ABSTRACT
ObjectiveTo determine the distribution of various antibiotic resistance genes （ARGs） in raw water from drinking water source， and to explore the correlation between the ARGs and common carbapenem-resistant and multidrug-resistant bacteria isolated from drinking water source， so as to provide scientific evidence for improving the safety of urban drinking water. MethodsA total of 30 raw water samples were collected from a major drinking water source in Shanghai in 2020. Bacterial strains were selectively cultured on Columbia blood agar medium containing 1 μg·μL-1 meropenem， and then identified by MALDI-TOF-MS mass spectrometry system. Minimum inhibitory concentration （MIC） of the strains was detected by broth microdilution method. The water samples were filtered through a 0.45 μm filter membrane and diversity of ARGs was determined by using high-throughput metagenomic sequencing. ResultsA total of 64 strains of carbapenem-resistant bacteria were isolated from the water samples， including Stenotrophomonas maltophilia， Enterococcus faecium， Pseudomonas aeruginosa， Acinetobacter baumannii and Klebsiella pneumoniae， which were resistant to a variety of common antibiotics. Using metagenomic sequencing，1 244 ARGs were identified. The relative average abundance of the top 100 ARGs accounted for 96.1%， and that of the multidrug-resistant ARGs accounted for 63.41%. Furthermore， the multidrug-resistant ARGs were mainly adeJ， mexT， adeC， oprM， mexF， mdfA， mexB， mdtK， adeK， etc. Using Spearman's correlation， five multidrug-resistant bacteria isolated from the drinking water source were significantly associated with the ARGs. ConclusionRelative abundance of multidrug-resistant ARGs is high in raw water from main drinking water source. The five isolated carbapenem-resistant and multidrug-resistant bacteria are significantly correlated with the ARGs. It warrants strengthening the rational and standardized application of antibiotics to protect water resources and ensure the safety of drinking water.
ABSTRACT
The purpose of this study was to observe whether human peripheral dervied monouncleas cells (hMNCs) could participate in the regeneration process of the ischemic hearts in the way of differentiating into cardiomyocytes, vascular endothelial cells and smooth muscle cells. hMNCs were transplanted into the bodies of the mice with myocardial infarction through the tail vein injection. Hearts were harvested 2-12 weeks after injection then sliced up into frozen sections of 5 micron thickness. Double immunofluorescence staining was used to test the differentiation of the grafted cells into cardiomyocytes, smooth muscle cells and vascular endothelial cells which revealed that cells expressing both HLA and TNT, HLA and alpha-SMA, HLA and vWF existed in the hearts of the mice. According to the study, it is probable that hMNCs could participate in the regeneration process of the infarcted hearts in the way of differentiation.