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Background: In the CONVERT study, treatment with amikacin liposome inhalation suspension (ALIS) added to guideline-based therapy (GBT) met the primary end point of increased culture conversion by month 6 in patients with treatment-refractory Mycobacterium avium complex lung disease (ALIS plus GBT, 29% [65/224] vs GBT alone, 8.9% [10/112]; P < .0001). Research Question: In patients who achieved culture conversion by month 6 in the CONVERT study, was conversion sustained (negative sputum culture results for 12 months with treatment) and durable (negative sputum culture results for 3 months after treatment) and were there any additional safety signals associated with a full treatment course of 12 months after conversion? Study Design and Methods: Adults were randomized 2:1 to receive ALIS plus GBT or GBT alone. Patients achieving culture conversion by month 6 continued therapy for 12 months followed by off-treatment observation. Results: More patients randomized to ALIS plus GBT (intention-to-treat population) achieved conversion that was both sustained and durable 3 months after treatment vs patients randomized to GBT alone (ALIS plus GBT, 16.1% [36/224] vs GBT alone, 0% [0/112]; P < .0001). Of the patients who achieved culture conversion by month 6, 55.4% of converters (36/65) in the ALIS plus GBT treated arm vs no converters (0/10) in the GBT alone arm achieved sustained and durable conversion (P = .0017). Relapse rates through 3 months after treatment were 9.2% (6/65) in the ALIS plus GBT arm and 30.0% (3/10) in the GBT alone arm. Common adverse events among ALIS plus GBT-treated patients (dysphonia, cough, dyspnea, hemoptysis) occurred mainly within the first 8 months of treatment. Interpretation: In a refractory population, conversion was sustained and durable in more patients treated with ALIS plus GBT for 12 months after conversion than in those treated with GBT alone. No new safety signals were associated with 12 months of treatment after conversion. Trial Registry: ClinicalTrials.gov; No.: NCT02344004; URL: www.clinicaltrials.gov

Nontuberculous mycobacteria (NTM) infections are increasing worldwide. Mycobacterium avium complex (MAC) and the M. abscessus species are the most commonly cultured NTM and treatment options are limited, especially for the M. abscessus species. In this study, the in vitro activity of eravacycline, a new tetracycline derivative, was tested against 110 clinical isolates of NTM. MIC testing was performed as recommended by the Clinical and Laboratory Standards Institute against 60 isolates of rapidly growing mycobacteria (RGM), of which ~70% were tetracycline resistant. These included M. abscessus subsp. abscessus (8 isolates), M. abscessus subsp. massiliense (5), M. chelonae (10), M. immunogenum (3), M. fortuitum group (20) including 12 doxycycline-resistant isolates, and M. mucogenicum group (10) including three doxycycline-resistant isolates. Due to trailing, eravacycline MICs were read at 80% and 100% inhibition. Eravacycline was active against all RGM species, with MIC(50) ranges of ≤0.015 to 0.5 and ≤0.015 to 0.12 μg/mL for 100% and 80% inhibition, respectively. For M. abscessus subsp. abscessus, MIC(50) values were 0.12 and 0.03 μg/mL with 100% and 80% inhibition, respectively. MICs for tigecycline were generally within 1 to 2 dilutions of the 100%-inhibition eravacycline MIC values. Fifty isolates of slowly growing mycobacteria (SGM) species, including 16 isolates of MAC, were also tested. While there was no trailing observed in most SGM, the eravacycline MICs were higher (MIC range of >8 μg/mL), except for M. kansasii and M. marinum which had MIC(50) values of 1 μg/mL. This study supports further evaluation of eravacycline, including clinical trials for the development of RGM treatment regimens, especially for M. abscessus.

Nontuberculous mycobacteria (NTM) infections are increasing worldwide. Mycobacterium avium complex (MAC) and the M. abscessus species are the most commonly cultured NTM and treatment options are limited, especially for the M. abscessus species. In this study, the in vitro activity of eravacycline, a new tetracycline derivative, was tested against 110 clinical isolates of NTM.

Recent studies have characterized a dominant clone (Clone 1) of Mycobacterium abscessus subspecies massiliense (M. massiliense) associated with high prevalence in cystic fibrosis (CF) patients, pulmonary outbreaks in the United States (US) and United Kingdom (UK), and a Brazilian epidemic of skin infections. The prevalence of Clone 1 in non-CF patients in the US and the relationship of sporadic US isolates to outbreak clones are not known. We surveyed a reference US Mycobacteria Laboratory and a US biorepository of CF-associated Mycobacteria isolates for Clone 1. We then compared genomic variation and antimicrobial resistance (AMR) mutations between sporadic non-CF, CF, and outbreak Clone 1 isolates. Among reference lab samples, 57/147 (39%) of patients with M. massiliense had Clone 1, including pulmonary and extrapulmonary infections, compared to 11/64 (17%) in the CF isolate biorepository. Core and pan genome analyses revealed that outbreak isolates had similar numbers of single nucleotide polymorphisms (SNPs) and accessory genes as sporadic US Clone 1 isolates. However, pulmonary outbreak isolates were more likely to have AMR mutations compared to sporadic isolates. Clone 1 isolates are present among non-CF and CF patients across the US, but additional studies will be needed to resolve potential routes of transmission and spread.

Nontuberculous mycobacteria (NTM) cause pulmonary disease in individuals without obvious immunodeficiency. This study was initiated to gain insight into the immunological factors that predispose persons to NTM pulmonary disease (NTMPD). Blood was obtained from 15 pairs of NTMPD patients and their healthy household contacts. Peripheral blood mononuclear cells (PBMCs) were stimulated with the M. avium complex (MAC). A total of 34 cytokines and chemokines were evaluated in plasma and PBMC culture supernatants using multiplex immunoassays, and gene expression in the PBMCs was determined using real-time PCR. PBMCs from NTMPD patients produced significantly less interleukin (IL)-1β, IL-18, IL-1α and IL-10 than PBMCs from their healthy household contacts in response to MAC. Although plasma RANTES levels were high in NTMPD patients, they had no effect on IL-1β production by macrophages infected with MAC. TLR2 and TWIK2 were impaired in response to MAC in PBMCs of NTMPD patients. A TLR2 inhibitor decreased all 4 cytokines, whereas a TWIK2 inhibitor decreased the production of IL-1β, IL-18, and IL-1α, but not IL-10, by MAC-stimulated PBMCs and monocytes. We suggest that an attenuated TWIK2-mediated IL-1 response may increase susceptibility to NTM pulmonary infection.

Background: Nontuberculous mycobacteria (NTM) causes disseminated disease in patients with immunodeficiency and pulmonary disease in individuals without obvious immunodeficiency. There is no clear information on how NTM pulmonary disease (NTMPD) develops in immunocompetent hosts. This profile study was initiated to gain insight into the immunological factors that predispose persons to pulmonary NTM infections.Methods: Blood samples were obtained from 15 pairs of NTMPD patients and age-matched healthy household contacts. Peripheral blood mononuclear cells (PBMCs) were stimulated with the heat-killed M. avium complex (MAC). A total of 34 cytokines and chemokines were evaluated in PBMCs culture supernatants and plasma using multiplex immunoassays. The mRNA expression of TLR2, P2X7R, TWIK2, THIK2 and TREK1 was measured by quantitative real-time PCR. In mechanistic studies, blood samples were obtained from healthy volunteers who had not been diagnosed or treated for NTM.Results: Interleukin (IL)-1β, IL-18, IL-1α and IL-10 production were significantly reduced in response to MAC in PBMCs of NTMPD patients compared with PBMCs of their healthy household contacts. RANTES was the only chemokine significantly elevated in the plasma of NTMPD patients compared with plasma of their healthy household contacts. TLR2 and TWIK2 expression were impaired in response to MAC in PBMCs of NTMPD patients compared with PBMCs of their healthy household contacts. RANTES had no effect on IL-1β production by macrophages infected with MAC. A TLR2 inhibitor decreased IL-1β, IL-18, IL-1α and IL-10 production by MAC-stimulated PBMCs and monocytes. A TWIK2 inhibitor decreased the production of IL-1β, IL-18, and IL-1α, but not IL-10, by MAC-stimulated PBMCs and monocytes.Conclusions: These findings suggest that impaired TWIK2 results in decreased production of IL-1 family cytokines (IL-1β, IL-18, and IL-1α) in response to MAC, consequentially may increase susceptibility to NTM pulmonary infection.

Whole-genome sequencing (WGS) has recently been used to investigate acquisition of Mycobacterium abscessus. Investigators have reached conflicting conclusions about the meaning of genetic distances for interpretation of person-to-person transmission. Existing genomic studies were limited by a lack of WGS from environmental M. abscessus isolates. In this study, we retrospectively analyzed the core and accessory genomes of 26 M. abscessus subsp. abscessus isolates collected over 7 years. Clinical isolates (n = 22) were obtained from a large hospital-associated outbreak of M. abscessus subsp. abscessus, the outbreak hospital before or after the outbreak, a neighboring hospital, and two outside laboratories. Environmental M. abscessus subsp. abscessus isolates (n = 4) were obtained from outbreak hospital water outlets. Phylogenomic analysis of study isolates revealed three clades with pairwise genetic distances ranging from 0 to 135 single-nucleotide polymorphisms (SNPs). Compared to a reference environmental outbreak isolate, all seven clinical outbreak isolates and the remaining three environmental isolates had highly similar core and accessory genomes, differing by up to 7 SNPs and a median of 1.6% accessory genes, respectively. Although genomic comparisons of 15 nonoutbreak clinical isolates revealed greater heterogeneity, five (33%) isolates had fewer than 20 SNPs compared to the reference environmental isolate, including two unrelated outside laboratory isolates with less than 4% accessory genome variation. Detailed genomic comparisons confirmed environmental acquisition of outbreak isolates of M. abscessus subsp. abscessus. SNP distances alone, however, did not clearly differentiate the mechanism of acquisition of outbreak versus nonoutbreak isolates. We conclude that successful investigation of M. abscessus subsp. abscessus clusters requires molecular and epidemiologic components, ideally complemented by environmental sampling.

RationaleMycobacterium avium complex, is the most common nontuberculous mycobacterial respiratory pathogen in humans. Disease mechanisms are poorly understood due to the absence of a reliable animal model for M. avium complex pulmonary disease.ObjectiveAssess the susceptibility, immunologic and histopathologic responses of the common marmoset (Callithrix jacchus) to M. avium complex pulmonary infection.Methods7 adult female marmosets underwent endobronchial inoculation with 108 colony-forming units of M. intracellulare and were monitored for 30 or 60 days. Prior to infection, chest radiograph and serum cytokines were assessed; serum cytokines were also monitored weekly for 30 days. At sacrifice 30 days (3 animals) or 60 days (4 animals) after infection, chest radiograph, serum and bronchoalveolar lavage cytokines, histopathology, and cultures of the bronchoalveolar lavage, lungs, liver, and kidney were analyzed.Measurements and Main ResultsFive of seven animals (two at 30 days and three at 60 days of infection) had positive lung cultures for M. intracellulare. Extra-pulmonary cultures were positive in three animals. All animals appeared healthy throughout the study. All five animals with positive lung cultures had radiographic changes consistent with pneumonitis. At 30 days, those with M. intracellulare lung infection showed granulomatous inflammation while at 60 days there was less inflammatory change, but bronchiectasis was noted. The cytokine response in the bronchoalveolar lavage fluid was uniformly greater in the animals with positive M. intracellulare cultures than those without a productive infection with greater levels at 30-days compared to 60-days. Similarly, serum cytokines were more elevated in the animals that had positive M. intracellulare cultures compared to those without a productive infection, peaking 14-21 days after inoculation.ConclusionEndobronchial instillation of M. intracellulare resulted in pulmonary mycobacterial infection in marmosets with a differential immune response, radiographic and histopathologic abnormalities, and an indolent course consistent with M. avium complex lung infection in humans.

Nontuberculous mycobacteria (NTM) infection is common in patients with structural lung damage. To address how NTM infection is established and causes lung damage, we established an NTM mouse model by intranasal inoculation of clinical isolates ofM.intracellulare. During the 39-week course of infection, the bacteria persistently grew in the lung and caused progressive granulomatous and fibrotic lung damage with mortality exceeding 50%. Lung neutrophils were significantly increased at 1 week postinfection, reduced at 2 weeks postinfection and increased again at 39 weeks postinfection. IL-17A was increased in the lungs at 1–2 weeks of infection and reduced at 3 weeks postinfection. Depletion of neutrophils during early (0–2 weeks) and late (32–34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. However, neutralization of IL-17A during early infection significantly reduced bacterial burden, fibrotic lung damage, and mortality in chronically infected mice. Since it is known that IL-17A regulates matrix metalloproteinases (MMPs) and that MMPs contribute to the pathogenesis of pulmonary fibrosis, we determined the levels of MMPs in the lungs ofM.intracellulare-infected mice. Interestingly, MMP-3 was significantly reduced by anti-IL-17A neutralizing antibody. Moreover,in vitrodata showed that exogenous IL-17A exaggerated the production of MMP-3 by lung epithelial cells uponM.intracellulareinfection. Collectively, our findings suggest that early IL-17A production precedes and promotes organized pulmonaryM.intracellulareinfection in mice, at least in part through MMP-3 production.

Nontuberculous mycobacterial (NTM) infections are increasing globally. Mycobacterium avium complex (MAC) and M. abscessus complex are the most commonly reported NTM. Oral treatment options are limited, especially for the M. abscessus complex. We tested delafloxacin, a new oral fluoroquinolone, against 131 isolates of NTM. Delafloxacin microdilution MICs were performed as recommended by the Clinical and Laboratory Standards Institute using cation adjusted Mueller-Hinton broth. The rapidly growing mycobacteria tested included M. abscessus subsp. abscessus (n = 16) and subsp. massiliense (n = 5), M. chelonae (n = 11), M. immunogenum (n = 5), M. fortuitum group (n = 13), M. porcinum (n = 7), M. senegalense (n = 7), M. mucogenicum group (n = 5), and M. goodii (n = 1). For the slowly growing NTM (SGM), M. avium (n = 16), M. intracellulare (n = 13), M. chimaera (n = 9), M. arupense (n = 5), M. simiae (n = 5), M. lentiflavum (n = 4), M. kansasii (n = 6), and M. marinum (n = 3) were tested. Delafloxacin was most active in vitro against the M. fortuitum and M. mucogenicum groups and M. kansasii, with MIC50 values of 0.12 to 0.5 μg/ml (MIC range, 0.001 to 4 μg/ml) compared to ≤0.06 to >4 μg/ml for ciprofloxacin and ≤0.06 to >8 μg/ml for moxifloxacin. For other SGM (including MAC), and the M. abscessus/M. chelonae, the delafloxacin MIC range was 8 to >16 μg/ml compared to ciprofloxacin and moxifloxacin of 0.5 to >4 μg/ml and ≤0.06 to 8 μg/ml, respectively. To our knowledge, this is the first MIC study with delafloxacin to use Clinical and Laboratory Standards Institute (CLSI) recommended methods. This study illustrates the potential utility of delafloxacin in treatment of infections due to some NTM.

Objectives This multicenter study’s aim was to assess the performance of two commercially available matrix-assisted laser desorption/ionization time of flight mass spectrometry systems in identifying a challenge collection of clinically relevant nontuberculous mycobacteria (NTM). Methods NTM clinical isolates (n = 244) belonging to 23 species/subspecies were identified by gene sequencing and analyzed using Bruker Biotyper with Mycobacterial Library v5.0.0 and bioMérieux VITEK MS with v3.0 database. Results Using the Bruker or bioMérieux systems, 92% and 95% of NTM strains, respectively, were identified at least to the complex/group level; 62% and 57%, respectively, were identified to the highest taxonomic level. Differentiation between members of Mycobacterium abscessus, M fortuitum, M mucogenicum, M avium, and M terrae complexes/groups was problematic for both systems, as was identification of M chelonae for the Bruker system. Conclusions Both systems identified most NTM isolates to the group/complex level, and many to the highest taxonomic level. Performance was comparable.

Nontuberculous mycobacterial (NTM) infections are increasing globally. Mycobacterium avium complex (MAC) and M. abscessus complex are the most commonly reported NTM. Oral treatment options are limited, especially for the M. abscessus complex. We tested delafloxacin, a new oral fluoroquinolone, against 131 isolates of NTM. Delafloxacin microdilution MICs were performed as recommended by the Clinical and Laboratory Standards Institute using cation adjusted Mueller-Hinton broth. The rapidly growing mycobacteria tested included M. abscessus subsp. abscessus (n = 16) and subsp. massiliense (n = 5), M. chelonae (n = 11), M. immunogenum (n = 5), M. fortuitum group (n = 13), M. porcinum (n = 7), M. senegalense (n = 7), M. mucogenicum group (n = 5), and M. goodii (n = 1). For the slowly growing NTM (SGM), M. avium (n = 16), M. intracellulare (n = 13), M. chimaera (n = 9), M. arupense (n = 5), M. simiae (n = 5), M. lentiflavum (n = 4), M. kansasii (n = 6), and M. marinum (n = 3) were tested. Delafloxacin was most active in vitro against the M. fortuitum and M. mucogenicum groups and M. kansasii, with MIC(50) values of 0.12 to 0.5 μg/ml (MIC range, 0.001 to 4 μg/ml) compared to ≤0.06 to >4 μg/ml for ciprofloxacin and ≤0.06 to >8 μg/ml for moxifloxacin. For other SGM (including MAC), and the M. abscessus/M. chelonae, the delafloxacin MIC range was 8 to >16 μg/ml compared to ciprofloxacin and moxifloxacin of 0.5 to >4 μg/ml and ≤0.06 to 8 μg/ml, respectively. To our knowledge, this is the first MIC study with delafloxacin to use Clinical and Laboratory Standards Institute (CLSI) recommended methods. This study illustrates the potential utility of delafloxacin in treatment of infections due to some NTM.

Infections caused by nontuberculous mycobacteria (NTM) are increasing globally. Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex are the most frequently encountered NTM, and oral treatment options are extremely limited for these pathogens, especially for the M. abscessus complex. In this study, the in vitro potency of omadacycline, a new tetracycline derivative, was tested against 111 isolates of NTM. MIC testing was performed as recommended by the Clinical and Laboratory Standards Institute against 70 isolates of rapidly growing mycobacteria (RGM), of which >90% were tetracycline resistant. These included M. abscessus subsp. abscessus (20 isolates), M. abscessus subsp. massiliense (3), Mycobacterium chelonae (15 isolates), Mycobacterium immunogenum (7 isolates), the Mycobacterium fortuitum group, including six doxycycline-resistant isolates (12 isolates), and the Mycobacterium mucogenicum group, including four doxycycline-resistant isolates (10 isolates). Forty-one isolates of slowly growing mycobacteria (SGM), including 16 isolates of MAC, were also tested. Omadacycline was active against all RGM species, with MIC(50) ranges of 0.004 to 0.25 and 0.06 to 1 μg/ml for 80% and 100% inhibition, respectively. For M. abscessus subsp. abscessus, MIC(50)s were 0.06 and 0.12 μg/ml with 80% and 100% inhibition, respectively. There was considerable trailing of the omadacycline endpoint with the RGM. MICs of tigecycline exhibited no trailing and were generally within 1 to 2 dilutions of the 100% inhibition omadacycline MICs. While there was no trailing observed in SGM, omadacycline MICs were higher (MIC range, 8 to >16 μg/ml; n = 41), as previously noted with tigecycline. This study supports further research of omadacycline, including clinical trials, for the treatment of RGM infections, especially M. abscessus.

Contains fulltext : 238192.pdf (Publisher’s version ) (Open Access) Rationale: Patients with refractory Mycobacterium avium complex (MAC) lung disease have limited treatment options. In the CONVERT study, amikacin liposome inhalation suspension (ALIS) added to guideline-based therapy (GBT) increased culture conversion rates versus GBT alone by Month 6. Limited data are available regarding >6-month treatment in a refractory population.Objectives: Evaluate 12-month safety, tolerability, and efficacy of ALIS+GBT.Methods: Adults with refractory MAC lung disease not achieving culture conversion by CONVERT Month 6 could enroll in this open-label extension (INS-312) to receive 590 mg once-daily ALIS+GBT for 12 months. Two cohorts enrolled: the "ALIS-naive" cohort included patients randomized to GBT alone in CONVERT, and the "prior-ALIS" cohort included those randomized to ALIS+GBT in CONVERT. Safety and tolerability of ALIS over 12 months (primary endpoint) and culture conversion by Months 6 and 12 were assessed.Results: In the ALIS-naive cohort, 83.3% of patients (n = 75/90) experienced respiratory treatment-emergent adverse events (TEAEs), and 35.6% (n = 32) had serious TEAEs; 26.7% (n = 24) achieved culture conversion by Month 6 and 33.3% (n = 30) by Month 12. In the prior-ALIS cohort, 46.6% of patients (n = 34/73) experienced respiratory TEAEs, and 27.4% (n = 20) had serious TEAEs; 9.6% (n = 7) achieved culture conversion by Month 6 (≤14 mo ALIS exposure) and 13.7% (n = 10) by Month 12 (≤20 mo ALIS exposure). Nephrotoxicity-related TEAEs and measured hearing decline were infrequent in both cohorts.Conclusions: In up to 20 months of ALIS use, respiratory TEAEs were common, nephrotoxicity and hearing decline were infrequent, and culture conversion continued beyond 6 months of therapy.Clinical trial registered with www.clinicaltrials.gov (NCT02628600).

In the CONVERT study, treatment with amikacin liposome inhalation suspension (ALIS) added to guideline-based therapy (GBT) met the primary end point of increased culture conversion by month 6 in patients with treatment-refractory Mycobacterium avium complex lung disease (ALIS plus GBT, 29% [65/224] vs GBT alone, 8.9% [10/112]; P .0001).In patients who achieved culture conversion by month 6 in the CONVERT study, was conversion sustained (negative sputum culture results for 12 months with treatment) and durable (negative sputum culture results for 3 months after treatment) and were there any additional safety signals associated with a full treatment course of 12 months after conversion?Adults were randomized 2:1 to receive ALIS plus GBT or GBT alone. Patients achieving culture conversion by month 6 continued therapy for 12 months followed by off-treatment observation.More patients randomized to ALIS plus GBT (intention-to-treat population) achieved conversion that was both sustained and durable 3 months after treatment vs patients randomized to GBT alone (ALIS plus GBT, 16.1% [36/224] vs GBT alone, 0% [0/112]; P .0001). Of the patients who achieved culture conversion by month 6, 55.4% of converters (36/65) in the ALIS plus GBT treated arm vs no converters (0/10) in the GBT alone arm achieved sustained and durable conversion (P = .0017). Relapse rates through 3 months after treatment were 9.2% (6/65) in the ALIS plus GBT arm and 30.0% (3/10) in the GBT alone arm. Common adverse events among ALIS plus GBT-treated patients (dysphonia, cough, dyspnea, hemoptysis) occurred mainly within the first 8 months of treatment.In a refractory population, conversion was sustained and durable in more patients treated with ALIS plus GBT for 12 months after conversion than in those treated with GBT alone. No new safety signals were associated with 12 months of treatment after conversion.ClinicalTrials.gov; No.: NCT02344004; URL: www.clinicaltrials.gov.

Rationale: Patients with refractory Mycobacterium avium complex (MAC) lung disease have limited treatment options. In the CONVERT study, amikacin liposome inhalation suspension (ALIS) added to guideline-based therapy (GBT) increased culture conversion rates versus GBT alone by Month 6. Limited data are available regarding >6-month treatment in a refractory population. Objectives: Evaluate 12-month safety, tolerability, and efficacy of ALIS+GBT. Methods: Adults with refractory MAC lung disease not achieving culture conversion by CONVERT Month 6 could enroll in this open-label extension (INS-312) to receive 590 mg once-daily ALIS+GBT for 12 months. Two cohorts enrolled: the “ALIS-naive” cohort included patients randomized to GBT alone in CONVERT, and the “prior-ALIS” cohort included those randomized to ALIS+GBT in CONVERT. Safety and tolerability of ALIS over 12 months (primary endpoint) and culture conversion by Months 6 and 12 were assessed. Results: In the ALIS-naive cohort, 83.3% of patients (n = 75/90) experienced respiratory treatment-emergent adverse events (TEAEs), and 35.6% (n = 32) had serious TEAEs; 26.7% (n = 24) achieved culture conversion by Month 6 and 33.3% (n = 30) by Month 12. In the prior-ALIS cohort, 46.6% of patients (n = 34/73) experienced respiratory TEAEs, and 27.4% (n = 20) had serious TEAEs; 9.6% (n = 7) achieved culture conversion by Month 6 (≤14 mo ALIS exposure) and 13.7% (n = 10) by Month 12 (≤20 mo ALIS exposure). Nephrotoxicity-related TEAEs and measured hearing decline were infrequent in both cohorts. Conclusions: In up to 20 months of ALIS use, respiratory TEAEs were common, nephrotoxicity and hearing decline were infrequent, and culture conversion continued beyond 6 months of therapy. Clinical trial registered with www.clinicaltrials.gov (NCT02628600).

A previously undescribed, rapidly growing, scotochromogenic species of the genus Mycobacterium (represented by strains PB739T and GK) was isolated from two clinical sources – the sputum of a 76-year-old patient with severe chronic obstructive pulmonary disease, history of tuberculosis exposure and Mycobacterium avium complex isolated years prior; and the blood of a 15-year-old male with B-cell acute lymphoblastic leukaemia status post bone marrow transplant. The isolates grew as dark orange colonies at 25–37 °C after 5 days, sharing features in common with other closely related species. Analysis of the complete 16S rRNA gene sequence (1492 bp) of strain PB739T demonstrated that the isolate shared 98.8 % relatedness with Mycobacterium wolinskyi . Partial 429 bp hsp65 and 744 bp rpoB region V sequence analyses revealed that the sequences of the novel isolate shared 94.8 and 92.1 % similarity with those of Mycobacterium neoaurum and Mycobacterium aurum , respectively. Biochemical profiling, antimicrobial susceptibility testing, HPLC/gas-liquid chromatography analyses and multilocus sequence typing support the taxonomic status of these isolates (PB739T and GK) as representatives of a novel species. Both isolates were susceptible to the Clinical and Laboratory Standards Institute recommended antimicrobials for susceptibility testing of rapidly growing mycobacteria including amikacin, ciprofloxacin, moxifloxacin, doxycycline/minocycline, imipenem, linezolid, clarithromycin and trimethropin/sulfamethoxazole. Both isolates PB739T and GK showed intermediate susceptibility to cefoxitin. We propose the name Mycobacterium grossiae sp. nov. for this novel species and have deposited the type strain in the DSMZ and CIP culture collections. The type strain is PB739T (=DSM 104744T=CIP 111318T).

We identified a pseudo-outbreak of Mycobacterium avium in an outpatient bronchoscopy clinic following an increase in clinic procedure volume. We terminated the pseudo-outbreak by increasing the frequency of automated endoscope reprocessors (AER) filter changes from quarterly to monthly. Filter changing schedules should depend on use rather than fixed time intervals.

Lengthy, multidrug, toxic, and low-efficacy regimens limit management of pulmonary nontuberculous mycobacterial disease.In this phase II study, we investigated the efficacy and safety of liposomal amikacin for inhalation (LAI) in treatment-refractory pulmonary nontuberculous mycobacterial (Mycobacterium avium complex [MAC] or Mycobacterium abscessus) disease.During the double-blind phase, patients were randomly assigned to LAI (590 mg) or placebo once daily added to their multidrug regimen for 84 days. Both groups could receive open-label LAI for 84 additional days. The primary endpoint was change from baseline to Day 84 on a semiquantitative mycobacterial growth scale. Other endpoints included sputum conversion, 6-minute-walk distance, and adverse events.The modified intention-to-treat population included 89 (LAI = 44; placebo = 45) patients. The average age of the sample was 59 years; 88% were female; 92% were white; and 80 and 59 patients completed study drug dosing during the double-blind and open-label phases, respectively. The primary endpoint was not achieved (P = 0.072); however, a greater proportion of the LAI group demonstrated at least one negative sputum culture (14 [32%] of 44 vs. 4 [9%] of 45; P = 0.006) and improvement in 6-minute-walk test (+20.6 m vs. -25.0 m; P = 0.017) at Day 84. A treatment effect was seen predominantly in patients without cystic fibrosis with MAC and was sustained 1 year after LAI. Most adverse events were respiratory, and in some patients it led to drug discontinuation.Although the primary endpoint was not reached, LAI added to a multidrug regimen produced improvements in sputum conversion and 6-minute-walk distance versus placebo with limited systemic toxicity in patients with refractory MAC lung disease. Further research in this area is needed. Clinical trial registered with www.clinicaltrials.gov (NCT01315236).

// Julie V. Philley 1 , Anbarasu Kannan 2 , David E. Griffith 1 , Megan S. Devine 1 , Jeana L. Benwill 1 , Richard J. Wallace, Jr. 1, 3 , Barbara A. Brown-Elliott 3 , Foram Thakkar 1 , Varsha Taskar 1 , James G. Fox 1 , Ammar Alqaid 1 , Hernaina Bains 1 , Sudeep Gupta 4 , Santanu Dasgupta 2 1 Departments of Medicine, The University of Texas Health Science Center at Tyler, Texas, USA 2 Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Texas, USA 3 The Mycobacteria/Nocardia Research Laboratory Department of Microbiology, The University of Texas Health Science Center at Tyler, Texas, USA 4 Medical Oncology, Tata Memorial Center, Mumbai, India Correspondence to: Santanu Dasgupta, email: santanu.dasgupta@uthct.edu Keywords: Exosomes, breast cancer, nontuberculous Mycobacterium, ECM1, biomarker Received: July 10, 2016 Accepted: January 10, 2017 Published: February 01, 2017 ABSTRACT Bronchiectasis Nontuberculous mycobacterium (NTM nb ) infection is an emerging health problem in breast cancer (BCa) patients. We measured sera exosome proteome in BCa-NTM nb subjects and controls by Mass Spectroscopy. Extracellular matrix protein 1 (ECM1) was detected exclusively in the circulating exosomes of 82% of the BCa-NTM nb cases. Co-culture of ECM1 + exosomes with normal human mammary epithelial cells induced epithelial to mesenchymal transition accompanied by increased Vimentin/CDH1 expression ratio and Glutamate production. Co-culture of the ECM1 + exosomes with normal human T cells modulated their cytokine production. The ECM1 + exosomes were markedly higher in sera obtained from BCa-NTM nb subjects. Exclusive expression of APN, APOC4 and AZGP1 was evident in the circulating exosomes of these BCa-NTM nb cases, which predicts disease prevalence independent of the body max index in concert with ECM1. Monitoring ECM1, APN, APOC4 and AZGP1 in the circulating exosomes could be beneficial for risk assessment, monitoring and surveillance of BCa-NTM nb .

SESSION TITLE: Respiratory Infections: What have We Learned About COVID-19 and New Trial Data for Management of Aspergilloma SESSION TYPE: Original Investigations PRESENTED ON: October 18-21, 2020 PURPOSE: To describe clinical characteristics of U S patients with pulmonary Mycobacterium avium complex (PMAC) whose sputum cultures were identified by gene sequence as M chimaera To highlight importance of MAC species identification (ID) following clinically focused assessment of PMAC patients METHODS: From 2013-2019, sputum samples from 89 patients seen at the University of Texas Health Science Center at Tyler (UTHSCT) underwent processing for smear and culture of mycobacteria with species ID using partial 16S rRNA gene and ITS sequencing at first visit and at a minimum every 6 months thereafter Clinical information was extracted from medical records Microbiological significance of M chimaera was assessed based on semi-quantitative colony count, smear positivity, and presence of the organism in broth only, broth and solid culture, and number of positive cultures Clinical significance was based on symptoms, lung function and radiographic features PMAC was defined according to 2007 ATS/IDSA criteria RESULTS: M chimaera was grown in 146 cultures from 89 patients The mean patient age was 70 4 +/-10 3 years and 69% were women The mean FEV1 percent predicted was 64% (SD, 24%) Only 4 patients were current tobacco smokers, 39% (35/89) patients had a history of >10 pack years M chimaera was associated with cavitary disease in 22% (20/89) patients and nodular bronchiectasis disease in 78% (69/89) of patients Of the patients with nodular bronchiectasis, 35% (24/69) had multiple samples yielding M chimaera A single positive culture of the species occurred in 63% (56/89) of patients Only 14% (20/146) cultures of M chimaera had positive AFB smears and only 65/146 (45%) of total cultures were positive on solid media while 79/146 (54%) were positive in broth only Isolates that were AFB smear negative and associated with a single positive culture grown only in broth did not meet ATS/IDSA guidelines for PMAC disease and therefore did not require therapy CONCLUSIONS: This is the first large study of pulmonary M chimaera in the U S PMAC infection with M chimaera manifests as a variable clinical picture in patients Identification of MAC species level ID is essential to understand the significance and pathogenicity of M chimaera CLINICAL IMPLICATIONS: ATS/IDSA criteria for PMAC disease was written in the context of M avium and M intracellulare infection These criteria may not be applicable for other MAC species ID of MAC isolates to the species level is an integral step in appropriate management of patients with sputum that grows M chimaera DISCLOSURES: Laboratory Research Grant relationship with Insmed Please note: >$100000 Added 06/01/2020 by Barbara Brown-Elliott, source=Admin input, value=Grant/Research Support Advisory Committee Member relationship with Insmed Inc Please note: $1001 - $5000 Added 06/12/2020 by David Griffith, source=Web Response, value=Consulting fee Consultant relationship with Insmed Inc Please note: >$100000 Added 06/12/2020 by David Griffith, source=Web Response, value=Grant/Research Support Consultant relationship with Insmed Inc Please note: $5001 - $20000 Added 06/12/2020 by David Griffith, source=Web Response, value=Consulting fee No relevant relationships by ELENA IAKHIAEVA, source=Web Response No relevant relationships by Pamela McShane, source=Web Response Consultant relationship with INSMED Please note: $1-$1000 by Julie Philley, source=Web Response, value=Honoraria Advisory Committee Member relationship with Janseen Please note: $1-$1000 by Julie Philley, source=Web Response, value=Honoraria Advisory Committee Member relationship with INSMED Please note: $1001 - $5000 by Julie Philley, source=Web Response, value=Consulting fee No relevant relationships by Carly Sigler, source=Web Response No relevant relationships by Sruthi Vasireddy, source=Web Response grant for labor tory study of arikace relationship with Insmed Please note: >$100000 Added 06/02/2020 by Richard Wallace, source=Web Response, value=grant to support lab work

BACKGROUND Actinomycetoma caused by Nocardia usually responds well to antibiotics. Emerging species of Nocardia, such as N. wallacei, can be a therapeutic challenge. AIMS Confirm the therapeutic effectivity of linezolid in multidrug resistant Nocardia Wallacei actinomycetoma. MATERIALS AND METHODS We evaluated the medical management of an 18-year-old man with multidrug resistant actinomycetoma of the left leg caused by N. transvalensis complex treated 17 years ago with linezolid 1200 mg a day. This bacteria was recently reclassified as Nocardia Wallacei by specific molecular biology technique. RESULTS The infection was cured after 3 months of treatment; the patient remained asymptomatic for the past 17 years. No adverse effects were found. DISCUSSION Frequently, strains of N. transvalensis complex have aminoglycoside resistance; in this case, we highlight the effectiveness of linezolid for the successful medical management of multidrug resistant actinomycetoma. CONCLUSION Linezolid can be an alternative for the treatment of multidrug resistant Nocardia Wallacei.

Recommendations for first-line and second-line drug testing and organism group, specific methodologies, and reporting recommendations have been addressed by the Clinical and Laboratory Standards Institute (CLSI) and are important in the selection of appropriate antimicrobial treatment regimens for nontuberculous mycobacteria (NTM) disease. This review also includes recent information on new antimicrobials proposed for the treatment of NTM but not yet addressed by the CLSI and molecular (gene sequencing) methods associated with the detection of antimicrobial resistance of two major therapeutic antimicrobials, clarithromycin and amikacin.

This single center study assessed the performance of a novel solid rapidly-growing mycobacteria (RGM) medium for the recovery of nontuberculous mycobacteria (NTM), especially Mycobacterium abscessus complex, in patients with underlying bronchiectasis. A total of 297 mycobacterial sputa from 116 patients were plated directly on RGM medium and, following decontamination, onto an agar biplate [Middlebrook 7H11 and Mitchison (selective) agar] and into broth media (VersaTrek). The recovery of M. abscessus complex was increased by approximately 12% by implementation of the RGM medium. Contamination was reduced to 2% from 48% and 95% on routine solid media and broth cultures respectively. Our study corroborated previous studies in that recovery of M. abscessus complex was enhanced and contamination was virtually eliminated without the need for specimen decontamination when utilizing RGM medium.

Mycobacterium chelonae is a member of the Mycobacterium chelonae-abscessus complex and a cause of opportunistic disease in fish, reptiles, birds, and mammals including humans. Isolates in the complex are often difficult to identify and have differing antimicrobial susceptibilities. Thirty-one previously identified rapidly-growing, non-tuberculous Mycobacterium sp. isolates cultured from biofilms, fish, reptiles, mammals, including humans, and three ATCC reference strains were evaluated with nine M. chelonae-abscessus complex whole genome sequences from GenBank by phylogenomic analysis, targeted gene comparisons, and in-vitro antimicrobial susceptibility patterns to assess strain variation among isolates from different sources. Results revealed minimal genetic variation among the M. chelonae strains. However, the core genomic alignment and SNP pattern of the complete 16S rRNA sequence clearly separated the turtle type strain ATCC 35752T from the clinical isolates and human reference strain "M. chelonae chemovar niacinogenes" ATCC 19237, providing evidence of two distinct subspecies. Concatenation of the partial rpoB (752 bp) and complete hsp65 (1,626 bp) sequence produced the same species/subspecies delineations as the core phylogeny. Partial rpoB and hsp65 sequences identified all the clinical isolates to the appropriate species level when respective cut-offs of 98% and 98.4% identity to the M. chelonae type strain ATCC 35752T were employed. The human strain, ATCC19237, was the most representative strain for the evaluated human, veterinary, and environmental strains. Additionally, two isolates were identified as Mycobacterium saopaulense, its first identification in a non-fish or non-human host.

A new name for most Mycobacterium species has been recently proposed. According to taxonomic rules novel and previous nomenclature coexist and are synonyms. The use of the latter has the advantage of avoiding confusion for healthcare and harm for patients.http://bit.ly/2XhTACc

Mycobacterium terrae complex has been recognized as a cause of tenosynovitis, with M. terrae and Mycobacterium nonchromogenicum reported as the primary etiologic pathogens. The molecular taxonomy of the M. terrae complex causing tenosynovitis has not been established despite approximately 50 previously reported cases. We evaluated 26 isolates of the M. terrae complex associated with tenosynovitis or osteomyelitis recovered between 1984 and 2014 from 13 states, including 5 isolates reported in 1991 as M. nonchromogenicum by nonmolecular methods. The isolates belonged to three validated species, one new proposed species, and two novel related strains. The majority of isolates (20/26, or 77%) belonged to two recently described species: Mycobacterium arupense (10 isolates, or 38%) and Mycobacterium heraklionense (10 isolates, or 38%). Three isolates (12%) had 100% sequence identity to each other by 16S rRNA and 99.3 to 100% identity by rpoB gene region V sequencing and represent a previously undescribed species within the M. terrae complex. There were no isolates of M. terrae or M. nonchromogenicum , including among the five isolates reported in 1991. The 26 isolates were susceptible to clarithromycin (100%), rifabutin (100%), ethambutol (92%), and sulfamethoxazole or trimethoprim-sulfamethoxazole (70%). The current study suggests that M. arupense , M. heraklionense , and a newly proposed species (“ M. virginiense ” sp. nov.; proposed type strain MO-233 [DSM 100883, CIP 110918]) within the M. terrae complex are the major causes of tenosynovitis and osteomyelitis in the United States, with little change over 20 years. Species identification within this complex requires sequencing methods.

Mycobacterium avium complex (MAC), which includes M. avium and M. intracellulare, is widely distributed in the environment, and exposure to these organisms is inevitable. Despite widespread exposure, the disease is unusual in immunocompetent hosts. During the past two decades, MAC represents a common cause of progressive pulmonary disease in the United States. To gain insight into the immunologic factors that predispose persons to MAC infections, we evaluated the immune responses of HIV negative (-) MAC patients with pulmonary diseases in comparison to their healthy HIV− household contacts (HHCs). Whole blood from 20 pairs of HIV− MAC patients and healthy HHCs was immunolabeled, and the percentages of various immune cell populations were determined by flow cytometry. Among various cell types, MAC patients have significantly lower ratio of monocytes compared to healthy HHCs. In 11 pairs of HIV− MAC patients and healthy HHCs, peripheral blood mononuclear cells (PBMC) of MAC patients produced lower levels of interleukin (IL)-10 and IL-1 family (IL-1β, IL-18, IL-1α) out of 34 cytokines and chemokines measured by multiplex ELISA upon MAC stimulation, compared with that of healthy HHCs. In two MAC patients, PBMC restricted MAC growth less efficiently compared with their healthy HHCs despite there was no deficiency in restricting MAC growth by monocyte derived macrophages of six MAC patients. Our findings suggest that the interactions among various immune cells are required for efficient clearance of MAC by macrophages in MAC patients. Studies are underway to pinpoint the nature of defective immune responses that prevents efficient clearance of MAC by macrophages of MAC patients.

This chapter discusses principles and methods for the laboratory identification of nontuberculous mycobacteria (NTM) beginning with biochemical and chemotaxonomic methods [high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC), and gas-liquid chromatography (GLC)] which have widely been replaced by the more definitive molecular methods including commercial probe technology, gene sequencing, and more recently mass spectrometry (MS) using the matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF). The MALDI-TOF-MS currently remains non-validated or beyond the capability of many clinical laboratories to implement into the NTM identification algorithm. As with all molecular methodologies, the creation and maintenance of adequate databases are critical to the success of implementation of these techniques. Notably, only limited gene sequencing (i.e., 16S rRNA gene) has been addressed by the Clinical and Laboratory Standards Institute (CLSI), and strict cutoff values for other genes are currently not available.

Outbreaks and pseudo-outbreaks of nontuberculous mycobacteria (NTM) have been increasingly reported worldwide. NTM thrive throughout the environment. They are commonly found in municipal and hospital water systems including hot water and chlorinated systems and cause various types of opportunistic infections in both immunocompetent and immunocompromised individuals. Most of these infectious outbreaks have exposure to water or water-based solutions as the common denominator. This chapter reviews many of the published NTM outbreaks and pseudo-outbreaks and seeks to provide guidance to the clinician and laboratory on when to suspect an NTM outbreak or pseudo-outbreak. Surveillance and control measures to prevent and mitigate these outbreaks are also described.

Item does not contain fulltext Nontuberculous mycobacteria, particularly the Mycobacterium avium complex (MAC) bacteria, are increasingly recognized as opportunistic pathogens of humans. As a result, studies on antibiotic treatment and taxonomy of the MAC are intensifying, but an updated definition of what constitutes the MAC, either for taxonomical studies or for clinical purposes, is lacking. On the basis of literature review and phylogenetic analyses, we propose to define the MAC as a grouping of slow-growing mycobacteria that show corresponding values in at least two of the following targets against either M. avium ATCC 25291(T) or Mycobacterium intracellulare ATCC 13950(T): >99.4 % sequence identity for the full 16S rRNA gene, >98.7 % for the partial (5') 16S rRNA gene, >97.3 % for hsp65 and >94.4 % for rpoB region V. A >97.5 % value in concatenated analyses of >2500 bp that includes 16S rRNA, hsp65 and rpoB gene sequence data or >/=85 % average nucleotide identity to M. avium ATCC 25291(T) or M. intracellulare ATCC 13950(T) on basis of whole genome sequencing data is recommended. This molecular definition is based on the distances observed between the classical members of the MAC, M. avium and M. intracellulare. Applying this definition, the complex currently consists of 12 validly published species: Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium chimaera, Mycobacterium colombiense, Mycobacterium arosiense, Mycobacterium vulneris, Mycobacterium bouchedurhonense, Mycobacterium timonense, Mycobacterium marseillense, Mycobacterium yongonense, Mycobacterium paraintracellulare and Mycobacterium lepraemurium.

Two mycobacterial strains with close similarity to the Mycobacterium tuberculosis complex (MTBC) were isolated from cutaneous lesions of patients in the USA and Italy. At the phenotypic level, similarities to the MTBC included slow growth rate, rough morphotype of the unpigmented colonies and nearly identical high-performance liquid chromatography profiles of mycolic acids. In contrast to the MTBC, the strains were niacin- and nitrate-negative, and catalase-positive both at 68 °C and in semi-quantitative tests. The clinical isolates were more closely related to M. tuberculosis than to any other known mycobacterium and scored positive with commercial DNA probes (Hologic AccuProbe M. tuberculosis ). Both average nucleotide identity and genome-to-genome distance suggested the strains are different from the MTBC. Therefore, given the distinguishing phenotypic and genomic-scale differences, we submit that the strains belong to a new species we have named Mycobacterium decipiens with type strain TBL 1200985T (=ATCC TSD-117T=DSM 105360T).

Nontuberculous mycobacterial lung disease (NTM), including Mycobacterium avium complex (MAC), is a growing health problem in North America and worldwide. Little is known about the molecular alterations occurring in the tissue microenvironment during NTM pathogenesis. Utilizing next generation sequencing, we sequenced sputum and matched lymphocyte DNA in 15 MAC patients for a panel of 19 genes known to harbor cancer susceptibility associated mutations. Thirteen of 15 NTM subjects had a diagnosis of breast cancer (BCa) before or after NTM infection. Thirty three percent (4/12) of these NTM-BCa cases exhibited at least 3 somatic mutations in sputa compared to matched lymphocytes. Twenty four somatic mutations were detected with at least one mutation in ATM, ERBB2, BARD1, BRCA1, BRCA2, AR, TP53, PALB2, CASP8, BRIP1, NBN and TGFB1 genes. All four NTM-BCa patients harboring somatic mutations also exhibited 15 germ line BRCA1 and BRCA2 mutations. The two NTM subjects without BCa exhibited twenty somatic mutations spanning BRCA1, BRCA1, BARD1, BRIP1, CHEK2, ERBB2, TP53, ATM, PALB2, TGFB1 and 3 germ line mutations in BRCA1 and BRCA2 genes. A single copy loss of STK11 and AR gene was noted in NTM-BCa subjects. Periodic screening of sputa may aid to develop risk assessment biomarkers for neoplastic diseases in NTM patients.

This multicenter study was designed to assess the accuracy and reproducibility of the Vitek MS v3.0 matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry system for identification of Mycobacterium and Nocardia species compared to DNA sequencing. A total of 963 clinical isolates representing 51 taxa were evaluated. In all, 663 isolates were correctly identified to the species level (69%), with another 231 (24%) correctly identified to the complex or group level. Fifty-five isolates (6%) could not be identified despite repeat testing. All of the tuberculous mycobacteria (45/45; 100%) and most of the nontuberculous mycobacteria (569/606; 94%) were correctly identified at least to the group or complex level. However, not all species or subspecies within the M. tuberculosis , M. abscessus , and M. avium complexes and within the M. fortuitum and M. mucogenicum groups could be differentiated. Among the 312 Nocardia isolates tested, 236 (76%) were correctly identified to the species level, with an additional 44 (14%) correctly identified to the complex level. Species within the N. nova and N. transvalensis complexes could not always be differentiated. Eleven percent of the isolates (103/963) underwent repeat testing in order to get a final result. Identification of a representative set of Mycobacterium and Nocardia species was highly reproducible, with 297 of 300 (99%) replicates correctly identified using multiple kit lots, instruments, analysts, and sites. These findings demonstrate that the system is robust and has utility for the routine identification of mycobacteria and Nocardia in clinical practice.

The accuracy and robustness of the Vitek MS v3.0 matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) system was evaluated by identifying mycobacteria from automated liquid-medium systems using patient samples. This is the first report to demonstrate that proteins within the liquid medium, its supplements, and decontamination reagents for nonsterile patient samples do not generate misidentification or false-positive results by use of the Vitek MS v3.0 system. Prior to testing with patient samples, a seeded-culture study was conducted to challenge the accuracy of the Vitek MS system at identifying mycobacteria from liquid medium by mimicking a clinical workflow. Seventy-seven Mycobacterium strains representing 21 species, seeded in simulated sputum, were decontaminated, inoculated into BacT/Alert MP liquid culture medium, incubated until positivity, and identified using the Vitek MS system. A total of 383 liquid cultures were tested, of which 379 (99%) were identified correctly to the species/complex/group level, 4 (1%) gave a "no-identification" result, and no misidentifications were observed. Following the simulated-sputum study, a total of 73 smear-positive liquid-medium cultures detected using BD BBL MGIT and VersaTREK Myco liquid media were identified by the Vitek MS system. Sixty-four cultures (87.7%) were correctly identified to the species/complex/group level; 7 (9.6%) resulted in no identification; and 2 (2.7%) were misidentified at the species level. These results indicate that the Vitek MS v3.0 system is an accurate tool for routine diagnostics of Mycobacterium species isolated from liquid cultures.

There is a paucity of efficacious antimicrobials (especially oral) against clinically relevant species of Nocardia . To date, all species of Nocardia have been susceptible to linezolid, the first commercially available oxazolidinone. Tedizolid is a new oxazolidinone with previously reported improved in vitro and in vivo (intracellular) potency against multidrug-resistant strains of Mycobacterium sp. and Nocardia brasiliensis . Using the current Clinical and Laboratory Standards Institute-recommended broth microdilution method, 101 isolates of Nocardia spp., including 29 Nocardia cyriacigeorgica , 17 Nocardia farcinica , 13 Nocardia nova complex, 21 Nocardia brasiliensis , 5 Nocardia pseudobrasiliensis , and 5 Nocardia wallacei isolates and 11 isolates of less common species, were tested for susceptibility to tedizolid and linezolid. For the most common clinically significant species of Nocardia , tedizolid MIC 50 values were 0.25 μg/ml for N. nova complex, N. brasiliensis , N. pseudobrasiliensis , and N. wallacei , compared to linezolid MIC 50 values of 1, 2, 0.5, and 1 μg/ml, respectively. Tedizolid and linezolid MIC 90 values were 2 μg/ml for N. nova complex and N. brasiliensis . Tedizolid MIC 50 and MIC 90 values for both N. cyriacigeorgica and N. farcinica were 0.5 μg/ml and 1 μg/ml, respectively, compared to linezolid MIC 50 and MIC 90 values of 2 and 4 μg/ml, respectively. Based on MIC 90 values, this study showed that tedizolid was 2- to 3-fold more active than linezolid in vitro against most common species of Nocardia , with the exception of the N. nova complex and N. brasiliensis , for which values were the same. These results may warrant evaluation of tedizolid as a potential treatment option for Nocardia infections.