title: The sequence of pbp2b from penicillin-resistant Streptococcus pneumoniae in Thailand.
abstract: OBJECTIVE
  Penicillin resistance in Streptococcus pneumoniae isolates results from altered penicillin-binding proteins (PBPs), especially PBP2, which has a reduced affinity to penicillin. This study evaluated drug resistance and the gene sequence of the conserved motif pbp2b of penicillin-resistant isolates in Thailand.
  
  
  METHODS
  Penicillin-resistant pneumococci with minimum inhibitory concentrations (MIC) for penicillin > or = microg/ ml and penicillin-susceptible strains were identified from clinical specimens. The pbp2b genes were amplified by polymerase chain reaction (PCR), and the purified PCR product was cloned into E. coli. The recombinant plasmid clones containing pbp2b were sequenced and evaluated for mutations corresponding to penicillin and cefotaxime resistance.
  
  
  RESULTS
  Penicillin-susceptible S. pneumoniae isolates were susceptible to 12 other antibiotics tested (range 95-100%) while penicillin-nonsusceptible isolates were resistant to most antibiotics except amoxicillin/clavulanate and levofloxacin. Sequence analysis of pbp2b showed a substitution of A for T451 next to the region of the SSN triad in all six resistant isolates tested and mutations clustered around the KTG triad in two isolates. Using the ClustalW alignment program, Thai isolates differed from those of European countries, but were more similar to those from Japan than Korea.
  
  
  CONCLUSIONS
  Penicillin or cefotaxime resistance in S. pneumoniae in Thailand was due to affinity reduction of PBP2b, similar to changes found in other Asian isolates.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Chanwit
authors.initials: C
authors.lastname: Tribuddharat
authors.forename: Pitimon
authors.initials: P
authors.lastname: Polwichai
authors.forename: Preecha
authors.initials: P
authors.lastname: Champreeda
authors.forename: Somporn
authors.initials: S
authors.lastname: Srifuengfung
mesh_terms: D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002439:Cefotaxime / Q000494:pharmacology*; D005784:Gene Amplification; D005798:Genes, Bacterial / Q000187:drug effects; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D010403:Penicillin Resistance / Q000235:genetics*; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D010406:Penicillins / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D013785:Thailand
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D019881:Aminoacyltransferases; C478701:penicillin-binding protein 2b, Streptococcus; D002439:Cefotaxime