Mutations within the rplD Gene of Linezolid-Nonsusceptible Streptococcus pneumoniae Strains Isolated in the United States

Abstract

Three invasive Streptococcus pneumoniae strains nonsusceptible to linezolid were isolated in the United States between 2001 and 2012 from the CDC's Active Bacterial Core surveillance. Linezolid binds ribosomal proteins where structural changes within its target site may confer resistance. Our study identified mutations and deletions near the linezolid binding pocket of two of these strains within the rplD gene, which encodes ribosomal protein L4. Mutations in the 23S rRNA alleles or the rplV gene were not detected.

FIG 1

Alignment of ribosomal protein L4 of linezolid-nonsusceptible isolates of S. pneumoniae and linezolid-susceptible strains. Mutations are shown in bold type. Dashes represent deletions, and identical sequences, in comparison to strain R6, are indicated by a straight line. Numbers underneath the specific amino acids (aa) represent the position in the R6 sequence.