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THE EFFECT OF A DOG'S AGE ON THE AMOUNT OF ORAL PENICILLIN RESISTANT BACTERIA

Abstract

The objective of this study was to investigate the impact of a dog’s age on the number of penicillin resistant bacteria in the dog’s mouths. Studies have shown that bacteria easily transfer from dogs to owners, therefore these penicillin resistant bacteria could transfer to the owner, causing disease. The mouths of three older dogs (four years and older), three middle-aged dogs (between 1 and 4 years old), and three puppies (less than one year old), were swabbed twice each. The swab was placed in 5 ml of sterile phosphate-buffered saline and then plated on Brain heart infusion plates with or without 100 ug/ml penicillin. Colonies were grown overnight at 37 degrees Celsius and then counted. Colony PCR was used to amplify a subset of bacterial rRNA genes, and the DNA was sequenced to identify species of bacteria. All dogs tested had penicillin resistant bacteria in their mouths. Middle aged dogs had the least penicillin-resistant bacteria with a mean of 29.556 colonies, which was significantly different than the number of penicillin-resistant bacteria (60.944) in the older dogs (p < 0.0003). The puppies had the most penicillin-resistant bacteria with a mean of 84.0 colonies. Middle aged dogs also had the least amount of total bacteria with a mean of 268.56 colonies and the puppies had the most with a mean of 564.56 colonies (p < 0.001). There were significantly less penicillin resistant bacteria than total bacteria in the mouths of all dogs (p < 0.001 for puppies and older dogs, p < 0.05 for middle aged dogs). Middle aged dogs may be healthier than both puppies and older dogs because puppies may be exposed to more bacteria and have less developed immune responses. Older dogs have likely been exposed to antibiotics over their lifetimes, allowing the evolution of resistant bacteria in their mouth.

Acknowledgements

YHC Undergraduate Research initiative

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