Detection of Pasteurella multocida-specific DNA in turkey flocks by use of the polymerase chain reaction.

A polymerase chain reaction (PCR)-based assay using primers constructed to amplify the gene (psl) encoding the P6-like protein (Psl) of Pasteurella multocida was developed. After Southern blotting and hybridization with psl, the assay (PCR-H) was found to be specific (it did not detect a variety of other avian bacterial pathogens) and sensitive (detected > or = 10 P. multocida organisms or > or = 24 femtograms of extracted P. multocida DNA). Samples were collected from the oropharynx of randomly selected birds housed on premises that had recently experienced an outbreak of avian cholera (outbreak farms) or from birds housed on premises that had not reported an outbreak of this disease during the preceding 12 mo (control farms). The PCR-H assay detected 11 infected turkeys out of a total of 178 sampled on six outbreak farms as compared with isolation of P. multocida from 23 turkeys by using mouse inoculation. Neither method detected P. multocida in samples collected from 174 turkeys sampled on six control farms. Statistical analysis using the Kappa test demonstrated that the results of the two tests showed poor agreement from five outbreak flocks (K = 0, 0, 0, 0.35, 0.47) and strong agreement from one outbreak flock (K = 0.89). Combined results from the outbreak flocks showed poor agreement (K = 0.49) between the two methods.