MLST typing of Pasteurella multocida associated with haemorrhagic septicaemia and development of a real-time PCR specific for haemorrhagic septicaemia associated isolates.

Two serovars of Pasteurella multocida, B:2 and E:2, have been reportedly associated with haemorrhagic septicaemia (HS), a peracute and devastating disease mainly affecting cattle and water buffaloes. We multilocus sequence typed (MLST) 64 isolates of P. multocida including 55 associated with HS and found that they mainly included sequence type (ST) 122 (n=50) and rarely ST63 (n=1), ST147 (n=2) and ST162 (n=2) compared to other members of the species isolated from other lesion types and hosts. Single-nucleotide polymorphisms suitable for specific detection of STs associated with HS were detected in the est gene. A new HS-est-RT-PCR (est indicating the target gene) specifically detected ST122, ST63, ST147 and ST162 associated with HS. The new HS-est-RT-PCR did not detect strains of ST151 with capsular type D isolated from pigs that were found positive with a previously published HS PCR detection method. The new HS-est-RT-PCR represents a fast and specific detection of the specific types of P. multocida involved in HS. The HS-est-RT-PCR developed in the current study seems to more accurately identify isolates of P. multocida associated with HS compared to PCR detection methods previously published.
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