Genetic analysis of pbp2x in clinical Streptococcus pneumoniae isolates in Quebec, Canada

J Antimicrob Chemother. 2005 Jun;55(6):832-9. doi: 10.1093/jac/dki118. Epub 2005 May 4.


Objectives: To investigate the nature of the amino acid motifs found in penicillin-binding protein (PBP) 2x of penicillin-resistant Streptococcus pneumoniae isolates across the province of Quebec (Canada), and to obtain preliminary information regarding the prevalence of these alterations.

Methods: The pbp2x genomic region encompassing codons 178-703, which includes the entire region of the transpeptidase domain, was sequenced and compared for 52 clinical isolates comprising 20 penicillin-susceptible (PSSP), 20 penicillin-intermediate (PISP) and 12 penicillin-resistant (PRSP) pneumococci.

Results: The degree of diversity within PBP2x correlated with increased resistance to beta-lactam antibiotics. There were an average of 5.0 +/- 1.8 mutations in PSSP, 37.9 +/- 4.4 in PISP, and 63.0 +/- 2.0 in PRSP isolates when compared with the control penicillin-susceptible strain R6. At least six distinct amino acid profiles were identified among PISP strains isolated in Quebec. In contrast, all PRSP isolates shared a similar pattern of altered amino acids compared with the sequence from susceptible strains.

Conclusions: These data will be useful in future studies to monitor the genetic changes associated with the emergence and spread of beta-lactam resistance in Quebec.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Humans
  • Molecular Sequence Data
  • Penicillin-Binding Proteins / chemistry
  • Penicillin-Binding Proteins / genetics*
  • Streptococcus pneumoniae / drug effects
  • Streptococcus pneumoniae / genetics*
  • Structure-Activity Relationship
  • beta-Lactam Resistance


  • Penicillin-Binding Proteins
  • PBP 2x protein, Streptococcus