Penicillin susceptibility of non-serotypeable Streptococcus pneumoniae from ophthalmic specimens

Nontypeable (NT) Streptococcus pneumoniae strains isolated from eyes were examined for both penicillin susceptibility by E-test and penicillin-binding protein (PBP) gene alterations using PCR. Of the 25 ophthalmic isolates, 15 proved to be sensitive (PSSP, MIC≦ 0.06 μg/ml) and 10 were shown as intermediately resistant to penicillin (PISP, MIC = 0.1-1 μg/ml). No penicillin-resistant S. pneumoniae (PRSP, MIC≧ 2 μg/ml) were found. PBP gene (pbp1a and pbp2b) alteration PCR indicated that 12 (80.0%) of the 15 ophthalmic PSSPs had unaltered pbp genes and that 3 (20.0%) had alterations in either pbp1a or pbp2b, whereas 8 (80.0%) of the 10 PISPs had unaltered pbp genes and 2 (20.0%) had alterations in both pbp1a and pbp2b. These data suggest that penicillin resistance is spread among NT pneumococci typically associated with ophthalmic infections.