Making Responsible Antibiotic Choices

Veterinarians help farmers develop plans to avoid disease outbreaks utilizing vaccines and other types of prevention measures. However, pigs can still get sick; and at times, treating with antibiotics is necessary to help save their lives.

If an antibiotic is warranted, there are three steps Pipestone Veterinarians take to make a responsible antibiotic choice.

For example, a veterinarian recently visited a farm that was experiencing diarrhea, dehydration and mortality, classic symptoms of an E. coli infection. Here is the three-step approach they would use in determining which antibiotic to prescribe.

#1 Antibiotic Sensitivity Analysis
They start by submitting fecal samples to be cultured at a diagnostic lab for an Antibiotic Sensitivity Analysis. The lab runs an antibiotic panel on these specific bacteria to determine which antibiotics would be resistant (not effective) or sensitive (effective) against that bacteria. Below is an example of the report veterinarians receive back from the lab. For example, fecal samples cultured may show an E. coli isolate that is sensitive (effective) to Chlortetracycline, Enrofloxacin, Gentamicin, Neomycin, Oxytetracycline, and Trimethroprim/Sulphamethoxazole.

#2 Resistance Database Trends
Veterinarians also access a historical database that can show me isolate trends. A database of 1,600 E. coli isolates suggests that Oxytetracycline and Chlortetracycline would be poor treatment choices.

#3 Clinical Knowledge
Finally, Veterinarians refer to their clinical knowledge and field experience that would suggest that Enrofloxacin injection and oral Gentamycin, Neomycin, and Trimethoprim/Sulphamethoxazole would be effective choices.

After going through their three-step approach, there are several potentially good therapeutic options to treat this group of pigs. Afterword, the veterinarian followed up with the farmer, and recommended the pigs be treated with Gentamycin.

This approach allows the veterinarian to choose the best treatment option for the pig, while practicing antibiotic stewardship.

Tracking Antibiotic Resistance Over Time

Veterinarians use resistance data when selecting proper treatment for sick animals. But has antibiotic use in animals contributed to antimicrobials resistance (AMR) over time? To better understand, Pipestone veterinarians took clinical case submissions from the veterinary diagnostic labs of South Dakota State University, Iowa State University, and the University of Minnesota from 2002-2017. This totaled up to 4,163 total cases over 15 years!

Based on whether bacteria recovered from these cases were sensitive (antibiotics would work) or resistant (antibiotics would not work) to the antibiotics in the food animal antimicrobial testing panels across these three labs, a resistance index was calculated and plotted over the 15-year period. This novel approach to tracking antibiotic resistance from swine cases seems to indicate that despite the use of antimicrobials over a prolonged period of time, the overall level of resistance has not changed. Calculation of the index will continue as new cases are added to the database. Stay tuned as we continue to learn and share.