title: Molecular epidemiology of Bordetella pertussis in the Philippines in 2012-2014.
abstract: OBJECTIVE
  The present study was designed to determine the genotypes of circulating Bordetella pertussis in the Philippines by direct molecular typing of clinical specimens.
  
  
  METHODS
  Nasopharyngeal swabs (NPSs) were collected from 50 children hospitalized with pertussis in three hospitals during 2012-2014. Multilocus variable-number tandem repeat analysis (MLVA) was performed on the DNA extracts from NPSs. B. pertussis virulence-associated allelic genes (ptxA, prn, and fim3) and the pertussis toxin promoter, ptxP, were also investigated by DNA sequence-based typing.
  
  
  RESULTS
  Twenty-six DNA extracts yielded a complete MLVA profile, which were sorted into 10 MLVA types. MLVA type 34 (MT34), which is rare in Australia, Europe, Japan, and the USA, was the predominant strain (50%). Seven MTs (MT29, MT32, MT33, and MT283-286, total 42%) were single-locus variants of MT34, while two (MT141 and MT287, total 8%) were double-locus variants of MT34. All MTs had the combination of virulence-associated allelic genes, ptxP1-ptxA1-prn1-fim3A.
  
  
  CONCLUSIONS
  The B. pertussis population in the Philippines comprises genetically related strains. These strains are markedly different from those found in patients from other countries where acellular pertussis vaccines are used. The differences in vaccine types between these other countries and the Philippines, where the whole-cell vaccine is still used, may select for distinct populations of B. pertussis.
authors: Research Institute for Tropical Medicine (RITM), Metro Manila, Philippines.
authors: Salvacion Rosario L
authors: SR
authors: Galit
authors: Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
authors: Nao
authors: N
authors: Otsuka
authors: Department of Virology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors: Yuki
authors: Y
authors: Furuse
authors: Research Institute for Tropical Medicine (RITM), Metro Manila, Philippines.
authors: Daryl Joy V
authors: DJ
authors: Almonia
authors: Research Institute for Tropical Medicine (RITM), Metro Manila, Philippines.
authors: Lydia T
authors: LT
authors: Sombrero
authors: Research Institute for Tropical Medicine (RITM), Metro Manila, Philippines.
authors: Rosario Z
authors: RZ
authors: Capeding
authors: Research Institute for Tropical Medicine (RITM), Metro Manila, Philippines.
authors: Socorro P
authors: SP
authors: Lupisan
authors: Department of Virology, Tohoku University Graduate School of Medicine, Miyagi, Japan; Tohoku-RITM Collaborating Research Center on Emerging and Reemerging Infectious Diseases, Metro Manila, Philippines.
authors: Mariko
authors: M
authors: Saito
authors: Department of Virology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors: Hitoshi
authors: H
authors: Oshitani
authors: Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
authors: Yukihiro
authors: Y
authors: Hiramatsu
authors: Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
authors: Keigo
authors: K
authors: Shibayama
authors: Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan. Electronic address: kamachi@nih.go.jp.
authors: Kazunari
authors: K
authors: Kamachi
mesh_terms: D001886:Bordetella pertussis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D002675:Child, Preschool; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D058889:Molecular Typing; D010679:Philippines / Q000453:epidemiology; D014917:Whooping Cough / Q000453:epidemiology* / Q000382:microbiology*
keywords: Bordetella pertussis; Genotype; Multilocus variable-number tandem repeat analysis; Philippines; Virulence-associated allelic gene