M. Abscessus Complex Research Articles

Synthesis of Novel Benzenesulfonamide-Bearing Functionalized Imidazole Derivatives as Novel Candidates Targeting Multidrug-Resistant Mycobacterium abscessus Complex.

Infections caused by drug-resistant (DR) Mycobacterium abscessus (M. abscessus) complex (MAC) are an important public health concern, particularly when affecting individuals with various immunodeficiencies or chronic pulmonary diseases. Rapidly growing antimicrobial resistance among MAC urges us to develop novel antimicrobial candidates for future optimization. Therefore, we have designed and synthesized benzenesulfonamide-bearing functionalized imidazole or S-alkylated derivatives and evaluated their antimicrobial activity using multidrug-resistant M. abscessus strains and compared their antimycobacterial activity using M. bovis BCG and M. tuberculosis H37Ra. Benzenesulfonamide-bearing imidazole-2-thiol compound 13, containing 4-CF3 substituent in benzene ring, showed strong antimicrobial activity against the tested mycobacterial strains and was more active than some antibiotics used as a reference. Furthermore, an imidazole-bearing 4-F substituent and S-methyl group demonstrated good antimicrobial activity against M. abscessus complex strains, as well as M. bovis BCG and M. tuberculosis H37Ra. In summary, these results demonstrated that novel benzenesulfonamide derivatives, bearing substituted imidazoles, could be further explored as potential candidates for the further hit-to-lead optimization of novel antimycobacterial compounds.

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

China has seen a drastic increase in the incidence of non-tuberculous mycobacteria (NTM) infection, which is a notable public health issue. Due to a lack of reliable epidemiological surveillance information, there is a need to gather accurate epidemiological and surveillance data, which can help clinicians effectively treat NTM patients. Moreover, drug susceptibility testing for NTM is not frequently performed in China. This retrospective study, therefore, determined the prevalence and resistance characteristics of NTM to provide a reference to control the NTM epidemic. Sputum, alveolar lavage fluid, and other respiratory specimens were collected from 3025 patients with suspected pulmonary tuberculosis attending The Second Affiliated Hospital of Hainan Medical University from January 2014 to December 2021. Strain identification and species distribution of NTM were performed by DNA chip technology and gene sequencing, and the drug resistance of NTM isolates was evaluated by calculating the minimum inhibitory concentration through antimicrobial susceptibility testing for NTM. From 2014 to 2021, 373 strains of NTM were isolated and identified from respiratory specimens of 3025 suspected tuberculosis patients. Except in 2014, NTM-infected patients accounted for more than 10% of suspected tuberculosis patients in other years. The median age of patients with NTM infection was 62.0 years (53.0, 71.0), and the male-to-female ratio among these patients was 0.79:1. Among culture-positive strains, 12.3% (373/3040; 95% CI 11.1-13.4%) were identified as NTM comprising forty species of NTM. The forty species of NTM included 23 slow-growing mycobacteria (SGM) and 17 rapidly-growing mycobacteria (RGM). Among the NTM isolates, 58.7% (219/373; 95% CI 53.7-63.7%) were SGM and 41.3% (154/373; 95% CI 36.3-46.3%) were RGM. M.avium complex(MAC)(41.3%; 95% CI 36.3-46.3%) and M.abscessus complex (MABC)(33.2%; 95% CI 28.4-38.0%) were the most frequently detected species, followed by M.simiae Complex (11.8%; 95% CI 8.5-15.1%), M.fortuitum group (5.1%; 95% CI 2.9-7.3%), and others. Drug sensitivity test results showed that most of the NTM isolates were susceptible to amikacin and clarithromycin with a drug resistance rate of less than 10%. However, clarithromycin could induce drug resistance, followed by linezolid and moxifloxacin, and their drug resistance rate was less than 50%. During 2014-2021, the number of NTM isolates detected in the respiratory specimens of the study patients in The Second Affiliated Hospital of Hainan Medical University increased year by year. M. intracellulare is the most common pathogenic NTM species, and there is a high incidence of NTM infection on Hainan Island. Our findings might be of great importance for diagnosing and treating this patient population in Hainan.

The Impact of Nontuberculous Mycobacteria Species on Mortality in Patients With Nontuberculous Mycobacterial Lung Disease.

Patients with nontuberculous mycobacterial lung disease (NTM-LD) have increased mortality. The impact of NTM species on the risk of mortality remains unclear, especially that of death by non-cancer causes. We conducted a retrospective cohort study from 2006 to 2018 in a tertiary-care hospital in Taiwan. We enrolled patients who fulfilled the microbiological diagnostic criteria of NTM-LD. The mortality causes within 8 years after diagnosis were identified, and the Cox proportional hazard regression was performed for risk factors of mortality. A total of 1,652 subjects with NTM-LD were included. Among them, 723 (43.8%) were infected by Mycobacterium avium complex (MAC), 408 (24.7%) by M. abscessus complex (MABC), 120 (7.3%) by Mycobacterium kansasii (MK), 304 (18.4%) by other rapid-growing mycobacteria (RGM), and 97 (5.9%) by other slow-growing mycobacteria (SGM) groups. The 8-year all-cause mortality was 45.2% for all and the highest in the MK-LD group (59.2%), followed by the MABC-LD and MAC-LD groups. The adjusted hazard ratios were 2.20 (95% confidence interval: 1.40–3.46) in the MK-LD, 1.85 (1.54–2.22) in the MABC-LD, and 1.65 (1.12–2.41) in the MAC-LD groups for all-cause mortality, compared with the SGM group. Kaplan–Meier survival curves showed that all-cause mortality, non-cancer mortality, and mortality due to chronic airway diseases were significantly correlated with NTM species (log-rank p = 0.0031, < 0.001, and 0.001, respectively). High 8-year mortality rates were found in patients with NTM-LDs according to different NTM species. Notably, the difference was significant in non-cancer mortality causes, especially in chronic airway diseases.

A novel DNA chromatography method to discriminate Mycobacterium abscessus subspecies and macrolide susceptibility.

BackgroundThe clinical impact of infection with Mycobacterium (M.) abscessus complex (MABC), a group of emerging non-tuberculosis mycobacteria (NTM), is increasing. M. abscessus subsp. abscessus/bolletii frequently shows natural resistance to macrolide antibiotics, whereas M. abscessus subsp. massiliense is generally susceptible. Therefore, rapid and accurate discrimination of macrolide-susceptible MABC subgroups is required for effective clinical decisions about macrolide treatments for MABC infection. We aimed to develop a simple and rapid diagnostic that can identify MABC isolates showing macrolide susceptibility.MethodsWhole genome sequencing (WGS) was performed for 148 clinical or environmental MABC isolates from Japan to identify genetic markers that can discriminate three MABC subspecies and the macrolide-susceptible erm(41) T28C sequevar. Using the identified genetic markers, we established PCR based- or DNA chromatography-based assays. Validation testing was performed using MABC isolates from Taiwan.FindingWe identified unique sequence regions that could be used to differentiate the three subspecies. Our WGS-based phylogenetic analysis indicated that M. abscessus carrying the macrolide-susceptible erm(41) T28C sequevar were tightly clustered, and identified 11 genes that were significantly associated with the lineage for use as genetic markers. To detect these genetic markers and the erm(41) locus, we developed a DNA chromatography method that identified three subspecies, the erm(41) T28C sequevar and intact erm(41) for MABC in a single assay within one hour. The agreement rate between the DNA chromatography-based and WGS-based identification was 99·7%.InterpretationWe developed a novel, rapid and simple DNA chromatography method for identification of MABC macrolide susceptibility with high accuracy.FundingAMED, JSPS KAKENHI

The Use of Amikacin Liposome Inhalation Suspension (Arikayce) in the Treatment of Refractory Nontuberculous Mycobacterial Lung Disease in Adults.

Nontuberculous mycobacteria (NTM) can cause and perpetuate chronic inflammation and lung infection. Despite having the diagnostic criteria, as defined by the American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA), clinicians find it challenging to diagnose and treat NTM-induced lung disease. Inhaled antibiotics are suitable for patients with lung infection caused by Pseudomonas aeruginosa and other organisms, but until recently, their utility in NTM-induced infection was not established. The most common NTM pathogens identified are the slow-growing Mycobacterium avium complex (MAC) and the rapid-growing M. abscessus complex (MABSC), both of which include several subspecies. Other less commonly isolated species include M. kansasii, M. simiae, and M. fortuitum. NTM strains are frequently more resistant than what is found in bacterial sputum cultures. Until recently, there was no approved inhaled antibiotic therapy for patients who were culture positive for pulmonary NTM infection. Of late, inhaled amikacin has been under investigation for the treatment of NTM-induced pulmonary infection. The FDA approved Arikayce (amikacin liposome inhalation suspension or ALIS) based on results from the ongoing Phase 3 CONVERT trial. In this study, the use of Arikayce met its primary endpoint of sputum culture conversion by the sixth month of treatment. The addition of Arikayce to guideline-based therapy led to negative sputum cultures for NTM by month 6 in 29% of patients compared to 8.9% of patients treated with guideline-based therapy alone. The effectiveness of Arikayce holds promise. However, due to limited data on Arikayce’s safety, it is currently useful only for a specific population, particularly patients with refractory NTM-induced lung disease. Future trials must verify the target group and endorse the clinical benefits of Arikayce.

Nontuberculous mycobacterial infections in a Brazilian pediatric population: a seven-year survey

ABSTRACTThe aim of this study was to describe the frequency of nontuberculous mycobacteria (NTM) isolation and their related outcomes among pediatric patients of a Brazilian university hospital from 2012 to 2019. NTM were identified in different clinical samples by microbiological culture and molecular-based methods. NTM were isolated from 14 patients, out of whom four (27%) were infected and were treated accordingly. Two were infected with Mycobacterium avium complex (MAC), two with M. abscessus complex (MABSC) and one with M. intracellulare. Two patients had cystic fibrosis-related lung disease and improved after successful NTM eradication. One patient was HIV-positive and died. One patient had severe combined immunodeficiency (SCID)-related pneumonia and is currently being followed-up. We conclude that NTM frequency in our center was low among pediatric patients. Whether this is inherent to Brazilian patients, due to the broad coverage of the Bacille Calmette-Guérin (BCG) vaccine in Brazil, or a result of underdiagnosis remains to be elucidated.

Development of a loop-mediated isothermal amplification coupled lateral flow dipstick targeting erm(41) for detection of Mycobacterium abscessus and Mycobacterium massiliense

Mycobacterium abscessus (M. abscessus) and Mycobacterium massiliense (M. massiliense) are major pathogens that cause post-surgical wound infection and chronic pulmonary disease. Although they are closely related subspecies of M. abscessus complex, their infections are associated with different drug-resistance and cure rate. In the present study, a loop-mediated isothermal amplification (LAMP) coupled with lateral flow dipstick (LFD) method was developed to simultaneous detect M. abscessus and M. massiliense, via specific erm(41) gene. The amplification was carried out at 65 °C for only 60 min, and the results could be visualized on a lateral flow strip. Positive results only occurred in M. abscessus and M. massiliense, no cross-reaction with other mycobacterial species was observed. Therefore, the cost-effective MABC (M. abscessus complex)–LAMP–LFD method developed here was able to correct the diagnose of M. abscessus and M. massiliense infection in a short time. Thus, this method could be used to guide clinicians in treatment of M. abscessus group infections.

RETROSPECTIVE ANALYSIS OF SLOVENIAN MYCOBACTERIUM AVIUM COMPLEX AND MYCOBACTERIUM ABSCESSUS COMPLEX ISOLATES AND MOLECULAR RESISTANCE PROFILE

Abstract. Mycobacteria belonging to Mycobacterium (M.) avium complex (MAC) and M. abscessus complex (MABSC) are the most frequent causes of mycobacteriosis in the world. In the last few years MAC and MABSC taxonomy was rapidly changing due to new molecular methods conveying the possibility to differentiate between species. New techniques are able to identify M. chimaera that was previously recognized as M. intracellulare and also differentiate subspecies of MABSC. Due to their natural habitat, non-tuberculous mycobacteria (NTM) are constantly exposed to various concentrations of antimicrobial drugs and other chemicals and consequently they had developed different mechanisms of resistance. Macrolides and aminoglycosides are frequently used drugs to treat MAC and MABSC infections. The aim of our nation-wide survey was to obtain information about MABSC subspecies prevalence in Slovenia and to assess the percentage of misidentifications of M. chimaera isolates as M. intracellulare in the past. Moreover, the purpose of our study was to reveal, which of the two species M. intracellulare or M. chimaera is clinically more relevant in Slovenia. Further, the aim of the study was to detect mutations in erm(41), rrl and rrs genes, which are known to convey macrolide resistance (erm(41) and rrl) and aminoglycoside resistance (rrs). One hundred and thirty-two Slovenian mycobacterial isolates obtained from the National Mycobacterial Collection that belong to MAC and MABSC were analysed. GenoType NTM-DR was used to differentiate M. intracellulare from M. chimaera and subspecies of MABSC. Our results showed that 48% of previously identified M. intracellulare isolates were actually M. chimaera isolates and that M. abscessus subsp. abscessus was the most frequent subspecies of MABSC. Most of the MABSC isolates carried the inducible macrolide resistance genes (erm(41) and rrl), however none of the isolates of MAC and MABSC had mutations in rrs genes for aminoglycoside resistance.

Preliminary Study on Drug Susceptibility Profile and Resistance Mechanisms to Macrolides of Clinical Isolates of Non-tuberculous Mycobacteria from China

ObjectiveMacrolide susceptibility and drug resistance mechanisms of clinical non-tuberculous mycobacteria (NTM) isolates were preliminarily investigated for more accurate diagnosis and treatment of the infection in China. MethodsFour macrolides, including clarithromycin (CLAR), azithromycin (AZM), roxithromycin (ROX), and erythromycin (ERY), were used to test the drug susceptibility of 310 clinical NTM isolates from six provinces of China with the broth microdilution method. Two resistance mechanisms, 23S rRNA and erm, were analyzed with nucleotide sequence analysis. ResultsVaried effectiveness of macrolides and species-specific resistance patterns were observed. Most Mycobacterium abscessus subsp. massiliense were susceptible and all M. fortuitum were highly resistant to macrolides. All the drugs, except for erythromycin, exhibited excellent activities against slow-growing mycobacteria, and drug resistance rates were below 22.2%. Only four highly resistant strains harbored 2,058/2,059 substitutions on rrl and none of other mutations were related to macrolide resistance. G2191A and T2221C on rrl were specific for the M. abscessus complex (MABC). Seven sites, G2140A, G2210C, C2217G, T2238C, T2322C, T2404C, and A2406G, were specifically carried by M. avium and M. intracellulare. Three sites, A2192G, T2358G, and A2636G, were observed only in M. fortuitum and one site G2152A was specific for M. gordonae. The genes erm(39) and erm(41) were detected in M. fortuitum and M. abscessus and inducible resistance was observed in relevant sequevar. ConclusionThe susceptibility profile of macrolides against NTM was demonstrated. The well-known macrolide resistance mechanisms, 23S rRNA and erm, failed to account for all resistant NTM isolates, and further studies are warranted to investigate macrolide resistance mechanisms in various NTM species.

(1010) - Antimicrobial Activity of Cysteamine Against Antibiotic Resistant Pathogens Isolated from Cystic Fibrosis and Non- CF Patients Including Mycobacterium abscessus Complex from Lung Transplant Recipients

Lung transplantation for cystic fibrosis (CF) patients colonised with pan resistant bacteria, in particular M abscessus complex (MABSC) may preclude them from lung transplantation due to poor outcomes. Treatment of MABSC generally consists of a 3 drug regime including nephrotoxic/ototoxic amikacin. Oral cysteamine is licenced for treatment of cystinosis and has recently been reported as having good antimicrobial, anti-biofilm and mucolytic activity against CF pathogens. We evaluated the antimicrobial activity of this compound against a collection of 31 strains of CF and non- CF pathogens including isolates from lung transplant recipients. We also evaluated the interaction of cysteamine with 12 anti-pseudomonal agents against 4 strains P aeruginosa (Pa). Microdilution MIC’s against 12 MABSC were performed and bactericidal activity was assessed by subculture. MIC’s were performed against a collection of 19 further strains including: Pa (n=3), Achromobacter spp. (n=2) and 1 each of the following: Burkholderia multivorans, Burkholderia cenocepacia, Ralstonia mannitolylitica, Pandoraea sp. Stenotrophomonas maltophilia, and Inquilinus limosus. NCTC strains of E coli, S aureus; C albicans, E faecalis and 4 carbapenemase-producing Enterobacteriacae (CPE) were also evaluated. The Multiple Combination Bactericidal Test (MCBT) was utilised to assess synergy by incorporating cysteamine at 500 mg/L with 12 agents at the systemic concentration. The 4 strains selected were only susceptible to colomycin. Cysteamine at 500 mg/L was bactericidal against all 4 strains of Pa and no antagonism was observed with antipseudomonal agents. The MIC’s of 12 MABSC were 256-1024 mg/L with bactericidal activity against 9 strains at 1024 mg/L and 512 mg/L for 2 strains. One strain was inhibited at 256 mg/L but no bactericidal activity observed at 1024 mg/L. The MIC’s of the 19 other isolates ranged from 64-1024 mg/L with bactericidal activity ranging from 128-1024 mg/L for all except C albicans. The results of this study demonstrate that cysteamine has potential as an antimicrobial for the treatment of severe infection caused by pan resistant bacteria in lung transplant patients with or without CF and warrants further evaluation.

Diagnosis and Treatment of Nontuberculous Mycobacterial Lung Disease.

Nontuberculous mycobacteria (NTM) are ubiquitous organisms; their isolation from clinical specimens does not always indicate clinical disease. The incidence of NTM lung diseases has been increasing worldwide. Although the geographic diversity of NTM species is well known, Mycobacterium avium complex (MAC), M. abscessus complex (MABC), and M. kansasii are the most commonly encountered and important etiologic organisms. Two distinct types of NTM lung diseases have been reported, namely fibrocavitary and nodular bronchiectatic forms. For laboratory diagnosis of NTM lung diseases, both liquid and solid media cultures and species-level identification are strongly recommended to enhance growth detection and determine the clinical relevance of isolates. Treatment for NTM lung diseases consists of a multidrug regimen and a long course of therapy, lasting more than 12 months after negative sputum conversion. For MAC lung disease, several new macrolide-based regimens are now recommended. For nodular bronchiectatic forms of MAC lung diseases, an intermittent three-time-weekly regimen produces outcomes similar to those of daily therapy. Treatment of MABC lung disease is very difficult, requiring long-term use of parenteral agents in combination with new macrolides. Treatment outcomes are much better for M. massiliense lung disease than for M. abscessus lung disease. Thus, precise identification of species in MABC infection is needed for the prediction of antibiotic response. Likewise, increased efforts to improve treatment outcomes and develop new agents for NTM lung disease are needed.

Treatment of Mycobacterium abscessus

Treatment of <i>Mycobacterium abscessus</i>

Non-tuberculous mycobacteria in cystic fibrosis

Non-tuberculous mycobacteria (NTM) are environmental organisms found in soil and water throughout the world that can cause chronic lung infection, usually in the context of structural lung disease or immunodeficiency.1 There is considerable evidence that rates of NTM infection are increasing in patients with Cystic Fibrosis (CF).2 In contrast to Mycobacterium tuberculosis, NTM do not seem to be transmissible from person to person nor re-activate following latent infection.3 Observed increases in NTM infection in CF patients are therefore likely to reflect increased exposure and/or increased susceptibility to infection. This review aims to summarize the epidemiology, diagnosis and treatment of NTM infection in CF patients focusing on the two most common mycobacterial groups causing disease: the M. avium-intracellulare complex (MAC) and the M. abscessus complex (MABSC).