Molecular epidemiology of Bordetella pertussis in the Philippines in 2012-2014.
OBJECTIVES
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.
['Galit|Salvacion Rosario L|SR|', 'Otsuka|Nao|N|', 'Furuse|Yuki|Y|', 'Almonia|Daryl Joy V|DJ|', 'Sombrero|Lydia T|LT|', 'Capeding|Rosario Z|RZ|', 'Lupisan|Socorro P|SP|', 'Saito|Mariko|M|', 'Oshitani|Hitoshi|H|', 'Hiramatsu|Yukihiro|Y|', 'Shibayama|Keigo|K|', 'Kamachi|Kazunari|K|', '|||']
D001886:Bordetella pertussis D002675:Child, Preschool D005838:Genotype D006801:Humans D007223:Infant D007231:Infant, Newborn D058889:Molecular Typing D010679:Philippines D014917:Whooping Cough
Bordetella pertussis Philippines Genotype Multilocus variable-number tandem repeat analysis Virulence-associated allelic gene