Characterization of Mycobacterium massiliense clinical strains: R49R and R49S

• Main Authors: Yu-Ting Cheng, 鄭榆婷
• Other Authors: Shiau-Ting Hu
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/78432702014323900161

碩士 === 國立陽明大學 === 微生物及免疫學研究所 === 102 === Mycobacterium abscessus complex belongs to the rapidly growing mycobacteria, which is resistant to most antibiotics and causes wide spectrum of infections. This complex recently been classified into three subspecies, M. abscessus sensu stricto, M. massiliense and M. bolletti based on the sequence of rpoB. Previous studies indicated that M. abscessus can spontaneously switch morphotype between rough and smooth forms, which are considered to be associated to glycopepetidolipid (GPL) expression and different morphologies that may affect bacteria virulence in human. In our study, clinically isolated M. massiliense from the same patient contained rough and smooth forms, named R49R and R49S, respectively, that had highly similar restriction enzyme digestion patterns. We found that R49R attached intensively to the surface of the plastic tube compared to other strains and had strong aggregation ability and lacked sliding ability. The GPL contents of R49S were significantly higher than that of R49R, but the sequences of GPL-locus genes are identical. Whole genome sequences analysis and comparison showed a 54-kb deletion within R49R genome. The 54-kb region of difference between R49R and R49S (R49-RD) is flanked with 19-mer direct repeats and comprises of 58 open reading frames (ORFs) with predicted functions including lipid biosynthesis/metabolism, transcriptional regulators and recombinase. Whether the deletion of R49-RD resulted from natural recombination and causing morphotype switch remains to be studied.