title: Loop-mediated isothermal amplification method targeting the lytA gene for detection of Streptococcus pneumoniae.
abstract: It is difficult to separate Streptococcus pneumoniae from the genotypically similar species Streptococcus mitis and Streptococcus oralis, which are commensals of the human oral cavity. A novel nucleic acid amplification technique, loop-mediated isothermal amplification (LAMP), which amplifies DNA under isothermal conditions (63 degrees C) with high specificity, efficiency, and rapidity, was examined regarding its applicability for detecting S. pneumoniae. An S. pneumoniae-specific LAMP primer targeting the lytA gene was designed. The primer specificity was validated using 10 Streptococcus and 7 non-Streptococcus species. Within 60 min, the assay could detect 10 or more copies of purified S. pneumoniae DNA with a sensitivity 1,000 times that of conventional PCR. Clinical isolates of 21 other strains (3 S. oralis, 17 S. mitis, and 1 Streptococcus species) that harbor virulence-factor-encoding genes (lytA or ply) were tried to differentiate S. pneumoniae. The detection of S. pneumoniae in clinical isolates was more selective using the LAMP method than using conventional PCR. Therefore, LAMP appears to be a sensitive and reliable means of diagnosing S. pneumoniae infection.
authors.affiliation: Department of Oral Health Sciences, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan. seki-m@dent.nihon-u.ac.jp
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Seki
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Torigoe
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Tsuda
authors.forename: Setsuko
authors.initials: S
authors.lastname: Sato
authors.forename: Masao
authors.initials: M
authors.lastname: Maeno
mesh_terms: D015373:Bacterial Typing Techniques; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D017931:DNA Primers; D006801:Humans; D008969:Molecular Sequence Data; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000235:genetics*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D011008:Pneumococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D012680:Sensitivity and Specificity; D013045:Species Specificity; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D017931:DNA Primers; D009238:N-Acetylmuramoyl-L-alanine Amidase