Comparison of DNA fingerprinting and serotyping for identification of avian Pasteurella multocida isolates

The DNA fingerprint profiles and serotypes of 63 avian Pasteurella multocida field isolates, 13 attenuated vaccine isolates (propagated from vaccines manufactured by five companies), and 16 somatic reference strains were compared. DNA fingerprinting established the relationship of isolates that could not be distinguished by serotyping. Of the 76 isolates, 28 DNA fingerprint profiles and 12 somatic types were recognized. One isolate was nonreactive with 16 reference somatic and 5 reference capsule-type antisera. Thirty-one field isolates and seven vaccine isolates were identified as capsule type A. Twenty-nine field isolates and six vaccine isolates were nonencapsulated. Three field isolates were capsule type F. Isolates of capsule types B, D, and E were not found. One field isolate, identified as somatic type 7, had a DNA fingerprint identical to that of the somatic reference type 6 profile. Twelve field isolates had profiles identical to the somatic reference type 3 strain profile; 11 of these were identified as somatic type 3, 4, and 1 was identified as somatic type 3. The DNA fingerprint profiles of 50 field isolates and 13 attenuated vaccine isolates did not match profiles of the 16 somatic type reference strains. Twenty-five DNA fingerprint profiles were recognized from 30 of these field isolates. The DNA fingerprint profiles of 20 field isolates and 13 attenuated vaccine isolates were identical. Three somatic types (3; 3,4; and 4,16) were identified from the field isolates, and two somatic types (3 and 3,4) were identified from the attenuated vaccine isolates. DNA fingerprinting is useful for accurate identification and epidemiologic study of P. multocida isolates.