Clinical features of infection caused by non-tuberculous mycobacteria: 7 years' experience

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.

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.

Mycobacterium xenopi related spine infections: A case report and systematic literature review

Background and purpose

Nontuberculous mycobacteria (NTM) disease is an important infection disease throughout the world. Mycobacterium xenopi (M. xenopi) is a common NTM. Extrapulmonary infections due to M. xenopi, particularly spine infections, are a rare occurrence, but lack of research is cited as a constraint for implementing NTM control in such patients. The purposes of this paper are to describe a case of spondylodiscitis, to review the published literature on cases of M. xenopi spine infections, and to summarize the predisposing factors, diagnosis, and treatment of infection.

Methods

A case of spondylodiscitis was caused by M. xenopi in a patient with systemic lupus erythematosus (SLE). Research was conducted using the PubMed, ScienceDirect, Embase, Wiley Online Library, and Scopus databases using the following search terms: "Mycobacterium xenopi", "vertebral", "spinal", "spondylodiscitis", "infection", and "osteomyelitis".

Results

We retrieved 14 cases published before August 2022. The risk factors for infection were iatrogenic infections (3/14, 21.43%), SLE (4/14, 28.57%), AIDS (4/14, 28.57%), and immunocompetence without any comorbidities (3/14, 21.43%). The most common sites of infection were thoracic vertebrae (10/14, 71.43%) and lumbar vertebrae (4/14, 28.57%). A total of 14 cases were isolated and identified as M. xenopi from a toad by mycobacterial culture. The identification time was 55.00 ± 7.55 days (the present report identification time of metagenomic next generation sequencing (mNGS) was only 2 days). All patients were treated with antibiotic therapy, and the duration of treatment was 13.18 ± 2.13 months. Clarithromycin-based therapy showed a higher improvement rate (5/6, 83.33%). Surgical intervention was performed in 5 patients. Only 1 patient did not show any improvement after surgical treatment.

Conclusion

M. xenopi spine infection in humans presents with atypical clinical symptoms. mNGS identification may be a good choice. M. xenopi may be considered in immunocompromised patients with spinal infection. We recommend a clarithromycin-containing regimen and prolonging the duration of treatment to ensure effectiveness.

Mycobacterium xenopi infection of the kidney and lymph nodes: A case report

The incidence of nontuberculous mycobacterial (NTM) infection has been increasing globally. Further, it has been reported that early NTM infection diagnosis and treatment can considerably improve patient prognosis. However, traditional methods for detecting pathogenic microorganisms are associated with several limitations, and optimal treatment regimens for several NTM infections have not yet been established. Here, we report the case of a 22-year-old woman with renal and lymph node Mycobacterium xenopi infection. This patient presented with repeated fever and systemic lymphadenopathy events for more than 2 years, but the etiology of the disease was unclear. We performed metagenomic next-generation sequencing (mNGS) using tissue sections from the patient's left kidney and successfully identified M. xenopi. Thereafter, the patient's condition was effectively controlled via treatment with rifampicin, clarithromycin, and ethambutol hydrochloride (orally administered after hemodialysis). Further, this case showed that the clinical symptoms of NTM infection are atypical and highly occult, especially for extrapulmonary NTM infections, which are difficult to diagnose. Therefore, mNGS may be a powerful tool for diagnosing NTM infections. The combination therapy used showed efficacy and thus could serve as a reference treatment for kidney and lymph node M. xenopi infection.

Risk Factors and Mental Health Status in Patients With Non-Tuberculous Mycobacterial Lung Disease: A Single Center Retrospective Study

According to the existing data, the incidence and prevalence of non-tuberculous mycobacteria (NTM) are increasing worldwide. The risk factors and mental health status of patients with NTM lung disease are important and deserve our attention. A total of 180 patients with NTM lung disease hospitalized from January 2018 to December 2021 were selected as the NTM group, and 90 patients with non-severe community-acquired pneumonia (CAP) who were hospitalized during the same period were selected as the control group. The Symptom Checklist-90 (SCL-90) was used to assess the mental health status of the patients. The data were analyzed using descriptive statistics, logistic regression, and receiver operating characteristic (ROC) curves. There were no significant differences in age, sex, marital status, or smoking history between the two groups (p > 0.05), but there were significant differences in educational level, underlying diseases, occupation, living environment, and body mass index (BMI) (p < 0.01). According to the classification of basic diseases, bronchiectasis was found in 82 (45.6%) patients, followed by hypertension in 66 (36.7%) patients, and chronic obstructive pulmonary disease (COPD) in 39 (21.7%) patients. The NTM strains were identified M. intercelleulare caused 41 cases (22.8%), followed by Mycobacterium avium and Mycobacterium gordonae, each with 35 cases (19.4%), and Mycobacterium abscessus with 32 cases (17.8%). The SCL-90 found that 160 (88.9%) of 180 patients with NTM lung disease had developed mental health problems, among which the four highest-scoring factors were anxiety (ANX: 29.4%), depression (DEPR: 18.8%), sleep and diet (SD: 16.9%), and somatization (SOM: 11.3%). Through multivariate logistic regression analysis, it was found that educational level, underlying diseases, living environment, and BMI were independent risk factors for the occurrence of NTM lung disease (p < 0.01). The Hosmer-Lemeshow test was used to check the model's fitness. The ROC curve showed that the area under the curve (AUC) was 0.896, the sensitivity was 83.3%, and the specificity was 85.6%. Patients with NTM lung disease have many risk factors and prominent mental health problems that may require interventions during the process of clinical diagnosis and treatment.

Mycobacterium chimaera as an Underestimated Cause of NTM Lung Diseases in Patients Hospitalized in Pulmonary Wards

Mycobacterium chimaera is the newly described species belonging to Mycobacterium avium complex (MAC), with morphology and growth characteristics closely related to Mycobacterium intracellulare. The aim of this retrospective study was to analyze the frequency and clinical significance of M. chimaera identification in the population of patients with previous positive respiratory cultures for M. intracellulare or MAC. 200 strains of M. intracellulare or MAC, isolated from respiratory specimens of patients hospitalized in pulmonary wards, between 2011 and 2020, were retrospectively analyzed with GenoType NTM-DR test. 88 (44%) of strains were re-classified to M. chimaera species. Analysis of clinical data in 30 patients with positive M. chimaera isolates revealed that they were diagnosed with chronic obstructive pulmonary disease (COPD) – 27%, past tuberculosis – 20%, or interstitial lung diseases – 17%, respectively. Non-tuberculous mycobacterial lung disease (NTMLD) caused by M. chimaera has been recognized in 53% of patients, most often in those presenting with post-tuberculous lung lesions. M. chimaera was almost exclusively isolated from respiratory specimens of patients with underlying lung diseases, especially those with COPD and/or past tuberculosis. NTMLD due to M. chimaera was diagnosed predominantly in patients with past tuberculosis.

Approach to the diagnosis and treatment of non-tuberculous mycobacterial disease

Non-tuberculous mycobacteria (NTM) is a collective name given to a group of more than 190 species of Mycobacterium. The clinical presentation for most NTM infections is non-specific, often resulting in delayed diagnosis. Further complicating matters is that NTM organisms can be difficult to isolate. Medications used to treat NTM infection can be difficult for patients to tolerate, and prolonged courses of anti-mycobacterial therapy are often required for adequate suppression or eradication. Herein, we review different NTM syndromes, appropriate diagnostic tests, and treatment regimens.

Non-Tuberculous Mycobacteria in Respiratory Specimens of Patients with Obstructive Lung Diseases-Colonization or Disease?

Non-tuberculous mycobacteria (NTM) are increasingly a cause of human respiratory tract colonization and mycobacterial lung disease (NTM-LD), especially in patients with chronic lung diseases. The aim of the present study was to find the factors predictive of NTM-LD in patients with obstructive lung diseases and NTM respiratory isolates. A total of 839 isolates of NTM, obtained from 161 patients between 2010 and 2020 in a single pulmonary unit, have been retrospectively reviewed. Of these isolates, 73 concerned 36 patients with obstructive lung diseases (COPD-26, asthma-3, COPD/asthma overlap syndrome-7). NTM-LD was recognized according to the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) criteria in 17 patients, colonization in 19. Lower BMI, elevated body temperature on admission, infiltrative/cavitary lesions on chest CT, and NTM species other than Mycobacterium gordonae were the significant predictors of NTM-LD recognition. Based on the above-mentioned predictive factors, an original scoring system was implemented. The diagnostic utility of the scoring system was higher than that of single parameters. We conclude that NTM-LD prediction in patients with obstructive lung diseases and positive respiratory isolates is difficult. A scoring system based on clinical, radiological and microbiological characteristics was capable of facilitating the differential diagnosis, but it needs further validation in a larger study group.

Clinical features of tuberculous lymphadenitis in a low-incidence country

BACKGROUND

Tuberculous lymphadenitis (TBLA) is the most common extrapulmonary manifestation of tuberculosis (TB) in Denmark. However, the clinical features of patients with TBLA have never been systematically studied in this setting.

METHODS

Patients treated for TBLA in Central Region Denmark from 2007 to 2016 were identified using the national TB surveillance register and The Danish Hospital Patient Registry. Data of clinical characteristics and treatment were extracted from hospital records.

RESULTS

Eighty-three TBLA patients were identified. The median age was 32 years (IQR 23-42); 71 (85.5%) were migrants; 58 (69.9%) presented with cervical lymphadenopathy; and 45 (54.2%) had one or more systemic TB symptom such as fever, chills, night sweats, fatigue, and weight loss. Sixty-five patients had no comorbidities (78.3%). HIV co-infection was seen in five (7.2%) of the 69 who were tested for HIV. Abscesses and/or draining sinuses were noted in 13 (15.7%) patients and 15 (18.1%) had concurrent pulmonary infection. The median time from first hospital contact to treatment initiation was 42 days (IQR 16-82) and admitted patients were hospitalised for a median of 7 days (IQR 3-13.5). For 24 patients (28.9%), lymph node material was not sent for mycobacterial culture and 52 (62.7%) had microbiologically confirmed TB. Treatment outcome was successful for 70 patients (84.3%).

CONCLUSION

In Denmark, TBLA is mainly seen among young and previously healthy migrants presenting with cervical lymphadenopathy and sparse systemic symptoms. The diagnosis is often considerably delayed and not microbiologically verified, implying diagnostic difficulties. Treatment outcome needs to be improved.

Incidence, comorbidities, and treatment patterns of nontuberculous mycobacterial infection in South Korea

Nontuberculous mycobacteria (NTM) are important pathogens in humans, and hospital-based studies have shown an increased incidence of NTM infection. However, little is known about the treatment pattern of NTM infection with respect to the number of cases per population in South Korea. This study evaluated the trends in the incidence of NTM infection, respiratory comorbidities, and treatment patterns in South Korea.National claims data from the Health Insurance Review and Assessment service database for the years 2009 to 2015 were reviewed, and codes related to NTM infection, respiratory comorbidities occurring from one year before NTM infection and associated treatments were identified.In total, 52,551 patients were included in the study and the average annual incidence per 100,000 person-years was 12.8. The annual incidence was found to have increased from 6.6 to 26.6 per 100,000 persons. Accompanied comorbidities were tuberculosis (33.7%), followed by bronchial asthma (33.2%), chronic obstructive pulmonary disease (25.6%), and lung cancer (5.8%). A total of 76.6% of patients did not receive any combination treatment within one year after the diagnosis of NTM infection. Macrolide-based treatment was administered to 18.8% of patients.A dramatic increase in the incidence of NTM infection was noted in the population of South Korea. Approximately three-fourth of the patients with NTM infection were clinically observed without treatment for at least 1 year after the identification of NTM infection and most patients who treated NTM infection received macrolide-based combination therapy.

Drug Susceptibility of Non-tuberculous Strains of Mycobacterium Isolated from Birds from Poland

Mycobacterioses are a constant problem in backyard poultry, as well as pet birds. To date, no evidence of direct transmission of atypical bacilli between humans has been demonstrated, but it cannot be ruled out that sick animals can be a source of infection for people in their environment. The aim of the study was to identify mycobacteria isolated from birds with diagnosed mycobacteriosis and to determine the susceptibility of mycobacterial isolates from these animals to antituberculous drugs most commonly used in the treatment of mycobacterial infections in humans. For drug susceptibility tests, drugs such as isoniazid, rifampicin, streptomycin, ethambutol, ofloxacin, capreomycin, cycloserine and ethionamide were used. A high degree of drug resistance was demonstrated, particularly in Mycobacterium avium . Isolates of Mycobacterium xenopi showed a relatively good susceptibility to the drugs tested. The drug resistance of Mycobacterium genavense has not been determined, but this mycobacterium was identified in ten cases, which is the second most frequent occurrence in the cases studied.

Mycobacterioses are a constant problem in backyard poultry, as well as pet birds. To date, no evidence of direct transmission of atypical bacilli between humans has been demonstrated, but it cannot be ruled out that sick animals can be a source of infection for people in their environment. The aim of the study was to identify mycobacteria isolated from birds with diagnosed mycobacteriosis and to determine the susceptibility of mycobacterial isolates from these animals to antituberculous drugs most commonly used in the treatment of mycobacterial infections in humans. For drug susceptibility tests, drugs such as isoniazid, rifampicin, streptomycin, ethambutol, ofloxacin, capreomycin, cycloserine and ethionamide were used. A high degree of drug resistance was demonstrated, particularly in Mycobacterium avium. Isolates of Mycobacterium xenopi showed a relatively good susceptibility to the drugs tested. The drug resistance of Mycobacterium genavense has not been determined, but this mycobacterium was identified in ten cases, which is the second most frequent occurrence in the cases studied.

Interferon Gamma Release Assays in Patients with Respiratory Isolates of Non-Tuberculous Mycobacteria - a Preliminary Study

Interferon gamma releasing assays (IGRAs) are extensively used in the diagnosis of latent tuberculosis infections. Comparing to tuberculin skin test (TST) they lack false positive results in the populations vaccinated with BCG, and in most non-tuberculous mycobacteria (NTM) infections. Nevertheless, Mycobacterium kansasii, Mycobacterium marinum, and Mycobacterium szulgai may induce positive IGRAs due to RD1 homology with Mycobacterium tuberculosis. The aim of the study was to investigate the possible influence of NTM respiratory isolates on the results of IGRAs. 39 patients (23 females and 16 males) of median age 61 years, with negative medical history concerning tuberculosis, entered the study. Identification of NTM was performed using the niacin test and molecular method GenoType CM test (Hain Lifescience). QFT-Plus was performed in 17 patients, T-SPOT-Tb - in 23 patients. Chest X-rays and a high-resolution computed tomography of the chest have been reviewed by the experienced radiologist blinded to the results of IGRAs, in search of past tuberculosis signs. Positive IGRAs results were obtained in three out of 39 patients (8%): 22% of patients with M. kansasii isolates and 18% of patients with radiological signs on HRCT that might be suggestive of past tuberculosis. Positive IGRAs correlated with radiological signs suggestive of past tuberculosis (r = 0.32, p = 0.04), and on the borderline with isolation of M. kansasii (r = 0.29, p = 0.06). These findings may suggest that a positive IGRAs result, in our material, could depend mostly on asymptomatic past Tb infection. The cross-reactivity of M. kansasii isolates with IGRAs was less probable; nevertheless, it requires further investigations.

Interferon gamma releasing assays (IGRAs) are extensively used in the diagnosis of latent tuberculosis infections. Comparing to tuberculin skin test (TST) they lack false positive results in the populations vaccinated with BCG, and in most non-tuberculous mycobacteria (NTM) infections. Nevertheless, Mycobacterium kansasii, Mycobacterium marinum, and Mycobacterium szulgai may induce positive IGRAs due to RD1 homology with Mycobacterium tuberculosis. The aim of the study was to investigate the possible influence of NTM respiratory isolates on the results of IGRAs. 39 patients (23 females and 16 males) of median age 61 years, with negative medical history concerning tuberculosis, entered the study. Identification of NTM was performed using the niacin test and molecular method GenoType CM test (Hain Lifescience). QFT-Plus was performed in 17 patients, T-SPOT-Tb – in 23 patients. Chest X-rays and a high-resolution computed tomography of the chest have been reviewed by the experienced radiologist blinded to the results of IGRAs, in search of past tuberculosis signs. Positive IGRAs results were obtained in three out of 39 patients (8%): 22% of patients with M. kansasii isolates and 18% of patients with radiological signs on HRCT that might be suggestive of past tuberculosis. Positive IGRAs correlated with radiological signs suggestive of past tuberculosis (r = 0.32, p = 0.04), and on the borderline with isolation of M. kansasii (r = 0.29, p = 0.06). These findings may suggest that a positive IGRAs result, in our material, could depend mostly on asymptomatic past Tb infection. The cross-reactivity of M. kansasii isolates with IGRAs was less probable; nevertheless, it requires further investigations.

A case of axillary lymphadenitis caused by Mycobacterium intracellulare in an immunocompetent patient

Axillary lymphadenitis caused by non-tuberculous mycobacteria is rare and has been reported in immunocompromised hosts. Herein, we report the case of a 67-year-old man without immunodeficiency who developed right axillary lymphadenitis caused by Mycobacterium intracellulare and showed a small nodular shadow in the left pulmonary apex. Biopsy of the right axillary lymph node revealed several epithelioid granulomas, and the culture of the lymph node aspirate yielded Mycobacterium intracellulare. The lymph node lesion and left lung apex shadow resolved spontaneously after careful outpatient monitoring. This case suggests that axillary lymphadenitis could be caused by Mycobacterium intracellulare in an immunocompetent patient.