Insertion sequences shared by Bordetella species and implications for the biological diagnosis of pertussis syndrome

Department of Biochemistry and Microbiology, Institute of Chemical Technology, Technicka 5, 166 28, Prague 6, Czech Republic.
European Journal of Clinical Microbiology (Impact Factor: 2.67). 08/2012; 32(1). DOI: 10.1007/s10096-012-1718-3
Source: PubMed


The molecular diagnosis of pertussis and parapertussis syndromes is based on the detection of insertion sequences (IS) 481 and 1001, respectively. However, these IS are also detected in the genomes of various Bordetella species, such that they are not specific for either B. pertussis or B. parapertussis. Therefore, we screened the genome of recently circulating isolates of Bordetella species to compare the prevalence of IS481, IS1001 and, also IS1002 with previously published data and to sequence all IS detected. We also investigated whether the numbers of IS481 and IS1001 copies vary in recently circulating isolates of the different Bordetella species. We used the polymerase chain reaction (PCR) method for screening the genome of circulating isolates and to prepare the fragments for sequencing. We used Southern blotting and quantitative real-time PCR for quantification of the numbers of IS. We found no significant diversity in the sequences of the IS harboured in the genomes of the Bordetella isolates screened, except for a 71-nucleotide deletion from IS1002 in B. bronchiseptica. The IS copy numbers in the genome of recently circulating isolates were similar to those in reference strains. Our results confirm that biological diagnosis targeting the IS481 and IS1001 elements are not specific and detect the species B. pertussis, B. holmesii and B. bronchiseptica (IS481), and B. parapertussis and B. bronchiseptica (IS1001).

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    • "This 2-step diagnostic method is expected to be useful for samples that are positive for IS1001 or positive for IS481 and negative for ptxA-Pr and hIS1001, as it will confirm the presence of either B. parapertussis or B. bronchiseptica DNA (Table 3). However, cases of coinfection with B. parapertussis and B. bronchiseptica isolates not carrying IS in their genome or carrying IS1001 would be problematic (Tizolova et al., 2013): B. bronchiseptica would not be detected in the samples. However, no such case of co-infection has ever been reported. "
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