Mutation of TonB-Dependent Receptor Encoding Gene Potentially Associates with Macrolides Resistance in Isolates.

Introduction: , which is an opportunistic pathogen and is one of the three major pathogens of community-acquired pneumonia, causes a variety of infections in clinic. In recent years, the isolation rate of has gradually increased. In China, due to the clinical empirical use of antibiotics, the resistance rate of isolated from children to β-lactam antibiotics has reached 99%. The non-susceptible rate of to macrolide antibiotics has also increased significantly.

Methods: Two isolates of (R17123922_R and R18013231_R) were isolated from in-patients and were confirmed to be resistant to macrolide antibiotics using the standard disk diffusion and broth microdilution method recommended by CLSI. Whole-genome sequencing (WGS) analysis was performed in these two resistant strains.

Results: A total of 696 SNVs (single nucleotide variations), and 79 indels (Insertion and Deletion) were found in R17123922_R and R18013231_R. These SNVs and indels were distributed evenly in the genome, and no centralized distribution occurred. Moreover, two isolates did not harbor any previously reported mutations in the 23S rRNA and ribosomal proteins.

Conclusion: A novel indel in the gene encoding TonB-dependent receptor protein was identified, and we speculated that TonB-dependent protein receptor may play an important role in macrolide resistance of .