Genetic analysis of serotype 23F Streptococcus pneumoniae isolates from several countries by penicillin-binding protein gene fingerprinting and pulsed-field gel electrophoresis

We characterized 21 strains of serotype 23F Streptococcus pneumoniae isolat ed in various countries with various levels of penicillin susceptibility by penicillin-binding protein (PBP) gene fingerprinting and pulsed-field gel electrophoresis (PFGE). Pneumococci isolated in Israel, Hungary, Bulgaria, Slovakia, Rumania, France, the United States, Spain and Japan were included . These strains were classified into 12 and 18 groups by PBP gene fingerpri nting and PFGE, respectively. Some of the pneumococci isolated in Spain, th e United States and France appeared to be genetically related by PFGE, show ed the same PBP gene pattern and had similar antimicrobial susceptibility p atterns. One penicillin-susceptible Bulgarian strain, with a similar PFGE p attern but a different fingerprinting pattern, may be an ancestral recipien t strain that became transformed into the resistant variants. Rumanian and Israeli strains were also genetically related by PFGE. These results indica te the existence of widely spread but related pneumococci in the world. PBP 2X gene profiles of pneumococci with MICs of 0.25 mu g/ml were different f rom each other and from penicillin-susceptible pneumococci (PSP). PBP 2B ge ne profiles of these resistant strains were identical. PBP 2B gene profiles of pneumococci (penicillin MICs greater than or equal to 0.5 mu g/ml) were different from PSP. PBP gene profiles may not only be useful for genetic a nalysis but also for presumed penicillin susceptibility.