Identification of twoNocardia farcinica strains isolated from clinic

Objectives To identify species of bacterium by gene sequencing technology so as to guide clinical treatment. Methods Two clinical strains 1520 and 4108 were inoculated on Lowenstein-Jensen medium separately, and the bacteria colonies were observed in logarithmic phase. DNA of the two colonies were extracted, which was used as template for amplification of their 16S rDNA gene by polymerase chain reaction (PCR). Then the amplification products were sequenced and the sequences were blasted on NCBI for the preliminary identification of strains. Results The two strains of No. 1520 and 4108 grew rapidly and formed small coarse granular with light yellow on the Lowenstein-Jensen medium, which was suspected as Nontuberculous Mycobacteria (NTM). The DNA homology of 16S rDNA genes of 1520 and 4108 compared with Nocardia farcinica were 99% respectively. Conclusions Strains of 1520 and 4108 isolated from two patients with pulmonary disease were Nocardia farcinicas, rather than suspected NTM, which provided strong evidence for clinic treatment. In the same time, DNA sequencing analysis is a fast, simple, and accurate way to identify strains of the species.