Molecular epidemiology of Bordetella pertussis in Cambodia determined by direct genotyping of clinical specimens

• Published in: International journal of infectious diseases 2017-09, Vol.62 (C), p.56-58
• Main Authors: Moriuchi, Takumi, Vichit, Ork, Vutthikol, Yong, Hossain, Md. Shafiqul, Samnang, Chham, Toda, Kohei, Grabovac, Varja, Hiramatsu, Yukihiro, Otsuka, Nao, Shibayama, Keigo, Kamachi, Kazunari
• Format: Article
• Language: English
• Subjects: Alleles; Bordetella pertussis; Bordetella pertussis - genetics; Bordetella pertussis - pathogenicity; Cambodia; Cambodia - epidemiology; DNA, Bacterial; Genotype; Humans; Minisatellite Repeats; Molecular Epidemiology; Molecular Typing; multilocus variable-number tandem repeat analysis (MLVA); Pertussis Toxin - genetics; Pertussis Vaccine - immunology; Promoter Regions, Genetic; Sequence Analysis, DNA; virulence-associated allelic gene; Whooping Cough - epidemiology; Whooping Cough - microbiology
• ISSN: 1201-9712; 1878-3511
• DOI: 10.1016/j.ijid.2017.07.015

•Bordetella pertussis in Cambodia was characterized by direct sequencing and MLVA typing.•MT27 and MT29 were the predominant MLVA strain types in Cambodia.•The predominant profile of virulence-associated allelic genes was ptxP3/ptxA1/prn2/fim3A.•The B. pertussis population resembled those of developed countries. This study sought to determine the genotypes of circulating Bordetella pertussis, the causative agent of pertussis, in Cambodia by direct molecular typing of clinical specimens. DNA extracts from nasopharyngeal swabs obtained from 82 pertussis patients in 2008–2016 were analyzed by multilocus variable-number tandem repeat analysis (MLVA). B. pertussis virulence-associated allelic genes (ptxA, prn, and fim3) and the pertussis toxin promoter ptxP were also investigated by DNA sequence-based typing. Forty-four DNA extracts (54%) yielded a complete MLVA profile, and these were sorted into 8 MLVA types (MT18, MT26, MT27, MT29, MT43, MT72, MT95, and MT200). MT27 and MT29, which are common in developed countries, were the predominant strain types (total 73%). The predominant profile of virulence-associated allelic genes was the combination of ptxP3/ptxA1/prn2/fim3A (48%). MT27 strains were detected during the entire study period, whereas MT29 strains were only found in 2014–2016. The B. pertussis population in Cambodia, where a whole-cell pertussis vaccine (WCV) has been continuously used, resembled those observed previously in developed countries where acellular pertussis vaccines are used. Circulating B. pertussis strains in Cambodia were distinct from those in other countries using WCVs.