Prevalence of nontuberculous mycobacteria and the emergence of rare species in Henan Province, China.

Nontuberculous mycobacteria (NTM) is a large group of mycobacteria other than the Mycobacterium tuberculosis complex and Mycobacterium leprae. Epidemiological investigations have found that the incidence of NTM infections is increasing in China, and it is naturally resistant to many antibiotics. Therefore, studies of NTM species in clinical isolates are useful for understanding the epidemiology of NTM infections. The present study aimed to investigate the incidence of NTM infections and types of NTM species. Of the 420 samples collected, 285 were positive for M. tuberculosis, 62 samples were negative, and the remaining 73 samples contained NTM, including 35 (8.3%) only NTM and 38 (9%) mixed (M. tuberculosis and NTM). The most prevalent NTM species were Mycobacterium intracellulare (30.1%), followed by Mycobacterium abscessus (15%) and M. triviale (12%). M. gordonae infection was detected in 9.5% of total NTM-positive cases. Moreover, this study reports the presence of Mycobacterium nonchromogenicum infection and a high prevalence of M. triviale for the first time in Henan. M. intracellulare is the most prevalent, accompanied by some emerging NTM species, including M. nonchromogenicum and a high prevalence of M. triviale in Henan Province. Monitoring NTM transmission and epidemiology could enhance mycobacteriosis management in future.

Clinical Features of Nontuberculous Mycobacterial Pulmonary Disease in the Yangtze River Delta of China: A Single-Center, Retrospective, Observational Study.

With increased focus on nontuberculous mycobacterial pulmonary disease (NTM-PD), and the improvement in detection methods, the global incidence continues to increase every year, but the diagnosis and treatment are difficult with a high misdiagnosis rate and poor curative effect. This study aimed to analyze the clinical indicators of different pathogenic NTM in the Yangtze River Delta. The study retrospectively analyzed the medical records of patients with NTM-PD, who resided in the Yangtze River Delta and were diagnosed using sputum or bronchial lavage fluid and hospitalized in Shanghai Pulmonary Hospital from March 2017 to February 2019. The clinical data of confirmed patients were collected. Among the 513 cases of NTM-PD, 482 cases were infected by four common bacteria: Mycobacterium intracellulare (224, 46.5%), M. abscessus (138, 28.6%), M. kansasii (84, 17.4%), and M. avium (36, 7.5%). The analysis found that different NTM strains have their corresponding positive and negative correlation factors (p < 0.05). M. intracellulare, M. abscessus, M. kansasii, and M. avium were the main pathogenic bacteria isolated from patients with NTM-PD in the Yangtze River Delta were. Different strains resulted in different clinical features, assisting in the early diagnosis and treatment of NTM-PD.

Mycobacterium intracellulare among TB suspected patients in Bulgaria - microbiological aspects.

INTRODUCTION: Nontuberculous mycobacteria (NTM) are representatives of the genus Mycobacterium with a worldwide distribution, associated mainly with water, soil, and biofilms. Some of NTMs, such as Mycobacterium avium complex (MAC), are etiological agents of human diseases - disseminated or with different localization, most often pulmonary. AIM: In the present study, we analyzed Mycobacterium intracellulare isolates recovered from clinical specimens of tuberculosis (TB) suspected patients in Bulgaria, 2018-2020. MATERIALS AND METHODS: The cultures were grown on solid and liquid media. For species identification, we used immune chromatographic (TB Ag MPT64) test and Line Probe Assay (LPA) from the positive cultures. RESULTS: M. intracellulare was identified in 32 patients from 82,780 specimens. It was predominantly isolated in females - 62.5% vs. 37.5% in males. The most affected age group was 65 years and over (38%). The distribution of the isolates in Bulgaria was uneven. Most of them (65.6%) were concentrated in two districts of the country: Plovdiv and Sofia-city. All strains were sensitive to macrolides and aminoglycosides except one with macrolide resistance. NTM pulmonary disease was confirmed in 16 patients with M. intracellulare isolate. CONCLUSIONS: Analysing the 32 M. intracellulare isolates identified among TB suspected patients in Bulgaria between 2018 and 2020, we found that only half of them met the American Thoracic Society (ATS) diagnostic criteria for NTM pulmonary disease. For the remaining patients with M. intracellulare isolates we did not have sufficient data to support this diagnosis. Efforts by Bulgarian respiratory and microbiological societies are needed for adherence to the international guidelines.

Trends and Species Diversity of Non-tuberculous Mycobacteria Isolated From Respiratory Samples in Northern China, 2014-2021.

Background: Pulmonary non-tuberculous mycobacteria (NTM) infection has become a public health concern in China and around the world. The objective of this study was to describe the longitudinal changes in the frequency and diversity of NTM in northern China. Methods: We retrospectively analyzed data on mycobacterium species in Beijing Chest Hospital from January 2014 to December 2021. The isolates were identified to species level by targeted DNA sequencing. Results: After excluding duplicates, 1,755 NTM strains were analyzed, which were from 27 provinces in China over 8 years. Among all mycobacteria, the proportion of NTM increased each year, from 4.24% in 2014 to 12.68% in 2021. Overall, 39 different NTM species were identified, including 23 slow growing mycobacteria (SGM) and 16 rapid growing mycobacteria (RGM). The most common species were M. intracellulare (51.62%), M. abscessus (22.22%), M. kansasii (8.32%), M. avium (7.75%) and M. fortuitum (2.05%). The number of NTM species identified also increased each year from 9 in 2014 to 26 in 2021. Most species showed stable isolation rates over the years; however, the proportion of M. avium increased from 3.85 to 10.42% during the study period. Besides, 81 non-mycobacteria strains, including Gordonia (21 isolates), Nocardia (19 isolates) and Tsukamurella (17 isolates), etc., were also discovered. Conclusion: The proportion of NTM and species diversity increased considerably in northern China from 2014 to 2021. M. intracellulare was the most common NTM isolated among respiratory specimens, followed by M. abscessus and M. kansasii. Rare NTM species and non-mycobacteria pathogens also need attention.

Occurrence revisited: Mycobacterium avium and Mycobacterium intracellulare in potable water in the USA.

Nontuberculous mycobacterium (NTM) infections are increasing in the USA and have a high cost burden associated with treatment. Thus, it is necessary to understand what changes could be contributing to this increase in NTM disease rate. Water samples from 40 sites were collected from around the USA. They represented three water types: groundwater disinfected with chlorine and surface water disinfected with chlorine or monochloramine. Two methods, culture and qPCR, were used to measure M. avium and M. intracellulare. Heterotrophic bacteria and NTM counts were also measured. M. avium and M. intracellulare were molecularly detected in 25% (73/292) and 35% (102/292) of samples. The mean concentrations of M. avium and M. intracellulare were 2.8 × 103 and 4.0 × 103 genomic units (GU) L-1. The Northeast sites had the highest sample positively rate for both M. avium and M. intracellulare. The highest NTM counts and M. avium concentrations were observed in the surface water treated with chloramine. Geographic location and source water/disinfectant type were observed to significantly influence M. avium and M. intracellulare occurrence rates. These studies can help improve public health risk management by balancing disinfectant treatments and diverse microbial loads in drinking water. KEY POINTS: • M. avium (MA) culture rate increased significantly: 1% (1999) to 13%. • Culture versus qPCR method: 13% vs 31% for MA and 6% vs 35% for MI. • The results of each method type tell two different stories of MA and MI occurrence.

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.

Difference in drug susceptibility distribution and clinical characteristics between Mycobacterium avium and Mycobacterium intracellulare lung diseases in Shanghai, China.

Introduction. Mycobacterium avium complex (MAC) has been reported as the most common aetiology of lung disease involving nontuberculous mycobacteria.Hypothesis. Antimicrobial susceptibility and clinical characteristics may differ between Mycobacterium avium and Mycobacterium intracellulare.Aim. We aimed to evaluate the differences in antimicrobial susceptibility profiles between two major MAC species (Mycobacterium avium and Mycobacterium intracellulare) from patients with pulmonary infections and to provide epidemiologic data with minimum inhibitory concentration (MIC) distributions.Methodology. Between January 2019 and May 2020, 45 M. avium and 242 M. intracellulare isolates were obtained from Shanghai Pulmonary Hospital. The demographic and clinical characteristics of patients were obtained from their medical records. The MICs of 13 antimicrobials were determined for the MAC isolates using commercial Sensititre SLOWMYCO MIC plates and the broth microdilution method, as recommended by the Clinical and Laboratory Standards Institute (CLSI; Standards M24-A2). MIC50 and MIC90 values were derived from the MIC distributions.Results. M. intracellulare had higher resistance rates than M. avium for most tested antimicrobials except clarithromycin, ethambutol, and ciprofloxacin. Clarithromycin was the most effective antimicrobial against both the M. avium (88.89 %) and M. intracellulare (91.32 %) isolates, with no significant difference between the species (P=0.601). The MIC90 of clarithromycin was higher for M. avium (32 µg ml-1) than M. intracellulare (8 µg ml-1). The MIC50 of rifabutin was more than four times higher for M. intracellulare (1 µg ml-1) than M. avium (≤0.25 µg ml-1). The percentages of patients aged >60 years and patients with sputum, cough, and cavitary lesions were significantly higher than among patients with M. intracellulare infection than M. avium infections.Conclusions. The pulmonary disease caused by distinct MAC species had different antimicrobial susceptibility, symptoms, and radiographic findings.

Comparative analysis of phenotypic and genotypic antibiotic susceptibility patterns in Mycobacterium avium complex.

OBJECTIVE: Phenotypic (Sensititre Myco, pDST) and genotypic drug susceptibility testing (GenoType NTM DR, gDST) in M. avium complex (MAC) have become available as standardized assays, but comparable data is needed. This study aimed to investigate the phenotypic and genotypic drug susceptibility patterns in MAC clinical isolates. METHODS: Overall, 98 isolates from 85 patients were included. pDST and gDST were performed on all isolates and results compared regarding specificity and sensitivity using pDST as a reference method. The impact of drug instability on pDST results was studied using a biological assay over 14 days. In addition, the evolution of antimicrobial resistance was investigated in sequential isolates of 13 patients. RESULTS: Macrolide resistance was rare, 1.2% (95% CI 0.7-7.3) of isolates in the base cohort. No aminoglycoside resistances were found, but 14.1% of the studied isolates (95% CI 7.8-23.8) showed intermediate susceptibility. The GenoType NTM DR identified two out of four macrolide-resistant isolates. Antibiotic stability was demonstrated to be poor in rifampicin, rifabutin, and doxycycylin. CONCLUSIONS: pDST results in NTM for unstable antibiotics must be interpreted with care. A combination of pDST and gDST will be useful for the guidance of antimicrobial therapy in MAC-disease.

Nontuberculous Mycobacterium infection complicated with Haemophagocytic syndrome: a case report and literature review.

BACKGROUND: Non-tuberculous mycobacterial (NTM) infection is usually observed in patients with immunosuppressive conditions. It may also cause unregulated immune responses. While there have been increasing numbers of reported tuberculosis-related HPS (haemophagocytic syndrome), HPS caused by NTM infection is still very rarely reported. CASE PRESENTATION: We report a previously healthy 21-year-old Chinese female with fever, night sweats and fatigue, in whom HPS was diagnosed according to the HLH-2004 criteria. Mycobacterium intracellulare was cultured from her peripheral blood. After treatment with corticosteroid, clarithromycin, rifampicin, ethambutol and amikacin, the patient finally recovered. We also reviewed relevant publications on NTM infection complicated with HPS and found 11 cases, including ours. Clinical presentations, diagnoses and prognoses were analysed and summarized to deepen our understanding of this rare condition. CONCLUSIONS: Most reported NTM-related cases were caused by disseminated infection. The lack of localized symptoms might add to the difficulty involved in making the right diagnosis. While it usually takes time to obtain tissue or blood culture results, granuloma in a bone marrow biopsy might be an early indicator of possible mycobacterial infection. Although treatment varied, the overall prognosis of NTM-related HPS was promising.

The Italian registry of pulmonary non-tuberculous mycobacteria - IRENE: the study protocol.

BACKGROUND: A substantial increase in pulmonary and extra-pulmonary diseases due to non-tuberculous mycobacteria (NTM) has been documented worldwide, especially among subjects suffering from chronic respiratory diseases and immunocompromised patients. Many questions remain regarding the epidemiology of pulmonary disease due to NTM (NTM-PD) mainly because reporting of NTM-PD to health authorities is not mandated in several countries, including Italy. This manuscript describes the protocol of the first Italian registry of adult patients with respiratory infections caused by NTM (IRENE). METHODS: IRENE is an observational, multicenter, prospective, cohort study enrolling consecutive adult patients with either a NTM respiratory isolate or those with NTM-PD. A total of 41 centers, including mainly pulmonary and infectious disease departments, joined the registry so far. Adult patients with all of the following are included in the registry: 1) at least one positive culture for any NTM species from any respiratory sample; 2) at least one positive culture for NTM isolated in the year prior the enrolment and/or prescribed NTM treatment in the year prior the enrolment; 3) given consent to inclusion in the study. No exclusion criteria are applied to the study. Patients are managed according to standard operating procedures implemented in each IRENE clinical center. An online case report form has been developed to collect patients' demographics, comorbidities, microbiological, laboratory, functional, radiological, clinical, treatment and outcome data at baseline and on an annual basis. An IRENE biobank has also been developed within the network and linked to the clinical data of the registry. CONCLUSIONS: IRENE has been developed to inform the clinical and scientific community on the current management of adult patients with NTM respiratory infections in Italy and acts as a national network to increase the disease's awareness. TRIAL REGISTRATION: Clinicaltrial.gov: NCT03339063.

Novel Mycobacterium avium Complex Species Isolated From Black Wildebeest (Connochaetes gnou) in South Africa.

A study was undertaken to isolate and characterize Mycobacterium species from black wildebeest suspected of being infected with tuberculosis in South Africa. This led to the discovery of a new Mycobacterium avium complex species, provisionally referred to as the Gnou isolate from black wildebeest (Connochaetes gnou). Sixteen samples from nine black wildebeest were processed for Mycobacterium isolation. Following decontamination, samples were incubated in an ordinary incubator at 37°C on Löwenstein-Jensen slants and in liquid medium tubes using the BACTEC™ MGIT™ 960 system, respectively. Identification of the isolate was carried out by standard biochemical tests and using the line probe assay from the GenoType® CM/AS kit (Hain Lifescience GmbH, Nehren, Germany). The DNA extract was also analysed using gene sequencing. Partial gene sequencing and analysis of 16S rRNA gene, and 16S-23S rRNA (ITS), rpoB and hsp65 and phylogenetic analyses by searching GenBank using the BLAST algorithm were conducted. Phylogenetic trees were constructed using four methods, namely Bayesian inference, maximum likelihood, maximum parsimony and neighbour-joining methods. The isolate was identified as Mycobacterium intracellulare using the GenoType® CM/AS kit and as Mycobacterium avium complex (MAC) by gene sequencing. The gene sequence targeting all the genes, ITS, 16S rRNA, rpoB and hsp65 and phylogenetic analyses indicated that this isolate presented a nucleotide sequence different from all currently published sequences, and its position was far enough from other MAC species to suggest that it might be a new species.

Mycobacterium Tuberculosis and Nontuberculous Mycobacteria Coinfection of the Lungs.

Tuberculosis is highly prevalent in our country and nontuberculous mycobacteria (NTM) are frequently found in respiratory specimens recently. A 65-year-old woman was admitted with complaints of fever, cough, weight loss, and hemoptysis. On the patient's chest radiography an upper lobe cavity in both lungs and consolidation was detected. Acid-fast bacilli 4+ were observed in smear of sputum and culture results M. intracellulare and M. tuberculosis were observed together. The patient's treatment was arranged. Through this case, we want to emphasize that tuberculosis and nontuberculous mycobacterial disease can coexist.