease in an Area of Northern Spain

Introduction

The epidemiology of nontuberculous mycobacteria (NTM) is not well known. In this study, we aimed to determine the incidence of NTM isolates and nontuberculous mycobacterial pulmonary disease (NTM-PD) in five closely located hospitals in an area of northern Spain and analyse differences between them.

Material and methods

Demographic, microbiological, clinical and radiological data were collected retrospectively from all patients with a NTM isolated from respiratory specimens at five hospitals between 2012 and 2019. Mycobacterium gordonae isolates were excluded. Once the data was collected, it was determined which patients met the NMT-PD criteria.

Results

594 patients were included in the study. The mean incidence rate of NTM isolates across all five hospitals in the period studied was 4.15 per 100,000 person-year, while the rate of NTM-PD was 1.2. The annual number of isolates showed an upward trend over this period, but the same did not occur in the number of cases of NTM-PD. The species most frequently isolated were Mycobacterium avium complex (MAC) and Mycobacterium xenopi and those most frequently causing disease were MAC and Mycobacterium kansassi. There were significant differences between the five centres.

Conclusions

Our results are in line with similar studies in Europe in terms of NTM isolation and NTM-PD incidence and species isolated; however, we do not see the upward trend in NTM-PD rates described elsewhere. The great variability in isolation and disease rates, as well as in species isolated in geographically close areas, underlines, in our opinion, the importance of local environmental factors.

New antibiofilm strategies for the management of nontuberculous mycobacteria diseases

INTRODUCTION

Nontuberculous mycobacteria (NTM) represent a group of microorganisms comprising more than 190 species. NTM infections have increased recently, and their treatment is a major challenge because to their resistance to conventional treatments. This review focuses on innovative strategies aimed at eradicating NTM biofilms, a critical factor in their resistance. Important areas addressed include biofilm formation mechanisms, current therapeutic challenges, and novel treatment approaches. The main objective is to compile and analyze information on these emerging strategies, identifying pivotal research directions and recent advancements.

AREAS COVERED

A review of the scientific literature was conducted to identify emerging novel therapies for the treatment of NTM infections and to explore potential synergies with existing treatments.

EXPERT OPINION

Experts highlights a limited understanding of optimal treatment regimens, often supported by insufficient scientific evidence. Current therapies are typically prolonged, involve multiple antibiotics with adverse effects, and frequently do not achieve patient cure. Certain species are even considered virtually impossible to eradicate. A thorough understanding of these new approaches is imperative for improving patients outcomes. This review provides a robust foundation for developing of more effective antibacterial strategies, which are essential because of the increasing incidence of NTM infections and the limitations of existing therapies.

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.

Epidemiology of Nontuberculous Mycobacteria in Tuberculosis suspects, Southwest of China, 2017-2022

Objectives

This study summarizes the epidemiological characteristics, species distribution, and drug sensitivity of clinical nontuberculous mycobacteria (NTM) isolates at the Public Health Clinical Center of Chengdu, China, from January 2017 to December 2022.

Methods

We retrospectively analyzed data from patients with clinically isolated NTM strains. Chi-square analysis assessed the rate of Mycobacterium strain isolation over 6 years.

Results

The number of samples tested for Mycobacterium tuberculosis (MTB) and/or NTM increased each year, while MTB detection decreased and NTM detection rose significantly each year (P=0.03). The average age of NTM patients was 51 ± 17.53 years, with a 14.1% HIV infection rate. The predominant isolates were Mycobacterium avium-intracellulare (MAC) and M. chelonae/M. abscessus, with 96.4% of cases being of Han ethnicity. Amikacin, moxifloxacin, and clarithromycin were effective against M. avium and M. intracellulare; linezolid, amikacin, and cefoxitin were effective against M. chelonae/M. abscessus. Over 90% of NTM cases originated from the respiratory tract.

Conclusion

The NTM isolation rate in Southwest China has risen in recent years, primarily among elderly patients with a high HIV co-infection rate. The main NTM isolates were MAC and M. chelonae/M. abscessus. Amikacin, moxifloxacin, clarithromycin, and linezolid exhibited strong antibacterial activity against SGM, while amikacin and linezolid displayed relatively better antibacterial activity against RGM. The prevalence of NTM infection may be positively associated with regional economic development and health conditions.

Pulmonary Nontuberculous Mycobacteria, Ontario, Canada, 2020

We measured annual prevalence of microbiologically defined nontuberculous mycobacterial lung disease in Ontario, Canada. Mycobacterium avium prevalence was 13 cases/100,000 persons in 2020, a 2.5-fold increase from 2010, indicating a large increase in true M. avium lung disease. During the same period, M. xenopi decreased nearly 50%, to 0.84 cases/100,000 persons.

Subspecies Distribution and Antimicrobial Susceptibility Testing of Mycobacterium abscessus Clinical Isolates in Madrid, Spain: a Retrospective Multicenter Study

Mycobacterium abscessus (MABS) is the most pathogenic and drug-resistant rapidly growing mycobacteria. However, studies on MABS epidemiology, especially those focusing on subspecies level, are scarce. We aimed to determine MABS subspecies distribution and its correlation with phenotypic and genotypic antibiotic profiles. A retrospective multicenter study of 96 clinical MABS isolates in Madrid between 2016 to 2021 was conducted. Identification at the subspecies level and resistance to macrolides and aminoglycosides were performed by the GenoType NTM-DR assay. The MICs of 11 antimicrobials tested against MABS isolates were determined using the broth microdilution method (RAPMYCOI Sensititer titration plates). Clinical isolates included 50 (52.1%) MABS subsp. abscessus; 33 (34.4%) MABS subsp. massiliense; and 13 (13.5%) MABS subsp. bolletii. The lowest resistance rates corresponded to amikacin (2.1%), linezolid (6.3%), cefoxitin (7.3%), and imipenem (14.6%), and the highest to doxycycline (100.0%), ciprofloxacin (89.6%), moxifloxacin (82.3%), cotrimoxazole (82.3%), tobramycin (81.3%), and clarithromycin (50.0% at day 14 of incubation). Regarding tigecycline, although there are no susceptibility breakpoints, all strains but one showed MICs ≤ 1 μg/mL. Four isolates harbored mutations at positions 2058/9 of the rrl gene, one strain harbored a mutation at position 1408 of the rrl gene, and 18/50 harbored the T28C substitution at erm(41) gene. Agreement of the GenoType results with clarithromycin and amikacin susceptibility testing was 99.0% (95/96). The rate of MABS isolates showed an upward trend during the study period, being M. abscessus subsp. abscessus the most frequently isolated subspecies. Amikacin, cefoxitin, linezolid, and imipenem showed great in vitro activity. The GenoType NTM-DR assay provides a reliable and complementary tool to broth microdilution for drug resistance detection. IMPORTANCE Infections caused by Mycobacterium abscessus (MABS) are increasingly being reported worldwide. Identifying MABS subspecies and assessing their phenotypic resistance profiles are crucial for optimal management and better patient outcomes. M. abscessus subspecies differ in erm(41) gene functionality, which is a critical determinant of macrolide resistance. Additionally, resistance profiles of MABS and the subspecies distribution can vary geographically, highlighting the importance of understanding local epidemiology and resistance patterns. This study provides valuable insights into the epidemiology and resistance patterns of MABS and its subspecies in Madrid. Elevated resistance rates were observed for several recommended antimicrobials, emphasizing the need for cautious drug use. Furthermore, we assessed the GenoType NTM-DR assay, which examines principal mutations in macrolides and aminoglycosides resistance-related genes. We observed a high level of agreement between the GenoType NTM-DR assay and the microdilution method, indicating its usefulness as an initial tool for early initiation of appropriate therapy.

Clinical Evaluation of Nontuberculous Mycobacteria (NTM) Elite Agar, a New Medium for the Isolation of NTM: a Multicenter Study

Nontuberculous mycobacteria (NTM) are gaining interest with the increased number of infected patients. NTM Elite agar is designed specifically for the isolation of NTM without the decontamination step. We assessed the clinical performance of this medium combined with Vitek mass spectrometry (MS) matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) technology for the isolation and identification of NTM in a prospective multicenter study, including 15 laboratories (24 hospitals). A total of 2,567 samples from patients with suspected NTM infection were analyzed (1,782 sputa, 434 bronchial aspirates, 200 bronchoalveolar lavage samples, 34 bronchial lavage samples, and 117 other samples). A total of 220 samples (8.6%) were positive with existing laboratory methods against 330 with NTM Elite agar (12.8%). Using the combination of both methods, 437 isolates of NTM were detected in 400 positive samples (15.6% of samples). In total, 140 samples of the standard procedures (SP) and 98 of the NTM Elite agar were contaminated. NTM Elite agar showed a higher performance for rapidly growing mycobacteria (RGM) species than SP (7% versus 3%, P < 0.001). A trend has been noted for the Mycobacterium avium complex (4% with SP versus 3% with NTM Elite agar, P = 0.06). The time to positivity was similar (P = 0.13) between groups. However, the time to positivity was significantly shorter for the RGM in subgroup analysis (7 days with NTM and 6 days with SP, P = 0.01). NTM Elite agar has been shown to be useful for the recovery of NTM species, especially for the RGM. Using NTM Elite agar + Vitek MS system in combination with SP increases the number of NTM isolated from clinical samples.

Mycobacterium biofilms

The genus Mycobacterium includes some of the deadliest pathogens of History (Mycobacterium tuberculosis, Mycobacterium leprae), but most of the species within the genus are environmental microorganisms. Because some of these nontuberculous mycobacteria (NTM) species can be human pathogens, the study of these mycobacterial biofilms has increased during the last decades, and the interest in this issue increased as well as the growing number of patients with diseases caused by NTM. Different molecular mechanisms have been described, being especially well known the importance of glycopeptidolipids. Moreover, the knowledge of the extracellular matrix has shown important differences with other microorganisms, especially because of the presence of lipidic molecules as a key component of this structure. The clinical importance of mycobacterial biofilms has been described for many chronic diseases, especially lung diseases and implant-related ones, both in vitro and in vivo, and even in patients. Moreover, the biofilm-producing capacity has been proven also in M. tuberculosis, while its importance is not well understood. Biofilm studies have also shown the increasing resistance of mycobacteria in sessile form, and the importance of this resistance in the management of the patients is beyond doubt, being surgery necessary in some cases to cure the patients. Diagnosis of mycobacterial diseases is still based on culture-based techniques designed for the detection of M. tuberculosis. Molecular biology-based methods are also broadly used but again designed for tuberculosis diagnosis. Antimicrobial susceptibility testing is also well developed for tuberculosis, but only some species of NTM have standardized techniques for this purpose. New tools or approaches are necessary to treat these patients, whose importance is increasing, as the number of potential hosts is also increasing throughout the world.

Screening and Drug Resistance Analysis of Non-Tuberculous Mycobacteria in Patients with Suspected Pulmonary Tuberculosis on the Hainan Island, China

Background

China has seen a drastic increase in the incidence of non-tuberculous mycobacteria (NTM) infection, which is a notable public health issue. Due to a lack of reliable epidemiological surveillance information, there is a need to gather accurate epidemiological and surveillance data, which can help clinicians effectively treat NTM patients. Moreover, drug susceptibility testing for NTM is not frequently performed in China. This retrospective study, therefore, determined the prevalence and resistance characteristics of NTM to provide a reference to control the NTM epidemic.

Methods

Sputum, alveolar lavage fluid, and other respiratory specimens were collected from 3025 patients with suspected pulmonary tuberculosis attending The Second Affiliated Hospital of Hainan Medical University from January 2014 to December 2021. Strain identification and species distribution of NTM were performed by DNA chip technology and gene sequencing, and the drug resistance of NTM isolates was evaluated by calculating the minimum inhibitory concentration through antimicrobial susceptibility testing for NTM.

Results

From 2014 to 2021, 373 strains of NTM were isolated and identified from respiratory specimens of 3025 suspected tuberculosis patients. Except in 2014, NTM-infected patients accounted for more than 10% of suspected tuberculosis patients in other years. The median age of patients with NTM infection was 62.0 years (53.0, 71.0), and the male-to-female ratio among these patients was 0.79:1. Among culture-positive strains, 12.3% (373/3040; 95% CI 11.1-13.4%) were identified as NTM comprising forty species of NTM. The forty species of NTM included 23 slow-growing mycobacteria (SGM) and 17 rapidly-growing mycobacteria (RGM). Among the NTM isolates, 58.7% (219/373; 95% CI 53.7-63.7%) were SGM and 41.3% (154/373; 95% CI 36.3-46.3%) were RGM. M.avium complex(MAC)(41.3%; 95% CI 36.3-46.3%) and M.abscessus complex (MABC)(33.2%; 95% CI 28.4-38.0%) were the most frequently detected species, followed by M.simiae Complex (11.8%; 95% CI 8.5-15.1%), M.fortuitum group (5.1%; 95% CI 2.9-7.3%), and others. Drug sensitivity test results showed that most of the NTM isolates were susceptible to amikacin and clarithromycin with a drug resistance rate of less than 10%. However, clarithromycin could induce drug resistance, followed by linezolid and moxifloxacin, and their drug resistance rate was less than 50%.

Conclusion

During 2014-2021, the number of NTM isolates detected in the respiratory specimens of the study patients in The Second Affiliated Hospital of Hainan Medical University increased year by year. M. intracellulare is the most common pathogenic NTM species, and there is a high incidence of NTM infection on Hainan Island. Our findings might be of great importance for diagnosing and treating this patient population in Hainan.

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.

Mortality association of nontuberculous mycobacterial infection requiring treatment in Taiwan: a population-based study

Background:

Infection due to nontuberculous mycobacteria (NTM) is an emerging issue worldwide, and we aimed to address the epidemiology and mortality association of NTM infection requiring treatment in Taiwan.

Methods:

We used the 2003–2018 data of 2 million representative individuals in Taiwan’s National Health Insurance Research Database. We identified patients with newly diagnosed NTM infection and received treatment as NTM cases. Age- and sex-matched (1:40) as well as propensity score-matched (PSM) (1:2) non-NTM individuals were selected as non-NTM controls. We used a Cox proportional hazard model to determine hazard ratios (HRs) with 95% confidence intervals (CIs).

Results:

We identified 558 patients with NTM infection requiring treatment. The mean age was 62.5 ± 15.4 years, and 57.5% of them were male. The incidence increased from 0.54 per 100,000 person-year in 2003 to 3.35 per 100,000 person-year in 2018. The overall mortality was 35.2%, with a mean follow-up duration of 4.1 ± 3.6 years. We found that NTM infection was independently associated with a greater risk of mortality (HR: 1.71; 95% CI: 1.47–1.98) compared with age- and sex-matched controls, and the association remained consistent (HR: 1.44; 95% CI: 1.19–1.75) compared with propensity-matched controls. We also found that old age, male, high Charlson comorbidity index, and the use of steroids or anti-neoplastic agents/immunosuppressants were associated with mortality risk.

Conclusion:

In conclusion, we found a steady increase in patients with NTM infection requiring treatment in Taiwan and further demonstrated that NTM infection was associated with greater risk of mortality using two comparable non-NTM control subjects.

Occurrence and risk factors of nontuberculous mycobacteria in tuberculosis-suspected patients in the north of Iran

Background and Objectives:

Some Nontuberculous Mycobacteria (NTM) can occasionally infect the human population and cause infections having symptoms similar to tuberculosis (TB). This study tried to provide updated data about the frequency and diversity of NTM species.

Materials and Methods:

Suspicious samples of Mycobacterium tuberculosis (MTB) with both positive results in Ziehl-Neelsen (ZN) staining and Löwenstein-Jensen medium culturing were evaluated during January 2016 and December 2018 in Gorgan, Iran. After determination of MTB isolates by the growth rate, pigmentation status, the niacin test, and the insertion sequence 6110 (IS6110) PCR assay, other unknown isolates (presumably NTM) were detected by the 16S rDNA sequencing method and drawing the phylogenetic tree. Based on the patients’ demographic information, their risk factors were also assessed.

Results:

Among 226 culture-positive samples, obtained from 2994 individuals with suspected symptoms of TB, the analyses found 12 (5.3%) NTM and three Mycobacterium caprae isolates. Mycobacterium simiae (6/12) was the most prevalent NTM species. The average nucleotide similarity value was 98.2% ± 3.7. In comparison to patients with MTB (211 confirmed cases), other mycobacterium infections were more common in patients over 65 years old (Odd ratio (95% convenience interval): 2.96 (0.69 – 12.59), P = 0.14).

Conclusion:

Although the NTM species has a small portion in TB suspected patients, their prevalence has increased, mainly in elderly patients. Moreover, M. simiae was the most prevalent NTM species in our region. Therefore, identification of common species in each region is recommended and clinicians should pay more attention to them in each region.

Nontuberculous Mycobacteria in Humans, Animals, and Water in Zambia: A Systematic Review

Nontuberculous mycobacteria (NTM) are environmental opportunistic pathogens of humans and animals that are emerging with a serious public health impact particularly in individuals with Acquired Immunodeficiency Syndromes. Recent scientific evidence is shifting from NTMs being known as traditional environmental organisms to serious pathogenic organisms in both animals and humans. In humans, factors attributable to this rise have been linked mainly to Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome pandemic. In recent years there has been an increase in multidrug resistant Tuberculosis in Zambia and it is thought that NTMs could possibly be the cause. This study was therefore formulated to review available information on the prevalence of NTM in humans, animals and the environment, species distribution, zoonotic potential and public health importance in Zambia. This review was conducted in accordance with PRISMA guidelines. A literature search was done in PubMed and Google scholar using predefined search terms such as ‘nontuberculous mycobacteria’, ‘atypical mycobacteria’, ‘mycobacteria other than mycobacterium tuberculosis’ and ‘Zambia’, in combination with Boolean operators (AND, OR). This particular systematic review draws findings based on literature search between 2000 and 2020. Through literature search 243 papers were identified, 23 duplicates were identified and removed and 206 articles were excluded as they did not meet the inclusion criteria. The full text of the remaining 14 articles were considered for this review. The overall prevalence of NTM in humans was 24.39%, in water 21.5%, in animals 16.05% of which the prevalence in cattle was 14.81% and Kafue Lechwe 1.23%. Mycobacterium intracellulare was the most common isolated nontuberculous mycobacteria in humans and cattle while Mycobacterium gordonae was the most common in water, and Mycobacterium stomatepiae sp Nov in Kafue Lechwe. Nontuberculous mycobacteria are an emerging public health threat in Zambia both in humans and animals and this calls for the need for molecular information on the zoonotic transmission of nontuberculous mycobacteria. Increased awareness of nontuberculous mycobacteria diseases among clinicians and laboratory personnel is crucial for patient management and an essential step for facilitating the identification of nontuberculous mycobacteria species in laboratories.