Journal Article

Molecular characteristics of <i>pbp1a</i> and <i>pbp2b</i> in clinical <i>Streptococcus pneumoniae</i> isolates in Quebec, Canada

Dominic Granger, Geneviève Boily-Larouche, Pierre Turgeon, Karl Weiss and Michel Roger

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 57, issue 1, pages 61-70
Published in print January 2006 | ISSN: 0305-7453
Published online November 2005 | e-ISSN: 1460-2091 | DOI:
Molecular characteristics of pbp1a and pbp2b in clinical Streptococcus pneumoniae isolates in Quebec, Canada

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Objectives: To investigate the nature of the amino acid motifs found in penicillin-binding protein (PBP) 2b and PBP1a of penicillin-resistant Streptococcus pneumoniae isolates across Quebec (Canada), and to obtain preliminary information regarding the prevalence of these alterations.

Methods: DNA sequences of pbp2b (codons 210–675) and pbp1a (codons 310–682) transpeptidase domains were determined and compared in 48 clinical isolates comprising 17 penicillin-susceptible (PSSP), 19 penicillin-intermediate (PISP) and 12 penicillin-resistant (PRSP) pneumococci.

Results: The degree of diversity within PBP1a and PBP2b correlated with increased resistance to β-lactam antibiotics. There were an average of 0.6 ± 0.4 and 2.9 ± 0.2 mutations in PSSP, 16.8 ± 1.4 and 36.3 ± 5.2 in PISP, and 18.7 ± 2.5 and 51.4 ± 1.3 in PRSP isolates compared with control penicillin-susceptible R6-PBP2b and R6-PBP1a sequences, respectively. At least seven PBP2b and six PBP1a distinct amino acid profiles were identified among intermediate or resistant strains isolated in Quebec. The pattern of distribution of the PBPs' altered amino acids differs from that of other countries, with pneumococci isolates from Quebec showing a unique genetic signature.

Conclusion: This study will serve as a basis for future monitoring of genetic changes associated with the emergence and spread of β-lactam resistance in Quebec, Canada.

Keywords: penicillin-binding proteins; β-lactams; pneumococci; serotypes; penicillin resistance; cefotaxime resistance

Journal Article.  4449 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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