AUTHOR=Fan Zheng , Feng Yanling , Xu Wenjian , Feng Junxia , Yan Chao , Fu Tongtong , Zhao Hanqing , Cui Jinghua , Gan Lin , Liu Shiyu , Du Shuheng , Zhang Rui , Xu Ziying , Li Nannan , Xue Guanhua , Yuan Jing 

TITLE=Rapid Detection of Multi-Resistance Strains Carrying mcr-1 Gene Using Recombinase-Aided Amplification Directly on Clinical Samples

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.852488

DOI=10.3389/fmicb.2022.852488

ISSN=1664-302X

ABSTRACT=<p>With the increasingly severe problem of bacterial resistance, colistin, as the last line of defense, has attracted attention again. Mobile colistin resistance (<italic>mcr</italic>-1) gene is involved in the horizontal transmission of colistin resistance in Gram-negative bacteria (GNB), which is a serious threat to human health. Therefore, rapid detection of <italic>mcr</italic>-1 gene presence in clinical samples is crucial. In this study, a Recombinase-aided amplification(RAA) method for <italic>mcr</italic>-1 was successfully constructed, with sensitivity of 20 copies/reaction. In addition, amplification signal could only be detected in the strain containing <italic>mcr</italic>-1 gene among 14 different bacterial species. The method was then used to test a total of 672 clinical samples from a pediatric hospital in Beijing. Five strains harbored <italic>mcr</italic>-1 genes were isolated from <italic>mcr</italic>-1-positive clinical samples and identified as <italic>Escherichia coli</italic>. Multi-locus sequence typing (MLST) analysis showed that the five <italic>E. coli</italic> belonged to different ST types. Notably, the <italic>mcr</italic>-1 gene from the isolates could be transferred conjugately to the recipient strain <italic>E. coli</italic> J53, with highest transfer efficiency up to 57–58%, suggesting that the <italic>mcr</italic>-1 gene was located on the plasmid. These findings showed that the RAA assay has potential to be a rapid and sensitive <italic>mcr</italic>-1 gene screening test for clinical samples, and <italic>mcr</italic>-1 could be transmitted vertically and horizontally between and within bacterial species in a plasmid-mediated manner.</p>