Partial characterization of R-plasmids from Pasteurella multocida isolated from turkeys

Area of Science:

• Veterinary Microbiology
• Molecular Biology
• Antimicrobial Resistance

Background:

• Fowl cholera, caused by Pasteurella multocida, is a significant disease in turkeys.
• Antimicrobial resistance in bacterial pathogens is a growing concern in animal agriculture.
• Extrachromosomal DNA elements like plasmids can carry resistance genes.

Purpose of the Study:

• To investigate the genetic basis of antimicrobial resistance in Pasteurella multocida isolated from a fowl cholera outbreak.
• To characterize the plasmids responsible for conferring resistance to specific antimicrobials.

Main Methods:

• Isolation and antimicrobial susceptibility testing of Pasteurella multocida.
• Agarose gel electrophoresis for DNA analysis.
• Plasmid DNA isolation using cesium chloride-ethidium bromide density centrifugation.
• Transformation of Escherichia coli with isolated plasmid DNA.
• Buoyant density and molecular weight determination of plasmids.
• Compatibility group testing.

Main Results:

• Pasteurella multocida isolates were resistant to tetracycline, streptomycin, and sulfonamides.
• Two plasmids were isolated and characterized.
• One plasmid (4.4 x 10^6 Da) conferred resistance to tetracycline, streptomycin, and sulfonamides.
• The second plasmid (3.44 x 10^6 Da) conferred resistance to streptomycin and sulfonamides.
• Streptomycin resistance was mediated by streptomycin phosphotransferase.
• Neither plasmid belonged to known conjugal plasmid compatibility groups.

Conclusions:

• Plasmids are responsible for the observed antimicrobial resistance in the outbreak strain of Pasteurella multocida.
• The characterized plasmids can transfer multiple drug resistance traits.
• Understanding plasmid-mediated resistance is crucial for managing fowl cholera and antimicrobial use in poultry.