ABSTRACT
Objective:To evaluate the clinical value of NG-Test Carba5 for rapid detection of carbapenemases produced by carbapenem-resistant Enterobacteriaceae (CRE) strains. Methods:A total of 1 210 CRE strains were collected during 2018-2022 from 77 hospitals in 21 provinces of China and were subjected to NG-Test Carba5 for rapid detection of carbapenemase. The whole genome sequencing (WGS) analysis was referenced as the gold standard method.Results:Overall, the NG-Test Carba5 demonstrated excellent performance in detection of five kinds of carbapenemases [Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-β-lactamase (NDM), imipenemase metallo-β-lactamase (IMP), Verona integron-encoded metallo-beta-lactamase (VIM) and oxacillinase-48-type carbapenemases(OXA-48)] from CRE strains, with a sensitivity of 98.47% (1 161/1 179), specificity of 100% (31/31), and positive predictive value of 100% (1 161/1 161). The sensitivity for detection of NDM, IMP, OXA and VIM reached 100% (307/307), and 97.70% (763/781) for KPC. For 11 strains carrying blaKPC-25, blaKPC-78, or blaKPC-93, NG-Test Carba5 reported positive KPC detection (11/11). For strains carrying blaKPC-33 and blaKPC-77, however, NG-Test Carba5 delivered negative results. Additionally, for those strains co-producing two or three kinds of carbapenemases, NG-Test Carba5 was able to report all of the targets with a sensitivity of 100% (91/91). Conclusions:NG-Test Carba5 showed excellent performance in rapid and accurate detection of carbapenemases from CRE strains. Nonetheless, for those strains with negative results, some other phenotypic and genotypic methods should be implemented alongside to avoid missing targets.
ABSTRACT
Objective To investigate the mycobactericidal efficacy of linezolid on multidrugresistant tuberculosis (MDR-TB) and nontuberculous mycobacteria (NTM) in vitro.Methods Seven hundred and sixty-two Mycobacterium tuberculosis and 20 NTM isolates from Hangzhou were identified by using hsp65 gene sequencing from March to June,2013.Seventy MDR-TB isolates,which were screened by using proportion method,and twenty NTM isolates were tested the MIC to linezolid,and the differences of MICs to linezolid between MDR-TB and NTM werw analyzed in vitro.Results All 70 MDR-TB isolates were inhibited at concentrations of ≤ 1 mg/L by linezolid,MIC50 was 0.5 mg/L and MIC90 1 mg/L.Of all 8 isolates inhibited at concentration of 1 mg/L,there were 6 isolates resistant to isoniazid,rifampin,streptomycin and ethambutol,suggesting this resistance pattern may reduce sensitivity to linezolid.Among the NTM isolates,18 Mycobacterium intracellulare isolates,whose MICs to linezolid at 8-16 mg/L,were non-resistant isolates,while 2 Mycobacterium abscessus isolates displaying MICs ＞ 32 mg/L,were resistant to linezolid.Conclusions Linezolid showed great activity to MDR-TB and there were no linezolid-resistant MDR-TB isolates identified in this study.However,MICs of MDR-TB against linezolid increased with their resistant numbers to first-line agents.This study also showed that different NTM species have varied sensitivity to linezolid.