Serotypes of 'Pasteurella' anatipestifer isolates from poultry in different countries.

'Pasteurella' anatipestifer (PA) isolates from ducks, turkeys and other birds were typed by agglutination tests using antisera against representative strains of existing serotypes. The majority of the isolates were from the USA, but some were from Singapore, England and Germany. Five new serotypes were identified, three from ducks in the USA and two from Singapore. Four isolates received from Germany did not react with any of the available antisera. The representative strain of serotype 4 (H) was excluded from this study because it grew on MacConkey agar and has been reported to have a cell-protein profile unlike that of other PA isolates. A revised serotype classification was proposed to include existing and new serotypes.