Molecular characteristics of pbp1a and pbp2b in clinical Streptococcus pneumoniae isolates in Quebec, Canada.
OBJECTIVE
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 beta-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.


CONCLUSIONS
This study will serve as a basis for future monitoring of genetic changes associated with the emergence and spread of beta-lactam resistance in Quebec, Canada.
Granger
Dominic
D
Laboratoire d'Immunogénétique, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame du CHUM, 1560 rue Sherbrooke est, Montréal, Québec, Canada.
Boily-Larouche
Geneviève
G
Turgeon
Pierre
P
Weiss
Karl
K
Roger
Michel
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020816:Amino Acid Motifs; D019881:Aminoacyltransferases / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002170:Canada / Q000453:epidemiology; D002675:Child, Preschool; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D010403:Penicillin Resistance / Q000235:genetics; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D010458:Peptidyl Transferases / Q000235:genetics*; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D020539:Sequence Analysis, Protein; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D046915:Penicillin-Binding Proteins; D019881:Aminoacyltransferases; C478701:penicillin-binding protein 2b, Streptococcus; C480727:PBP1a protein, Streptococcus pneumoniae; D010458:Peptidyl Transferases