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Mutation rate of avian intestinal coliform bacteria when pressured with fluoroquinolones
W M Medders1, R E Wooley, P S Gibbs
1Department of Medical Microbiology, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Abstract:
The purpose of this study was to determine the rate at which resistance developed in avian coliform bacteria when exposed to nalidixic acid, sarafloxacin, or enrofloxacin. In in vitro studies, the rates of mutation of avian isolates of Escherichia coli and Salmonella were determined following nalidixic acid, sarafloxacin, or enrofloxacin pressure. The rates of mutation were similar for nalidixic acid and sarafloxacin, whereas a lower rate of mutation was seen after enrofloxacin pressure. In in vivo studies, the quinolones were administered in the drinking water to broiler chickens at a concentration of 40 ppm for five consecutive days. Samples of feces were inoculated onto appropriate media and the frequency of resistance was determined. The frequency rates of resistance to nalidixic acid and sarafloxacin were similar. Enrofloxacin-medicated birds did not develop enrofloxacin-resistant coliform bacteria. The in vitro and in vivo data appear to correlate.
Insights
This study examined how quickly avian coliform bacteria developed resistance to nalidixic acid, sarafloxacin, and enrofloxacin. Enrofloxacin showed a lower mutation rate in vitro and no resistance in vivo, suggesting it may be more effective against these bacteria.
Area of Science:
- Veterinary Microbiology
- Antimicrobial Resistance
- Food Safety
Background:
- Antimicrobial resistance in avian coliforms is a growing concern in poultry production.
- Quinolone antibiotics like nalidixic acid, sarafloxacin, and enrofloxacin are used to treat bacterial infections in poultry.
- Understanding the development of resistance is crucial for effective treatment strategies.
Purpose of the Study:
- To determine the mutation rates of avian coliform bacteria (Escherichia coli and Salmonella) exposed to nalidixic acid, sarafloxacin, and enrofloxacin in vitro.
- To assess the frequency of resistance development in vivo after administering these quinolones to broiler chickens.
- To correlate in vitro mutation rates with in vivo resistance frequencies.
Main Methods:
- In vitro studies involved exposing avian isolates of Escherichia coli and Salmonella to nalidixic acid, sarafloxacin, or enrofloxacin to determine mutation rates.
- In vivo studies administered quinolones (40 ppm in drinking water for 5 days) to broiler chickens.
- Fecal samples from treated chickens were analyzed to determine the frequency of resistance to the tested antibiotics.
Main Results:
- In vitro mutation rates for nalidixic acid and sarafloxacin were similar, while enrofloxacin exhibited a lower mutation rate.
- In vivo studies showed similar resistance frequencies for nalidixic acid and sarafloxacin.
- Broiler chickens treated with enrofloxacin did not develop enrofloxacin-resistant coliform bacteria, and in vitro/in vivo data correlated.
Conclusions:
- Enrofloxacin appears to induce a lower rate of resistance development in avian coliforms compared to nalidixic acid and sarafloxacin.
- The in vitro findings align with in vivo observations, suggesting enrofloxacin may be a more favorable choice for controlling coliform infections in poultry.
- Further research is warranted to fully understand the implications of quinolone resistance in avian pathogens.