EXTRACELLULAR NEURAMINIDASE PRODUCTION BY PASTEURELLA SPECIES ISOLATED FROM INFECTED ANIMALS

A total of 721 field isolates of various Pasteurella species (haemolyt ica, multocida, and testudinis) from various regions of the United Sta tes were examined for extracellular neuraminidase production. All stra ins were grown and tested in the same way. Included were 372 P. haemol ytica serotype 1 isolates, 181 P. haemolytica serotype 2 isolates, 63 P. haemolytica serotype 6 isolates, 101 Pasteurella multocida isolates , and 4 Pasteurella testudinis isolates. All Pasteurella species exami ned produced the enzyme. The data revealed the following: (1) Several transfers of P. haemolytica strains on blood agar medium did not cause a decrease in enzyme activity. (2) P. haemolytica serotypes 2 and 6 p roduce more neuraminidase than P. haemolytica serotype 1, P. multocida , and P. testudinis isolates. (3) There was no apparent change in neur aminidase production by P. haemolytica serotypes 1 and 2 obtained from the same animal taken on different days in the feedyard. (4) There wa s no significant change in neuraminidase production by P. haemolytica serotype 2 isolates taken from the same animal at the auction market a nd later at the feedyard.