Infection and Drug Resistance (Jul 2019)
Multiplex loop-mediated isothermal amplification (multi-LAMP) assay for rapid detection of mcr-1 to mcr-5 in colistin-resistant bacteria
Abstract
Lan-Lan Zhong,1,2,* Qian Zhou,3,* Cui-Yan Tan,3,* Adam P Roberts,4,5 Mohamed Abd El-Gawad El-Sayed Ahmed,1–2,6 Guanping Chen,1,2 Min Dai,7 Fan Yang,8 Yong Xia,9 Kang Liao,10 Yingjian Liang,3 Yongqiang Yang,1,11 Siyuan Feng,1,2 Xiaobin Zheng,3,* Guo-Bao Tian1,2,*1Program in Pathobiology, The Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-Sen University, Guangdong 519000, People’s Republic of China; 2Ministry of Education, Key Laboratory of Tropical Diseases Control, Sun Yat-sen University, Guangzhou 510080, People’s Republic of China; 3Department of Respiratory Medicine, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai 519000, People’s Republic of China; 4Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK; 5Centre for Drugs and Diagnostics, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; 6Department of Microbiology and Immunology, Faculty of Pharmaceutical Sciences and Drug Manufacturing, Misr University for Science and Technology (MUST), Cairo, Egypt; 7School of Laboratory Medicine, Chengdu Medical College, Chengdu 610500, People’s Republic of China; 8Department of Microbiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang 453003, People’s Republic of China; 9Department of Clinical Laboratory Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, People’s Republic of China; 10Department of Clinical Laboratory, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, People’s Republic of China; 11School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Guangzhou 510006, People’s Republic of China*These authors contributed equally to this workPurpose: The discovery of the plasmid-mediated colistin resistance genes, mcr, revealed a mechanism of transmission of colistin resistance, which is a major, global public health concern especially among individuals infected with carbapenem-resistant Gram-negative bacteria. To monitor the spread and epidemiology of mcr genes, a convenient and reliable method to detect mcr genes in clinical isolates is needed, especially in the primary care institutions. This study aimed to establish a restriction endonuclease-based multiplex loop-mediated isothermal amplification (multi-LAMP) assay to detect mcr genes (mcr-1 to mcr-5) harbored by colistin-resistant bacteria.Methods: A triple-LAMP assay for mcr-1, mcr-3, and mcr-4 and a double-LAMP assay for mcr-2 and mcr-5 were established. The sensitivity and specificity of the LAMP reactions were determined via electrophoresis and visual detection.Results: The sensitivity of the LAMP assay was 10-fold greater than that of PCR, with high specificity among the screened primers. Specific mcr genes were distinguished in accordance with band numbers and the fragment length of the digested LAMP amplification products. Furthermore, the LAMP assay was confirmed as a rapid and reliable diagnostic technique upon application for clinical samples, and the results were consistent with those of conventional PCR assay.Conclusion: The multi-LAMP assay is a potentially promising method to detect mcr genes and will, if implemented, help prevent infections by drug-resistant bacteria in primary-care hospitals due to rapid and reliable surveillance. To our knowledge, this is the first study to report the application of LAMP to detect mcr-2 to mcr-5 genes and the first time that multi-LAMP has been applied to detect mcr genes.Keywords: mcr genes, colistin resistance, multi-LAMP, rapid detection, enzyme digestion
