Subtype I Is Associated With Clarithromycin Resistance in China.

is the second most common cause of slowly growing non-tuberculous mycobacteria diseases in China. The aim of the present study was to analyze subtypes isolated from patients in China, and to explore the antimicrobial susceptibility of the differentiation among these diverse subtypes. A total of 78 strains from 16 provinces of China were enrolled in this study. Amikacin (AMK) was the most highly active against strains, and only 4 isolates (5.1%) exhibited resistance to AMK. The percentage of levofloxacin (LFX) resistant strains among the 78 isolates was 39.7% (31/78), which was significantly higher than that of moxifloxacin (16.7%, = 0.001) and gatifloxacin (19.2%, = 0.005). By using PCR-restriction fragment analysis of the gene (PRA), all the isolates were classified as four different subtypes. Of these four subtypes, subtype I was the most frequent genotype in China, accounting for 71.8% (56/78) of isolates. Resistance to clarithromycin (CLA) was noted in 26.8% (15/56) of subtype I isolates, which was significant higher than that of other subtypes (4.5%, = 0.031). DNA sequencing revealed that the presence of mutations in 23S rRNA was associated with 56.2% (9/16) of CLA-resistant isolates. In conclusion, our data demonstrate that AMK is the most active agent against , while the high proportion of CLA resistance is noted in isolates. In addition, the predominant subtype I is associated with CLA resistance in China.