In Vitro Synergistic Effects of Omadacycline with Other Antimicrobial Agents against Mycobacterium abscessus.

The clinical importance of Mycobacterium abscessus species (MABS) infections has been increasing. However, the standard treatment regimens recommended in the current guidelines often result in unfavorable outcomes. Therefore, we investigated the in vitro activity of omadacycline (OMC), a novel tetracycline, against MABS to explore its potential as a novel therapeutic option. The drug susceptibilities of 40 Mycobacterium abscessus subsp. abscessus (Mab) clinical strains obtained from the sputum of 40 patients from January 2005 to May 2014 were investigated. The MIC results for OMC, amikacin (AMK), clarithromycin (CLR), clofazimine (CLO), imipenem (IPM), rifabutin (RFB), and tedizolid (TZD) alone and their combined effects (with OMC) were examined using the checkerboard method. Additionally, we studied the differences in the effectiveness of the antibiotic combinations based on the colony morphotype of Mab. The MIC50 and MIC90 of OMC alone were 2 and 4 µg/mL, respectively. The combinations of OMC with AMK, CLR, CLO, IPM, RFB, and TZD showed synergy against 17.5%, 75.8%, 25.0%, 21.1%, 76.9%, and 34.4% of the strains, respectively. Additionally, OMC combined with CLO (47.1% versus 9.5%, P = 0.023) or TZD (60.0% versus 12.5%, P = 0.009) showed significantly higher synergy against strains with rough morphotypes than those with smooth morphotypes. In conclusion, the checkerboard analyses revealed that the synergistic effects of OMC were observed most frequently with RFB, followed by CLR, TZD, CLO, IPM, and AMK. Furthermore, OMC tended to be more effective against rough-morphotype Mab strains.

Isolation of Mycobacterium talmoniae from a patient with diffuse panbronchiolitis: a case report.

BACKGROUND: Mycobacterium (M) talmoniae isolated from a patient with cystic fibrosis was first described in 2017, and cases of M. talmoniae remain exceedingly rare. CASE PRESENTATION: A 51-year-old woman had respiratory symptoms for 10 years. Diffuse panbronchiolitis (DPB) was detected at the first visit at our hospital. A cavity lesion in the apex of the left lung was found, and sputum and bronchoalveolar lavage fluid were acid-fast bacillus (AFB) smear- and culture-positive besides Pseudomonas aeruginosa. M. talmoniae was finally identified, and the standard combination therapy for non-tuberculous mycobacteria (NTM) was administered for 2 y referring to the drug-susceptibility test. Thereafter, the AFB culture was negative, the wall thickness of the lung cavity was ameliorated, and oxygen saturation improved. CONCLUSIONS: We encountered a rare case of M. talmoniae with DPB, for which standard combination therapy was effective. M. talmoniae may be considered a potential pathogen of lung disease, especially in patients with bronchiectatic lesions.

Isolated splenic Mycobacterium tuberculosis complex infection in an immunocompetent individual with FDG-PET positive mass.

Tuberculosis, caused by Mycobacterium tuberculosis complex, is a leading cause of mortality in the world, and 15% of the patients may present with extrapulmonary diseases, including splenic lesion. However, isolated splenic infection with M. tuberculosis complex is very rare. A 19-year-old otherwise healthy woman presented with left flank pain, revealing FDG-avid nodules in the spleen. She did not have pulmonary lesions. Histopathology of splenectomized sample showed granuloma, and subsequent PCR revealed amplification of IS6110, a genetic sequence exclusively detected in M. tuberculosis complex. A wide range of differential diagnosis of isolated splenic lesion should include M. tuberculosis infection regardless of pulmonary involvement. An elective splenectomy may be mandatory in timely manner.

A solitary pulmonary nodule caused by Mycobacterium tuberculosis var. BCG after intravesical BCG treatment: a case report.

BACKGROUND: Intravesical instillation of bacillus Calmette-Guérin (BCG) as a treatment for superficial bladder cancer rarely causes pulmonary complications. While published cases have been pathologically characterized by multiple granulomatous lesions due to disseminated infection, no case presenting as a solitary pulmonary nodule has been reported. CASE PRESENTATION: A man in his 70 s was treated with intravesical BCG for early-stage bladder cancer. After 1 year, he complained of productive cough with a solitary pulmonary nodule at the left lower lobe of his lung being detected upon chest radiography. His sputum culture result came back positive, with conventional polymerase chain reaction (PCR) identifying Mycobacterium tuberculosis complex. However, tuberculosis antigen-specific interferon-gamma release assay came back negative. Considering a history of intravesical BCG treatment, multiplex PCR was conducted, revealing the strain to be Mycobacterium tuberculosis var. BCG. The patient was then treated with isoniazid, ethambutol, levofloxacin, and para-aminosalicylic acid following an antibiotic susceptibility test showing pyrazinamide resistance, after which the size of nodule gradually decreased. CONCLUSION: This case highlights the rare albeit potential radiographic presentation of Mycobacterium tuberculosis var. BCG, showing a solitary pulmonary nodule but not multiple granulomatous lesions, after intravesical BCG treatment. Differentiating Mycobacterium tuberculosis var. BCG from Mycobacterium tuberculosis var. tuberculosis is crucial to determine whether intravesical BCG treatment could be continued for patients with bladder cancer.

Pregnancy parturition scars in the preauricular area and the association with the total number of pregnancies and parturitions.

OBJECTIVES: The aim of the present study was to clarify the association between the degree of development of pregnancy parturition scars (PPSs) and the total number of pregnancies and parturitions (TNPPs) on the basis of new identification standards for PPS in the preauricular area. MATERIALS AND METHODS: Preauricular grooves were macroscopically observed on the pelves of 103 early modern males and 295 females (62 early modern females; 233 present-day females). Three categories of PPS in the preauricular area were defined. The association between the degree of development of PPS in the preauricular area and the TNPP was analyzed in 90 present-day females with detailed lifetime data. RESULTS: PPS could not estimate the exact TNPP. However, it was shown that no PPS indicated no TNPP, weak PPS indicated a lower TNPP, and developed PPS indicated a higher TNPP. DISCUSSION: Even though the possibility remains that some PPS indicate no TNPP, the results showed that the percentage of each PPS category indicated fertility in the population, suggesting that the strength of the association between the degree of development of PPS and the TNPP was affected by the classification system, the reliability of lifetime data, and the statistical methods used for analysis.

Antimicrobial susceptibility testing of Mycobacteroides (Mycobacterium) abscessus complex, Mycolicibacterium (Mycobacterium) fortuitum, and Mycobacteroides (Mycobacterium) chelonae.

The drug susceptibility of rapidly growing mycobacteria (RGM) varies among isolates. Treatment strategies similarly differ depending on the isolate, and for some, no clear strategy has been identified. This complicates clinical management of RGM. Following Clinical and Laboratory Standards Institute standard M24-A2, we assessed the susceptibility of 140 RGM isolates to 14 different antimicrobial drugs by measuring their minimal inhibitory concentrations (MICs). We also investigated the correlation of clarithromycin (CAM) MICs with the erm(41) and rrl gene mutations in the Mycobacteroides (Mycobacterium) abscessus complex, the rrl mutation in Mycobacteroides (Mycobacterium) chelonae, and the erm(39) mutation in Mycolicibacterium (Mycobacterium) fortuitum to determine the contribution of these mutations to CAM susceptibility. The five species and subspecies examined included 48 M. abscessus subsp. abscessus isolates (34.3%), 35 (25.0%) being M. abscessus subsp. massiliense, and two (1.4%) being M. abscessus subsp. bolletii. The M. abscessus complex accounted for 85 isolates (60.7%) in total, whereas 43 isolates (30.7%) were M. fortuitum, and 12 (8.6%) were M. chelonae. Our results demonstrated species-specific susceptibility to antimicrobials. In most cases, susceptibility to CAM could be predicted based on genetic pattern, but since one isolate did not fit that pattern, MIC values needed to be measured. Some isolates also exhibited rates of resistance to other drugs that differed from those previously reported in other locations, indicating that accurate identification of the bacterial isolate and use of the correct method for determining MIC are both important for the diagnosis of RGM.

A case of Mycobacterium tuberculosis laboratory cross-contamination.

SETTING: A laboratory cross-contamination event was suspected because Mycobacterium tuberculosis was unexpectedly detected at a high incidence in the cultures of several clinical specimens at the National Hospital Organization, Tokyo National Hospital, Japan. OBJECTIVE: To describe a case of Mycobacterium tuberculosis laboratory cross-contamination. DESIGN: We reviewed the medical records of 20 patients whose clinical specimens were suspected to have been contaminated by Mycobacterium tuberculosis. Variable number of tandem repeat analysis with 15 loci, the Japan Anti-Tuberculosis Association-12, and three additional hyper-variable loci, was performed to identify the cross-contamination event. RESULTS: The clinical, laboratory, and variable number of tandem repeat data revealed that the cross-contamination had possibly originated from one strongly positive specimen, resulting in false-positive results in 11 other specimens, including a case treated with anti-tuberculosis drugs. CONCLUSION: Clinical and laboratory data must be re-evaluated when cross-contamination is suspected and variable number of tandem repeat analysis should be used to confirm cross-contamination. Furthermore, original isolates should be stored appropriately, without sub-culturing and genotyping should be performed at the earliest possible for better utilization of variable number of tandem repeat for the identification of cross-contamination.

Prediction of Local Transmission of Mycobacterium tuberculosis Isolates of a Predominantly Beijing Lineage by Use of a Variable-Number Tandem-Repeat Typing Method Incorporating a Consensus Set of Hypervariable Loci.

Strain genotyping based on the variable-number tandem repeat (VNTR) is widely applied for identifying the transmission of Mycobacterium tuberculosis A consensus set of four hypervariable loci (1982, 3232, 3820, and 4120) has been proposed to improve the discrimination of Beijing lineage strains. Herein, we evaluated the utility of these four hypervariable loci for tracing local tuberculosis transmission in 981 cases over a 14-month period in Japan (2010 to 2011). We used six different VNTR systems, with or without the four hypervariable loci. Patient ages and weighted standard distances (a measure of the dispersion of genotype-clustered cases) were used as proxies for estimating local tuberculosis transmission. The highest levels of isolate discrimination were achieved with VNTR systems that incorporated the four hypervariable loci (i.e., the Japan Anti-Tuberculosis Association [JATA]18-VNTR, mycobacterial interspersed repetitive unit [MIRU]28-VNTR, and 24Beijing-VNTR). The clustering rates by JATA12-VNTR, MIRU15-VNTR, JATA15-VNTR, JATA18-VNTR, MIRU28-VNTR, and 24Beijing-VNTR systems were 52.2%, 51.0%, 39.0%, 24.1%, 23.1%, and 22.0%, respectively. As the discriminative power increased, the median weighted standard distances of the clusters tended to decrease (from 311 to 80 km, P < 0.001, Jonckheere-Terpstra trend test). Concurrently, the median ages of patients in the clusters tended to decrease (from 68 to 60 years, P < 0.001, Jonckheere-Terpstra trend test). These findings suggest that strain typing using the four hypervariable loci improves the prediction of active local tuberculosis transmission. The four-locus set can therefore contribute to the targeted control of tuberculosis in settings with high prevalence of Beijing lineage strains.

The prevalence and morphological types of non-carious cervical lesions (NCCL) in a contemporary sample of people.

Non-carious cervical lesions (NCCLs) were examined in 6541 extracted human teeth and classified based on the morphology of the lesions. As a result, NCCLs were found on 38.7% of teeth (41.6% on maxillary teeth and 36.0% on mandibular teeth), and were most frequent on canines and first premolars. According to the new method of classification, the morphology of NCCLs was classified both by the surface contour (SC) and by the cross-sectional contour (CC). Three types of NCCLs appeared to be dominant. The causes of these NCCLs were discussed based on their morphologies, positions where these NCCLs were frequently found, and the results of previous studies. NCCLs with a horizontal oval SC and a round CC (Type I), which were frequent on the labial surfaces of maxillary canines and buccal surfaces of maxillary first premolars, may be associated with wear by friction and chemical degradation. NCCLs with a vertical oval SC and a round CC (Type II), which were frequent on the lingual surfaces of mandibular incisors and canines, might be mainly related to chemical degradation. NCCLs with a horizontal oval SC and a wedge shape CC (Type III), which were extensively found on the buccal surfaces of maxillary premolars, had formed most probably due to wear by friction and microstructural loss by stress. This new method can classify the morphology of NCCLs more precisely and deduce the mechanisms of the formation of NCCLs more clearly than former methods.

[SPECIFICITY EVALUATION OF TRCReady® MTB AND TRCReady® MAC FOR IDENTIFYING MYCOBACTERIUM TUBERCULOSIS COMPLEX, MYCOBACTERIUM AVIUM AND MYCOBACTERIUM INTRACELLULARE].

[Objective] To evaluate the specificity of TRC- Ready® MTB and TRCReady® MAC (Tosoh Bioscience, Japan) for identifying M.tubercidosis complex (MTC), M.avium and M. intracellulare. [Method] We tested TRCReady® MTB and TRCReady® MAC using TRCReady®-80 (Tosoh Bioscience, Japan), which is an automated nucleic amplification test instrument, with 151 Mycobacterium species (4 MTC and 147 Non-tuberculosis Mycobacterium (NTM) type strains). [Results] The specificity of TRCReady® MTB was 100%, however, TkCReady® MAC misidentified a total of six NTMs, M.arosiense, M.chimaera, M.colombiense, M.marseillense, M. vulneris and M.yongonense, as M. intracellulare. Then, the specificity for TRCReady® MAC was 96.0% (145/151). [Discussion] TRCReady® MTB and TRCReady® MAC are highly specific for identifying MTC, M.avium and M. intracellulare. Six NTM species which have been rarely isolated in Japan showed false-positive results as M.intra- celludare. However, when a sample was identified as M.in- tracellulare, the phenotypic characteristics like colony mor- phology would be carefully examined.

[EXTERNAL QUALITY ASSESSMENT OF ANTI-TUBERCULOSIS DRUG SUSCEPTIBILITY TESTING FOR DIAGNOSING EXTENSIVELY DRUG-RESISTANT MYCOBACTERIUM TUBERCULOSIS].

[Objective] The infectious disease control law has been amended in May 2015, and the category definition of Mycobacterium tuberculosis as infectious pathogen has been changed, following the definition of extensively drug-resistant M.tuberculosis (XDR-TB) by World Health Organization. To assess the diagnostic capacity of XDR-TB, we conducted an external quality assessment (EQA) for the anti-tuberculosis drug susceptibility testing (DST). [Method] A total of 10 M.tuberculosis strains with known drug susceptibility were sent to each participating laboratory. The drugs assessed were isoniazid (INH), rifampicin (RFP), streptomycin (SM), ethambutol (EB), levofloxacin (LVFX), and kanamycin (KM). DST was performed using each routine method(s), and the results were compared with the judicial diagnoses. The sensitivity, specificity, overall agreement (effi- ciency) and kappa coefficient were calculated for each drug tested. In addition, the diagnostic accuracy of multidrug-resis- tant M. tuberculosis (MDR-TB) and XDR-TB was assessed. [Results] A total of 88 institutes including 67 hospitals, 16 commercial laboratories, and 5 public health laboratories par- ticipated in the EQA. With 2 laboratories submitting 2 sets of results, a total of 90 independent data sets were analyzed. As for INH, RFP and LVFX, the efficiency was over 95%, but we found two strains each for SM, EB and KM with the efficiency less than 95%. Especially, strain 1 and strain 2 showed efficiency of 72.2% and 71.1% to SM, respectively. This error was mainly found in a certain test kit. If we consider the passing score as showing ≥95 % sensitivity and specificity both to INH and RFP, the diagnostic accuracy of MDR-TB was 92.2% (83/90) in this study. With the same criteria to INH, RFP, LVFX and KM, that of XDR-TB was 79.7% (63/79). [Discussion] The diagnostic capacity of XDR-TB was not sufficient in the current study. Good case management and pathogen control requires higher accuracy. The government may need to conduct a constant EQA and relevant remedial actions.

In vitro effects of the new oral ß-lactamase inhibitor xeruborbactam in combination with oral ß-lactams against clinical Mycobacterium abscessus isolates.

Non-tuberculosis mycobacteria (NTM), particularly Mycobacterium abscessus subsp. abscessus (M. abscessus), are increasingly being recognized as etiological agents of NTM pulmonary disease. However, treatment options for M. abscessus are limited owing to their natural resistance to most antibiotics, including ß-lactams. M. abscessus produces a class A ß-lactamase, whose activity is inhibited by cyclic boronic acid ß-lactamase inhibitors. We aimed to evaluate the in vitro effects of xeruborbactam, a cyclic boronic acid ß-lactamase inhibitor, against M. abscessus when combined with five ß-lactams (amoxicillin, tebipenem, cefdinir, cefuroxime, and cefoxitin). The drug susceptibilities of 43 M. abscessus clinical isolates obtained from 43 patients between August 2005 and May 2014 were tested. The MIC results for each ß-lactam with or without 4 µg/mL xeruborbactam were examined. Xeruborbactam lowered the MIC90 values of tebipenem, amoxicillin, cefuroxime, and cefdinir by 5, ≥4, 3, and 3 dilutions, respectively. The MIC90 values of cefoxitin without xeruborbactam were 32 µg/mL and did not change upon the addition of xeruborbactam. The lowest MIC90 value was obtained for tebipenem with xeruborbactam. Almost all isolates had an MIC of 4 µg/mL; one isolate had an MIC of 2 µg/mL. With respect to the susceptibility to the same family drug, the number of susceptible isolates increased from 1/43 (2%) to 43/43 (100%) for tebipenem with xeruborbactam. Combining tebipenem and xeruborbactam could be considered an effective all-oral regimen that benefits outpatient treatment of M. abscessus pulmonary disease. IMPORTANCE: Mycobacterium abscessus subsp. abscessus (M. abscessus) disease is treated in two phases; injectable drugs for initial followed by others for continuation. There is a need to develop all-oral treatment methods for M. abscessus infection, especially in the continuation phase. However, treatment options for M. abscessus are limited owing to their natural resistance to most antibiotics. This is the first report to evaluate the in vitro effects of xeruborbactam, a cyclic boronic acid ß-lactamase inhibitor capable of inhibiting the class A ß-lactamase produced by M. abscessus, against 43 M. abscessus clinical isolates when combined with five ß-lactam antibiotics. Xeruborbactam lowered the MIC90 values of tebipenem by five dilutions, and the number of susceptible isolates increased from 1/43 (2%) to 43/43 (100%). We showed that the tebipenem-xeruborbactam combination might be of interest to explore further as a potentially effective oral regimen for outpatient treatment of M. abscessus pulmonary disease.

Vertebral Osteomyelitis Caused by Mycobacterium arupense Mimicking Tuberculous Spondylitis: First Reported Case and Literature Review.

Mycobacterium arupense is a slow-growing, nontuberculous mycobacterium widely found in the environment and is known to cause tenosynovitis and osteomyelitis, mainly in the hands and wrists. We present the first case of vertebral osteomyelitis caused by M arupense in a 78-year-old man with renal cell carcinoma. The patient had a history of tuberculous pleuritis in childhood. Although the nucleic acid amplification test of the vertebral tissue for Mycobacterium tuberculosis was negative, we initiated tuberculosis treatment based on the history and pathological findings of auramine-rhodamine-positive organisms and epithelioid cell granulomas. Subsequently, the isolated mycobacterium was identified as M arupense by genome sequencing. Accordingly, the treatment regimen was changed to a combination of clarithromycin, ethambutol, and rifabutin. Owing to a subsequent adverse event, rifabutin was switched to faropenem, and the patient was treated for a total of 1 year. In previous literature, we found 15 reported cases of bone and soft tissue infections caused by M arupense, but none of them had vertebral lesions. Physicians should be aware that M arupense can cause vertebral osteomyelitis mimicking tuberculous spondylitis. In addition, molecular testing of isolated mycobacteria is essential for diagnosis, even if tuberculous spondylitis is suspected.

Complete Genome Sequences of 14 Nontuberculous Mycobacteria Type Strains.

Here, we present the complete genome sequences of 14 nontuberculous mycobacteria type strains. The addition of type strain data may provide a concrete basis for further research.

Mandibular premolar identification system based on a deep learning model.

OBJECTIVES: For constructing an isolated tooth identification system using deep learning, Igarashi et al. (2021) began constructing a learning model as basic research to identify the left and right mandibular first and second premolars. These teeth were chosen for analysis because they are difficult to identify from one another. The learning method itself was proven appropriate but presented low accuracy. Therefore, further improvement in the learning data should increase the accuracy of the model. The study objectives were to modify the learning data and increase the learning model accuracy for enabling the identification of isolated lower premolars. METHODS: Static images of the occlusal surface of the premolars made from the dental plaster casts of dental students were used as the training, validation, and test data. A convolutional neural network with 32 hidden layers, AlexNet, convolutional architecture for fast feature embedding, and stochastic gradient descent was used to construct four learning models. RESULTS: The accuracy of the identification model increased using static images of the occlusal surface of the teeth with the adjacent teeth deleted as the training and validation data; however, a learning model that could perfectly identify the teeth could not be realized. CONCLUSIONS: Static images of the occlusal surface of the teeth with the adjacent teeth deleted should be used as both training and validation data. The ratio of the numbers of training, validation, and test data should be optimized.

In vitro activity of tedizolid and linezolid against multidrug-resistant Mycobacterium tuberculosis: a comparative study using microdilution broth assay and genomics.

The effects of tedizolid (TZD) against multidrug-resistant Mycobacterium tuberculosis isolates were investigated. This is possibly the first study to evaluate the MIC of TZD against Japanese Mycobacterium tuberculosis isolates. As TZD had a significantly lower MIC than LZD (P < 0.01), it was suggested to be a better, non-toxic alternative to LZD.

Clinical evaluation of the cobas® MTB-RIF/INH reagent and the cobas® 6800 for the detection of isoniazid and rifampicin resistance.

We aimed to validate the performance of a newly developed real-time PCR assay using cobas® MTB-RIF/INH reagent on the cobas® 6800 system for detecting isoniazid (INH) and rifampicin (RIF) resistance, using Japanese Mycobacterium tuberculosis (MTB) isolates. In total, 119 mock sputum specimens spiked with resistant MTB were tested using the cobas® MTB-RIF/INH reagent. The whole genomes of all MTB isolates were sequenced by MiSeq and analysed for mutations/indels causing drug resistance. All isolates were tested for phenotypic drug susceptibility, then MTB negative sputa were collected and pooled to prepare mock sputum specimens for the study. The sensitivity and specificity for INH resistance at a concentration equal to 3 × the limit of detection were 77.8% and 90.0%, respectively; those for RIF resistance were 91.8% and 93.5%, respectively. The sensitivities for INH and RIF were statistically different (P = 0.014), but not the specificities (P = 0.624). Twenty-two false-susceptible and two false-resistant results were obtained in INH; meanwhile, six false-susceptible and three false-resistant results were obtained in RIF. False-resistance for INH and RIF was mainly due to disputed mutations. The cobas® MTB-RIF/INH reagent showed better performance than other rapid molecular tests.

Development of a nucleic acid chromatography assay for the detection of commonly isolated rapidly growing mycobacteria.

Introduction. Non-tuberculosis mycobacterium infections are increasing worldwide, including those caused by rapidly growing mycobacteria (RGM).Gap Statement. The identification of the aetiological agent in the context of infections is essential for the adoption of an adequate therapeutic approach. However, the methods for the rapid distinction of different RGM species are less than optimal.Aim. To develop a nucleic acid chromatography kit to identify clinically common RGM.Methodology. We tried to develop a nucleic acid chromatography kit designed to detect four RGM species (including three subspecies) i.e. Mycobacterium abscessus subsp. abscessus, Mycobacterium abscessus subsp. bolletii (detected as M. abscessus/bolletii) Mycobacterium abscessus subsp. massiliense, Mycobacterium fortuitum, Mycobacterium chelonae and Mycobacterium peregrinum. The amplified target genes for each species/subspecies using multiplex PCR were analysed using a nucleic acid chromatography assay.Results. Among the 159 mycobacterial type strains and 70 RGM clinical isolates tested, the developed assay correctly identified all relevant RGM without any cross-reactivity or false-negatives. The limits of detection for each species were approximately 0.2 pg µl-1.Conclusion. The rapid and simple nucleic acid chromatography method developed here, which does not involve heat denaturation, may contribute to the rapid identification and treatment of RGM infections.

Efficacy estimation of a combination of triple antimicrobial agents against clinical isolates of Mycobacterium abscessus subsp. abscessus in vitro.

BACKGROUND: Mycobacterium abscessus subsp. abscessus (M. abscessus) is a rapidly growing mycobacterium that is resistant to most antibiotics. The number of patients with pulmonary disease caused by M. abscessus is increasing in several regions, and therapy involves long-term antibiotic combination treatments, although no standard treatment regimen has been established. OBJECTIVES: To examine candidate regimens for maintenance of antimicrobial treatment against M. abscessus by measuring MIC using the three-drug chequerboard method. METHODS: We evaluated the drug susceptibility of 70 clinical isolates of M. abscessus using the three-drug chequerboard method. We tested the antimycobacterial agents bedaquiline, clofazimine, amikacin, and sitafloxacin (which showed a relatively low MIC range when used as single agents) alone and in combinations. RESULTS: The three-drug combinations of bedaquiline/clofazimine/amikacin, and bedaquiline/clofazimine/sitafloxacin were studied. Among isolates for which the fractional inhibitory concentration index (FICI) could be calculated, 29/70 isolates (41%) and 11/70 isolates (16%) showed a synergistic response (FICI ≤0.75) with combined use of bedaquiline/clofazimine/amikacin, or with bedaquiline/clofazimine/sitafloxacin, respectively. CONCLUSIONS: The combination of bedaquiline with clofazimine plus either amikacin or sitafloxacin may be useful as maintenance regimens when treating pulmonary disease caused by M. abscessus.

Ultrasensitive enzyme-linked immunosorbent assay for the detection of MPT64 secretory antigen to evaluate Mycobacterium tuberculosis viability in sputum.

OBJECTIVES: This study examined Mycobacterium tuberculosis (MTB)-secreted MPT64 as a surrogate of bacterial viability for the diagnosis of active pulmonary TB (PTB) and for follow-up treatment. METHODS: In this proof-of-concept prospective study, 50 PTB patients in the Tokyo metropolitan region, between 2017 and 2018, were consecutively included and 30 healthy individuals were also included. Each PTB patient submitted sputum on days 0, 14 and 28 for diagnosis and follow-up, and each healthy individual submitted one sputum sample. The following were performed: smear microscopy, Xpert MTB/RIF, MGIT and solid culture, and MPT64 detection on the sputum samples. Ultrasensitive ELISA (usELISA) was used to detect MPT64. The receiver operating characteristic analyses for diagnosis and follow-up revealed the optimal cut-off value of MPT64 absorbance for detecting culture positivity at multiple intervals. RESULTS: The sensitivity of MPT64 for diagnosing PTB was 88.0% (95% CI 75.7-95.5) and the specificity was 96.7% (95% CI 82.8-99.9). The specificity of MPT64 for predicting negative culture results on day 14 was 89.5% (95% CI 66.9-98.7). The sensitivity of MPT64 for predicting positive culture results on day 28 was 81.0% (95% CI 58.1-94.6). CONCLUSIONS: This study revealed that MPT64 is useful for diagnosing active PTB in patients and predicting treatment efficacy at follow-up.