Detection of penicillin-binding protein 2b gene alteration in Streptococcus mitis by polymerase chain reaction.
Three isolates of beta-lactam-resistant streptococci from the saliva of healthy adults were identified as Streptococcus mitis. Minimum inhibitory concentrations (MICs) were 2 to 4 micro g/ml for ampicillin (ABPC) and 64 to more than 128 micro g/ml for cefaclor (CCL). To determine the position of base alterations of the penicillin-binding protein 2b ( pbp2b) gene, upstream primers containing possible mutation points were designed, and used for polymerase chain reaction (PCR), together with a downstream primer. Alterations adjacent to the conserved motifs of the pbp2b gene were apparent. DNA sequencing data indicated replacements in deduced amino acid sequences in all resistant isolates: from threonine to alanine just after the serine-serine-asparagine (SSN) motif, and from alanine to glycine two residues downstream of the lysine-threonine-glycine (KTG) motif. These changes were the same as those in penicillin-resistant Streptococcus pneumoniae (PRSP), suggesting importance for the enzymatic activity of the protein. Thus, Beta-lactam susceptibility of S. mitis may be partially predicted by PCR using our primer set for pbp2b.
Usui
Hiroyuki
H
Second Department of Oral and Maxillofacial Surgery, Tsurumi University School of Dental Medicine, Yokohama, Japan. usui-h@tsurumi-u.ac.jp
Takao
Ayuko
A
Nakayama
Ayako
A
Nagashima
Hiroyuki
H
Sasaki
Fumihiko
F
Maeda
Nobuko
N
Ishibashi
Katsunori
K
D019881:Aminoacyltransferases; D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D002433:Cefaclor / Q000494:pharmacology; D017931:DNA Primers; D005798:Genes, Bacterial / Q000235:genetics*; D006602:Hexosyltransferases / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics*; D009154:Mutation; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012463:Saliva / Q000382:microbiology; D034361:Streptococcus mitis / Q000187:drug effects / Q000235:genetics*; D018440:beta-Lactam Resistance
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D017931:DNA Primers; D046915:Penicillin-Binding Proteins; D002433:Cefaclor; D000667:Ampicillin; D019881:Aminoacyltransferases; C478701:penicillin-binding protein 2b, Streptococcus; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase