Use of restriction endonuclease analysis and ribotyping to study epidemiology of Pasteurella multocida in closed swine herds
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G Zhao1, C Pijoan, M P Murtaugh
1Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul 55108.
Abstract:
One hundred and sixty-four clinical isolates of Pasteurella multocida recovered from two swine herds in Minnesota were characterized by restriction endonuclease analysis (REA) and rRNA gene restriction fragment length patterns. Bacterial DNA was digested with HpaII and electrophoresed in 0.55% agarose. Restriction fragments were transferred by Southern blot to nylon membranes and then hybridized with digoxigenin-dUTP-labeled Escherichia coli rRNA. Four different REA patterns were observed among the 156 serotype A strains isolated from herds A and B. The two most common REA types (1 and 2) represented 92% of the strains analyzed, while REA types 3 and 4 were observed only in lung samples and accounted for 8% of the isolates. Two different ribotypes were observed for these serotype A isolates. Ribotype I consisted of the most common types, 1 and 2, found by DNA fingerprinting. Ribotype II included REA types 3 and 4. Results from both herds suggest that in closed swine populations, a single strain of P. multocida predominates and causes disease. It is concluded that these genomic fingerprinting techniques were highly discriminatory and that capsular serotyping in combination with REA or ribotyping is an appropriate technique for epidemiological studies of P. multocida of swine origin.
Insights
Genomic fingerprinting identified a predominant Pasteurella multocida strain in swine herds. This technique, combined with serotyping, is effective for tracking swine bacterial infections.
Area of Science:
- Veterinary Microbiology
- Bacterial Genomics
- Swine Disease Epidemiology
Background:
- Pasteurella multocida is a significant pathogen in swine, causing respiratory diseases.
- Understanding the genetic diversity of P. multocida is crucial for effective disease control in swine herds.
Purpose of the Study:
- To genetically characterize Pasteurella multocida isolates from two Minnesota swine herds.
- To evaluate the discriminatory power of Restriction Endonuclease Analysis (REA) and rRNA gene restriction fragment length polymorphism (ribotyping) for epidemiological studies.
Main Methods:
- Bacterial DNA from 164 P. multocida isolates was analyzed using REA with HpaII digestion.
- Southern blot hybridization with labeled E. coli rRNA was performed for ribotyping.
- Isolates were also characterized by capsular serotyping.
Main Results:
- Four distinct REA patterns were identified among 156 serotype A isolates.
- Two common REA types (1 and 2) accounted for 92% of isolates; types 3 and 4 were less common (8%) and found in lung samples.
- Two ribotypes correlated with REA patterns, with Ribotype I matching common REA types and Ribotype II matching rarer types.
- Results indicated a predominant P. multocida strain within these closed swine populations.
Conclusions:
- Genomic fingerprinting techniques (REA and ribotyping) are highly discriminatory for P. multocida.
- Combining capsular serotyping with REA or ribotyping is a suitable approach for swine P. multocida epidemiological investigations.
- A single P. multocida strain appears to dominate and cause disease in closed swine populations.