A total of 145 penicillin-nonsusceptible Streptococcus pneumoniae strains
were isolated from young carriers in Greece and analyzed by antibiotic
susceptibility testing, serotyping, restriction fragment end labeling
(RFEL), and penicillin-binding protein (PBP) genotyping. The serotypes 23A
and 23F (54%), 19A and 19F (25%), 9V (5%), 15A, 15B, and 15C (4%), 6A and
6B (4%), and 21 (4%) were most prevalent in this collection. Fifty-three
distinct RFEL types were identified. Sixteen different RFEL clusters,
harboring 2 to 32 strains each, accounted for 82% of all strains. Eight of
these genetic clusters representing 60% of the strains were previously
identified in other countries. A predominant lineage of 66 strains (46%)
harboring five RFEL types and the serotypes 19F and 23F was closely
related to the pandemic clone Spain(23F)-1 (genetic relatedness of > or
=85%). Another lineage, representing 11 strains, showed close genetic
relatedness to the pandemic clone France(9V)-3. Another lineage of 8
serotype 21 strains was Greece specific since the RFEL types were not
observed in an international collection of 193 genotypes from 16 different
countries. Characterization of the PBP genes pbp1a, pbp2b, and pbp2x
revealed 20 distinct PBP genotypes of which PBP type 1-1-1, initially
observed in the pandemic clones 23F and 9V, was predominantly present in
11 RFEL types in this Greek collection of penicillin-nonsusceptible
strains (55%). Sixteen PBP types covering 52 strains (36%) were Greece
specific. This study underlines the strong contribution of
penicillin-resistant international clones to the prevalence and spread of
penicillin-nonsusceptible pneumococci among young children in Greece