Risk factor of non-tuberculous Mycobacterium infection in patients with rheumatoid arthritis and other autoimmune diseases receiving biologic agents: A multicenter retrospective study.

BACKGROUND: Evidence regarding the association of the usage of biologic agents (Etanercept, Tocilizumab, adalimumab and so on), such as anti-tumor necrosis factor α, with the incidence and risk factors of non-tuberculous Mycobacteria (NTM) infection is limited. Therefore, this study aimed to investigate the incidence and risk factors of NTM and their associations with biologic agents' usage, and also investigated the potential of Mycobacterium avium complex (MAC) antibodies as a predictor of NTM infection development. METHODS: This retrospective study included 672 patients with autoimmune diseases from four hospitals in Nagasaki, Japan, from January 1, 2011, to June 30, 2019, who fulfilled the inclusion criteria. RESULTS: Of the 672 patients, 9 (1.3%) developed complicated NTM infection, including two with disseminated infection, after the introduction of biologic agents. Of the nine patients, two died due to NTM infection but none tested positive for MAC antibodies prior to initiation of biologic agents. The mortality rate was higher in patients complicated with NTM than without NTM (22.2% vs 2.6%, P = 0.024). The corticosteroids dosage at the time of initiating the biologic agents was significantly higher in the NTM group than in the non-NTM group (median, 17 mg vs 3 mg, P = 0.0038). CONCLUSION: In the patients undergoing therapy with biologic agents, although NTM complication was rare, it could be fatal. In particular, for patients on a relatively high dose corticosteroids, careful observation is essential for identifying NTM complication, even if the MAC antibody test is negative.

Mycobacterium avium complex prosthetic joint infection: A systematic review of the literature and pooled analysis.

BACKGROUND: Mycobacterium avium complex (MAC) prosthetic joint infection (PJI) has been rarely reported. METHODS: This study aimed to investigate the epidemiology and outcomes of MAC PJI. A systematic review of the literature regarding the MAC infection following total joint arthroplasty including hip and knee joint was performed. Multiple databases were searched for published English-written articles up to May 2023. Studies that reported cases of PJI by MAC were reviewed. RESULTS: A total of 17 patients were identified and analyzed from 11 published studies. All patients presented with joint symptom of pain or swelling prior to the diagnosis and MAC was confirmed by culture. The most of the patients (16/17 patients, 94.1%) were noted to have underlying medical condition(s) that might have affected immunity. Treatment consisted of anti-MAC medication therapy only in two patients and anti-MAC medication therapy plus surgery in 15 patients. Among the patients who underwent surgery, 14 patients (82.3%) had removal of the prosthesis including seven patients who had two-stage surgery to have reimplantation of the prosthesis. No relapse of MAC infection was reported despite of one case of relapse of infection caused by different pyogenic bacteria. The rate of overall mortality was 29.4%, however, identified attributable mortality due to MAC infection was low (5.9%). CONCLUSION: PJI by MAC is a rare disease. However, MAC needs to be considered in the differential diagnosis in immunocompromised patients presenting with symptoms of PJI. Two-stage exchange arthroplasty may result in successful treatment outcomes without higher risks of relapse of infection if undertaken in association with appropriate active anti-MAC antibiotic therapy.

Correlation of drug exposure and bacterial susceptibility with treatment response for Mycobacterium avium complex lung disease: protocol for a prospective observational cohort study.

INTRODUCTION: The burden of Mycobacterium avium complex (MAC) lung disease is increasing globally and treatment outcome is in general poor. Therapeutic drug monitoring has the potential to improve treatment outcome by ensuring adequate drug exposure. However, very limited population-based studies exist for MAC lung disease. This study aims to describe the distribution of drug exposure for key antimycobacterial drugs at population level, and to analyse them in relationship to treatment outcome in patients with MAC lung disease. METHODS AND ANALYSIS: A prospective cohort aiming to include 100 adult patients diagnosed with and treated for MAC lung disease will be conducted in Shanghai Pulmonary Hospital, China. Blood samples will be collected after 1 month MAC treatment for measurement of macrolides, rifamycin, ethambutol, amikacin and/or fluoroquinolones, using a validated liquid-chromatography tandem mass spectrometry method. Respiratory samples will be collected at inclusion and once every 3 months for mycobacterial culture until treatment completion. Minimum inhibitory concentration (MIC) determination will be performed using a commercial broth microdilution plate. In addition to mycobacterial culture, disease severity and clinical improvement will be assessed from the perspective of lung function, radiological presentation and self-reported quality of life. Whole genome sequencing will be performed for any longitudinal isolates with significant change of MIC to explore the emergence of drug resistance-conferring mutations. The relationship between drug exposure and treatment outcome will be analysed and potential confounders will be considered for adjustment in multivariable models. Meanwhile, the associations between drug exposure in relation to MIC and markers of treatment response will be explored using Cox proportional hazards or binary logistic regression models, as appropriate. ETHICS AND DISSEMINATION: This study has been approved by the ethics committee of Shanghai Pulmonary Hospital (No. K22-149Z). Written and oral informed consent will be obtained from all participants. The study results will be submitted to a peer-reviewed journal. TRIAL REGISTERATION NUMBER: NCT05824988.

Epidemiology of non-tuberculous mycobacterial diseases in Slovakia during the years 2016-2021.

Nontuberculous mycobacteria (NTM) are opportunistic human pathogens found worldwide, primarily in the environment. They predominantly affect the lungs, especially in individuals with compromised immune systems. Recent studies suggest an increasing incidence of NTM disease; however, their actual clinical impact in Slovakia remains uncertain. In this study, we conducted a retrospective analysis using a representative collection of NTM cases in the country. We searched the national database for patients with positive NTM cultures between January 2016 and December 2021. A total of 1355 NTM-positive cultures were identified in Slovakia, with no significant increase observed during the study period. Among these, 358 cases (26.4%) were confirmed as NTM disease. The incidence of the disease was notably higher in individuals over 55 years old (p < 0.0001). Moreover, women diagnosed with NTM disease exhibited a significantly higher average age than men (p = 0.0005). The majority of NTM disease cases were attributed to Mycobacterium (M.) intracellulare (39.9%) and M. avium (38.5%). Geographically, the highest incidence of NTM disease was observed in the Bratislava region (10.69 per 100,000 population).

M ycobacterium avium complex genomics and transmission in a London hospital.

BACKGROUND: Non-tuberculous mycobacteria (NTM) are environmental microorganisms and opportunistic pathogens in individuals with pre-existing lung conditions such as cystic fibrosis (CF) and non-CF bronchiectasis. While recent studies of Mycobacterium abscessus have identified transmission within single CF centres as well as nationally and globally, transmission of other NTM species is less well studied. METHODS: To investigate the potential for transmission of the Mycobacterium avium complex (MAC) we sequenced 996 isolates from 354 CF and non-CF patients at the Royal Brompton Hospital (London, UK; collected 2013-2016) and analysed them in a global context. Epidemiological links were identified from patient records. Previously published genomes were used to characterise global population structures. RESULTS: We identified putative transmission clusters in three MAC species, although few epidemiological links could be identified. For M. avium, lineages were largely limited to single countries, while for Mycobacterium chimaera, global transmission clusters previously associated with heater-cooler units (HCUs) were found. However, the immediate ancestor of the lineage causing the major HCU-associated outbreak was a lineage already circulating in patients. CONCLUSIONS: CF and non-CF patients shared transmission chains, although the lack of epidemiological links suggested that most transmission is indirect and may involve environmental intermediates or asymptomatic carriage in the wider population.

Development of Human Cell-Based In Vitro Infection Models to Determine the Intracellular Survival of Mycobacterium avium.

The Mycobacterium avium (Mav) complex accounts for more than 80% of all pulmonary diseases caused by non-tuberculous mycobacteria (NTM) infections, which have an alarming increase in prevalence and vary in different regions, currently reaching 0.3-9.8 per 100,000 individuals. Poor clinical outcomes, as a result of increasing microbial drug resistance and low treatment adherence due to drug-toxicities, emphasize the need for more effective treatments. Identification of more effective treatments, however, appears to be difficult, which may be due to the intracellular life of NTM and concomitant altered drug sensitivity that is not taken into account using traditional drug susceptibility testing screenings. We therefore developed human cell-based in vitro Mav infection models using the human MelJuSo cell line as well as primary human macrophages and a fluorescently labeled Mav strain. By testing a range of multiplicity of infection (MOI) and using flow cytometry and colony-forming unit (CFU) analysis, we found that an MOI of 10 was the most suitable for Mav infection in primary human macrophages, whereas an MOI of 50 was required to achieve similar results in MelJuSo cells. Moreover, by monitoring intracellular bacterial loads over time, the macrophages were shown to be capable of controlling the infection, while MelJuSo cells failed to do so. When comparing the MGIT system with the classical CFU counting assay to determine intracellular bacterial loads, MGIT appeared as a less labor-intensive, more precise, and more objective alternative. Next, using our macrophage Mav infection models, the drug efficacy of the first-line drug rifampicin and the more recently discovered bedaquiline on intracellular bacteria was compared to the activity on extracellular bacteria. The efficacy of the antibiotics inhibiting bacterial growth was significantly lower against intracellular bacteria compared to extracellular bacteria. This finding emphasizes the crucial role of the host cell during infection and drug susceptibility and highlights the usefulness of the models. Taken together, the human cell-based Mav infection models are reliable tools to determine the intracellular loads of Mav, which will enable researchers to investigate host-pathogen interactions and to evaluate the efficacy of (host-directed) therapeutic strategies against Mav.

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.

Analysis of adverse drug events in pulmonary Mycobacterium avium complex disease using spontaneous reporting system.

BACKGROUND: In Japan, Mycobacterium avium complex lung disease (MAC-LD) is the most common in nontuberculous mycobacterial lung disease. Patients often experience adverse events, resulting in the discontinuation of treatment, which causes treatment failure. The JADER (Japanese Adverse Drug Event Report) database is a database of adverse events that allows us to collect real-world data on adverse events. We can collect large-scale data cost-effectively and detect signals of potential adverse events such as reporting odds ratio (ROR) by using spontaneous reporting systems. In this study, we aimed to elucidate the adverse events of clarithromycin (CAM), ethambutol (EB), and rifampicin (RFP) using the JADER database. METHODS: We included cases of MAC-LD between April 2004 and June 2017. We investigated sex, age, and medications that may have caused the adverse events, outcomes, and time of onset. We calculated the safety signal index as the ROR. Time-to-event analysis was performed using the Weibull distribution. RESULTS: The total number of adverse events of CAM, EB, and RFP was 2780, with 806 patients. In the overall adverse events, hematologic and lymphatic disorders were the most common adverse events, with 17.3%, followed by eye disorders (16.6%), and hepatobiliary disorders (14.0%). The outcomes were as follows: recovery, 40.0%; remission, 27.1%; non-recovery, 11.2%; and death, 7.1%. Regarding the most common onset time of CAM, EB, and RFP was within 120 days at 40%, 181-300 days at 43.6%, and within 120 days at 88.5%. For CAM, the RORs of infections and infestations, hepatobiliary system disorders, and immune system disorders were 4.13 (95% confidence interval [CI], 2.3-7.44), 2.61 (95% CI, 1.39-4.91), and 2.38 (95% CI, 1.04-5.44). For EB, the ROR of eye disorders was 215.79 (95% CI, 132.62-351.12). For RFP, the RORs of renal and urinary tract disorders and investigations were 7.03 (95% CI, 3.35-14.77) and 6.99 (95% CI, 3.22-15.18). The ß value of EB was 2.07 (95% CI, 1.48-2.76), which was classified as a wear-out failure type. CONCLUSIONS: For MAC-LD, the adverse event which has the highest ROR is infections and infestations in CAM, eye disorders in EB, renal and urinary tract disorders in RFP. Adverse events of EB occur after 180 days, whereas the adverse events of CAM and RFP occur early in the course of treatment.

Progression and Dissemination of Pulmonary Mycobacterium Avium Infection in a Susceptible Immunocompetent Mouse Model.

Pulmonary infections caused by the group of nontuberculosis mycobacteria (NTM), Mycobacterium avium complex (MAC), are a growing public health concern with incidence and mortality steadily increasing globally. Granulomatous inflammation is the hallmark of MAC lung infection, yet reliable correlates of disease progression, susceptibility, and resolution are poorly defined. Unlike widely used inbred mouse strains, mice that carry the mutant allele at the genetic locus sst1 develop human-like pulmonary tuberculosis featuring well-organized caseating granulomas. We characterized pulmonary temporospatial outcomes of intranasal and left intrabronchial M. avium spp. hominissuis (M.av) induced pneumonia in B6.Sst1S mice, which carries the sst1 mutant allele. We utilized traditional semi-quantitative histomorphological evaluation, in combination with fluorescent multiplex immunohistochemistry (fmIHC), whole slide imaging, and quantitative digital image analysis. Followingintrabronchiolar infection with the laboratory M.av strain 101, the B6.Sst1S pulmonary lesions progressed 12-16 weeks post infection (wpi), with plateauing and/or resolving disease by 21 wpi. Caseating granulomas were not observed during the study. Disease progression from 12-16 wpi was associated with increased acid-fast bacilli, area of secondary granulomatous pneumonia lesions, and Arg1+ and double positive iNOS+/Arg1+ macrophages. Compared to B6 WT, at 16 wpi, B6.Sst1S lungs exhibited an increased area of acid-fast bacilli, larger secondary lesions with greater Arg1+ and double positive iNOS+/Arg1+ macrophages, and reduced T cell density. This morphomolecular analysis of histologic correlates of disease progression in B6.Sst1S could serve as a platform for assessment of medical countermeasures against NTM infection.

The Mycobacterium avium complex - an underestimated threat to humans and animals.

INTRODUCTION AND OBJECTIVE: The Mycobacterium avium complex (MAC) is a group of acid-resistant bacteria within the Mycobacteriaceae. Their cell walls have a specific structure impervious to many disinfectants. Mycobacteria are widespread in the environment and can also be found in food. This aim of the article is to review the current state of knowledge about the sources of infection, symptoms and treatment of MAC diseases in humans and animals, and summarizes the available methods for identifying the bacteria. It pays a special attention to the zoonotic potential of MAC bacteria and possible routes of transmission between humans and animals, including possible food-borne routes. BRIEF DESCRIPTION OF THE STATE OF KNOWLEDGE.: MAC bacterial infections occur both in immunocompetent people and those with functional predispositions and compromised immunity, particularly during HIV infection or immunosuppressive treatment. The incidence of MAC infections in humans is growing, with the most common form of infection being pulmonary disease (MTC-PD); however, there are conflicting reports on the role of Mycobacterium avium paratuberculosis (MAP) in the development of Crohn's disease. MAC bacteria can also attack livestock, household pets, and wild animals. Unfortunately, treatment is lengthy and often fails due to microbiological relapse; there is also increasing evidence of MAC bacteria are developing multi-drug resistance. CONCLUSIONS: Although new antibiotics are being created to inhibit the growth and division of Mycobacterium avium, there is clearly a need for further research into the virulence factors associated with MAC bacteria. Further studies should also examine the role of MAP in the etiopathogenesis of Crohn's disease.

Impact of emphysema on the prognosis of Mycobacterium avium complex pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a major comorbid disease of Mycobacterium avium complex pulmonary disease (MAC-PD). Emphysema is one of the main pathological findings in COPD, a risk factor for chronic pulmonary aspergillosis (CPA), and is associated with poor prognosis. We aimed to clarify the effect of emphysema on mortality in MAC-PD. METHODS: We retrospectively analyzed 203 patients with MAC-PD at The Jikei Daisan Hospital between January 2014 and December 2018. We investigated the mortality and CPA development rates after MAC-PD diagnosis in patients with or without emphysema. RESULTS: Multivariate Cox proportional hazards regression analysis showed the following negative prognostic factors in patients with MAC-PD: emphysema (hazard ratio [HR]: 11.46; 95% confidence interval [CI]: 1.30-100.90; P = 0.028); cavities (HR: 3.12; 95% CI: 1.22-7.94; P = 0.017); and low body mass index (<18.5 kg/m2) (HR: 4.62; 95% CI: 1.63-13.11; P = 0.004). The mortality and occurrence of CPA were higher in MAC-PD patients with than without emphysema (log-rank test, P < 0.0001 and P < 0.0001). CONCLUSION: Our study findings showed that emphysema detected by computed tomography was associated with an increased risk of CPA development and mortality in MAC-PD.

High genetic heterogeneity of Mycobacterium intracellulare isolated from respiratory specimens.

BACKGROUND: M. intracellulare is a frequent causative pathogen of nontuberculous mycobacteria infection that causes infections in the respiratory tract, whose incidence is increasing in many countries. This study aimed at determining the VNTR-based genetic diversity of a collection of 39 M. intracellulare human strains isolated from respiratory specimens over the last 5 years. RESULTS: The VNTR analysis showed that M. intracellulare strains displayed a high genetic diversity, indicating that the M. intracellulare genotypes are quite heterogeneous in our geographical area. Moreover, a comparison with VNTR profiles of strains from other countries confirmed that genotypes of clinical strains of M. intracellulare are not related to geographical origin. CONCLUSIONS: VNTR typing has proved to be a highly discriminatory method for better understanding the molecular epidemiology of M. intracellulare.

Identification of and discrimination between the Mycobacterium abscessus complex and Mycobacterium avium complex directly from sputum using quadruplex real-time PCR.

Introduction. Cystic fibrosis (CF) is a serious disease with multisystemic clinical signs that is easily and frequently complicated by bacterial infection. Recently, the prevalence of nontuberculous mycobacteria as secondary contaminants of CF has increased, with the Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex (MABSC) being the most frequently identified. The MABSC includes subspecies of significant clinical importance, mainly due to their resistance to antibiotics.Gap statement. Sensitive method for early detection and differentiation of MABSC members and MAC complex for use in routine clinical laboratories is lacking. A method based on direct DNA isolation from sputum, using standard equipment in clinical laboratories and allowing uncovering of possible sample inhibition (false negative results) would be required. The availability of such a method would allow accurate and accelerated time detection of MABSC members and their timely and targeted treatment.Aim. To develop a real time multiplex assay for rapid and sensitive identification and discrimination of MABSC members and MAC complex.Methodology. The method of DNA isolation directly from the sputum of patients followed by quadruplex real-time quantitative PCR (qPCR) detection was developed and optimised. The sensitivity and limit of detection (LOD) of the qPCR was determined using human sputum samples artificially spiked with a known amount of M. abscessus subsp. massiliense (MAM).Results. The method can distinguish between MAC and MABSC members and, at the same time, to differentiate between M. abscessus subsp. abscessus/subsp. bolletii (MAAb/MAB) and MAM. The system was verified using 61 culture isolates and sputum samples from CF and non-CF patients showing 29.5 % MAAb/MAB, 14.7 % MAM and 26.2 % MAC. The LOD was determined to be 1 490 MAM cells in the sputum sample with the efficiency of DNA isolation being 95.4 %. Verification of the qPCR results with sequencing showed 100 % homology.Conclusions. The developed quadruplex qPCR assay, which is preceded by DNA extraction directly from patients' sputum without the need for culturing, significantly improves and speeds up the entire process of diagnosing CF patients and is therefore particularly suitable for use in routine laboratories.

In vitro activity of bedaquiline against Mycobacterium avium complex.

Introduction. Nontuberculous mycobacteria (NTM) are widespread in the environment and can cause various diseases in humans, especially immunocompromised patients.Hypothesis. Treatment of diseases caused by NTM is a complicated issue, mainly due to the resistance of the pathogen to most antimicrobial agents. Bedaquiline (Bdq) is now widely used for the treatment of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB).Aim. The main goal of our study was to evaluate the activity of Bdq against Mycobacterium avium complex (MAC), the most common species among NTM.Methodology. A total of 166 MAC cultures (124 Mycobacterium avium and 42 Mycobacterium intracellulare) were studied. The minimum inhibitory concentrations (MICs) of Bdq for M. avium and M. intracellulare were obtained by twofold serial dilutions in the Middlebrook 7H9 medium. MIC ranges were determined and the MIC50, MIC90 and ECOFF values were obtained.Results. The MICs in respect of M. avium ranged from 0.003 to 1.0 µg ml-1; those for M. intracellulare ranged from 0.003 to 0.5 µg ml-1. The Bdq MIC50 and MIC90 values were found to be 0.015 and 0.12 µg ml-1 , respectively, for M. avium and 0.007 and 0.06 µg ml-1, respectively, for M. intracellulare. The tentative ECOFF values for M. avium and M. intracellulare were 0.12 and 0.06 µg ml-1, respectively.Conclusion. The main bedaquiline susceptibility parameters for MAC strains isolated in the Moscow region were determined.

Population Genomics and Inference of Mycobacterium avium Complex Clusters in Cystic Fibrosis Care Centers, United States.

Mycobacterium avium complex (MAC) species constitute most mycobacteria infections in persons with cystic fibrosis (CF) in the United States, but little is known about their genomic diversity or transmission. During 2016-2020, we performed whole-genome sequencing on 364 MAC isolates from 186 persons with CF from 42 cystic fibrosis care centers (CFCCs) across 23 states. We compared isolate genomes to identify instances of shared strains between persons with CF. Among persons with multiple isolates sequenced, 15/56 (27%) had >1 MAC strain type. Genomic comparisons revealed 18 clusters of highly similar isolates; 8 of these clusters had patients who shared CFCCs, which included 27/186 (15%) persons with CF. We provide genomic evidence of highly similar MAC strains shared among patients at the same CFCCs. Polyclonal infections and high genetic similarity between MAC isolates are consistent with multiple modes of acquisition for persons with CF to acquire MAC infections.

Association of serum antibodies against the Mycobacterium avium complex and hemoptysis: a cross-sectional study.

BACKGROUND: Hemoptysis is very common and can be life threatening in clinical practice for nontuberculous mycobacteria. The serum antibody against the Mycobacterium avium complex (MAC-Ab), the majority of nontuberculous mycobacteria species, is well known to reflect the activity of MAC lung disease; however, there is no study investigating the association between the MAC-Ab and hemoptysis in MAC patients. Therefore, we assessed whether the MAC-Ab is a good biomarker for hemoptysis among subjects with MAC lung disease. METHODS: This study was conducted as a five-year retrospective survey at the National Hospital Organization Fukuoka National Hospital. A total of 155 patients aged ≥20 years with MAC lung disease were enrolled and separated into seropositive and seronegative groups using the cutoff for MAC-Ab levels of 0.7 U/ml. The prevalence of hemoptysis and odds ratios for the presence of hemoptysis were estimated and compared between the groups. To investigate the linear trends in the relationship between MAC-Ab levels and hemoptysis, the subjects were classified into three groups using the tertile distribution of the MAC-Ab. RESULTS: The prevalence of hemoptysis was twice as high in the seropositive group than in the seronegative group (42.2 and 21.7%, respectively, P = 0.02). The multivariable-adjusted risk of hemoptysis was elevated in the seropositive group as compared with the seronegative group (odds ratio = 2.79 (95% confidence interval 1.15-7.44)). Likewise, when categorizing the subjects into three groups, the risk of hemoptysis increased with increasing MAC-Ab levels (P = 0.03 for trend). CONCLUSIONS: A positive MAC-Ab level was a significant risk factor for hemoptysis among patients with MAC lung disease. There were also positive trends in the association between the MAC-Ab titer and the likelihood of hemoptysis. Measuring the MAC-Ab may contribute not only to early detection of the risk of hemoptysis but also to early intervention with anti-NTM therapy and, as a result, to the prevention of hemoptysis in MAC patients.

Isolation of non-tuberculous mycobacteria among tuberculosis patients, a study from a tertiary care hospital in Lahore, Pakistan.

BACKGROUND: There is scarce knowledge on the prevalence of diseases caused by non-tuberculous mycobacteria (NTM) in Pakistan. In the absence of culture and identification, acid-fast bacilli (AFB) causing NTM disease are liable to be misinterpreted as tuberculosis (TB). Introduction of nucleic acid amplification testing for Mycobacterium tuberculosis complex (MTBC) offers improved diagnostic accuracy, compared with smear microscopy, and also assists in differentiating MTBC from other mycobacteria. This study aimed to investigate the prevalence of NTM among patients investigated for TB and describe NTM disease and treatment outcomes at a tertiary care hospital in Pakistan. METHODS: This is a retrospective study, data on NTM isolates among culture-positive clinical samples over 4 years (2016-19) was retrieved from laboratory records. Information on clinical specimens processed, AFB smear results, and for the AFB positive isolates, results of species identification for MTBC, and for NTM isolates, results of species characterization and drug susceptibility testing was collected. Additional clinical data including patient characteristics, treatment regimens, and outcomes were collected for patients with NTM disease treated at Gulab Devi Hospital, Lahore. RESULTS: During the study period, 12,561 clinical specimens were processed for mycobacterial culture and 3673 (29%) were reported positive for AFB. Among these 3482 (95%) were identified as MTBC and 191 (5%) as NTM. Among NTM, 169 (88%) were isolated from pulmonary and 22 (12%) from extrapulmonary specimens. Results of NTM speciation were available for 60 isolates and included 55% (n = 33) M. avium complex and 25% (n = 15) M. abscesses. Among these patients, complete clinical records were retrieved for 12 patients with pulmonary disease including nine infected with M. avium complex and three with M. abscessus. All 12 patients had a history of poor response to standard first-line anti-TB treatment. Ten patients were cured after 18 months of treatment, whereas, one with M. abscessus infection died and another was lost to follow up. CONCLUSION: In TB endemic areas, NTM can be misdiagnosed as pulmonary TB leading to repeated failed anti-TB treatment and increased morbidity, emphasizing the need for improved diagnosis.

Posttreatment Lymphopenia Is Associated With an Increased Risk of Redeveloping Nontuberculous Lung Disease in Patients With Mycobacterium avium Complex Lung Disease.

BACKGROUND: Lymphopenia has been reported as a risk factor for poor prognosis in various infectious diseases, including Mycobacterium avium complex lung disease (MAC-LD), and recurrence in several infectious diseases. However, the association between lymphopenia and the risk of redeveloping nontuberculous lung disease (NTM-LD) after completed treatment for MAC-LD is unknown. METHODS: We performed a retrospective cohort study with 147 patients with MAC-LD who successfully completed guideline-based therapy. Lymphopenia was defined as an absolute lymphocyte count (ALC) <1000 cells/µL based on commonly accepted reference values. RESULTS: During the median follow-up period of 41.9 months after treatment completion, 59 (40.1%) patients redeveloped NTM-LD. Patients with NTM-LD redevelopment had significantly lower posttreatment ALCs (median, 1260 vs 1420 cells/µL) than those without, and the univariate Cox proportional hazard analysis identified posttreatment ALC as a predictive factor for redevelopment (hazard ratio, .94 [95% confidence interval, .89-.99] for every increase of 100 cells/µL; P = .04). In the multivariate analysis, posttreatment ALC and the extent of bronchiectasis were independently associated with NTM-LD redevelopment. The cumulative rate of NTM-LD redevelopment was significantly higher in patients with posttreatment lymphopenia than in those without (P = .008). CONCLUSIONS: Posttreatment lymphopenia could predict an increased risk of NTM-LD redevelopment after completed treatment for MAC-LD.

[Hot tub lung: A retrospective analysis of 14 cases]. / Poumon de jacuzzi : analyse rétrospective de 14 cas.

INTRODUCTION: Hot tub lung (HTL) is a hypersensitivity pneumonitis (HP) related to inhalation of non-tuberculous mycobacteria (NTM) when exposed to ejected jet droplets from a jacuzzi. The aetiological debate is not completely settled in the literature. METHOD: An observational study of 14 cases of HTL, diagnosed at the University Hospital of Besançon, France, between 2004 and 2018 according to the diagnostic criteria used in the clinic. RESULTS: This cohort corresponds to type I HP (inflammatory), with one case of type II HP. Decrease of lung transfer for carbon monoxide was present in 86% of examinations (n=12/14). In total, 84% of bronchoalveolar lavages showed a lymphocytic cellular pattern≥30% (n=11/13). The environmental survey enabled the identification of NTM in 93% of cases (n=13/14), mainly Mycobacterium avium. Serum precipitins directed against NTM were found in 10% of the cases (n=2/20). Three cases received corticosteroid therapy and none received antibiotics. Antigenic eviction has improved the symptomatology in all cases. CONCLUSIONS: Our cohort supports the hypothesis that HTL is predominantly a type I HP. Avoidance of the agent involved (NTM) is necessary. The diagnosis is difficult because serum precipitins against NTM are not easily demonstrable. An environmental survey could facilitate the identification of the NTM. Prevention of HTL depends on education of the clinician and the patient.

Evaluation of plasma anti-GPL-core IgA and IgG for diagnosis of disseminated non-tuberculous mycobacteria infection.

Detection of IgA antibody against Mycobacterium avium complex (MAC) glycopeptidolipid (GPL) has recently been shown to improve the diagnosis of MAC pulmonary disease but has yet to be tested in disseminated Non-tuberculous mycobacteria (NTM) infection. In this study, we address the diagnostic efficacies of an anti-GPL-core ELISA kit in disseminated lymphadenopathy patients positive for NTM culture and anti-IFN-γ autoantibodies. The study was conducted in a tertiary referral center in northeastern Thailand and patients with NTM, tuberculosis, melioidosis, and control subjects were enrolled. Plasma immunoglobulin A (IgA) and G (IgG) antibodies against GPL-core were detected in the subjects and the specificity and sensitivity of the assay was assessed. Anti-GPL-core IgA and IgG levels were significantly higher in NTM patients than other groups (p < 0.0001). Diagnostic efficacy for NTM patients using anti-GPL-core IgA cut-off value of 0.352 U/ml showed good sensitivity (91.18%) and intermediate specificity (70.15%). Using a cut-off value of 4.140 AU/ml for anti-GPL-core IgG showed the same sensitivity (91.18%) with increased specificity (89.55%) and an 81.58% positive predictive value. Most patients with moderate levels (4.140-7.955 AU/ml) of anti-GPL-core IgG had rapidly growing mycobacteria (RGM) infection. Taken together, the detection of anti-GPL-core antibodies could provide a novel option for the diagnosis and management of disseminated NTM infected patients.