Single nucleotide polymorphism leads to daptomycin resistance causing amino acid substitution-T345I in MprF of clinically isolated MRSA strains

• Published in: PloS one Vol. 16; no. 1; p. e0245732
• Main Authors: Nakamura, Masaki, Kawada, Hayato, Uchida, Hiroki, Takagi, Yusuke, Obata, Shuichi, Eda, Ryotaro, Hanaki, Hideaki, Kitasato, Hidero
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22-01-2021; Public Library of Science (PLoS)
• Subjects: Acid resistance; Amino acid substitution; Amino acids; Antibiotics; Bacteria; Biology and life sciences; Cell surface; Cell walls; Clinical isolates; Cloning; Daptomycin; Deoxyribonucleic acid; Development and progression; Disease control; DNA; Drug resistance; Drug resistance in microorganisms; Drug therapy; Editing; Genes; Genetic aspects; Genomics; Graduate schools; Graduate studies; Gram-positive bacteria; Health aspects; Health sciences; Histology; Hospitals; Infections; Kinases; Life sciences; Low level; Medical research; Medicine and health sciences; Methicillin; Microbiology; Minimum inhibitory concentration; Mutation; Nucleotides; Physical Sciences; Plasmids; Point mutation; Polymorphism; Public health; Research facilities; Reviews; RNA polymerase; RpoB protein; Single nucleotide polymorphisms; Single-nucleotide polymorphism; Staphylococcus aureus; Staphylococcus aureus infections; Staphylococcus infections; Surface charge; Thickening; University graduates; Japan; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0245732

Daptomycin (DAP) is one of the most potent antibiotics used for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. Due to an increase in its administration for combating MRSA infections, DAP non-susceptible (DAP-NS) MRSA strains have recently been reported in clinical settings. The presence of single nucleotide polymorphisms (SNPs) in the multiple peptide resistance factor (mprF) gene is the most frequently reported cause for the evolution of DAP-NS MRSA strains; however, there are some variations of SNPs that could lead to DAP-NS. In this study, we used two clinical MRSA strains, including DAP susceptible (DAP-S) and DAP-NS, isolated from the same patient at different time points. We introduced T345I SNP to mprF of the DAP-S MRSA strain using the gene exchange method with pIMAY vector. Further, we investigated the phenotype of the mutant strain, including drug susceptibility, cell surface positive charge, and growth speed. The mutant strain exhibited (i) resistance to DAP, (ii) up-regulation of positive surface charge, (iii) slower growth speed, and (iv) thickened cell walls. Hence, the SNP in mprF may have caused an up-regulation in MprF function, with a subsequent increase in positive surface charge. Cumulatively, these results demonstrated that the T345I amino acid substitution in mprF represents one of the primary causes of DAP-NS in MRSA strains.