Abstract: Sun Mingyan, Wu Qianqian, Wang Yexin, Wang Nan, Liu Yanxia, Tao Yuanyong Clinical Laboratory, Affiliated Hospital of Weifang Medical University, Shandong 261031, China （Sun MY, Wu QQ, Wang N, Liu YX, Tao YY）; Department of Joint Surgery, Affiliated Hospital of Weifang Medical University, Shandong 261031, China （Wang YX） Corresponding author: Tao Yuanyong, Email: taoyuanyong@163.com 【Abstract】 Objective To identify a clinical isolate of Mycobacterium abscessus. Methods A pus sample was collected from a patient with suspected nontuberculous mycobacterial infection who visited the Affiliated Hospital of Weifang Medical University on December 18, 2017, and was subjected to bacterial culture, Gram staining and acid-fast staining. Drug sensitivity test was conducted by the proportion method. The genome DNA of the strain was extracted and amplified by PCR with the universal primer of 16S rRNA. The PCR products were sequenced after collection and purification, and were compared with the known sequence of Mycobacterium abscessus in GenBank database. The isolate was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF MS）. Results The clinical isolate was identified as Mycobacterium abscessus both by MALDI-TOF MS and 16S rRNA gene sequencing. The drug sensitivity test showed that the strain was sensitive to amikacin, moxifloxacin, levofloxacin, but was resistant to streptomycin, isoniazid, rifampicin, ethambutol, ofloxacin, kanamycin, capreomycin, aminosalicylic acid, protionamide and rifabutin. The patient was diagnosed with subcutaneous soft tissue infection in the left knee joint. According to the results of drug sensitivity test, the patient was treated with amikacin and levofloxacin, and her condition was improved after treatment. Conclusion The 16S rRNA gene detection and MALDI-TOF MS both can be applied in the identification of Mycobacterium abscessus.

Key words: Nontuberculous mycobacteria, RNA, ribosomal, 16S, Spectrometry, mass, matrix?assisted laser desorption?ionization, Microbial sensitivity tests, Mycobacterium abscessus