title: DNA-based culture-independent analysis detects the presence of group a streptococcus in throat samples from healthy adults in Japan.
abstract: Group A Streptococcus (GAS; Streptococcus pyogenes) causes a range of mild to severe infections in humans. It can also colonize healthy persons asymptomatically. Therefore, it is important to study GAS carriage in healthy populations, as carriage of it might lead to subsequent disease manifestation, clonal spread in the community, and/or diversification of the organism. Throat swab culture is the gold standard method for GAS detection. Advanced culture-independent methods provide rapid and efficient detection of microorganisms directly from clinical samples. We investigated the presence of GAS in throat swab samples from healthy adults in Japan using culture-dependent and culture-independent methods.
  
  
  
  Two throat swab samples were collected from 148 healthy volunteers. One was cultured on selective medium, while total DNA extracted from the other was polymerase chain reaction (PCR) amplified with two GAS-specific primer pairs: one was a newly designed 16S rRNA-specific primer pair, the other a previously described V-Na+-ATPase primer pair. Although only 5 (3.4 %) of the 148 samples were GAS-positive by the culture-dependent method, 146 (98.6 %) were positive for the presence of GAS DNA by the culture-independent method. To obtain serotype information by emm typing, we performed nested PCR using newly designed emm primers. We detected the four different emm types in 25 (16.9 %) samples, and these differed from the common emm types associated with GAS associated diseases in Japan. The different emm types detected in the healthy volunteers indicate that the presence of unique emm types might be associated with GAS carriage.
  
  
  
  Our results suggest that culture-independent methods should be considered for profiling GAS in the healthy hosts, with a view to obtaining better understanding of these organisms. The GAS-specific primers (16S rRNA and V-Na+-ATPase) used in this study can be used to estimate the maximum potential GAS carriage in people.
authors.affiliation: Department of Molecular Craniofacial Embryology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, 113-8510, Japan.|Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Tejaswini
authors.initials: T
authors.lastname: Kulkarni
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Aikawa
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nozawa
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Murase
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan. maruyama.fumito.5e@kyoto-u.ac.jp.
authors.forename: Fumito
authors.identifier: 0000-0003-2347-616X
authors.initials: F
authors.lastname: Maruyama
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Nakagawa
mesh_terms: D000328:Adult; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques / Q000379:methods; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis; D005838:Genotype; D006801:Humans; D007564:Japan; D008875:Middle Aged; D058889:Molecular Typing / Q000379:methods; D010614:Pharynx / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012703:Serotyping; D013290:Streptococcal Infections / Q000175:diagnosis / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000235:genetics* / Q000302:isolation & purification*; D055815:Young Adult
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: Asymptomatic carriage; Culture-independent detection; Emm-type; Group A Streptococcus; Species-specific primers