Relatedness of penicillin-binding protein 1a genes from different clones of penicillin-resistant Streptococcus pneumoniae isolated in South Africa and Spain.

Abstract

Penicillin‐resistant strains of Streptococcus pneumoniae have been common in South Africa and Spain for several years. Multilocus enzyme electrophoresis identified one clone of capsular type 6B which was prevalent in Spain and another clone of type 23F that was present in both countries. Genes for penicillin‐binding proteins (PBPs) in penicillin‐resistant strains are often mosaics where parts of the pneumococcal genes are replaced by homologous genes from other species. We have compared the mosaic structures of the PBP 1a genes from the two clones as well as from genetically distinct South African isolates. Four classes of mosaic PBP 1a genes were found that contained blocks of sequences divergent by 6–22% from those of sensitive genes; two classes contained sequences coming from more than one external source. Data are presented showing that the PBP 1a genes from the 23F and the 6B clone are related, and that the two PBP 1a genes from the South African isolates are also related. We suggest that the type 23F clone originated in Spain prior to distribution into other continents.

Functional Characterization of Penicillin-Binding Protein 1b fromStreptococcus pneumoniae

“…Low-affinity PBP variant genes conferring resistance are mostly acquired by homologous recombination and have a mosaic structure, in which parts of genes are replaced by equivalent parts from drug-resistant bacteria (7,19,22). PBP2b and PBP2x constitute the most-common resistance determinants, and they confer low-level resistance to piperacillin and cefotaxime, respectively (13).…”

Penicillin-Binding Protein 1A, 2B, and 2X Alterations in Canadian Isolates of Penicillin-Resistant Streptococcus pneumoniae

“…Pneumococcal resistance to penicillin is attributed to altered PBPs 1A, 2B, and 2X with reduced affinities for ␤-lactam antibiotics (4,13,15). The mosaic genes that encode these low-affinity variants are the product of interspecies recombinational events involving horizontal transfer of PBP genes from closely related species (6,15,17).…”

All Detectable High-Molecular-Mass Penicillin-Binding Proteins Are Modified in a High-Level β-Lactam-Resistant Clinical Isolate of Streptococcus mitis

“…A fragment of 0.8 kb could be obtained with primers 1AUp 786 (5Ј-CGGCATTCGATTTGAT TCGCTTCT-3Ј) (36) and 1A2Dw 1598 (5Ј-GGGTCATATTGGTTTGGTGC-3Ј) (37). Based on the known fragment sequence, the LA PCR cloning kit (Takara Shuzo Co., Kyoto, Japan) was used following the manufacturer's instructions.…”