An update on the MLST scheme for Pasteurella multocida

Pasteurella multocida is a cause of economically important diseases in almost all domestic livestock species, as well as wildlife. While a range of typing methods have traditionally been used, the development of a Multi-Locus Sequence Typing (MLST) scheme in 2010 represented the first standardised, sequence based, Web supported typing scheme. The initial scheme (termed the RIRDC MLST scheme) was based on 63 avian isolates from diseased Australian poultry and three international reference strains, which formed 29 Sequence Types (STs). The MLST database (http://pubmlst.org/pmultocida_rirdc/) now contains data from over 560 isolates that form 220 STs. The use of the scheme in published studies to date has demonstrated some key points: A) the highly clonal nature of haemorrhagic septicaemia (HS) isolates; B) bovine respiratory isolates are typically very distinct from HS isolates; C) evidence of host/niche association (i.e. some STs are associated with specific hosts); and D) the distinct genotype of P. multocida isolates of capsule type B from calf pleuritis and peritonitis cases in New Zealand. The continued use of this MLST scheme by research groups around the world will add to our understanding of the population structure and host associations of this major veterinary pathogen