The looming tide of nontuberculous mycobacterial infections in Portugal and Brazil

Drinking Water Microbiota, Entero-Mammary Pathways, and Breast Cancer: Focus on Nontuberculous Mycobacteria

The prospect of drinking water serving as a conduit for gut bacteria, artificially selected by disinfection strategies and a lack of monitoring at the point of use, is concerning. Certain opportunistic pathogens, notably some nontuberculous mycobacteria (NTM), often exceed coliform bacteria levels in drinking water, posing safety risks. NTM and other microbiota resist chlorination and thrive in plumbing systems. When inhaled, opportunistic NTM can infect the lungs of immunocompromised or chronically ill patients and the elderly, primarily postmenopausal women. When ingested with drinking water, NTM often survive stomach acidity, reach the intestines, and migrate to other organs using immune cells as vehicles, potentially colonizing tumor tissue, including in breast cancer. The link between the microbiome and cancer is not new, yet the recognition of intratumoral microbiomes is a recent development. Breast cancer risk rises with age, and NTM infections have emerged as a concern among breast cancer patients. In addition to studies hinting at a potential association between chronic NTM infections and lung cancer, NTM have also been detected in breast tumors at levels higher than normal adjacent tissue. Evaluating the risks of continued ingestion of contaminated drinking water is paramount, especially given the ability of various bacteria to migrate from the gut to breast tissue via entero-mammary pathways. This underscores a pressing need to revise water safety monitoring guidelines and delve into hormonal factors, including addressing the disproportionate impact of NTM infections and breast cancer on women and examining the potential health risks posed by the cryptic and unchecked microbiota from drinking water.

Self-recycling and partially conservative replication of mycobacterial methylmannose polysaccharides

The steep increase in nontuberculous mycobacteria (NTM) infections makes understanding their unique physiology an urgent health priority. NTM synthesize two polysaccharides proposed to modulate fatty acid metabolism: the ubiquitous 6-O-methylglucose lipopolysaccharide, and the 3-O-methylmannose polysaccharide (MMP) so far detected in rapidly growing mycobacteria. The recent identification of a unique MMP methyltransferase implicated the adjacent genes in MMP biosynthesis. We report a wide distribution of this gene cluster in NTM, including slowly growing mycobacteria such as Mycobacterium avium, which we reveal to produce MMP. Using a combination of MMP purification and chemoenzymatic syntheses of intermediates, we identified the biosynthetic mechanism of MMP, relying on two enzymes that we characterized biochemically and structurally: a previously undescribed α-endomannosidase that hydrolyses MMP into defined-sized mannoligosaccharides that prime the elongation of new daughter MMP chains by a rare α-(1→4)-mannosyltransferase. Therefore, MMP biogenesis occurs through a partially conservative replication mechanism, whose disruption affected mycobacterial growth rate at low temperature.

Detection of non-tuberculosus mycobacteria (NTMs) in lung samples using 16S rRNA

BACKGROUND

Non-tuberculous mycobacteria (NTMs) cause diseases known as mycobacteriosis and are an important cause of morbidity and mortality. The diagnosis of pulmonary disease caused by NTM is hampered by its clinical similarity with tuberculosis (TB) and by the lack of an accurate and rapid laboratory diagnosis.

OBJECTIVES

Detect DNA from NTMs directly from lung samples using real-time polymerase chain reaction (qPCR) for amplification of 16S rRNA. Additionally, DNA sequencing (hsp65 and rpoB genes) was used to identify the species of MNTs.

METHODS

A total of 68 sputum samples (54 with suspected NTMs and 14 with TB) from patients treated at a referral hospital were used.

FINDINGS

Of these, 27/54 (50%) were qPCR positive for NTMs and 14/14 TB patients (controls) were qPCR negative with an almost perfect concordance (Kappa of 0.93) with the Mycobacterium spp. culture. Sequencing confirmed the presence of NTM in all positive samples. The most common species was Mycobacterium gordonae (33%), followed by Mycobacterium abscessus (26%), Mycobacterium fortuitum (22%), Mycobacterium avium (15%) and Mycobacterium peregrinum (4%).

MAIN CONCLUSIONS

The qPCR technique for detecting NTMs targeting 16S rRNA has the potential to detect NTMs and rapidly differentiate from Mycobacterium tuberculosis. However, it is necessary to identify the species to help in the differential diagnosis between disease and contamination, and to guide the choice of the therapeutic scheme.

Non-tuberculous mycobacteria isolation from presumptive tuberculosis patients in Lambaréné, Gabon

OBJECTIVE

The prevalence of clinical cases of pulmonary non-tuberculous mycobacteria (NTM) is increasing worldwide. The aim of this study was to determine the proportion and the NTM species isolated from presumptive tuberculosis patients in Lambaréné, Gabon.

METHOD

From January 2018 to December 2020, sputum samples from presumptive TB patients were analysed at the tuberculosis reference laboratory of the Centre de Recherches Médicales de Lambaréné. Two sputum samples were collected per patient, and culture was performed using Bactec MGIT 960. The GenoType Mycobacterium CM/AS was used for NTM isolates confirmation and species differentiation.

RESULTS

Among 1363 sputum samples analysed, 285 (20.9%) were Auramin acid fast bacilli (AFB) smear-positive. NTM were isolated in 137/1363 (10%) of the samples. The most prevalent NTM species was Mycobacterium intracellulare (n=74; 54%).

CONCLUSION

These results show the presence of NTM among presumptive TB patients in Gabon, which could potentially complicate TB diagnosis. This presents a new public health challenge, and emphasises the need to consider NTM in planning the prevention and management of tuberculosis control.

Retrospective Analysis of 10 Cases of Disseminated Nontuberculous Mycobacterial Disease with Osteolytic Lesions

Purpose

Disseminated nontuberculous mycobacterial (DNTM) infection can involve multiple organs, including the lungs, skin and soft tissues and lymph nodes. However, NTM infection leading to osteolysis has been rarely reported. Here, we analyzed the clinical features, osteolytic mechanisms, treatment and prognosis of patients with DNTM disease with osteolytic lesions.

Patients and Methods

This retrospective study was conducted between January 1, 2011, and December 31, 2020, at the First Affiliated Hospital of Guangxi Medical University and the Fourth People’s Hospital of Nanning City. Patients who had culture and/or histopathological proof of DNTM disease with osteolytic lesions were included.

Results

Ten HIV-negative patients with DNTM disease with osteolytic lesions were enrolled. Five of these patients had underlying diseases. Seven and three of the patients were positive and negative for anti-interferon-γ autoantibodies (AIGAs), respectively. The AIGA positivity rate was 70% (7/10). Ostealgia and anemia were the most common symptoms, followed by fever, emaciation, cough, expectoration, anorexia, subcutaneous abscesses and lymphadenopathy. Leukocyte and neutrophil counts were increased. The most common sites were the vertebrae, sternum, clavicle and ribs, although the femur, ilium, humerus, and scapula were also involved. Radiography and computed tomography (CT) showed moth-eaten or irregular destruction of bone, bone defects, pathological fracture, periosteal proliferation and surrounding abscesses. Emission CT (ECT) bone scans showed significantly increased uptake in many skeletal regions. Positron emission tomography(PET)/CT showed metabolic activity in multiple bones. All patients received anti-nontuberculous therapy, and five underwent surgery. Two died during treatment.

Conclusion

DNTM infection of bone and leading to osteolysis usually occurs in patients with AIGA-positive antibodies. DNTM disease with osteolysis is characterized by increased leukocytes and neutrophil counts, focal suppurative granulomas, and multiple areas with moth-eaten or irregular destruction of bone with increased radioactive concentrations. Early diagnosis and timely, effective combination anti-NTM therapy can improve the prognosis.

Identification of nontuberculous mycobacteria species by multiplex real-time PCR with high-resolution melting

INTRODUCTION:

Nontuberculous mycobacteria (NTM) species, as human pathogens, are increasing in the world, as is the difficulty of accurately identifying them. Differential diagnosis, especially between the M. tuberculosis complex and NTM species, and the characterization of NTM species is important. This study aimed to evaluate the performance of a molecular system based on multiplex real-time PCR with high-resolution melting (HRM) for the identification and differentiation of NTM species of clinical importance of an endemic area for tuberculosis in northeastern Brazil.

METHODS:

The technical protocol of the molecular system was based on multiplex real-time PCR-HRM, and evaluated the sensitivity and specificity of the detection of NTM species in mycobacterial clinical isolates from the studied region. The gold standard method was specific gene sequencing.

RESULTS:

The sensitivity and specificity of multiplex real-time PCR-HRM modified for differentiation between NTM and M. tuberculosis were 90% and 100%, respectively. The PCR-HRM sensitivities for the characterization of NTM species (M. kansasii, M. abscesses, M. avium, and M. fortuitum) were 94.59%, 80%, 57.14%, and 54%, respectively.

CONCLUSIONS

The multiplex real-time PCR-HRM modified assay has the potential to rapidly and efficiently identify nontuberculous mycobacteria of clinical importance, which is crucial for immediate implementation of the appropriate therapy and thus avoiding complications and sequelae in patients.

Recovery of Non-tuberculous Mycobacteria from Water is Influenced by Phenotypic Characteristics and Decontamination Methods

Infections related to non-tuberculous mycobacteria (NTM) have recently increased worldwide. The transmission of these microorganisms from the environment has been suggested as the main source for human infections. To elucidate the epidemiological aspects and distribution of these pathogens, many studies have evaluated several decontamination methods and protocols to properly isolate NTM from environmental samples, mainly from water. However, no satisfactory strategy has been found for isolation of most of the NTM species harboring different phenotypic characteristics. Here, we evaluated the susceptibility of 23 NTM strains presenting variable growth rate and pigmentation patterns to eight different methods: oxalic acid (2.5% and 5%), cetylpyridinium chloride (CPC) (0.0025% and 0.005%), sodium hydroxide (NaOH) (2% and 4%), and sodium dodecyl sulfate (SDS) plus NaOH (SDS 1.5%-NaOH 0.5% and SDS 3%-NaOH 1%). It was found that the viability of NTM exposed to different decontamination methods varies according to their phenotypic characteristics and two methods (SDS 1.5% plus NaOH 0.5% and CPC 0.0025%) were necessary for effective isolation of all of the species tested. These findings supply important insights for future studies on the environmental occurrence of mycobacteria and improving the sensibility of traditional strategies.

Studies of antimicrobial resistance in rare mycobacteria from a nosocomial environment

BACKGROUND

Nontuberculous mycobacteria (NTM) are ubiquitous in nature and recognized agents of opportunistic infection, which is often aggravated by their intrinsic resistance to antimicrobials, poorly defined therapeutic strategies and by the lack of new drugs. However, evaluation of their prevalence in anthropogenic environments and the associated antimicrobial resistance profiles have been neglected. In this work, we sought to determine minimal inhibitory concentrations of 25 antimicrobials against 5 NTM isolates recovered from a tertiary-care hospital surfaces. Antimicrobial susceptibilities of 5 other Corynebacterineae isolated from the same hospital were also determined for their potential clinical relevance.

RESULTS

Our phylogenetic study with each of the NTM isolates confirm they belong to Mycobacterium obuense, Mycobacterium mucogenicum and Mycobacterium paragordonae species, the latter initially misidentified as strains of M. gordonae, a species frequently isolated from patients with NTM disease in Portugal. In contrast to other strains, the M. obuense and M. mucogenicum examined here were resistant to several of the CLSI-recommended drugs, suggestive of multidrug-resistant profiles. Surprisingly, M. obuense was susceptible to vancomycin. Their genomes were sequenced allowing detection of gene erm (erythromycin resistance methylase) in M. obuense, explaining its resistance to clarithromycin. Remarkably, and unlike other strains of the genus, the Corynebacterium isolates were highly resistant to penicillin, ciprofloxacin and linezolid.

CONCLUSIONS

This study highlights the importance of implementing effective measures to screen, accurately identify and control viable NTM and closely related bacteria in hospital settings. Our report on the occurrence of rare NTM species with antibiotic susceptibility profiles that are distinct from those of the corresponding Type strains, along with unexpected resistance mechanisms detected seem to suggest that resistance may be more common than previously thought and also a potential threat to frail and otherwise vulnerable inpatients.

Mycobacterium avium paratuberculosis and Mycobacterium avium complex and related subspecies as causative agents of zoonotic and occupational diseases

Mycobacterium avium complex (MAC) and Mycobacterium avium paratuberculosis (MAP) cause zoonotic infections transmitted by birds and livestock herds. These pathogens have remained as serious economic and health threats in most areas of the world. As zoonotic diseases, the risk of development of occupational disease and even death outcome necessitate implementation of control strategies to prevent its spread. Zoonotic MAP infections include Crohn's disease, inflammatory bowel disease, ulcerative colitis, sarcoidosis, diabetes mellitus, and immune-related diseases (such as Hashimoto's thyroiditis). Paratuberculosis has classified as type B epidemic zoonotic disease according to world health organization which is transmitted to human through consumption of dairy and meat products. In addition, MAC causes pulmonary manifestations and lymphadenitis in normal hosts and human immunodeficiency virus (HIV) progression (by serotypes 1, 4, and 8). Furthermore, other subspecies have caused respiratory abscesses, neck lymph nodes, and disseminated osteomyelitis in children and ulcers. However, the data over the occupational relatedness of these subspecies is rare. These agents can cause occupational infections in susceptible herd breeders. Several molecular methods have been recognized as proper strategies for tracking the infection. In this study, some zoonotic aspects, worldwide prevalence and control strategies regarding infections due to MAP and MAC and related subspecies has been reviewed.

Mycobacterium avium: an overview

Mycobacterium avium is an environmental microorganism found in soil and water sources worldwide. It is the most prevalent species of nontuberculous mycobacteria that causes infectious diseases, especially in immunocompromised individuals. This review discusses and highlights key topics about M. avium, such as epidemiology, pathogenicity, glycopeptidolipids, laboratory identification, genotyping, antimicrobial therapy and antimicrobial resistance. Additionally, the main comorbidities associated with M. avium infection are discussed.

Quantitative N-Terminal Footprinting of Pathogenic Mycobacteria Reveals Differential Protein Acetylation

N-terminal acetylation (NTA) is a post-transcriptional modification of proteins that is conserved from bacteria to humans. In bacteria, the enzymes that mediate protein NTA also promote antimicrobial resistance. In pathogenic mycobacteria, which cause human tuberculosis and other chronic infections, NTA has been linked to pathogenesis and stress response, yet the fundamental biology underlying NTA of mycobacterial proteins remains unclear. We enriched, defined, and quantified the NT-acetylated populations of both cell-associated and secreted proteins from both the human pathogen, Mycobacterium tuberculosis, and the nontuberculous opportunistic pathogen, Mycobacterium marinum. We used a parallel N-terminal enrichment strategy from proteolytic digests coupled to charge-based selection and stable isotope ratio mass spectrometry. We show that NTA of the mycobacterial proteome is abundant, diverse, and primarily on Thr residues, which is unique compared with other bacteria. We isolated both the acetylated and unacetylated forms of 256 proteins, indicating that NTA of mycobacterial proteins is homeostatic. We identified 16 mycobacterial proteins with differential levels of NTA on the cytoplasmic and secreted forms, linking protein modification and localization. Our findings reveal novel biology underlying the NTA of mycobacterial proteins, which may provide a basis to understand NTA in mycobacterial physiology, pathogenesis, and antimicrobial resistance.

Isolation and characterization of nontuberculous mycobacteria from patients with pulmonary tuberculosis in Ghana

OBJECTIVE/BACKGROUND

Nontuberculous mycobacterial (NTM) species are assuming public health importance in pulmonary diseases; they are increasingly being isolated, and importantly, most NTMs do not respond to routine tuberculosis (TB) drugs. This study aimed to identify NTMs isolated from pulmonary TB cases and also determine their susceptibility to streptomycin (STR), isoniazid (INH), and rifampicin (RIF).

METHODS

A total of 1755 mycobacterial isolates, obtained between August 2012 and July 2014, from 2036 smear-positive pulmonary cases were identified using polymerase chain reaction amplification of IS6110, and hsp65 gene sequencing analysis. Drug susceptibility testing (DST) was then performed for the identified NTMs against STR, INH, and RIF using microplate Alamar blue assay. The results were analyzed against patients' biodata for statistical associations.

RESULTS

Of the 1755 analyzed isolates, we identified 43 (2.5%) NTMs, which included 18 (41.9%) Mycobacterium intracellulare, 13 (30.2%) Mycobacterium avium subs. paratuberculosis, 5 (11.3%) Mycobacterium abscessus, 3 (7.0%) each of Mycobacterium mucogenicum and Mycobacterium colombiense, and 1 (2.3%) Mycobacterium simiae. Patients infected with NTMs (52.0%) were more likely to be human immunodeficiency virus-positive (P = 0.001, odds ratio = 6.6, 95% confidence interval = 2.7-16.2) than those infected with M. tuberculosis complex (5.8%). All the 43 (100%) NTMs were resistant to INH, whereas 32 (74%) and 19 (44%) were resistant to RIF and STR, respectively. Furthermore, 16 (37.2%) NTMs were resistant to all three drugs, 20 were resistant to INH and RIF, and 3 were resistant to STR and INH. All the M. abscessus isolates were resistant to all the three drugs, whereas all the M. avium isolates were resistant to INH and RIF, but only three were resistant to STR. Among the M. intracellulare isolates, 8, 18, and 15 isolates were resistant to STR, INH, and RIF, respectively.

CONCLUSION

The observed high-resistance level to INH and RIF supports the need for rapid species identification and DST of nonresponding TB cases before retreatment.

Clinical aspects in patients with pulmonary infection caused by mycobacteria of the Mycobacterium abscessus complex, in the Brazilian Amazon

OBJECTIVE

To describe the clinical manifestations of patients with pulmonary infection caused by mycobacteria of the Mycobacterium abscessus complex (MABSC), and to compare these manifestations with those of patients infected with other nontuberculous mycobacteria (NTM).

METHODS

This was a retrospective cohort study involving 43 patients divided into two groups: the MABSC group, consisting of patients with pulmonary infection caused by MABSC (n = 17); and the NTM group, consisting of patients with pulmonary infection caused by NTM other than MABSC (n = 26). Patients were previously treated with a regimen of rifampin, isoniazid, pyrazinamide, and ethambutol before the diagnosis of NTM was confirmed by two culture-positive sputum samples. The nucleotide sequences of the hsp65, 16S rRNA, and/or rpoB genes were analyzed to identify the mycobacteria. Data were collected on demographic, clinical, and radiological characteristics, as well as on treatment responses and outcomes.

RESULTS

Loss of appetite was the only clinical manifestation that was significantly more common in the MABSC group than in the NTM group (p = 0.0306). The chance of having to use a second treatment regimen was almost 12 times higher in the MABSC group than in the NTM group. Treatment success was significantly higher in the NTM group than in the MABSC group (83.2% vs. 17.6%; p < 0.0001). The chance of recurrence was approximately 37 times higher in the MABSC group than in the NTM group.

CONCLUSIONS

In the study sample, treatment response of pulmonary disease caused by MABSC was less favorable than that of pulmonary disease caused by other NTM.

HIV-negative pulmonary disease caused by nontuberculous mycobacteria in Southern Brazil: clinical and microbiological characterization

Background

Nontuberculous mycobacteria (NTM) have been identified with increasing frequency in the clinical practice. The aim of this study was to characterize NTM isolates in respiratory specimens from patients with pulmonary disease and to correlate this with clinical/radiological findings, decision to start treatment and outcomes.

Methods

A cross-sectional descriptive study was performed and included all patients who had at least one NTM isolated in respiratory specimens between 2011 and 2014. NTM culture was performed in liquid medium followed by immunochromatographic identification (anti-MPT64). Species identification was based on nucleic acid amplification followed by restriction analysis of a 441 bp fragment of the hsp65 gene (hsp65 PRA) and patients' records were reviewed.

Results

From 14,394 cultures in 4 years, 590 (4.10%) grew NTM and 305 (51.7%) isolates were characterized till species level, representing 290 patients including those with and without human immunodeficiency virus (HIV) infection. Two hundred and eleven non-HIV patients had NTM isolated from respiratory specimens, 49 (23.2%) had criteria for active disease based on the American Thoracic Society (ATS) 2007. The majority was men above 51 years old and M. intracellulare was detected in 59.2% (29/49), followed by M. avium 14.3% (7/49), and M. abscessus 12.2% (6/49).

Conclusions

Old age, nodular and nodular/bronchiectasis radiographic pattern, previous tuberculosis (TB) treatment and M. intracellulare were more frequent among NTM-disease patients compared to those only colonized. Positive culture and maintenance of clinical symptoms (poor outcome) was a rule when M. abscessus caused NTM-disease. Positive acid-fast smear in respiratory specimen is a strong predictor of disease.

The many lives of nontuberculous mycobacteria

Nontuberculous mycobacteria (NTM) include species that colonize human epithelia, as well as species that are ubiquitous in soil and aquatic environments. NTM that primarily inhabit soil and aquatic environments include the Mycobacterium avium complex (MAC, M. avium and Mycobacterium intracellulare) and the Mycobacterium abscessus complex (MABSC, M. abscessus subspecies abscessus, massiliense, and bolletii), and can be free-living, biofilm-associated, or amoeba-associated. Although NTM are rarely pathogenic in immunocompetent individuals, those who are immunocompromised - due to either an inherited or acquired immunodeficiency - are highly susceptible to NTM infection (NTMI). Several characteristics such as biofilm formation and the ability of select NTM species to form distinct colony morphotypes all may play a role in pathogenesis not observed in the related, well-characterized pathogen Mycobacterium tuberculosis The recognition of different morphotypes of NTM has been established and characterized since the 1950s, but the mechanisms that underlie colony phenotype change and subsequent differences in pathogenicity are just beginning to be explored. Advances in genomic analysis have led to progress in identifying genes important to the pathogenesis and persistence of MAC disease as well as illuminating genetic aspects of different colony morphotypes. Here we review recent literature regarding NTM ecology and transmission, as well as the factors which regulate colony morphotype and pathogenicity.

Production, crystallization and structure determination of a mycobacterial glucosylglycerate hydrolase

Glucosylglycerate hydrolase is highly conserved among rapidly growing mycobacteria and has been found to be involved in recovery from nitrogen starvation by promoting the rapid mobilization of the glucosylglycerate that accumulates under these conditions. Here, the production, crystallization and structure determination of glucosylglycerate hydrolase from Mycobacterium hassiacum using two-wavelength anomalous diffraction of selenomethionine-substituted crystals are described. The monoclinic (space group P21) crystals diffracted to ∼2.0 Å resolution at a synchrotron-radiation source and contained four molecules in the asymmetric unit, corresponding to a Matthews coefficient of 3.07 Å3 Da-1 and a solvent content of 59.9%. The quality of the experimental phases allowed the automated building of 1677 of the 1792 residues in the asymmetric unit.