In vitro assessment of 17 antimicrobial agents against clinical Mycobacterium avium complex isolates.

BACKGROUND: Recently, Mycobacterium avium complex (MAC) infections have been increasing, especially in immunocompromised and older adults. The rapid increase has triggered a global health concern due to limited therapeutic strategies and adverse effects caused by long-term medication. To provide more evidence for the treatment of MAC, we studied the in vitro inhibitory activities of 17 antimicrobial agents against clinical MAC isolates. RESULTS: A total of 111 clinical MAC isolates were enrolled in the study and they were identified as M. intracellulare, M. avium, M. marseillense, M. colombiense, M. yongonense, and two isolates could not be identified at the species level. MAC strains had relatively low (0-21.6%) resistance to clarithromycin, amikacin, bedaquiline, rifabutin, streptomycin, and clofazimine, and the resistant rates to isoniazid, rifampin, linezolid, doxycycline, and ethionamide were very high (72.1-100%). In addition, M. avium had a significantly higher resistance rate than that of M. intracellulare for ethambutol (92.3% vs 40.7%, P < 0.001), amikacin (15.4% vs 1.2%, P = 0.049), and cycloserine (69.2% vs 25.9%, P = 0.004). CONCLUSIONS: Our results supported the current usage of macrolides, rifabutin, and aminoglycosides in the regimens for MAC infection, and also demonstrated the low resistance rate against new drugs, such as clofazimine, tedizolid, and bedaquiline, suggesting the possible implementation of these drugs in MAC treatment.

Gene expression analysis reveals immune and metabolic candidate pathways in the pathogenesis of chronic otitis media.

OBJECTIVES: Chronic otitis media (COM) is a common disease and causes significant hearing impairment in many adults. Our study aimed to investigate the immune response in COM adult patients through RNA sequencing. METHODS: In this study, we enrolled four adult COM patients and five healthy controls (HCs) to analyze and compare the mRNA signatures in their peripheral blood mononuclear cells (PBMCs). Gene Ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed on the differentially expressed genes between the COM patients and the HCs. Furthermore, the immune cell proportions of the two groups were estimated by CIBERSORT. The GSE125532, GSE27990, and GSE23140 gene expression profiles were also retrieved and analyzed for comparison with our results. RESULTS: Many immune pathways and genes were upregulated in the COM patients, including the IL-17 pathway and NLRP3. Monocytes and macrophages increased (P=0.005 and P=0.033, respectively), and the CD8+ T cells decreased (P=0.033) in the COM patients compared to the HCs. The COM patients' signatures also reflected a hypoxic state. CONCLUSIONS: Our findings emphasized the roles of several immune pathways and a hypoxic state in interpreting host responses during COM, and may enable the development of novel therapeutic tools for the disease.

In vitro Susceptibility of Nontuberculous Mycobacteria to Tedizolid.

Objective: Nontuberculous mycobacteria (NTM) can cause pulmonary and extrapulmonary diseases. Tedizolid (TZD) is a new oxazolidinone with in vitro activity against NTM such as Mycobacterium avium complex (MAC), Mycobacterium fortuitum, and Mycobacterium abscessus complex. The aim of this study was to evaluate the TZD susceptibility profiles of clinical isolates of NTM. Methods: The microdilution method was used to identify the minimum inhibitory concentration (MIC) of TZD and linezolid (LZD) for 133 clinical NTM isolates. Broth microdilution chequerboard assays were used to investigate the synergistic effects of TZD and three antibiotics on two reference isolates and eleven clinical isolates of NTM. Results: The TZD MIC50 and MIC90 for M. abscessus complex were 2 and 4 µg/mL, 16 and >32 µg/mL for MAC, respectively. TZD exhibited lower MICs than that of LZD for most NTM, which were positively correlated. Due to the high MIC values of TZD against MAC, it is necessary to conduct drug sensitivity tests before TZD administration. TZD-clarithromycin combination had synergistic response on M. abscessus complex in 3 of the 8 isolates, which lasted only 3-5 days. TZD-cefoxitin had synergistic effect against all five M. fortuitum isolates. Conclusion: Our study demonstrates that TZD had greater in vitro potency than LZD, and synergy studies suggested that TZD may be an important component of multi-drug treatment regimen.

Establishment of a Risk Score Model for Early Prediction of Severe H1N1 Influenza.

H1N1 is the most common subtype of influenza virus circulating worldwide and can cause severe disease in some populations. Early prediction and intervention for patients who develop severe influenza will greatly reduce their mortality. In this study, we conducted a comprehensive analysis of 180 PBMC samples from three published datasets from the GEO DataSets. Differentially expressed gene (DEG) analysis and weighted correlation network analysis (WGCNA) were performed to provide candidate DEGs for model building. Functional enrichment and CIBERSORT analyses were also performed to evaluate the differences in composition and function of PBMCs between patients with severe and mild disease. Finally, a risk score model was built using lasso regression analysis, with six genes (CX3CR1, KLRD1, MMP8, PRTN3, RETN and SCD) involved. The model performed moderately in the early identification of patients that develop severe H1N1 disease.

Transcriptional signatures of human peripheral blood mononuclear cells can identify the risk of tuberculosis progression from latent infection among individuals with silicosis.

CLINICAL TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02430259).

Analysis of Serial Multidrug-Resistant Tuberculosis Strains Causing Treatment Failure and Within-Host Evolution by Whole-Genome Sequencing.

The cure rate of multidrug-resistant tuberculosis (MDR-TB) is relatively low in China. The reasons for the treatment failure and within-host evolution during treatment have not been sufficiently studied. All MDR-TB patients receiving standard treatment from January 2014 to September 2016 at a designated TB Hospital in Zhejiang Province were retrospectively included and grouped according to their known treatment outcome. Clinical information was collected. Baseline strains of all patients and serial strains of treatment-failure patients were revived. Drug susceptibility tests (DSTs) of 14 drugs and single nucleotide polymorphism (SNP) analysis based on whole-genome sequencing (WGS) were performed. The genetic distance and within-host evolution were investigated based on SNPs. In total, 20 treatment failure patients and 74 patients who succeeded in treatment were included. The number of effective drugs for patients who failed treatment was no more than three. Eighteen (90.0%) treatment-failure patients were characterized by a continuous infection of the primary strain, of which 14 patients (77.8%) developed phenotypic or genotypic acquired drug resistance under ineffective treatment. Acquired resistance to amikacin and moxifloxacin (2.0 mg/ml) was detected most frequently, in 5 and 4 patients, respectively. The insufficient number of effective drugs in the combined treatment regimen was the main reason for MDR-TB treatment failure. The study emphasizes the importance of DST for second-line drugs when implementing the second-line drug regimen in MDR-TB patients. For patients with risk factors for MDR-TB, DST of second-line antituberculosis drugs should be performed at initiation of treatment. Second-line drugs should be selected based on the results of DST to avoid acquired resistance. WGS detects low-frequency resistance mutations and heterogeneous resistance with high sensitivity, which is of great significance for guiding clinical treatment and preventing acquired resistance.IMPORTANCE Few studies have focused on the reasons for the low cure rate of multidrug-resistant tuberculosis in China and within-host evolution during treatment, which is of great significance for improving clinical treatment regimens. Acquired resistance events were common during the ineffective treatment, among which resistance to amikacin and high-level moxifloxacin were the most common. The main reason for the treatment failure of MDR-TB patients was insufficient effective drugs, which may lead to higher levels of drug resistance in MDR-TB strains. Therefore, the study emphasizes the importance of DST in the development of second-line treatment regimen when there is a risk of MDR. By performing whole-genome sequencing of serial strains from patients with treatment failure, we found that WGS can detect low-frequency resistance mutations and heterogeneous resistance with high sensitivity. It is thus recommended to conduct drug susceptibility tests at the beginning of treatment and repeat the DST when the sputum bacteria remain positive.

Corrigendum: Evaluation of Whole-Genome Sequence Method to Diagnose Resistance of 13 Anti-tuberculosis Drugs and Characterize Resistance Genes in Clinical Multi-Drug Resistance Mycobacterium tuberculosis Isolates From China.

[This corrects the article DOI: 10.3389/fmicb.2019.01741.].

Evaluation of Whole-Genome Sequence Method to Diagnose Resistance of 13 Anti-tuberculosis Drugs and Characterize Resistance Genes in Clinical Multi-Drug Resistance Mycobacterium tuberculosis Isolates From China.

Background: Whole-genome sequencing (WGS) is a viable and financially feasible tool for timely and comprehensive diagnosis of drug resistance in developed countries. With the increase in the incidence of multidrug-resistant tuberculosis (MDR-TB), second-line anti-TB drugs are gaining importance. However, genetic resistance to second-line anti-TB drugs based on WGS has not been fully studied. Methods: We randomly selected 100 MDR-TB and 10 non-MDR-TB isolates from a hospital in Zhejiang Province, China. Drug susceptibility tests against 13 anti-TB drugs were performed, and 34 drug resistance-related genes were analyzed using WGS in all isolates. For each drug, the accuracy, sensitivity, specificity, and positive and negative predictive values of WGS were compared with those of the conventional drug susceptibility test. Results: The overall sensitivity and specificity for WGS were respectively, 99.0 and 100.0% for isoniazid (INH), 99.0 and 100.0% for rifampicin (RIF), 94.8 and 65.3% for ethambutol (EMB), 86.2 and 84.4% for pyrazinamide (PZA), 95.6 and 95.6% for levofloxacin (LFX), 89.5 and 65.3% for moxifloxacin (MFX), 91.3 and 95.1% for streptomycin (SM), 90.9 and 99.0% for kanamycin, 90.9 and 100.0% for amikacin, 88.9 and 98.0% for capreomycin, 87.0 and 85.1% for prothionamide (PTO), 85.7 and 99.0% for para-aminosalicylic acid (PAS), and 66.7 and 95.9% for clofazimine (CLO). Conclusions: WGS is a promising approach to predict resistance to INH, RIF, PZA, LFX, SM, second-line injectable drugs (SLIDs), and PTO with satisfactory accuracy, sensitivity, and specificity of over 85.0%. The specificity of WGS in diagnosing resistance to EMB, and high-level resistance to MFX (2.0 mg/L) needs to be improved.